My tires had a huge amount of wear after that last autocross. The edges were all worn off and there was wear on the sidewalls on the front tires. On the right front, there was wear on the sidewall all the way down to the rim. That can't be normal or safe. The car was understeering and it felt like I was fighting to get traction.
Do my tires need more air? I checked the cold pressure and it was at 35 for the front tires and 37 at the rear. The car recommends 35 front 33 rear. The tire size is 215/45/17 and they are on 17x7 wheels.
Would bigger sway bars help keep the tires planted? The stock sway bars are thin.
Is it just my driving?
Its probably the tires from what I've experienced on my car. If you increase the PSI it won't wear on the sidewalls as much. I had to put 40 psi in my tires to make them wear properly at autocrosses. And they suggest not going over 35 psi ever
if you were experiencing understeer, power on would not correct the issue. All you were doing is burning rubber.
try entering the corner slightly slower or with a better angle, to carry more speed through.
mightyS Wrote:Do my tires need more air?
Yes. With street tires I generally run 10 psi higher than on the road at auto-x's.
Or more negative camber, though I think you have a subaru (if I remember right) which means you'd have to get replacement suspension parts to get camber. I can't comment on your line as I didn't see you run, but I think it's a safe guess to say you could probably improve it.
Three things I'd mention...
1. The Subarus I have autocrossed had fronts in 38-40 range and rear in 38- 36 range... it was done intentionally to allow the back end to rotate on turns. If you like to swing the tail around a little, reverse the pressures above...and add remove a pound to get them closer each run until you get it where you like it. Also, set up alignment negative 3 camber in front, negative 1.5 in rear... zero toe all around. That's what a lot of the guys that run SCCA AX start at when dialing in. Should be close.
2. You should not see tire wear down to the rim. Last year, Tj and I were co-driving and he had his tires set at X front and Y rear. He made a run and said front needs to drop a pound....but he walked away and took the tire gauge with him. I grabbed my back up gauge (same brand) and checked tire pressures. They showed 5 pounds lower than he set them.. different than what he said.... and they were hot! When he came back, I checked the $65 tire gauges and ... both purchased same time, same brand, less than a year old and one was off by 3.5 pounds. Usually not a big deal but if you're running lower pressures on a AWD and then take 5 or 6 off... that could be bad. I've seen the old pen air gauges be off by 10 pounds. Check your gauge for accuracy. Take 2 or three readings...see if it's consistant and accurate against several others. If not, your changes are not only hurting, they could be dangerous. I saw a few tires de-bead... not too cool.
3. That surface at Anderson is rough but not THAT bad. If you were running newer R comps at G-Braves stadium, that will wear them out really fast! If you are locking up the tires a lot, that can scrub off a lot of rubber... work on smoother braking on and off and smoother steering transitions. When the car is sliding, the rubber is leaving the tire. Fast braking or steering inputs makes it break loose faster. Usually, the place you want to be is limit of adhesion... right before it starts sliding... faster and tires last longer too.
Just something to try when adding tire pressure for autocross...
I like to chalk my tires before each run, so I can see where the tires are wearing. This helps keeps you from over-inflating the tire, specially from heat.
I think increasing the rear sway bar size can add to overseer, which might help if you are really pushing. But this may cause more problems than it helps.
I pumped up my tires quite a bit before the autocross... around 40 in the front, mid 40's in the rear (around 45psi). For the autocross I went to in Carowinds, I didn't adjust the tire pressures at all, and I DEFINITELY felt a difference. It was terrible, my sidewalls felt so flexible, and it was far less responsive than usual. I made sure to pump up the tires this time, and I'm glad I did. My car was very responsive and easy to handle, with it being very apparent where there limits are. The car was also very easy to recover with if I did push past those limits (LIFT THROTTLE OVERSTEER FTW!!)
I noticed that the tires wore very quickly when I didn't have them with as high of pressure, so definitely try pumping them up next time. You'll see a very noticeable difference. Tire pressure adjusting is one of the easiest ways to change how your car drives and handles, and can really make all the difference. :-)
Try not to push too hard... I think that's what my brother did in the Accord, he was apparently sliding all over the place. Back when I drove that car and had recently put in the new sway bars, that thing was very hard for me to actually cause the tires to really break loose. I believe he needs some work, but he's learning. He doesn't autocross very often and really gets annoyed when I talk about cars too often. :-P
ALSO! When I had the Accord, I made the mistake once with one of those power air pumps for the tires (completely read the wrong meter... wow that was a big mistake) and filled those 15 inch wheels with the puffy 195/65 tires up to 78 psi.
The car handled like crap and had an absolutely tiny contact patch... was very floaty on the highway. When I tested with my awesome digital tire pressure gauge, it told me of that unbelievable number, and I immediately dropped the pressures. I drove several hundred miles on those tires with that much pressure in them, AND an autocross, so its safe to assume that they really can take a lot more than you'd expect.
That's pretty funny David!
More camber and higher air pressures
smooth = fast
slow in, fast out
Um, be the tire?
Hope all these suggestions help. Did you have any "instructors" ride along or drive your car? That would show you how it's done.
Understeer sucks.
Thanks for the replies.
I have a 05 Subaru Legacy so it is awd. My tires are the Bridgestone re92 (multiseason) I looked them up on Tire Rack and they were the lowest rated tire! Plus they had 56,000 miles and 5 years on them.
Nope, I didn't have an instructor with me this time. I had Sam help me last November. Last time (my first autocross), my times dropped at each run from 92 sec to a 78. This time I started at a 85 and dropped to a 79. My tires were loud and squealed at every turn and constantly through the sweeper. I noticed other cars going through turns much faster than me without the wheels squealing.
I'd rather not change the camber just for autocross. This is my everyday car. Plus I'd need new control arms to do it.
lol, David your brother was tossing the shit out of that Accord. I laughed so hard seeing that little econobox fly around corners with the back end coming out
Yea with our subies you generally have to go slow in and and fast out to utilize the awd. I agree with whoever said get a good tire pressure gauge, Ive found the most accurate ones are the "round dial" type, Ive had a pen and digital one and they were very inaccurate. The pressures I used for the autocross were 40 front and 38 rear on my Azenis but you might need even more than that with softer sidewalls. The tires should generally not wear past the little arows on the sidewall, and chalk helps to confirm this.
mightyS Wrote:Thanks for the replies.
I have a 05 Subaru Legacy so it is awd. My tires are the Bridgestone re92 (multiseason) I looked them up on Tire Rack and they were the lowest rated tire! Plus they had 56,000 miles and 5 years on them.
Nope, I didn't have an instructor with me this time. I had Sam help me last November. Last time (my first autocross), my times dropped at each run from 92 sec to a 78. This time I started at a 85 and dropped to a 79. My tires were loud and squealed at every turn and constantly through the sweeper. I noticed other cars going through turns much faster than me without the wheels squealing.
I'd rather not change the camber just for autocross. This is my everyday car. Plus I'd need new control arms to do it.
Sounds like new(er) tires and/or a dedicated set of autocross rims and rubber and tire pressures, depending on how much money you're looking to spend.
Is it a manual or auto? Was it trying to shift into 3rd or 4th? I know most slushbox people put it in "2" and leave it for most autox courses.
I'm buying new tires this week. I think I will be living here in the South so I can get summer tires and not worry about driving in snow. If I move back north, I'll buy a set of all-season tires again. I'll also look for a better tire gauge.
My Subaru has a 5 speed manual. I shifted into 2nd after the first right turn and left it in 2nd.
For the next autocross, I need an experienced awd driver to show me how it is done.
mightyS Wrote:I shifted into 2nd after the first right turn and left it in 2nd.
This is probably best, smooth = fast.
Rymans2k Wrote:lol, David your brother was tossing the shit out of that Accord. I laughed so hard seeing that little econobox fly around corners with the back end coming out
Lol I'm glad you were watching, and actually got several pics of the car. :-D I think that car was invisible to everyone else taking pictures, not willing to waste any film or memory space on it, but hey, I used to toss that bitch around myself. I'm glad you got to capture a bit of my brother's handywork. ;-)
I really wish he wasn't running directly after me, I wanted to watch him really bad and give him some pointers. As stupid tall and unresponsive as that car's second gear is, if driven carefully it can keep its speed through the slalom incredibly well. It's definitely capable of getting to the high 70's range.
I really appreciate the pictures though, I sent them to my brother. :-)