The autocross events around here are typically run on very dirty lots. One of them is inside a horse racing track so it has a fine layer of silty dirt over much of the course. Another location has weeds growing out between the cracks in the pavement so they have to bring weed whackers. Our lots are generally old and gravelly as well. Anyways, you can imagine that these are not the best lots you could ask for, but that's all they can get. I've noticed many times on my car that the outside shoulder on my tires never really get worked very hard at all. My car has 255 RS3s with 2.3 degrees of camber in the front and 2.6 in the rear. This is quite a bit less than what other RS3 users claim to be optimum (3+ degrees). I've noticed in the local chapter that none of the cars, including s2k's, run significant amounts of camber. They all look like they have less than 1.5 degrees. They all seem to hook up much better than my car though. My car handles great on curvy roads where traffic has cleaned all the dirt off, but on the dirty autox courses it feels like I'm driving in the wet.

Is it possible to gain more grip on dirty pavement by decreasing my camber to more conservative numbers? I would really love the extra tire life, that's for sure.

 

Bump. Does everyone here just race on perfectly groomed lots and tracks?

 

up here in the Northeast we are spoiled with a good site. But a loose surface may likely prevent you from taking advantage of that camber. one way to find out right? can you take a picture of the shoulders on your tires where the wear indicator is and maybe a video?

 

What tire pressures are you running? If your pressures are too high you could get the same symptoms of less grip and no outer shoulder wear.

 

yes it's possible that your lot is so low grip that you need lower camber than most here. A tire pyrometer would help you get a better idea of what's going on. Or you could just try lower camber and see how it goes.

 

We have a lot here that is smooth and dusty. Time differentials between morning to afternoon can be upwards of a second. The cars that are sprung softer and/or aligned with less negative camber all do a bit better here.

It is not unheard of for the upper echelon of competitors having a spring or alignment change for certain venues.

 

If you can't load up the tyres as hard laterally as the track guys on sticky tyres, then your static camber is a waste as it's supposed to account for sidewall flex that won't be there, you'll still want a bit for camber thrust mind.
Having said that, it depends how rough your events are, but I often run more camber than I need to just because it protects the tyres against being pulled off the bead over holes/sharp edges that grab at the tyre.

 

I guess the only thing I can do is test and see. I don't often get to drive on the actual courses or at events though because of my schedule. I do my own alignments so they are free, just time consuming.

Another part of my theory is that my car is not sprung as stiffly as more competitive STR cars going by the STR thread. I have 670 lb/in springs in the front and 560 in the rear with stock '02 roll bars, so I still have some body roll. I'm thinking the less body roll you have, the more static camber you need since you're not using as much of the camber curve as the suspension compresses.