I was mostly focusing on AX and finally took my car to the track after a long time this weekend. Just to put what I will describe into context, I have a bone stock RS with A046s, running 0 toe all around, 1.8/1 f/r camber and 41/34 psi hot.

The rear was not planted at all in the corners. It felt like I had really tall and soft sidewall tires at the rear. The rear was not taking a firm set, but rather wallowing. I remember reading here somewhere that a certain bushing at the rear would degrade very quickly and needs to be changed on tracked Evos. I searched, but cannot find where I read it. Can someone please point me in the right direction?

This was less apparent during an AX, especially because we have a small lot with slower speeds, but any time we had a fast corner, I would get turn-in oversteer, which was probably caused by the same problem..

Thanks!
Akad

 

track, as in road course?

Your pressures need changed. Need anywhere from 6-10 psi more in the rear, and drop the fronts. I'd recommend playing in the 40-44 range, slightly less in the front.

 

Yes, road course. The car already had a lot of oversteer at those pressures (especially at trun-in). Any more would make it undriveable. It really felt like something was not right...

 

The bushings that you mentioned are rear trailing arm bushings. I've also read somewhere here that any tracked evo should get these bushings upgraded...not sure whether it's true or not... Does anyone know whether these bushings need to be upgraded or not?

 

I think your rear pressures are just plain too low, given that they are HOT pressures. You aren't at the point where increasing pressure will reduce rear grip. Rather, adding rear pressure from your starting point should increase rear grip and improve stability at turn-in and mid-corner. At a certain point, adding rear pressure reduces rear grip by reducing contact patch, but you aren't in that ballpark yet.

 

I picked up a small infrared (sp?) thermometer this weekend. Works great at the track as you can drag it along the tire and get a constant reading! Basically looking for a similar temp all across the tire to verify even wear. At least this was my strategy, lemme know if anyone disagrees.
Initially start around 35psi personally, but all depends on weather conditions and tire size...etc etc.
After cooldown, was seeing 175 in the front outside and just 135 in the rear drivers from the road-course! But as long as the temps were consistent across the tire; I'd leave the pressures along! Oh, and rotated frequently for even wear!

Btw, is 175 pretty high or normal? Running RA1's that are pretty fresh yet.

 

those aren't good for tire temps, you need a probe-type meter.

you want to measure the cord temp, not the surface, as that'll change much quicker when you come in, and are cooling it off.

That being said, i'd say that i bet my car would be completely undriveable at 41/34 too. I guess that'd be like starting at 34-30 cold?

 

Last time I was at the track I had tires that I had never tracked before on.

I used the sidewall of the tire as my guide to tire pressures. If the sidewall has any wear, the tire is folding over and you need more pressure. If the sidewall has no wear and you have to look up onto the shoulder near the tread, less pressure. You get the idea.

If you have tracked your tires before, you can use white shoe polish to mark the tire and go from there.

I ended up being real happy with 41f / 37r.

 

I did try pressures up to 42 at the rear at autocross and found that at anything above 36 the handling would become way too oversteery. I found the best balance at 40/34 (by the way I had a national driver test and reach the same conclusion in case anyone wonders if it is my driving)

It may be different on a road course, but Blackhawk Farms is very narrow and lacking in run-off areas to experiment at extremes. I tried 32-36 psi but the car felt the same except for some slight change in grip levels. Tires are certainly not rolling even at 32 psi (and I was within 0.2 sec of the track record set by Ron Adee in an STI, so I was pushing).

I guess I will start with the bushings and experiment with pressures more when I go to Autobahn next month.

Thanks for all the feedback!

 

what tires are you running?

 

To get started on setting pressures I first use a best guess on the pressures (usually 2-3 psi above stock pressures) then chalk the tire tread on the sides. That is, rub white chalk on the tread area all the way to the sidewall. After a session this will show how far over you're going. Once I make sure I'm not rolling over off the tread I adjust pressures slightly for balance (.5 increments).

 

+1
This is really the pressure to go with in the rear.

I know you've already gotten a lot of consensus in this thread on raising your rear temps, but I wanted to add that (despite all the experiences I heard suggesting 38-40f/40-44r) I've still tried a lot of different pressure combinations with the stock Evo setup and similar alignment to yours. I've found that when the rear pressures are that low the back end feels very wallowy and loose, unstable in fact. Putting the rear pressures around 42-44 with front around 38-40 keeps the tail end a bit loose (well, for a stock Evo) but most find that necessary given the huge inherent understeer in the Evo. The difference though is that once the tires are warm even though the rear becomes a bit loose it is very predictable, the very opposite of what I've found with rear pressures under 35. If you want to keep the rear in check I would still suggest bumping up the rears, but perhaps not quite over 40, maybe 38-39, still with 38f.

Good luck!

 

I figured my little temperature thingy was too good/cheep to be true! Is a probe-meter the one with a needle?


I also use the wearbar indicators for reference. Very easy to do the first few times out. After that, it gets more difficult, but you also should have a good frame of reference for your setup by then!

I think I need to get some of the chalk that was mentioned. Will anything do or recommend something specific?

 

A little toe in at the rear can also help.

When I do tire temps I don't try and make them read the same all the way accross the tire but rather make sure that the temp change is linear.

The center of the tire should not be cooler than the inside and outside. If it is then add air. If the center temp is warmer then drop some air. This is really all you can control with tire pressures. Anything else and you are looking at alignment and toe.

Another consideration is to do your temps when the car is hot and you have just run a fast lap -- ideally in a hot pit. If you do a cooldown lap and then drive through the paddock you will no longer get an accurate reading.

Good luck

 

I am running stock Advan A046s. Very stiff sidewalls as I am sure you know...