Handling Issues?

[Dan57 0]

I have been using my 1.9 gti as a budget track car this year. I have managed to overcome most issues but still having one regarding cornering. It seems to be only at high speed and not necessarily tight corners. the car feels generally unstable above about 70 mph but when cornering from about 50 mph upward the back end feels very light and has on several occassions stepped out. Also when braking hard the back end locks up before the front, this may or may not be related. the more you throw the car into the corner the worse the oversteer becomes. I have tried adapting my driving style e.g keeping on the throttle through the corner but it still feels sooo wrong.

 

I have a 10 pt roll cage fitted, ventura 40mm lowering spring, lowered rear one spline, standard shocks (I don't think these are at fault as the car is very stiff.) solid rear subframe bushes (however I do not have the poly bushes for the front of the rear subframe. The bodywork has also been cut, inner boot lid and front doors, fully stripped incl no heater.

 

I have changed the tyres to Dunlop formula R DJ01's

 

My thoughts are:

1) If I stiffen the front roll bar this will induce understeer hopefully curing the problem.

2) Because of the lack of spare wheel perhaps the air flow collecting behind the bumper and is lifting the rear of the car.

3) That's just the way it is.

 

Can anybody shed some light or have any tips or suggestions?

[Guest wingnut]

Stiffening the rear might make it understeer for a while, but get too complacent and she'll bite yer nads off when she snaps and oversteers.

 

Perhaps adjusting the toe settings on the front to get a little less responsiveness there may help? At least then you can keep on the gas all the way. Downside will be scrubbing the tyres though...

[Dan57 0]

Any suggestions on toe setting? I have adjusted the toe but only the factory settings, I can't remember of hand what these are though. My tires cost £150 each so don't really want to scrub them unneccessarily.

 

I thought stiffening the front would make it understeer???

 

A little understeer would be nice as there is absolutely none. The grip on the front really is phenominal and it just grips until the back starts to go.

 

Another thought could it just be that the tires are to good for the back of the car and I cannot get enough heat into them? I have only ever driven the car on these tyres and some really poor tyres that may have well been made of plastic.

[Baz 421]

I'd say check the condition of the rear brake compensators if the rear/biassing is doing funny things, they're quite common to c*ck up!!

 

But mainly, i think no. 3. They are very light at the rear and have a tendency to oversteer, especially when the throttle's lifted at high speed!!

[Dan57 0]

Just fitted new compensator to the n/s as I had no brake there at all . I had that thought too and was convinced that this would solve the problem. I knew about the oversteer issues on these before i bought one but never realised it would be this bad. I may have a play with roll bars and see what happens.

[AdamP 0]

Problem is that you've removed all the mass from the rear of the car, which has the same effect as stiffening the springs (in this case torsion bars and ARB). This 'stiffening' of the rear ARB means the back end is more likely to lift the inside wheel, losing grip. Stiffening the front arb to match will cause the front to lose grip before the rear, masking the problem but not solving it. Ideally you want to get a smaller rear arb which will allow the inside wheel to stay in contact with the tarmac better, and stiffer torsion bars so make up for the extra roll.

 

Hope that makes sense, it does in my head!

[Dan57 0]

That does make perfect sence. It does feel like it picks a wheel but obviously when I am driving I cannot see it I am hopefully tacking on track again on Sunday so may try fitting a spare wheel for that. At least the added weight will be low down, and very good in case of a puncture. Where would I get a weaker rear arb and stiffer torsion bars from?

[AdamP 0]

That does make perfect sence. It does feel like it picks a wheel but obviously when I am driving I cannot see it I am hopefully tacking on track again on Sunday so may try fitting a spare wheel for that. At least the added weight will be low down, and very good in case of a puncture. Where would I get a weaker rear arb and stiffer torsion bars from?

 

A weaker arb could be found on a lower spec 205... stiffer torsion bars off a 309 GTi? Not sure about those!

[t16ryan 1]

Have you had the rear beam rebuilt sounds like it could possib;y be on its way out??

[welshpug 1,627]

blimey what tyres do you run???

[pug_ham 242 3 Cars]

blimey what tyres do you run???

 

I have changed the tyres to Dunlop formula R DJ01's

 

stiffer torsion bars off a 309 GTi? Not sure about those!

They won't fit the 205 beam but the whole 309 GTi beam can be fitted to the 205 which also widens the rear track.

 

I could be just #3. Mine isn't quite as stripped as your car & a slightly different spec (uprated shocks & springs front & rear, 309 rear beam & 24mm rear arb) & I'm running the 1.6 front rear split braking set up which can make locking the rear pretty easy.

 

I've just fitted 309 front wishbones, driveshafts & 266mm front brakes but as yet haven't been on track with it. (that'll be fixed on Saturday. ) but I never had any problem like as this with the 205 stuff fitted up front.

 

Have you checked your wishbone bushes etc? Standard Peugeot bushes are as good as polybushes (better than some) & cheap at under £20 for a set to do both wishbones with new bolts (part # 3599 07).

 

Graham.

[brianthemagical 1]

mineoversteers, just gentle and progessive on the limit. it has 309 wishbones and all new wearables, thats it inc interior. have you had the geometry checked? something may be knackered.

 

This 'stiffening' of the rear ARB means the back end is more likely to lift the inside wheel, losing grip.

 

the inside wheel has little effect on grip as all the weight is on the outside.

[James_R 3]

I run parallel toe on my car.

 

The light tail does party sound normal if you're running near standard suspension, a larger rear ARB helps stability as the car will roll less.

 

Do you have solid rear beam mounts? I couldn't work out if you did as there's no subframe on the back?

 

What pressures do you run in the car??

 

Have you tried a few laps on road tyres to see if it's not as bad?

[tom_m 0]

its sounds to me like thats just the way it is. you can adjust your driving style to work with it rather than against it James_R ^ has been known to do this rather effectivly.

 

if you don't like it tho maybe its time to start looking into corner weighting and redistributing heavy objects/ballasting to get a better weight distribution. in a standard car its approx 60/40 front rear bias, which will be closer to 70/30 once you've stripped it out.

 

i've always found mine more neutral with a heavy load in the back (spare wheel and girlriends travelling wardrobe etc)

Edited September 13, 2007 by tom_m

[kyepan 291]

solid rear subframe bushes (however I do not have the poly bushes for the front of the rear subframe.

 

so you have the metal discs that replace the sandwich rubbers, but not the 4 x urithane inserts that go into the larger forward part of the beam.

 

from what i understood those other urithane bushes really stabilised the car through the high speed corners.

 

 

J

[James_R 3]

Oh didn't spot that, that will be causing the interesting handling on the slicks, will pull them around loads.