rear steer on ACB10s

[Beej]

so what have I done wrong? Went out on my new ACB10s at Goodwood on Saturday and I've still got the problem (in the dry) that I was having in the semi damp on the worn predecessors (which I put down to it being damp and worn out). The problem is that the rear feels like it wants to overtake the front. On lift off, braking and turn in the effect is a very disconcerting tendancy to wander about at the back - as though it was toeing out (which it isn't). Under power on exit you can adjust with throttle and steering but its not right. The car handles very neutrally on "normal" tyres.

 

It must be something to do with the cross plies. Any ideas from anyone?

 

BTW, even with the nervy set up, it was still a hoot and very very grippy. Big fun.

[TorAtle]

Are you using the correct deDion ears for crossplies?

[Beej]

No. At least, they aren't the right colour and don't have a stamp on top, so I assume not. That being said I could not detect any static camber, so I am not so certain. Even so, extra camber at the back is more likely to resist rear steer than create it, isn't it? I know it "feels" like its from the back but I wonder if its actually to do with the front?

[robmar]

any idea what compound you are using and what pressures you have in 🤔

 

where they brand new or second hand 🤔

 

I once ran some 2nd hand acb's on a standard setup and had very skittish handling, was never sure if it was the tyres or the setup

 

rob

[Paul McKenzie]

No wonder if you're running the wrong camber settings 😳 You need to correct the cambers by fitting 0.25 rear ears (or a 0.5mm ally shim on the top two bolts). This will remove the excess negative camber which the radial ears give and bring the wheels upright which you need for crossplies.

 

Also you need to reset the front camber to about 0.25 degs negative, zero camber to all intents and purposes. If you know how much negative camber you have on the front already, you can remove it by winding out the top link..each full turn is worth a quarter degree of camber.

 

ACB10's are horrible on the wrong camber settings

 

Paul

[Beej]

brand new. 33's (I think). 18 psi all round.

 

it looks like its the camber thats caused the handling trait. I guess I'll have to change it and try again.

[Peter Carmichael]

Don't jump to the conclusion that it is the camber. The first standard factory superlights came with normal de dion ears 1.5 deg negative and A30 compound ACB10s. These cars were lauded by the press as "the best Seven ever". I know mine worked fine with the standard settings although I have since changed to reduced camber settings to match bigger tyres and to give more grip.

 

What you are describing doesn't sound like a camber problem. Sounds more like a ride height and tyre pressure problem.

 

Sahf London;

every 1st Wednesday from 19:30 at The Duck just around the corner from Clapham Junction station

[RESOLVIWOLF]

very unlikey to be camber

 

i ran slicks with lots of camber for a bit and i would have been over teh moon if the rear was as loose as you just described 😬

 

 

check all teh normal stuff liek rake, pressures, arbs, rear toe, spring rates etc...

 

 

[Beej]

ok now I'm really confused. Simon Lambert thinks its camber and so do several other people on this thread but may be it isn't? The car is not tail happy in a "no grip at the rear = lots of sideways fun" good way - say like runnning some knackered old tyres in the wet. Its tail happy in a nasty, snappy, no where near the loud pedal but still wants to leap about way. And I should point out that it handles perfectly on radials - Yoko 21s in the dry are pretty sticky when they are warmed up and had none of these snappy characteristics.

 

Does anybody know what tyres the Vx race cars ran on? My car was built by Taylors foundry as a Vx Challenge car but never raced and subsequently road registered. Its reasonable to assume that it was set up for the control tyre. If those were ACB10s then I'm really flummoxed.

 

Cheers

 

Mark

[Paul McKenzie]

Beej,

Control tyre was a 7" avon crossply slick on a 6" rim. I'd get awheel alignment check if I were you..only then will you know if you're running correct cambers...for anything!

Paul

 

Edited by - Paul McKenzie on 27 Jul 2004 10:26:56

[Beej]

oh bugger. so ACB10s should handle pretty much the same? May be I should talk to Taylors?

[Gary Furst]

Beej.

 

What size wheels are you using with the ACB10s? ACB10s are (when fitted to the right diameter wheels) very much stiffer than the equivalent radial tyre. If as I tried once fitting 7" wide ACB10s to 6" wide rims the car felt looser both turning in with less precision and then oversteering. If you have say 6" rims all round and are trying 6" tyres on the front and 7" on the rears then you might get the oversteer without the initial understeer that I got.

[Beej]

Gary,

 

13" 6.5J minators (minilite style)

 

According to Avon, they are the right size tyres for the wheels but I am sure you are right, the sidewalls will move about more or less depending on the fitment.

 

Mark

[Gridgway]

it sounds to me that Simon is eliminating an obvious 'wrong' thing. But I agree with Peter (it's a miracle) that it's very unlikely to be camber. I ran

my R500 happily on 'radial' settings with ACBs with no sign of snappiness at the back.

 

Graham

(PS It was Simon who told me given the above info, that it didn't really matter!)