911

I currently hill climb my STi V3 on Toyo TS1's (surprisingly good!)
The car's suspension is all Whiteline and MRT top mounts, AVO adjustable struts etc, all set to Whiteline REX 2 spec; 3 deg neg camber + 4 deg pos caster, with the rear 2 deg neg.

Question: What do I change the front to to deal with Avon crossply slicks? Do I back-off the front camber to 1.5 neg?
Any thoughts welcome...
Graham

Pavlo

You might not need to, best people to speak to would be Avon, they might have some data. However, temperature testing with tyre pyrometer accros the tyre will yield good data. you want to be about 3 degrees C hotter on the insides, moreso on the tyres that get the most work (but most hill climbs are quite even).

ALso the less roll you get the less Neg camber you need anyway (generally). How are the Toyos currently wearing? You might get some better bite into the corner with less negative camber. Tyre pressures also play a part, as higher ones will yield lower sidewall flex.

Also bear in mind, the less neg camber you can run on the front, the better the brakes are going to be when tyres are cold, quite important on a hill climb.

I haven't run slicks on a scoob (or any road car) so not best placed to say, very dependant on the paticular tyre.

Paul

911

Thanks for coming back to me. Got it wrong on my message above, the front is running 3 deg Neg.Rest is correct.
Hillclimbed the STi over Easter on these new Whiteline settings. During the 3 practice runs (hill is one mile long and very twisty)the tyres at the front were even temperature to my hand, and the rears much the same evenness, just a bit cooler.
Had all the wheels off yesterday to check all is well underneath the car after a bit of an 'off' during my last race climb, and the tread wear is even right across the tyres. Leaving the startline and braking are fine, but I am thinking the front camber is too much. I've emailed Whiteline for advice.
I've found that 35psi all round, dry and wet, suit this car and my style, the whole tread block is working, but not the sidewall! I'm running Scooby 16'' wheels with 16x205x50 tyre size.
Last year the car without all the Whiteline bits used to understear so bad I once went round a tight bend on full lock!
Always pleased to discuss these tech details, thanks again for the reply.
Graham.

Pavlo

I found that changing to much stiffer coilover suspension meant running about 1.2' neg camber on the front rather than 2.5' due to reduced body roll and weight transfer (lowered too).

but some of those crossply slicks can run more neg camber.

Also, get a tyre pyrometer to measure tyre temps accurately, I use one that has an adjustable spike on the end, so I have about 3mm of the probe stabbed into the tyre to make the measurement.

What I'm not sure of is the effects of the very tight turns you get on hill climbs, as that will put the wheels at some odd angles you might not get on even a twisty race track.

Paul

911

Whiteline have asked for a full spec on the car's set-up so they can advise.
My friend who hill climbs has a Cossie and has left his set-up for road tyres(SO2's) the same for Avons. Avon hillclimb slicks are very very very soft compared to track compounds, but I have been offered some with special re-enforced carcase construction, good for heavy cars.
I think I've read too much about this subject and I'm now confused.
The bends in a hill climb are tighter than country lanes, are single track wide and lined with trees and Armco barriers everywhere, not much room for the odd 'mistake'! Nothing like a race track.
Graham