Why Anti Dive?

Conceptually, Anti Dive is not really a difficult geometric program to understand. Engineers find a way to overcomplicate what is simple. Hey, we need engineers, but our chassis builders build in only so much adjustment for Anti Dive so we really can’t get in too much trouble if we have a basic understanding of the mechanics involved. On a stock car, that has upper A-Arms and lower control arms (like the cars that you see in this magazine), it pays to simplify Anti Dive to the point of practicality. On a stock car, we can only take the adjustment to certain limitations so we can focus within the relative boundaries that a typical stock car situation presents.

Your car brand of car has the Anti Dive pre-set to match the philosophy of your chassis builder Still, all car builders give you a multitude of adjustments. With care, adjusting Anti Dive can be the fine tuning tool that helps you overcome a chassis problem, which in turn starts a positive domino effect that results in more speed.

Before you start playing around with Anti Dive as an adjustment, it does help if you know what it is? Randomly moving things falls in the luck category. While random adjustments are less than desirable, over thinking is equally as dangerous. Your car is built with limitations so the Anti Dive adjustments that fall in the practical category are pretty easy. Unless you get out a cutting torch – you can adjust way as if you are moving the panhard bar up and down. Just do it – and then undo it if the driver doesn’t like it. Keep it simple certainly applies.

So just what is Anti Dive? From the side view of your front suspension you have pivot points for the upper A-Arm and pivot points for the lower control arm. These pivots and their relative location to each other create Anti Dive. Anti Dive can be different on the LF and the RF. Manipulating Anti Dive differential at the LF and RF can be an adjustment that you can use to your advantage. Anti Dive is the common term, but we can use Pro Dive as part of the adjustment option set?

To visualize, have a look at your right front suspension. In general, the upper A-Arm pivots are parallel to the frame. If you look at the connection points at the bottom and visualize those as parallel to the frame you have zero Anti Dive. Now, maintain the visual of the bottom pivots being parallel to the frame – then move the back of the RF Arm down ½”. You just put Anti Dive in the Car. In this example, if you were to lower the front of the RF A-Arm pivot, from parallel, you would put Pro-Dive into the suspension. The same holds true on the Left side.

In this photo you can see that the RF A-Arm is nearly parallel to the frame. If you look at the lower pivot points they are parallel as well. Raising the front of the RF A-Arm, so that the front pivot is higher off the frame (ground) than the rear pivot, creates a an A-Arm arrangement that is identified as Anti Dive.

So, lowering the back of your A-Arms puts Anti Dive in the car – it’s an easy adjustment that you can make right at the track. You can adjust Anti Dive with the lower control arms, but for this article we are focusing on the upper A-Arms so that the concept is the focus. Hopefully, concentrating on the upper A-Arms reduces confusion in our quest to promote a new possibility. The goal is to get you to think out the information so you can see if you want to add adjusting the Anti dive to your adjustment arsenal this week.

This view again shows the A-Arm parallel to the frame, which creates zero percent Anti Dive. you can adjust the Anti Dive with the lower pivots, but for this article we are focusing on the Upper A-Arms so that proving the concept is the focus. The concept is simple, but by taking the lower points out of the equation, for now, confusion is reduced and your understanding of Anti Dive will allow you to understand the adjustment. Once the engineering is understood - you will find that using the lowers to adjust Anti Dive has a dramatic affect and a little goes a long way. The Billet Nut Plate is a cool option that keeps your hands away from hot headers.

If the Upper pivots are parallel to the frame and the lower pivots are parallel to the frame then you have zero percent Anti Dive. You can adjust until you have 100% Anti dive and when the brakes are applied the front end will effectively be locked up and the suspension will not drop at all. The Anti Dive will carry the weight of the car based on the transfer from the rear coupled with the weight transfer affiliation of the Center of Gravity of the car – so there is the science. How about we just slap in some slugs and remove the complicated engineering speak?

Using A-Arm frame mounts with slots allows for the use of slugs making track side adjustments quick and easy. Slugs allow you to make adjustments in 1/8” (or smaller) increments and the solid mount ensures you can repeat adjustments with easy documentation. You can make a change and if the driver likes it then great – if not, a quick slug replacement gets you right back to your baseline. You can save the heavy math and engineering for when you have graph paper and a lot of time at the shop. At the track – simply slap in a slug to make a 1/8” to ½” adjustment at the upper A-Arm pivot and you have plenty of adjustment for Anti Dive or Pro Dive right at the track. You can make the change in 5 minutes and the slug system gives you hardware that is recordable and repeatable. Good science always comes with repeatability.

If you look closely, you will see a slug at the rear pivot of the Upper A-arm. The slug raises the back of the A-Arm as the offset is larger than the front. The slug combination raises the back of the A-Arm and this angle creates Pro Dive. A simple slug adjustment allows you to quickly change the amount of Pro or Anti Dive right at the track. Typically, slugs are made in 1/8" increments so you can run Pro Dive as shown in the photo to help set your car into the turns. The slugs give you a solid mounting system that is secure and recordable.

Now that you see how easy it is to move the A-Arm mounting slug hardware – why should you run Anti Dive? Or, why run Pro Dive? When it comes to racecar suspensions, everything is about timing. Anti Dive is creates mechanical resistance under braking. The percentage of Anti Dive can be drawn out on paper easily in the shop - at the track just toss in the different slugs to accomplish your goals. Under braking, Anti Dive resists the dropping movement at the front end under braking. With the mechanical resistance created by running Anti Dive, you can potentially run softer springs and the Anti Dive will carry you through the braking zone. When you get to the middle and lift off the brakes, the soft springs can allow the car to roll or drop as Anti-Dive is reduced to nearly zero when you are not loading the suspension with brake torque. Remember, the Anti Dive resistance occurs under braking so a bumpy track can potentially cause trouble – Anti Dive works best on smooth tracks.  Well, I think it works best on smooth tracks and you will find that crew chiefs have varying opinions on this issue.

To help with the mental picture – if you have your RF A-Arm parallel to the frame, then the A-Arm is free to move up and down without any friction or mechanical resistance. If you were to exaggerate the adjustment and place the A-Arm so that the pivots were 90 degrees to the frame, instead of parallel, then you can see the suspension would be locked and could not move. Since practicality only lets us move the A-Arm pivot about ½” up or down, in comparison to the other mounting hole on your A-Arm, you can see that the braking force resists movement based on the amount of adjustment that your slotted A-Arm ear allows for. Again, you can get more adjustment on the bottom if you need it, but we are focused on the top for simplicity of proving the concept.

Running a slotted A-Arm frame ear on your car allows you to use pre-measured slugs that mate perfectly  for a secure mounting system. Slugs that are engraved with the offset give you an easy reference so your team can record Anti Dive or Pro Dive adjustments in your set up book. Half inch slugs installed in the front of the ear and at the back of the ear give you a full inch of adjustment in a 6" space. For most purposes, the percentage of Anti Dive achieved with the use of (2) opposing 1/2" slugs is a large adjustment. With Anti Dive - a little goes a long way.

By now, hopefully you have an idea of Anti Dive, but what about Pro Dive? When would you want Pro Dive? If Anti Dive resists the nose dropping under braking then Pro Dive (when the front of the A-Arm pivot is lower than the rear  of the A-Arm pivot) helps the nose to drop under braking. On a street car, Anti Dive is put in the right and left side to create braking stability. The same amount is run on both sides.

For racing, running Pro-Dive on the LF with Anti-Dive on the RF can help pull the car into the turn. In effect, the car gets some automatic steering under braking promoting a good set at corner entry. You can experiment with running Anti Dive on both sides, or running Anti Dive on the RF and a bit of Pro Dive on the LF. Simple slug changes allow you to see what works best at your track and with your driver.

Slugs that mate with A-Arm ears are marked allowing for the ultimate in adjustment and repeatability. Simply record the slug numbers and your set up book will contain an easy reference to repeat adjustments. 

Considerations that come into play are the amount of braking force – if the track calls for heavy braking then the Anti Dive or Pro Dive is going to be accentuated by the full on brake force. If the track allows for smooth braking then maybe you can run more Anti Dive to accomplish your goal. In general, Anti Dive can help give the car stability at corner entry under braking – when the brakes are released your soft springs can ride over the bumps and roll easily into the turn. Running Anti Dive might allow you to run the soft springs that help in the middle or over bumps as the mechanical resistance created by Anti Dive carries you over the braking portion of the track.

Pro Dive on the LF might help set you into the turn – maybe you will be able to run a little less stagger by using a small amount of Pro Dive at the LF. Potentially, less stagger will keep your car hook up on corner exit? The trick is to mix the amount of Pro Dive on the LF with Anti Dive on the RF to help you overcome a problem without changing a spring that could hurt the car later in the turn. Maybe, the Pro-Dive in this scenario starts the dominos in the right direction allowing you to run less stagger?

You can also measure Anti Dive by using an accurate level to record the A-Arm angle in degrees. An accurate Digital Level will give you a number that you can record in seconds. 

The same holds true for bite, stagger and all of the adjustments at your disposal. If you think out the when and where, Anti Dive can help you to fix a spot in the corner that is giving you trouble you can potentially use Anti Dive or Pro Dive to your advantage. While running Anti Dive is common place, Pro Dive can be a good place to experiment. It is standard to run Anti Dive on both front corners. It is very common to run Anti Dive on the RF with Pro Dive on the LF. All that said – there is no rule that says that Pro-Dive can’t be bolted into both front corners – just be careful that the car is stable under braking. All of my articles hammer on the concept that a car that is unstable at corner entry must be fixed or it is going to be a long night. I never risk a set up that has any possibility of being loose on corner entry – period.

By realizing that Anti-Dive resists movement under braking, and Pro-Dive promotes movement under braking, your team can overcome obstacles with another adjustment mechanism in your chassis set up tool box. Small changes go a long way. Using slugs allows you to make changes 1/8” at a time. 1/8” may not sound like much, but it is 1/8” on a 6” bolt pattern so the degree change is significant. Using a ½” slug turned up on the front of the RF A-Arm and a ½” slug turned down on the back of the RF A-Arm provides you with a ton of degrees of adjustment. I just write down the slugs dimensions – you can measure degrees with a digital level in about 3 seconds – keeping the article understandable is my goal.

The limitation is not in the hardware, but rather in your need to truly need Anti Dive or Pro Dive to fix a real problem. Just because you can adjust the Anti/Pro Dive doesn’t mean you should. In this case, a little goes a long way and under doing it is better than going overboard. Still – top teams adjust the A-Arm angle with the same mental ease as changing stagger or Panhard bars. Experiment and maybe you will learn a new speed secret for your particular car and track. Or, by understanding the adjustment – you can ensure that your car is assembled properly and the Anti/Pro Dive is set within parameters that your car builder had in mind. Measure, experiment, document and repeat – that sound pretty scientific to me.

Go Forward – Move Ahead.

Jeff Butcher

08/01/12

Brake Balance Adjustment

Balanced stopping is as important as a balanced set up. To win, you need all 4 calipers doing their share of the work. Ensuring that your braking system shares the load proportionately will create a fast and stable car on corner entry. Your brake manufacturer can utilize past experience to help your team to select the correct components for your car weight, tires, horsepower, track size and banking. When I was young, my Dad taught me that 4 tires work better than 3 when it came to chassis set ups. The same holds true for braking. Getting all the tires to share the load results in faster lap times and improves consistency.

Once you have installed the correct brake system components, a brake balance bar is one of the few adjustment tools the driver can utilize right from the seat. For your brake balance bar adjuster to work properly, it is vital that you set up your pedal balance bar per the instructions provided with the hardware. For trouble free operation the pedal balance bar must be parallel to the frame rails when the pedal is full depressed. Often, teams set the balance bar parallel to the frame in the static position – this will cause binding and problematic performance. Installing the pedal balance bar parallel to the frame in the depressed position allows the front brakes to come on first promoting a stable corner entry.

After you have verified that your parts are installed correctly, you can begin choosing a brake balance bar adjuster that meets your needs. A quality brake balance cockpit adjuster will give your driver a tool that can be used during racing action.

This Brake Balance Adjuster is lightweight and mounts without dis-assembly. The steel braided flex hose is reinforced with Nylon tubing on the interior nearly eliminating the chance of binding.

Understanding how the brake balance performs will help you to get the most out of your brakes and your driver accessible adjustments. By cranking on the adjuster you are changing the percentage of leverage force to each master cylinder. Adding front brake changes the angle of the pedal balance bar assembly. In a given amount of pedal travel – adding front brake reduces the travel distance of the rear master cylinder piston. Reduced travel equal less total braking force.

Adjusting the brakes with a brake balance bar comes with compromise. Today’s brake systems are very advanced. The small reduction in overall braking force is often a good trade off as gaining the adjustment ability can be the difference between winning and losing. At tracks that work the brake system to extremes, it is important to consider that overall braking force is reduced. If you run at the same track every week you may want to explore different brake components verses relying on the adjustment method. If you find yourself dialing to all front or all rear every week then replacing components may be a choice that allows your brake balance adjuster to be more effective.

Changing the leverage percentage to favor the front brakes promotes a solid corner entry. Getting your car into the corner in a stable fashion is mandatory for drivability and builds driving comfort. If you go too far with the front percentage then your car can exert too much force to the front tires and the car can begin to pick up the dreaded middle push. Adding front braking percentage is a great choice if the car is twitchy or uncomfortable at corner entry.

Conversely, if your car has a pushing condition then dialing more rear brake can help to set the car into the turn via the rear brake assist. More rear brake percentage can be a great tool that helps a car to turn. Use caution as going too far can create rear brake lock up should the driver need to smash the brakes to avoid an accident.

Caliper mounted Brake Pressure Gauges allow you to check the pressure at each caliper. Regular use can help you to identify brake system issues. If you see a reading that is outside your norm you should inspect your brake system to find the root of the problem

At tracks that create bright red glowing rotors your goal should be to work towards having the rear brakes do as much of the stopping work as possible. Identifying the point where too much rear brake causes unstable corner entry provides a record of the setting to avoid. Once the maximum rear brake bias leverage point is established a few turns to the front for stability will help to minimize the potential for an unstable entry. Achieving the maximum from the rear brakes takes load off the front. At heavy braking tracks, obtaining maximum safe force out of the rear calipers can prevent overworking the front brakes.

There are many brake balance bar adjuster systems on the market. Be sure to mount your version properly. Utilizing a robust flex connecter at your pedal assembly prevents unwanted binding. Steel braided versions have a rigid Teflon interior that resists binding – a guide support and a straight shot into the pedal assembly promote smooth operation.

 If your brake balance adjuster system is a speedometer cable style, be sure to have a straight connection point and provide a cable guide support near the pedal assembly. Speedometer cable style units can flip into a loop rendering your adjuster useless at exactly the wrong time. Proper installation will prevent the cable from flipping into a knot. The rubberlike coating on the speedometer style cable can melt with heat. Often, the melting happens with a new car when the rubber cable sleeve is strapped to close to sources of heat. Route away from heat sources or insulate the rubberlike coated cable versions to prevent the outer coating from melting onto the cable.

Driver brake adjustment, used properly, can be the final touch to get the last ounce of speed from a good handling racecar. Further, cockpit brake adjustment can help drivers to adjust to changing track conditions or wearing tires.

Gain can come with pain. Over use of the brake adjuster can cause teams to chase their car handling characteristics. If you think of the brake balance adjuster as a fine tuning tool you will rely on chassis adjustments to balance corner handling – keeping the balance adjuster in the center of the range when the green flag drops provides the maximum adjustment ability during the race. Starting the race with the pedal balance bar perfectly parallel to the frame in the depressed position puts your brake system in the center of the range and provides maximum braking force.

Brake Balance Adjusters with a measuring scale make recording your setting an easy task. You should record your brake balance setting as a routine part of your set up process.

Recording your brake balance adjustment should be a weekly routine. You can measure the setting with a cockpit adjuster system that utilizes a scale to indicate balance position. Another option is to track the amount of turns front or rear “off of center”. If you count turns you simply record the number of adjustment turns with center being the pedal balance bar being parallel to the frame when depressed. For more accuracy, you can use calipers to measure the pedal balance bar location by measuring the master cylinder rods before and after each race.

Dash mounted Brake Pressure Gauges give you a quick reference to witness the line pressure difference created with just one turn on the Brake Balance Adjuster. Dash mounted gauges can give you an early warning to braking system leaks or problems.

You can utilize brake bias pressure gauges to witness the affect of turning the brake balance adjuster. Just one turn can make a significant change on the bias gauges. Understanding your bias gauge readings can help you to establish a baseline for your brake set up. Keep in mind, that pressure is just one element in your braking system. Variables such as piston size, quantity and master cylinder size must be taken into consideration. A brake bias gauge set provides an easily viewable baseline helping you to leave the shop ready to go – or should I say stop?

As with any adjustment, it is only good if you can repeat the change in a consistent and predictable fashion. With the proper hardware, your team can eliminate problems and orchestrate a bias towards winning.

Go Forward – Move Ahead

Jeff Butcher

04/1/12

Instant Center Adjustment

Why do we care about the Instant Center in the front suspension? We know our car builder spent plenty of time engineering the proper roll center. Instant Center of the Left and Right side front suspension are a piece in the puzzle that creates Roll Center.

Since I am opposed to over engineering at the track, I prefer to focus on Instant Centers and adjust them with the same freedom that is applied to adjusting the rear roll center. “Just try it” is my philosophy when it comes to adjusting the Instant Center at the track.

Before you start moving parts around it does pay to understand the geometry that creates instant centers. I like to explain mechanical design by using words like “stuff” or “things” instead of complicating simple topics with big phrases such as “dynamic roll propagated via G-Force induced dynamic wheel loading”. Really, we can explain stuff by simply understanding that there is more front end travel at a high speed high banked track than you would find if you set up some orange cones in a parking lot.

Timing your suspension travel by balancing spring rate, roll bars and shocks with the leverage created by Instant Centers can maximize your Big Bar set up. For that matter - any set up is benefited by experimenting with Instant Center locations.

Instant Centers are easy to visualize. You find the little spot the same way on both sides of the front of the car. For this review we will take a snap shot of the RF suspension. Your A-Arm is bolted to the frame via an ear that is welded to the frame horn. Your lower control arm bolts onto the cross member. You have a spindle pin and the tire size sets the height of the wheel center off the ground. Your A-Arm is about 7” to 12” long and your lower control arm is probably around 16” to 18” long for your typical late model that has a 63.0” track width. Basically, if you have a stock car, the parts that create the Instant Center are similar regardless of your brand of car.

My goal is here is to eliminate the fear that can be associated with the big pile of details that create the magical Roll Center. Really, roll center is often found at about 1.5” off the ground to 2.5” off the ground for most cars – give or take an inch. The left to right location moves all over the place depending A-Arm length. Of course, as soon as you run the suspension through travel the roll center moves about. With a huge roll bar, the rules have changed and once the car has been pulled down to the ground with your insanely stiff rebound shocks, the roll center and instant centers move around much less as compared to when we had a pair of 350’s on the coilovers and an 1-1/8” bar.

Big Bars require new thinking. Since planting the nose piece to the ground is the new norm, then it would seem that the suspension layout is less important – or is it? With the nose piece held to the ground by huge rebound numbers and a sway bar that nearly eliminates body roll, then why do we care about roll centers and instant centers at all?

While the movements are less, they are still there. We still have dive, roll and plenty of bumps. But, all of those movements happen faster and the distance traveled, once the nose pieces is sucked down, is less. With this “new” information how can we make an effective adjustment utilizing Instant Centers along with shocks and springs?

It pays to think about the mechanical leverage of the Instant Center. Adjusting the Instant Center can be the subtle adjustment that compensates for the reduced actual center of the corner travel induced by giant sway bars. Since the Instant Center is 2 simple lines per side we can visualize it easily. The first line is drawn through the center of the upper ball joint and extending through the inner pivot. Be sure to find the true center of the ball joint provided by your ball joint manufacturer. The second line extends from the lower ball joint through the inner pivot on the lower control arm. Extend both lines until they intersect. Boom – the Instant Center is created. Through suspension travel the intersect point moves based on the length, angle and connection point of the upper A-Arm and the lower control arm. See the accompanying photo for the visual and you will see that Instant Centers are pretty simple to understand.

The Instant Center is easy to visualize right at the track. Simply follow the lines of the upper and lower arms until they meet. Be sure to utilize the actual ball joint center provided by your ball joint manufacturer.

Now examine the RF Instant Center and how we can use mechanical leverage to our advantage. Let’s assume our track width is 63.0”.  If the hypothetical RF Instant Center is 4 inches off the ground and 3 feet left of the vehicle centerline we end up with about 49.5” (close enough) of leverage. If we make the RF A-Arm Longer and keep the same connection point on the frame ear pivot we move the RF Instant Center more to the left. The longer A-Arm gets flatter and it takes the imaginary line longer to run into the line from the lower control arm. The change lowers the RF Instant Center as well. So, hypothetically, let say we moved the RF Instant Center to left about a foot and down 2” (Since we are starting from a known baseline all we care about is the direction of the adjustment – we can repeat the change by tracking the slugs we use).

 A-Arm length and mounting height have a dramatic effect on Instant Center Location. Carrying an inventory of A-Arm lengths gives you more Instant Center Adjustment choices right at the track.

The longer lever arm created by the adjustment scenario in the prior paragraph compresses the RF spring more than it would have in our baseline set up. The car speed and banking provide the same amount of force, but the longer lever creates more travel at the RF. Really – it is like running a softer RF spring when the chassis rolls. Lowering the RF Instant Center promotes more roll. The longer lever from the Center of Gravity gives an additional boost to roll.

Bolt on tube sections make quick work out of changing A-arm length. Moving Instant Centers at the track is an adjustment you should try more often. The bolt on tube section is a rigid advantage on snouts where the A-Arm wraps around the frame.

Here is where the fun starts – let’s keep it simple. You can draw your suspension and do the actual math and record it for future reference. For now – let’s just think about the concept. Moving the RF Instant Center to the Left effectively softens the RF spring through chassis roll. But, if you want a softer RF spring, why not just put one in? Well, this is where you need to think about the corner entry, when the car is relatively traveling in a straight line, and the corner middle where the car is in full roll. If you balance the Instant Centers, and consider all of the compromises that come with race car set ups, you can make subtle adjustments by manipulating the timing of suspension compression (corner entry) and suspension roll (corner middle).

When your car is going perfectly straight, the giant sway bar is doing about zero. If the car is going straight and you smash the brakes then the ultra soft springs you have up there may not hold the car for a stable entry. You can fix the problem by adding stiffer springs for straight line (entry) braking, but then the middle may suffer due to the stiffer springs you thought you needed? From your baseline, adding front spring to get some help with corner entry stability coupled with moving Instant Center to the left creates a lever to help the car roll – now you get help under braking without suffering more spring rate during roll. The game is in balancing the Instant Center with the entry “dive” and the mid-corner “roll”.

Your car builder has the baseline figured out when it comes to Instant Center and Roll Center. But, track conditions change and driver styles vary. Maybe you can utilize Instant Center changes just like you use the Panhard bar? Try it and see if “Mikey likes it”.

The adjustment idea I like best for Instant Center manipulation is to use the same length A-Arm but simply move the upper frame pivot point up and down to get your desired result. I prefer moving the pivot point of the upper A-Arm for subtle adjustments. The benefit of moving the upper pivot point is that hardware is available to make it easy, you can make subtle changes, you avoid messing up the bump steer and the camber curves stay in line. Your car builder spent a mountain of time and testing on your baseline front end design so it pays to make adjustments that are subtle verses stretching the design parameters to extremes.

Using a slotted ear and slugs makes adjustments easy. You can move the pivot point in small increments by carrying a slug kit. You can raise and lower the Instant Center right at the track. If you want more roll, but don’t feel like you can run softer springs, you can simply change a slug and raise the RF A-Arm Pivot point. Raising the pivot point will move the RF Instant Center farther left and lower. The subtle adjustment gives you some turning help without decreasing braking stability. The RF gives you easy adjustment and you can “feel” the affect of the change just like when you move the panhard bar. You do have to readjust camber – easy deal.

Slugs that are marked give you an easy way to record Instant Center changes. A 1/4" slug makes a profound difference. Draw it out when you have time. At the track, just bolt in a pair!

A slotted A-Arm frame tab works perfectly with the slug system allowing for quick and precise adjustments.

The LF Instant Center is important too. You can use the LF to raise or lower the roll center. You can also use the LF to move the roll center left or right. You can accomplish the same thing with the RF, but this article is trying to provide simple examples to help your team see the concept and give you the confidence to try what may be a new adjustment for your team. You can certainly draw it all out, but for today just think about what happens when you move the Instant Center with simple A-Arm slugs.

When you run a Shorter RF A-Arm you generally move the roll center to the right. The shorter RF A-Arm has more angle and intersects with the lower control arm line faster – that is easy to understand, right? If the Roll Center is closer to the right it speeds the rate of travel and the car reacts quicker. Go too far and you will blast through the travel before the full force of the center of the corner arrives. When this situation occurs, the “soft push” is usually the result. So, this is a magazine article and you have a race car going around a real track. Reading is fun and accepting the limitations within this article will help you to just try adjustments. There are a ton of variables and the goal of this lesson is to simply discuss one element as if Instant Centers were not connected to anything else – of course they are! But, if by forgetting about all of the other “stuff” we can learn how to manipulate Instant Center adjustments to overcome a problem then we have learned something new.

Changing A-Arm length requires the camber to be reset. A billet nut plate speeds changes when time is short. An accurate billet caster camber gauge is a must for any race team.

Since your car builder spent the time to build your car with a proven Roll Center location we want to be careful to not adjust so much that we erase the years of testing and knowledge that our car gives you when you buy a frame. So, from a prior article Roll Center is explained here:

Roll Center Explained:

To simplify the Front Roll Center thought process it helps to understand the creation of the so called magical point.  Front Roll Center is a calculated point verses a physical place. To find it you must first locate the Instant Center both left and right.

The RF Instant Center is found by drawing a line through the center of the RF upper A-Arm ball joint extended out though the center of the A-Arm inner pivot point on the frame. Another line is drawn from the RF lower outer ball joint center though the lower control arm frame pivot. The RF lower control arm line is extended out until it meets the RF upper control arm line. Where these lines intersect is called the Instant Center. The LF Instant Center is found in the same way.

After both Instant Centers are located you can now find the Roll Center. From the RF Instant Center you draw a line back to the RF contact patch center. From the LF Instant Center you draw a line back to the LF contact patch center. Where these two imaginary lines, running from the contact patches to the corresponding Instant Center intersect, is the Roll Center. Remember – the Roll Center moves as the suspension goes through travel.

Spend time to learn about Roll Center when you are in the shop. At the track - trial and error is still common, even for Cup teams with full time engineers. 

Note:

Since the “Roll Center” location is a moving point is space it gets complicated – carrying graph paper at the track is not feasible, I prefer to spend time thinking about roll center during the design stage of building a chassis – and much thought is placed into Roll Center when designing any suspension.

 At the track, it is easy to visualize Instant Centers and difficult to think out roll center. By simplifying, I can adjust Instant Center locations right at the track as I can easily see how the upper A-Arm line passes through the lower control arm line. With simple visual estimation, I can have another adjustment method at the track and I carry slugs to make repeatable changes just like I would move the Panhard bar or change a spring.

If you use a RF A-Arm frame mounting plate that is slotted for height adjustment you can use slugs to ensure you have repeatable and documentable changes. For the Front Instant Center adjustment you can simply record that you moved the RF inner A-arm mounting point up a1/8th inch with a slug. Changing a slug is pretty easy.  If the driver doesn’t like the adjustment you can simply bolt the original slug back in.

Instant Center adjustments at the track can be used to create the feel of stiffer front springs under braking yet have the front springs feel softer in the center of the turn due to the longer lever that is created by the Instant Center length change. Many variables come into play and the teams that get the variables closest wins.

At the track – I usually focus on Instant Center adjustments by moving slugs on the upper A-Arms. You can move the lower points too, but you bring in rack location issues and bump steer corrections. The upper adjustment is easy to understand especially when track time is limited.

Lowering the RF A-Arm inner pivot raises the Front Roll Center and moves it to the right. Negative Camber is added and may need to be reset.

Raising the RF A-Arm inner pivot lowers the Front Roll Center and moves it to the left. Negative camber is reduced and may need to be reset.

Lowering the LF A-Arm inner pivot raises the Front Roll Center and moves it to the left. Positive camber is reduced and may need to be reset.

Raising the LF A-Arm inner pivot lowers the Front Roll Center and moves it to the right. Positive camber is added and may need to be reset.

The reality is that Front Roll Center is simply a derivative of the Instant Center locations.  Instant Centers are simple even through dynamic roll. Why complicate your trackside thought process with imaginary lines? Keep it simple at the track and use slugs to maintain records and repeatability. You can engineer at will after the race and study the Roll Center changes you accomplished and measure the affects of bolting in a few simple slugs.

Engineering becomes more important in racing every day. When time is short, educated experimenting is equally as valuable.

Go Forward – Move Ahead

Jeff Butcher

06/08/12

Cockpit Comfort

To win, your driver needs to be up on the wheel all through the race. Proper cockpit layout will allow your driver to be there at the end. All components in the cockpit area should be precisely located and as much time as needed should be utilized to place your driver in position “A”. Designing a cockpit layout that functions in a seamless fashion will help your team to avoid crashes, make more passes and find Victory Lane on a regular basis.

Many states have banned hand held cell phone use while driving. Even at highway speeds the distraction factor in holding a cell phone causes poor driving and accidents. We have all seen cars on the highway driving in an erratic fashion due to cell phones. Why is the car in front of you is doing 48 miles an hour in a 60 mile an hour zone? As you blast by the car, traveling at an unexplained slow speed, it is easy to spot the cell phone causing the distraction. It was a little disappointing, this morning, when I drove by our local sheriff jamming up traffic on I-5 while talking on his cell phone going 48 miles an hour in the middle lane. The speed limit on that section of the freeway is 60MPH. Unbelievable!

If a simple cell phone causes street drivers to lose focus and drive erratically, then it follows that race drivers performing at the highest level could easily lose positions or find more wrecks due to a poorly laid out cockpit. Working to place cockpit items properly, takes more time than money. Even if you have to move cockpit items multiple times to find the perfect locations, your efforts will be worth the work. Drivers are so constrained, due to tight cockpits and safety devices, that a premium must be placed on everything they need so they can stay focused on racing instead of fumbling around and becoming distracted.

Steering wheels should be mounted close to the chest to give drivers increased leverage on the wheel resulting in more control and reduced back strain. Mounting the Steering wheel on the perfect angle and directly between the driver’s shoulders provides improved longevity. An adjustable steering column mount easily slides side to side on the dash bar making it simple to get the location right both left to right and up and down. Adjustment is so simple that teams can re-adjust until the steering wheel is in the perfect location. Adding a steering spacer can be the final touch in finding a comfortable wheel position for the driver.

An steering column mount that is easily moved can be adjusted by the driver right from the seat. Adjusting the steering wheel location so it is close to the chest and at the perfect angle keeps drivers fresh.

Steering Wheel spacers quickly bolt on giving your team a simple way to locate the steering wheel perfectly. If your driver ate one too many burgers, your crew can install a different thickness spacer quickly. Keeping a variety of spacers of different thicknesses on hand is a good idea. 

Adjustable throttle pedals allow for easy fitting helping your team to locate the throttle in perfect location. Mounting the seat leg support properly gives the driver a natural place to rest their leg. Battling centrifugal force for the entire night has worn out more than one driver. Driver comfort and position in the car are paramount. Leg angles, with pedals in a comfortable position, keep your driver fresh. A slightly bent knee gives the driver throttle control for a smooth drive off the corner. A floor mounted pedal can be precisely located to fit foot position and angle. The easy adjustment of a billet hanging pedal allows for quick adjustments in the shop or right at the track.

A steering column leg brace like this one bolts right to the adjustable steering shaft mount. For high speed high banked tracks a leg brace keeps your driver fresh for a strong finish.

Quality throttle pedal systems offer adjustability for comfort and precision for the smooth application of power

Switches that are in easy reach of the driver can save a motor. On those nights when the engine faces a problem, a well located ignition switch can save thousands of dollars. All switches should be within easy reach and located so the natural reaction of the driver can quickly slap the Red Aircraft cover in an instant. Gauges should be positioned so all information is gathered with a quick glance. At race speed, any distraction that takes the eyes off the action can result in a torn up car. Spending the extra time to find perfect viewing angles can save an engine and can reduce accidents.

Switch panel brackets fit right on your roll bar so you can mount the switches within easy reach of the driver.

Brake Balance adjusters are a great tool for dialing in the set up. Often, drivers are dialing in brake bias adjustments at race speed. An ergonomic positioning of the balance bar adjuster allows the driver to focus on driving instead of blindly searching for the adjuster handle. A balance bar with a smooth action and handle that is designed for race gloves is a must. Regardless of the type of racing, fireproof race gloves are mandatory – whether it is a track rule or not. Racing without fireproof gloves is a game of Russian Roulette that should never be played. We race for fun and safety needs to be continuously in the forefront of every member of your racing organization.

This brake balance adjuster has an easy to operate handle that is designed for adjustment when wearing fire resistant gloves. Your team can mount this version right out of the package - wide mounting holes allow you to mount it with out the need for dis-assembly.

Radios should be located so the driver can reach the controls. More than once I have seen cars where a team member needs to turn on the radio as the controls are out of reach of the driver. Too often, the race starts only to find out that the crew forgot to turn the radio on. Driver’s should be able to easily reach the volume control and on off switch. Changing channels is a reality so make sure your driver can easily reach the radio controls.

Radios are smaller today - using the right size box protects your investment. The clamp on this model rotates so you can mount on a roll bar within easy reach of the driver. Radios should be mounted so that the driver can operate the controls. If turning on the radio is forgotten - the driver should be able to easily reach the controls.

Drink bottles with an anti siphon valve ensure that drivers get needed hydration even if the hose falls. An anti siphon valve is a simple solution – if the hose falls the driver can simply grab anywhere on the hose to get an easy drink. Drink bottle fluid seems to always end up all over the floor at the hottest races of the year. Be sure to use a sports hydration fluid that supplies the driver with needed nutrition during practice and throughout the race. On a hot race day drivers fuel their calorie burn with plenty of adrenaline. Assign a crew member to clean the drink bottle right after the race. Poisoning your driver with a moldy drink bottle is a bad deal. Feeding your driver liquid that is better suited for a science experiment is not exactly the best way to prepare to win.

Drink bottles that are big enough to hydrate your driver for an entire night are a good idea. Anti-Siphon bite valves keep fluid in the bottle when it is most important. Be sure to sanitize the drink bottle and the end of every race night. The last thing your team needs is to have your driver ingesting a science experiment created by leaving fluid in a hot car to ferment.

A side view mirror and a rear view mirror need to be located so that the driver can see the entire envelope around their car in an instant. With your driver strapped in at the shop, verify that there are zero blind spots. A crew member can quickly walk around the car to verify that your driver can see everything directly with their eyes or with a rapid glance to the mirrors. Adjust and remount mirrors as needed to eliminate all blind spots. Mirrors are a safety device and while spotters play a great role – the buck stops with the driver and clear vision is needed at all times.

A wide angle mirror side view mirror should be designed for the job at hand verses being a bunch of cobbled up junk that imitates a real race part.

Safety in the cockpit should be given the highest priority. Sealing up every crack keeps carbon monoxide out of the cockpit. A fire resistant shifter boot seals out fumes and debris and is a must have item for fire protection. Fresh air is a must and a cooling fan supplying outside air through the helmet maintains the health of your driver. A window net kit should be installed so the window net is stretched tight inside of the roll bars and an easy to grip handle should have free and clear access. 1/10ths of a second matter should your driver need to get out of the car. Spend the time on safety. Treat your driver like a family member – because they probably are at your family reunion.

A fire extinguisher is a high pressure cylinder. Can you imagine the chaos, in the cockpit, if a fire extinguisher were to come loose? With the contents of the fire extinguisher being randomly sprayed about, visibility would be zero at race speed. Breathing would be difficult and the mess is difficult to clean up. A billet fire extinguisher mount solves the problem and allows for a mounting location that provides instant access. Spending ample time on fire protection is a responsibility for any team at every level of racing.

When it comes to mounting your fire bottle, safety is the primary concern.

By covering the basics of proper cockpit layout, you will improve driving focus and driver safety. Many of the covered topics may seem obvious yet, every time I am at the track I see numerous examples, from multiple teams, where proper time has not been spent on the obvious. Just about all racers have more time than money – spending the time needed for proper safety and driver comfort will actually gain you time. Proper effort placed into your cockpit layout will save you dollars that takes only a little time to spend.

Go Forward – Move Ahead

Jeff Butcher
9/1/11

Mounting Hardware

The building season brings many challenges relating to constructing a car that is lightweight, built to perform, and easy to work on. Back in the day, we had to fabricate all of our hardware – somehow the job got done, but often the results looked like a kindergarten art project gone bad.

 Today, there are so many pieces available at your local race dealer, the car building experience has transformed from duct tape and bailing wire to billet and strength. Really, you can bolt on about any manufactured part saving valuable construction time. As an added benefit, professionally manufactured parts make working on the car easy and efficient throughout the course of the year. During the ongoing maintenance that occurs over the course of the season a part made for the job saves a ton of time. Sometimes building a mount yourself saves money, but if it takes 3 nights to build it and you miss the first race then how much is really saved?

If you have built many cars, past experience assists you in making the choice of fabricating on your own, or paying a modest price for a part that is manufactured specifically for the job at hand. Luckily for racers, racing manufactures work on thin profits and often teams can buy a professional part for less money than if they were to make a one off part on their own. A manufactured part is nearly always cleaner, stronger and lighter weight. If it is your first car build, then buying parts can eliminate many frustrating nights. That said – if you can do a quality fabrication job and save money then I am all for it. If the savings of making an item in your shop helps you to get your team to more races, then building it yourself can be a great idea.

Recently, I answered a comment about a Facebook post – a customer was smack talking about building their own bump shims instead of buying a manufactured version. Hey, if you can make a professional part you should – saving money in racing is hard to do and if savings means you can make one more race then more power to the innovation of the garage fabricator. Making your own Bump Shims is not too difficult, but when you factor in the time, hassle, and gas costs spent chasing down materials a production made kit starts to look pretty good. It pays to consider the big picture before starting and take note that a professional kit will come with all the small details handled right out of the box.

A Professional Bump Shim Kit comes with an organizational case, a variety of shim thicknesses, and a billet wrench. The billet wrench reaches in between the spring coils making track changes quick and pain free. Download the JOES App KalcPack 1 and use the Bump ShimKalc to adjust your bump stops from your shop baseline setting. To download for free go here: JOES App Store

A case in point is a radiator mount. Anybody that has built a stock car has spent multiple nights making a mount to hold their expensive aluminum radiator in place. When it is time to put on the hood on the day of your first race, it is a painful to learn that the radiator is sticking above the hood line. Often, the need to re-fabricate the radiator mount is discovered after you frame has been powder coated. For the balance of the year, your team gets to endure the pain of looking at burnt paint and a cobbled up mount every time the hood is opened. Of course, fellow competitors are happy to toss a barb your way to cement the negative effects of choices made during the off season.

An adjustable radiator mount quickly adjusts from left to right. Multiple mounting holes ensure that your team can get the mounting height exactly right, even in the event of a body style change. The bolt on design makes quick work out of repairing damage.

Many series have shock rules that are designed to keep costs down. Other series utilize shock packages that come with a budget that would run a small city. If you have a pretty penny invested in shocks, then ensuring that your expensive hardware is mounted safely is a top priority. Nylon zip ties cost pennies a piece and hold shock canisters from falling off the car. With a zip tie the penalty is that your freshly painted frame gets scratched up and the cool anodize on your shock canister gets worn very quickly. Further, the smallest of dents in your expensive remote shock canister renders it useless. If you can build a nice canister mount in a reasonable amount of time then I say fabricate away. Before you start building four canister mounts to cover the corners of your car, it might pay to at least consider the parts that you can buy right off the shelf. Clean, quick, lightweight pieces that are optimally designed for quick adjustments at the track are features that are built into professional versions.


A Remote Canister Mount should have a rubber isolator reducing foaming. Doing it right protects your expensive investment and keeps your frame from getting scratched up.

I have seen body braces made out of scrap sheet metal strips, spare rod, or even scrap Lexan window material. These options work fine, but often the craftsmanship leaves a bit to be desired. And, if you want to make an adjustment to your fender width at the track then your team is burdened with the task of trying to fabricate in the pits without the luxury of the specialized tools that are available in the shop. Usually, manufacturing parts at the track creates a major panic due to the track schedule and fabricating in the field creates a ton of pressure at a time when teams should be focused on car speed.

Professional body mounts come fully prepared and ready to go. Depending on your type of racing you can chose a body brace that flexes with your fiberglass panels – their design pops the fiberglass right back into place after incidental contact. You can choose a rigid mount to hold your fenders steady in the wind created by high speeds improving aerodynamic performance. Whatever your choice, a manufactured version is ready right out of the package and installs in minutes. I am always amazed at how long it takes to fabricate something as simple as a fender brace. Still, if making body braces on your own is the money saving task that gets you to the track, then save some dollars and build away.

A solid body mount with an aluminum rod will hold your body panels rigidly in place at high speeds for aerodynamic performance. Flexible mounts pop fiberglass panels right back into position after incidental short track contact.

When it comes to spoiler supports I recommend purchasing a manufactured spoiler brace. Sure, you can make a support easy enough, but it is difficult to make adjustable spoiler braces in the shop. You should consider that you need 8 matching spoiler braces before you start fabricating on your own. A machined professional unit comes with all the needed hardware and is built for good looks and quick spoiler angle adjustments. I always recommend Lexan rear spoilers if allowed by your rules. The vision increase is dramatic. Spoiler braces often need support washers and manufactured aluminum versions provide a clean look while keeping your Lexan spoiler from cracking. A simple washer can provide support, so pick and choose which purchased items fit your budget.

 

Usually your rear spoiler needs eight supports. The ability to adjust your spoiler angle quickly can gain needed speed. Be sure to consider the big picture before jumping into making spoiler supports on your own. Often, you can purchase a professionally manufactured unit for less than you can make one on your own.

Hood pins work great to hold the hood in position especially if your hood is completely removable and lightweight. If you have a hinged hood or a steel hood, then purchasing manufactured hood hinges makes working on the car much easier. Billet versions lock in place and a quick tap releases the hood to close up the engine area quickly. Anyone that has been around racing long has had a hood fall on their head and the associated headache does little for productivity. If you can make good hood supports, then have a ball. Still – I am busy on that night and would choose to buy a pair. Manufactured hood hinge supports look good and have the strength to keep you working. Think about how many times you open the hood on a Saturday night?

Billet hood supports lock the hood in place in the open position, allowing for easy engine compartment access while saving your crew from bumps on the head. A quick tap on the hinge quickly releases the locking action. Mounting the hood to the car helps to prevent scratches on the roof and keeps your hood from flying off in the wind.

Your fire bottle is another area where buying a good mount can be beneficial. With care, you can make a solid mount for your fire bottle. Be sure to form fit any sheet metal and use hardware that handles the weight. Fire bottles are quite heavy and should you bounce off of something then you need to have a guarantee that the fire suppression bottle stays put so it can perform when you need it most. If you make fire bottle supports in your shop, think safety and be sure to use materials that can handle the heavy weight.

Mounting your fire bottle requires materials that handle the heavy weight of your fire suppression system. Safety first absolutely applies here.

A well designed shifter boot helps you to access the shifter lever bolts assisting in a quick engine or transmission change both at the track and in the shop. Making one is possible, but be sure to use fire resistant material for the boot. Safety items are simply not the area to save money so if you choose to make your own – do it right. For this project I would buy the best kit I can find.

A Shifter boot that snaps into place gives you quick access to the shifter bolts. Engine or transmission changes can be accomplished quickly. Fire resistant material offers protection and the reflective lining reduces cockpit temperatures.

Window nets can be difficult to mount on your own. Window nets need to be tight when buttoned up and the installation configuration can help your car to be more aerodynamic. If you make your own kit, be sure to paint steel parts preventing rust from deteriorating the window net fabric. A window net kit is a nice luxury when building or renovating a car. Safety first applies for sure. Ensure that the latch mechanism is easy to operate for both your team members and emergency personnel.

Window Net mounting hardware should be rigid, ensuring a window net that is tight. The latch mechanism needs to be easily operable for your crew as well as track safety workers.

Car wiring is a mystery for many teams. You can choose wire up your car and make simple mounts for your switches and lights. Be sure to use a red flip up cover for the ignition shut off. In an emergency such as a stuck throttle, an easily seen big flip up cover helps your driver to hit the switch shutting down the engine quickly. You can install switch components on your own if you have the time. Keep in mind that you need to purchase the switches that are rated and sized properly. Rubber boots keep moisture and dirt out of the switches helping your car to keep running at all times. Solder all the joints so that you finish races. Over time, crimped connectors, that don’t seal the wire connections with solder, can corrode and fail. Washing the car can fill the wiring connections and switches with dirt and grease. It is always tough to see the race leader loose speed coming off turn 4 because a 10 cent connection failed on the last lap. I have seen more than one wreck due to a car loosing speed at the wrong time. Wiring is an area where you can do things on your own. If you tackle the wiring, spend the few extra minutes to use solder and heat shrink at all connections.

Manufactured switch panels make wiring the car a breeze. Billet mounts professionally locate switch panels in easy reach of the driver. Bolt on mounts allow you to adjust location with worrying about cutting off a welded on tab. Always use a red flip-up cover so your driver can slap the ignition off quickly in the event of an emergency. Rubber sealed switches keep your car running when it matters most.

In the end, building a car with professional components may be the choice that keeps your car running for that next win. A well built car may attract a sponsor out of the grandstands helping you to fund your fun. Building your car right is what matters regardless of where the parts come from. Safety items must be installed without compromise. If you can build a professional part, without spending 2 weeks per project, then self fabricating can be a great idea to save cost. If you place a premium on constructing a car that is easy to maintain, then purchasing well designed manufactured parts may actually save you time and money over the course of a long year. At 2:00 a.m., on the night before the race, the light bulb moment comes as you enter the self imposed sleep deprivation period that comes from trying to do too much on your own. If every race weekend comes with a Friday night all nighter, then the lack of sleep can help you to determine when to buy and when to build. If your team members are tired on race day it does show up in your finish results.

If you fabricated too many parts on your own for this build season, then experience might guide you for the next time you are ready to construct a new car. The goal should always be to build a better car than you had before. Prior experience will guide the way and your luck will be based on your preparation creating sustainable opportunity.

Go Forward – Move Ahead

Jeff Butcher

3/1/12