Tires & Temperature

You spend piles of time figuring out how to make more horsepower, optimizing shocks and building lighter cars which all come together where the rubber meets the road. Every speed secret on your car is applied at the contact patch so creating the optimal footprint is the meeting place for all of your hard work. Tires are the single most important aspect of speed as every adjustment from motors to springs relies on the grip you manufacture at the contact patch.

Measuring tire temperatures accurately will provide the information you need to produce even grip and maximum friction where it matters most. Using pyrometers correctly provides valuable information. Often, a tire sheet is handed to the crew chief and the numbers on the paper sets in motion a flurry of adjustments. The thrash begins and springs fly. Orders are barked and the crew moves quickly to get the car back on the track with hopeful anticipation of new found speed. Temps are taken to see how the new adjustments worked out and too often the intended chassis improvements are 180 from what is needed. The driver reports the car is even worse than before the recent round of adjustments. Did the missed set up attempt occur due to a poor choice on the chassis adjustment? Or - were the wrong changes made due to poorly measured numbers on the original tire temp sheet?

It is worth noting that tire temps and pyrometers are one of the few ways that you can analyze real time data right at the track. If the temperature measurements are taken correctly, chassis specialists can calculate the best changes that will perform for the length of the run. Using up important practice time and valuable practice tires with wrong way adjustments is expensive. Choosing the correct pyrometer to produce scientific information and assigning the crew member that is dedicated to precision is paramount.





To dissipate heat racing tires are very thin. Thick tire rubber holds in heat and the potential for blistering increases. Tire engineers balance the rubber thickness with tire compounds to produce a package that considers car weight, corner speed, track abrasiveness, outside temperature, intended lap use and several other variables. Since the thickness of tire rubber can vary you need a pyrometer with an adjustable tip length probe. We want consistency and measuring tire temperature down at the cord is the best way to ensure accurate and repeatable numbers. If your team is measuring tire temps at varying depths then the information on the tire sheet is going to set in motion changes that could slow your car down.

Pyrometers must be used constantly - scientifically. Rubber is a poor conductor of heat yet it is a great insulator. If you are trying to assess camber temperature curves then you want to know the inside, middle and outside temps based on your camber setting and corner performance. If you measure the inside location at the rubber surface, the middle location and mid tread depth and the outside at the cord your temp sheet is going to have more inconsistency than Michael Jackson has had cosmetic procedures. The cord heat is insulated away from the outside elements and the most heat will be found beneath the rubber and down at the cord. Scientifically – it makes sense to measure all 12 locations at cord depth where the purest temperature is located.

Adjust your pyrometer probe so that the adjuster stops the probe penetration just before the probe reaches the tire cord. Using the stop on the adjustable tip will allow your crew to quickly and consistently get down to a consistent depth near the cord each and every time. Your temp sheet will provide scientific quality information due to the repeatable and consistent probe depth.


Reading rubber temperature down at the cord is best as the friction of your tire pulls and stretches the tire rubber. The stretching effect creates heat just like when you bend a coat hanger back and forth. More friction creates more contact rubber stretch. Measuring down near the cord displays the data resulting in efficient chassis adjustments.

If you have a pyrometer with a fixed tip you can make it work but you introduce depth variables. How many times have you seen a temp sheet that showed you needed to take out RF camber and sent the car back out without an adjustment. A second temp reading shows you have too much camber – I will bet probe depth variation is the issue. With a fixed tip your crew needs to “feel” the cord to ensure the probe is at a repeatable and consistent depth.

Your probe tip is made of thin steel which heats up quickly sucking the heat out of the pin hole made in the tire rubber. Be sure to move quickly. If you leave the probe in one spot in the tire rubber and watch the display you will see the temp rise and then begin to fall as the heat is sucked out of the test location. You need to record the maximum temp in each probe location. High quality pyrometers lock in the maximum temperature automatically increasing accuracy. Utilizing a temp lock feature gets you around the car in nearly half the time.

I am often asked if Infra Red pyrometers are good for tires. You certainly can use Infra Red pyrometers for tires but it is a quick check and the information is simply less precise than using an adjustable tip probe. IR pyrometers measure the tire surface. The surface temperature is impacted by engine heat, brake heat, puddles etc. Camber in the front tires places only a few inches of the tire on the ground at the low speeds encountered when travelling back to the pit area. The track surface is cooler than tire operating temps so the tire surface area in contact with the ground pull heat from the strip in contact with the track at a different rate than the rest of the tire – this difference skews your camber curve readings. The rubber down at the cord is insulated for a longer period giving you more time to measure temps relative to on track performance and probes can reach down past the surface for a better look.

When using IR pyrometers for tire temps bear in mind that the surface recordings will be much cooler in comparison to probes and you will lose the fine detail that can be found with probe type pyrometers. IR pyrometers are great tools for measuring track, header, brake and cockpit temps. Using the right tool for the job is usually sound advice.

To ensure the best relative tire temp readings follow these steps:

1. Use a properly adjusted pyrometer probe tip to measure down at the cord.
2. Get to the car quickly – speed matters!
3. Record the highest temp at each location with an automatic max temp feature or by manually witnessing the highest temperature. Move around the car quickly.
4. Start at the same tire each and every time and record the individual Inside, Middle and Outside for all 4 tires. Consistency is the goal.
5. Record track temp and outside air temperature on your tire sheet to monitor the difference that these variables have on your tire temps – over time you will be able to forecast better compensating adjustments.
6. Keep in mind that tire temps are of more value on a car that is handling well and with tires that are in good shape. Tire temps on cars that are in left field are about as valuable as politicians’ promises.

Using your scientific tire temps you can evolve my rule of thumb tips shown below. My tips are based on a car that is set up properly and just needs fine tuning. Your team should adjust the suggestions below based on your real world testing and document your own pre-determined adjustment to form your own game plan. Creating a game plan in advance will allow you to quickly asses your adjustment options improving your decision making when things get hectic at the track.

Camber Adjustments.
Your tire sheet temperatures suggest a camber adjustment is needed but knowing the adjustment amount is an educated guess. My rule of thumb for adjusting camber is a 1/8” shim for 12 degrees of temp difference between the inside and the outside. A 1/16th shim is a good start for 6 degrees difference. Trial and error starts somewhere and your team can modify my rule of thumb based on your actual conditions. Strive to find and document a pre-determined shim thickness associated with the degree difference across the tires on your car.

Starting Cold Air Pressure.Air pressure and tire temperature work hand in hand. If you take precision tire temp measurements you can gain an advantage over the competition by adjusting your cold air pressures before the race based on data you have collected over time. You can adjust your pre-race air pressures to a finer degree if you record outside and track surface temps in conjunction with your tire temperatures. If it is really hot out and you have tire temps that are 20 degrees higher than your last trip to a given track you can adjust the cold temps for better race performance. The rule of thumb that I used on a 2900 pound touring late model with bias ply tires was 1 degree of pressure gain for every 10 degrees of additional tire heat. You can visualize that there would be more pressure gain in the heat of summer verses a cool spring. Testing dictates your actual heat induced air pressure compensations. Adjusting your pressures based on recorded results will help you to optimize pressures for more speed on a long green flag run. Understanding the correlation between pressure and temperature will help you to optimize pre-race pressures during those times when your race set has residual temperature from practice and the race is going to start before the tires cool completely. Strive to know the actual temperature induced pressure gain based on your driver, track and conditions.

Air pressure adjustments.Inflating each individual tire properly means better grip, more wear and more speed. With accurate tire temps my rule of thumb is to adjust individual pressures 1 pound for every 5 degrees of over or under inflation shown as hot or cold center temps on my temp sheet. Your team can tailor the starting point of this rule of thumb to your actual situation. Your team may decide on 1 pound per 4 degrees or something different but the goal is to find the pressure needs for your car and tires. Establishing a baseline for inflation pressure adjustments will help you to dial in the winning set up and add consistency to your set up process.

Measure and record your tire temps with a quality pyrometer. Use the scientific data to form a pre-race game plan. Use your game plan to make the right call when it matters most. By using science you can take the black magic mystery out of your tires by building consistency in your adjustment process.

Go Forward – Move Ahead.

Jeff Butcher


Tools Courtesy of JOES Racing Products, Inc www.joesracing.com

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Camber and the Tire Contact Patch

Drivers like cars that cut into the turn. Optimizing your camber and understanding the tire contact patch will make for a faster car that stays fast through out the race. With today’s highly engineered tires, bump stop set ups and high level competition adjusting camber for maximum grip will help you win.

Camber is simply the tilt of the tire. Standing in front of the car if the top of either of the tires tilts towards the engine it is negative camber – if the top of the tire tilts away from the engine it is positive camber. To measure camber a quality all billet camber gauge will have the perfect surfaces to provide accurate and repeatable readings.



A billet caster camber gauge has the machined surfaces for accurate readings.
Camber is essential to match the contact patch to the bank of the turn balanced against your Upper A-Arm and Lower Control Arm lengths. Even if the corner were flat we would want camber. We need camber to work with the Upper and Lower Control Arms to achieve proper camber gain through suspension travel. Camber coupled with gain will optimize the tire contact patch taking advantage of the tire construction parameters.


Think about the changing camber angles in your race car through travel. We adjust the suspension and camber to achieve reasonably even tire wear producing tire temperatures that are balanced. That said, what we really want is the entire foot print of the tire on the ground under full corner load by using correct camber to match the spring load of the inner and outer sidewall. Too much camber loads the inside side wall too much and not enough camber loads the outside sidewall too much. If you want your car to cut through the center of the turn then it would make sense to have all of the available rubber firmly in contact with the ground.

Tire Contact Patch Explained
For this tire contact patch exercise think of a trampoline – we are going to compare a trampoline to how a race tire works. Imagine a trampoline to create a mental illustration of how the tire contact patch is stretched. Think of the trampoline outer frame as the tire bead. Now think of the tire side wall as the trampoline springs. Compare the trampoline surface to the tire rubber contact patch and visualize how tightly and evenly the trampoline surface is stretched by springs towards the frame. Our goal is to have the tire contact patch stretch evenly and tightly just like the trampoline surface. The tire bead is very rigid and creates a sturdy frame. The side wall of the tire is a spring that absorbs loads. By using camber to maximize the power of the sidewall springs the contact patch stretches flat and stays in full contact with the ground producing more grip.

The ideal amount of camber is achieved when the inside sidewall sets into the track to provide maximum pull at the tire contact surface. The stretch pulls evenly from the inside sidewall to the outside sidewall. The correct camber setting will utilize the entire contact patch. If you have too much camber the inside of the tire will not have enough initial surface area to pull the contact patch across and the spring of the outer sidewall will not be engaged. Not enough camber and the contact patch will deform and ball up at the inside edge – the contact patch rolls up and off the ground as the inner side wall spring needs more loading.

We use pyrometers to measure the tires on the inside, middle and outside. When the pyrometer shows a hot temp on the outside of the RF we add camber. Too hot on the inside RF and we take camber out. There is an exception that goes against the common thought of taking out camber when the pyrometer shows a hot reading on the inside. When would you add camber even though it opposes the pyrometer readings? Understanding the tire contact patch will help you set the camber through the exception.

With your trampoline comparison at the front of mind visualize the RF tire surface as it rolls through the turn. Think about the part of the turn where cars choose to cut or push. At this full tire load point, if you do not have enough camber, the contact foot print will not be stretched tightly between the two sidewalls (like in our trampoline comparison) and the pyrometer will show excessive heating on the inside of the tire and the exception occurs. In this condition we add camber even with higher inside RF temps. The excessive heating on the inside generally indicates to take camber out – thinking outside of the numbers may be in opposition to typical camber adjustments.


This exagerated view of a contact patch buldge illustrates how too little camber can show a hot reading on the inside. Understanding the contact patch will help you to make the right adjustment.

You may indeed need to take out camber of the RF due to the excessive inside readings but before you do inspect the tire and look for the exception. Look for rolling at the outside edge. If you see scuff marks extending to the outside sidewall this is clue one. If the outside edge looks rounded this is clue two. Now the important clue – closely inspect the inside of the RF tire about 1” inch from the inside edge. Look for a strange wear area that is about ½” wide that looks different than the surrounding rubber. It will look grainy, be cupped or perhaps mimic wind blown sand on the desert. Remember – it is more effective to dial in camber with new tires. Worn tires may have been misused and can provide false readings. Added attention should be paid to tire temps when you bolt on a new set and high quality pyrometers should always be used. Tire Temps make the most sense when the car is close. Feedback from temps can be erratic if the car is way off.

Exception Explained

If you do not have enough RF camber inside sidewall will be under loaded. The outside sidewall gives way and folds in deforming the contact patch. The deformed tire footprint pulls up off the track surface – as the deformed contact patch reaches the inner sidewall it is forced back down creating a protruding bulge as it curves back to the inner sidewall. Remember the trampoline comparison, we need the contact patch stretched evenly from the sturdy outside bead, through the outside sidewall spring, tightly across the contact patch, through the inner sidewall to the firm inner bead. In this exception adding camber at the RF will load the inside tire wall with the ability to firmly hold the inner edge of the tire foot print. The rolling or protruding of rubber at the inside edge is due to inadequate static RF camber. Don’t be fooled by this short term and artificial temperature. The extra temperature is created from the deformed contact patch bulge as it curves back to the inner sidewall. The bulge rubber will quickly grind off permanently damaging the tire. and the true pyrometer reading will show up! Proper camber will give the inside of the tire the maximum grip allowing the contact patch to stretch trampoline tight all the way across. Proper camber will allow the outside side wall to be pulled in by the contact patch rubber connecting the inner and outer sidewalls in unison and with equal load.

Camber - Old School

Camber gain through travel is related to your static camber, your Upper A-Arm and Lower Control Arm lengths. Consider the amount of travel your front end experiences. If you have an old school set up verses a Bump Stop Set Up there is less overall travel and the Upper A-Arm will be short. With Bump Stop Set Ups there is more travel from your static ride height and much longer Upper A-Arms slow camber gain.

For a pavement touring late model old school thinking was about 1 degree of camber gain per inch of travel. This guideline was a rough starting point with traditional set up and would be adjusted as needed to actual conditions. With a 17 ¾” RF Lower Control Arm a typical Upper A-Arm would range from 7 to 8.5” +/-. The increased angle of the Upper A-Arm provided for camber gain from static to maximum load. With standard suspension travel and a static camber of 3.5 degrees negative you would achieve about 5 to 6 degrees of camber in the center of the turn. Gain would be 1.5 to 2.5 degrees of camber through travel. Every car and track is different and these ball parks give are a simple view of old school camber

Camber - Bump Stop Set Ups
Bump Stop Set Ups require Upper A-Arms to be considered in an entirely different way. Longer Upper A-Arms slow down camber gain so it is wise to measure your camber with the car on the bump stops emulating the center of the turn. Static ride height is of zero value on a Bump Stop Set Up – as soon as you reach race speed the car is down on the stops and never sees static height again until you load it back in the trailer. Since shocks with mammoth amounts of rebound hold the car down on the bump stops the ride height static camber is not even worth checking. Bump Stop Set Ups use much longer Upper A-Arms, such as 8” to 12”, yet the Lower RF Control Arm is still around 17 ¾ on a touring late model.
When using bump stops be sure to consider your A -arm lenghts and angles.
The Goal

Your goal in identifying the proper camber is to find the optimal camber amount that creates maximum tension across the tire surface by equally loading the inner and outer sidewall. Dialing in the camber for the conditions will help the car turn. Too much RF camber and the inside edge will not hold – not enough and you will get balling up at the inside edge.

To set camber with your Bump Stop Set Up I would pick a repeatable ride height down on the stops that represents your best estimation of ride height in the center of the turn. A repeatable middle of the corner ride height number will make a better week to week reference point then trying to chase a ride height that varies based on how you adjust the shock body etc. For a Bump Stop Set Up I would start with 4.5 degrees of negative camber at the RF at my mid corner reference point and would not even care about static ride height camber. I would dial in the optimal camber with my pyrometer and tire inspections. I would look for consistent tire temps on short runs with new tires and longer runs with the same new tires. Adding or subtracting from my initial set up would be based on the feedback the car provides. The left front starting setting would be 3 degrees positive with the car on the stops and I would experiment there.

Tire Temp Tip

From experience my fastest cars had RF inside temps that were 10 to 14 degrees hotter than outside temps. The small amount of extra inside heat ensured that I was just reaching over the edge giving me the best shot at a fully stretched contact patch. I made sure to verify the temps on both short and long runs with new tires. The LF has less load so 12 to 16 degrees hot on the outside temp showed me LF outside tire wall was digging in with everything it had.

Go Forward – Move Ahead.

Jeff Butcher
Courtesy of JOES Racing Products

Bump Steer & Bump Stops

Under maximum corner load, where races are won, excessive Bump Steer can slow your car down and make it more difficult to find the optimal set up. Understanding Bump Steer will increase corner speed and give you more options in finding the winning set up.

What is Bump Steer? Bump steer is the toe in and toe out of your front wheels created by the up and down movement of your suspension. Really – bumps aren’t even needed! When the nose lifts under acceleration do you want the wheels to turn in or out on their own? What about when you are under heavy braking? Do you need the Right Front wheel to go one way and the left the other? Think about when the car transitions between compression and extension – we want the driver to steer and not have to correct for the inconsistencies caused by improper front end settings. When the suspension oscillates over bumps the last thing we want is to have the tires turn themselves due to excessive Bump Steer.

Bump Steer is caused when the swing arc of the suspension is not matched to the swing arc of the tie rod. Different swing arcs of the tie rod and suspension are what causes Bump Steer. To match the arcs you must follow a few simple design principles that were considered by your car builder.

Stock car suspensions are comprised of an Upper A-arm and a Lower Control Arm. Your frame sets the inner pivots and your spindle and ball joints set the outer pivots. Your car builder thought long and hard about all of layout dynamics to engineer the hardware that allows you to properly position components to attain Zero Bump Steer (Fig 1).

(Fig 1). Your car builder carefully engineered the pivot points, angles and lengths. Setting the Bump Steer is like Blue Printing the suspension to exactly match the design specifications.
The layout, lengths, and angles of the upper A-Arm work together with Lower Control Arm to encompass what engineers refer to as an Instant Center. To help understand the Instant Center you can visualize a triangle (Fig. 2). Draw a line from the center pivot of the top ball joint down to the center pivot of the lower ball joint. Now draw a line from the center of the top ball joint through the inner A-Arm pivot and extend it towards the middle of the car. Complete the triangle by drawing a line from the center of the lower ball joint through the inner pivot of the Lower Control Arm and extend it to the spot where it meets the Upper A-Arm line. The intersect point of the two lines is the Instant Center of your suspension. The RF and LF have independent Instant Centers.
(Fig.2) Your pivot points work together and intersect at the Instant Center. The illustration shows the RF suspension from the front view.
With your triangle drawing (Fig 2.) you can imagine a very long tie rod – one so long it would not fit on a late model as we know it. Connect your imaginary long tie rod with a mental bolt at the Instant Center. Extend your imaginary tie rod out towards the spindle and connect it to the center of the line between the upper and lower ball joint. With this layout you can see that the imaginary tie rod would follow the same arc through travel as the suspension (upper and lower control arms) and the car would achieve zero Bump Steer.

Matching the arc of your actual suspension to the arc of the tie rod completes a design scenario that points your tires straight ahead through suspension movement. To apply the matching arc concept to the design of your late model you will need to consider three design principles for ZERO BUMP.

Your outer tie rod pivot must fall on a line drawn through the upper and lower ball joints.
Your inner tie rod pivot must fall on a line that is drawn through the Upper A-Arm pivot and Lower Control Arm pivot.
The angle of the tie rod must create a line that when extended intersects with the Instant Center.

Race cars are made from welded steel that bows and twists from the heat of welding. Rack plates, steering box mounts and spindles all can have variations that we need to account for by utilizing shims to locate the pivots considering our 1-2-3 design elements. Setting the Bump Steer is like blue printing an engine – you are simply going the extra mile to match your car exactly to the car builder design specifications (Fig 3.).


(Fig 3.) Typically Stock Car tie rods follow the Lower Control Arm line. In our drawing we are illustrating that you can mount the tie rod elsewhere as long as the outer tie rod end falls on the Ball Joint Axis line, the inner tie rod end falls on the Upper A-arm and Lower Control Arm pivot line – and the angle of the tie rod ends intersect with the Instant Center.

Often rack plates are mounted too low for direct mounting of the rack. To achieve the proper pivot points detailed in our 1-2-3 instructions we may need to space the rack up (Fig 4). Using CNC machined billet rack spacers adds to the precision or simple washers can be used if you have the correct thickness on hand. Shims may also be needed on the spindle side to account for caster changes or spindle variations.


(Fig. 4) Mounting the rack at the proper height allows for zero Bump Steer.

To measure the Bump Steer you need a precision Bump Steer gauge and you will find a digital version speeds up the project. Suspension settings need to be racing ready and the proper components need to be fully installed and tightened. All front end settings need to be set – exactly. Tackling the Bump Steer measuring process should only begin when the car is truly race ready. Prepare your car in the following order and consult your car builder for their recommended front end specs. Make sure you have the right parts on your car!


(Fig. 5) A Precision Bump Steer Gauge that is billet rigid and utilizes one dial indicator will do the math for you for a faster and more accurate Bump Steer process.

Prepare the car to measure your Bump Steer per the following Check list:

1. Set the tires – air pressures and stagger.
2. Set the ride height.
3. Adjust the camber.
4. Adjust the caster.
5. Match your tie rod lengths per the1-2-3 instructions.
6. Center the steering by centering the inner tie rod ends with the Lower Control Arm inner pivot per the 1-2-3 instructions. Lock the steering in place to ensure solid measurements.
7. Set the toe.
8. Record a reference point while your car is on the ground and at your design ride height. Measure from the floor to the lower grease fitting or other repeatable spot such as the sway bar mount on the lower control arm – remember to write the number down.
9. Place the car on jack stands matching your ride heights and adjust for the jack stand height. The goal is to maintain your suspension angles while on jack stands matching the ride height on the ground.
10. Bolt on the Bump Steer plate to the hub and set it to level. Jack the suspension to ride height and note where the dial indicator touches the Bump Steer plate. Setting Bump Steer is a trial and error process and noting where the dial indicator touches the Bump Steer plate indicator marks will allow you to return to your ride height quickly after attempted adjustments.
11. Jack the suspension fully through compression with bump stop set ups (or at least 2”) and through at least 2” of rebound travel. Write down your results and refer to the Quick Shim Guide (Fig. 6).
12. Shim as needed.

To help you shim your way to proper Bump Steer here is a Quick Shim Guide that you can use after taking an initial Bump Steer measurement (Fig 6):

Quick Shim Guide

Toe out in compression & toe in on extension.
Reduce shim thickness at spindle or lower the inner tie rod end by lowering the rack or drag link.
Toe in on compression & toe out on extension.
Add shim thickness at spindle or raise the inner tie rod end by raising the rack or drag link.
Toe in on both compression & extension.
Lengthen the tie rod.
Toe out on both compression & extension.Shorten the tie rod.
Toe out on compression. Toe in on extension and then toes out with additional extension.
Reduce shim at spindle and shorten tie rod.
Toe in on compression. Toe out on extension and then toes in with additional extension.
Add shim at spindle and lengthen tie rod.

Bump Steer is stated as X amount of Bump Steer (in or out) in 1” of travel. The starting point for measuring Bump Steer is your static ride height. In today’s world of bump stop set ups the reward for zero Bump Steer is even greater. Bump stop set ups allow for more travel – in fact bump stop set ups use all of the travel! More travel multiplies Bump Steer geometry errors and spending the time to get it right does mean more speed and more importantly it produces a fast car all the way to the end. Why fade when you can win? Is improper Bump Steer one of the reasons why some cars slow down at the end of races?

If you have excessive Bump Steer you are un-necessarily heating your tires and wearing them out. The tires go over the bumps in a very fast manner and those millions of in and out toe oscillations generated by too much Bump Steer produces un-wanted tire heat and instability. You can think of it nearly as a toe vibration – in and out – back and forth in rapid motion. Remember, the movements occur through travel not just from bumps. Braking, acceleration, roll, transition all create movements that will magnify Bump Steer. Get rid of Bump Steer and let the driver turn the wheels verses letting the tires turn unpredictably on their own!

So – now that we see the Bump Steer light it is time for the golden question. How much Bump Steer should we run? It’s a matter of opinion and every set up guy has their magic formula. My answer is as close to zero as possible. What ever Bump Steer amount you use should be a recorded and repeatable number that is adjusted verses being an accident. Repeatability in race set up is the way to go.

A small amount of Bump Out is stable. Bump In can cause an unstable car – I always stay away from Bump In. A small amount of Bump Out ensures that my cars avoid Bumping In. A small amount of Bump Out ensures that you avoid Bump In through component flex and it covers unforeseen variations. With Bump Stop Set Ups and Big Bar Soft Spring Set Ups my recommended number is .004 of Bump Out per 1” of travel both left and right.

Before Bump Stop set ups - utilizing a common set up in a 2900 pound touring late model my base Bump Steer set up was .002 to .005 of Bump Out on the RF and .005 to .008 of Bump Out on the LF. Consult your car builder and use his experience. Remember, every car builder has their own idea of Bump Steer settings. Consistency and repeatability are the goal.

“A qualifying trick is to bolt in an extra .187 shim on the LF for your qualifying run which adds about .010 of additional Bump Steer at the LF for a qualifying total of .018 verses my standard .008. Sticker tires and their extra short term grip cover the negative effects of the added Bump for a lap or two. The benefit of the extra Bump Steer is that it manufactures some quick heat in the LF. Under the stress of a one or two lap banzai run the added LF quick heat helps set the car into the middle of the turn - sticker tires make it work”.

Go forward – move ahead.

Jeff Butcher

Tools Courtesy of JOES Racing Products, Inc. www.joesracing.com