911

Racing this year on full-on Avon hill climb crossply slicks.
Any suggestions for the front/rear camber settings? I have a stack of negative at each corner at present using road tyres, adjustable cam bolts all round and adjustable top mounts to at the front.
Any suggestions?
Graham.

dowser

I run -5 at front, and -3.5 rear with 1mm per side toe out at front, same toe in at rear. This is on KW v3 lowered about 2.5cm's from OE with uprated springs, plus front/rear ARB's and an ALK. I am much slower on a bumpy b-road than in the old Koni/Eibach days....but much, much faster on track

Depending on the new diffs (STi7 stock [Suretrac] front and centre, plated STi V3 rear), I will probably try a little more camber and a more parallel toe set-up this year.

Road tyres don't last long like this though, and braking stability suffers (I guess because of front toe-out?).

But I find what works for one, doesn't necessarily work for others. And if I focused more on hill climbing then I guess I'd be softening spring rates a bit....which would probably have knock-on effects elsewhere. The whole geometry and suspension set-up comes down to personal preferences and driving style really. You need to change, test, change, test, etc. Can get time consuming, and expensive!

Richard

TopBanana

I've heard they work best at about 0.75 neg deg on the front, 0.5 neg deg on the back.

911

That's what I thought John, near verticle, BUT, does it not depend on the body roll? Vertical to the road at full cornering force?
We have a members practice day at the local hill climb at the end of March, so will leave alone till then, if it is dry, then I will find out soon enough....
Hows your preparation coming along John for this season?
Graham.

TopBanana

Hi Gareth - sorry, forgot about this thread. Yes I the camber will change with body roll - I think that's why lots of caster is so important. Have you got decent gauges? Are you able to change your settings easily? I guess it's a case of getting out there and tweaking. What anti-roll bars are you running?

My preparation hasn't started, been way too busy getting two houses up together I'll probably still run in a few events later in the year to get an idea of how everything works though.

Mark A

iTrader: (1)

0.75 & 0.5 seems like a very small amount of negative camber to use ? Can somebody explain why ?

Mark A

TopBanana

Crossply tyres need much less negative camber to work well. Not sure why, but I guess if you think about it, you can imagine a crossply tyre deforming very differently under lateral load.

911

Whiteline have advised that I keep the road tyre geometry for now. Run the slicks and check the surface temperatures after a run. Adjust the camber to get an even temperature. Will try this by experiment at the Club'd practice day at our track end of March.
Graham.

LeMans

Hi Graham,

At a Castle Combe trackday where I ran my slicks to try them out I ran normal road tyre geometry and after 15 minutes of lapping very fast the tyre pressures had only increased marginally although the tyres were nice and sticky on the outside, so I came to the conclusion that the geometry should be okay for my hillclimbs - but only time will tell !.

Will be interested to see what you find at your track day in March.

Stuart

Pavlo

Let temps be your guide. Ideally run about 3º hotter on insides of rear tyres, as this is the way the heat is scrubbed.

Different tyre contructions, even within crossply design can be different. Some are very flat, some quite curved.

I would say running low neg camber might be a hill climb special, as you don't get much time to get heat into tyres, and you don't want to be braking on the inside edges on the first few turns. Although this will be balanced with pressures too.

Plated rear diff may require more caster for hill climb too, as you may want to unweight inside rear tyre using the fronts to avoid pushing on.

Give it a go as is and see, gotta start somewhere!

paul

Mark A

iTrader: (1)

Graham,

How much did your slicks cost and where did you buy them from (e-mail if you want). I've been offered a set of yokohama slicks cheapish but don't know if they are crossply, how can I find out ?
I bought a CF bonnet from the US in the end, it weighs 5.5kgs.

Mark A

CarMan

Graham

You really do need a pyrometer to check those tyre temps and if you are too tight to buy mine then I guess I will have to lend it to you. Unless, of course someone else has bought it by then!

Rob

911

Thanks for the logical advice Paul, as ever, always interesting!
As for bloody Carman, he has a killer RA and too many things to play with...
Seriously, the palm of the hand is resonably accurate as you are comparing temperature changes not recording the actual temperature.
Mark, getting slicks from BMTR here in Birmingham in 2 weeks time. They are strengthened with Kevlar(!) that will make Paul think! and were very successful on a fast Escort cossie with about 450bhp.
Cost will be a sky high £170............each. Remember these are hill climb specials by Avon. Hope my transmission will take it.
Beware of 'other' slicks if you hill climb you need the right compound. they heat up very very fast, and will be scrubbing inside of a 60 second hill climb blast, about 3 corners at Donnington!
Thanks to everyone, even 'V8 Landie carman' what a title Rob!