Traction

[AdamH]

Hi Weasels,

My car is just spinning the large 315's on the car at will... I need more traction on corner exit....

so....

the rear has -3 degrees right now of camber....should I lower that..so the tires lay flatter..and sacrifice some cornering on the rear? (the rear tires are wearing on the inside edge...)

any comments or solutions

[Matt]

I noticed you burning rubber on turn exit a lot. Now, I'm no expert, but I play a lot of Forza (haha)... I would say that you would reduce your rear camber and soften the rear shocks. Did you play with tire pressures at all? Maybe a little less pressure in the back instead of reduced camber?

[mxqisit]

It's a logical conclusion, and a proven technique. Why wouldn't you try it?

[Nova_Dust]

So I guess the -3 camber gives you good cornering grip at the moment?

I would think lower the camber spec makes sense.

[AdamH]

yeah...will take a few clicks out of the rear dampening..and reduce camber to 1.5 degrees..and see how that goes...


Adam

[mxqisit]

One change at a time!!!!!!!!!!!!!

[Matt]

^^ good point.

[AdamH]

ok..will do camber first and see how that goes...

its a real pisser having lots of power on tap and not being able to lay it down..those subaru's have a very distinct advantage on power delivery for sure...at least on tight tracks

[Maxi]

Sounds like you definitely need less camber based on the wear pattern on your rear tires. Have you taken any tire temp readings? If not, buy or borrow a probe-style pyrometer and check your tire temps (do not do a cool down lap, just pull in the pits hot and immediately take tire temps on the outside, middle, and inside portions of the contact patch). From the temps you'll easily be able to tell if you need more/less camber. If the inside is hotter than the middle and outside, you have too much camber. If it's even across the entire contact patch, you have perfect camber (for that track and those track and tire conditions). If you have too much outside temp, then you need more camber.

Also keep in mind that if you're running too much rear camber on your RWD car, you're not only overheating the inside portion of it, which reduced grip, but you're also reducing your effective contact patch, which also reduced grip.

And, um, don't stomp on the gas so hard coming out of tight corners :p

[pigeon]

When taking temps that way right out of a hot lap, is there anything you could do to prevent damage to the brakes?

[AndrewW]

Buy some real dampers!!!!!!!!!!!!!!!!!!!!!!!!!!!
Moton FTW!!!!!!!!!!!!!!!!!

With the 944 we were at 396whp and never had issues putting power down with 275 RA1.
we ran approx -1.8 rear camber and 0 toe. The wider tires are more sensitive to high camber settings.

I would expect that lowering camber will help, but your dampers are probably the main source of your power down issues. Too much high speed damping causing grip disturbance.

[1999_ITR]

To prevent damage to the brakes just roll into pits and stop and immediatly take your foot of the brake, try to find a spot where the car is level so you don't have to hold the brake.

Adam even though I don't have as much power as you...my power to weight is similar. I really had to learn to ease into the throttle with my car on tight corners...I'm sure it's waaay worse for you. I agree start with the camber then soften the shocks etc etc.

[Matt]

with or without a cooldown lap, those temperature ratios can still be misleading. For example, if we run the DDT clockwise, you have a huge straight before the pit. If your tire temps are perfectly even after that straight, then the outside was probably overheating in the turns.

Or... if you are running the GP track and you want to be well set up for t5, your tire temps in the pits are useless after that long straight.

If anybody wants to fund my 95% complete on-board real-time tire temperature display/datalogger, you can get really good indication of your alignment and pressure settings without even stopping the car :)

Anything less is for circle racers :)

[pigeon]

Adam, are your shocks dual or single adjustable?
To prevent damage to the brakes just roll into pits and stop and immediatly take your foot of the brake, try to find a spot where the car is level so you don't have to hold the brake.
Wouldn't this still cause uneven cooling of the rotor, and potentially boiling the fluid in the caliper?

[pigeon]

with or without a cooldown lap, those temperature ratios can still be misleading. For example, if we run the DDT clockwise, you have a huge straight before the pit. If your tire temps are perfectly even after that straight, then the outside was probably overheating in the turns.

Or... if you are running the GP track and you want to be well set up for t5, your tire temps in the pits are useless after that long straight.

If anybody wants to fund my 95% complete on-board real-time tire temperature display/datalogger, you can get really good indication of your alignment and pressure settings without even stopping the car :)

Anything less is for circle racers :)
For inputting the temperatures into a computer they could be misleading, but if you're discussing it with someone or analyzing it yourself, you would need to take into account the track, the ambient temperature, driver style, car setup, and other stuff to properly interpret the data. It wouldn't be exact, but im sure its still rather useful.

I messed up by using the infrared instead of the probe last time I tried... next time i'll try again using the probe and seeing what happens.

[Matt]

My system is infrared, but that is fine since it is real-time. Probe is much better for pit-checks. The difference is carcass vs. tread temperature. carcass temperature has a much slower change rate and is approximately the rolling average of the tread temp. Tread temp, on the other hand can change very rapidly between the straight, the braking zone, the turn in, the power-on and the exit.

Back on topic though... Adam, maybe for more traction you should try a four-cylinder engine!

[Taylor]

I don't think having the straight prior to the exit is going to be a big deal in terms of finding out how far off the tire temps are outside-middle and inner. Using a probe will take the temp below the surface which would take longer to cool off. I think that's entering anal territory which is reserved for racing teams with a cash prize at the end of it.

Adam is a bit of a point and shoot driver, so it's possible a little right foot sensitivity training would help, but yeah sounds like there's too much camber there.

If Adam is actually concerned about that I think there's a Kensai big track day coming up so hook that up. Turn 8 and 9 should set you up well with some cornering heat before the pit (though it's right after the back straight, so maybe not so much). Course the turns at Mosport are so much wider I think the "loss of traction" effect is going to be minimized since the arcs through the turns will have a much larger radius than say DDT. so any adjustments made there may not be optimal for the larger percentage of the tracks (smaller) we run in SoloSprint. Actually DDT clockwise (which maybe things have changed, but I've never run it CW in SoloSprint before) is really the only config (save maybe Fabi) that this exit location issue could matter. DDT CCW, Nelson, Full, Pro, Cayuga all exit prior to the straights.

[Slowpoke]

those subaru's have a very distinct advantage on power delivery for sure...at least on tight tracks
Like Andrew inferred... could be the nut behind the wrench. :cool:

[AdamH]

only have single adjustable Tein Ra's

hmmm..yes I think too much camber is the issue..and too much right foot..


will adjust the car this week and see how it goes at the first events at DDT..

[AndrewW]

adam, what HP/Torque are you at? over 400whp? With the tires you are using you shouldn't be having big issues putting down power. What tire pressures are you at hot?
Is something binding in the rear suspension? What bushings are you using?
Slightly less camber will help a bit, but that isn't going to cure this.

[AdamH]

hmmm...hp torque ..not sure....never dynoed the engine yet

305whp since its a 98 LS1..however I have headers..and air intake..and all the stock Ls1's dyno about 310-320rwhp...

so max lets say 320rwhp + 10hp for headers and intake=330rwhp..and maybe 350ftlbs torque or so...guessing around that..all though it has tons of torque through the whole RPM range

running 30psi cold..and about 35psi hot..

bushings are all stock...suspension is working fine..no binding ect...

i think its camber..the inside of the tire is all worn out vs the rest of the tire...

[AdamH]

ok....

so over the weekend..I took all the camber I could out of the rear...its now down to -2.2 in the rear..which should be ok..and also reduced the front to
-3.7

..also have the rear rims off and am getting the rear tires flipped to help with the uneven wear..

Adam

[mxqisit]

Have you looked into aftermarket traction control systems? :D