FWD Oversteer, whats going on?

Firestar_3x

Firestar_3x

Firestar_3x

Caporegime
Joined
11 Mar 2005
Posts
32,233
Location
Leafy Cheshire
Quick Summary

FWD car - Tighter country road corners around 40 - 50mph, mid corner (around the apex), steady or no throttle, not forcing any weight shift and the back end either wants to break away, does break away or the rear end feels very nervous during the corner and you can feel a slight weight shift going on at the rear.

What could it be?

Detailed

Over the past week my cars decided it would much rather oversteer than understeer, i noticed this last week whilst following another car into a tight corner, the road was damp but i know the corner very well, adjusted my speed to match the conditions but around the apex of the corner the back end broke free and i slid round the corner reasonably sideways.

I put the above down to the damp road conditions but i was a little shocked, roll on yesterday was on the way back home following a classic impreza, dry road this time same sort of corner (Large roundabout style stuff) about apex and i could feel the backend wanted to brake away, just been doing some testing and the car feels very nervous at the rear.

Now i can't hear any clunking (so to speak) i think its just by backbox knocking on the rear valance, i have new Sessantas on the rear (1k old) pressures are correct, i noticed a few weeks back whilst dropping the car off the gravel section of my drive that the rear bounced a little more than expected, just done a bounce test and i'm not sure on the results.

So my question is would leaking rear shocks cause this sort of oversteer situation since they can't damp the loading on the rear causing the backend to break away?

Little confused by this tbh, never had a tailend happy fwd car before and this car deffo wasn't till a week ago.
 
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I presume you have checked the obvious e.g. tyre pressures? Worn bushes can cause transient toe out conditions that will make the rear end feel loose.
 
Had the car up on jacks today can't see any leaking on the rear shocks but they have a massive dust cover over the piston end so can't really see the rods, might take them off mid week and have a proper look, yea tyre pressures seem spot on, i even swaped my front and rear tyres around today with no effect.

I was half thinking bushes on the rearbeam but i can't see any cracking in them, the speed the rears gone from feeling fine to totally nervous has got me thinking its a large failure of something rather than something smaller but i've never felt the difference between a worn and non worn bush so i've got no idea on the effect.
 
I had similair symptoms to this I had the rear end come round on a roundabout with my old Polo when it was wet. Turned out to be partially seized rear passanger caliper, I think my old Polo shares the same rears as yours which were known for seizing up.

I was suprised myself that the brakes caused the syptoms I put it down to almost doing a handbrake turn mid corner it was only once you got past a certain angle it felt a bit rear happy and when you were going at a fair pace.
 
Ah good idea, i've just changed my rear pads a few weeks back, could well be something in the caliper is sticking on mid corner and wanting to bring the rearend of the car around, good thinking that!
 
Why, that's all that's changed by the sounds of things, probably still have some release agent on, or maybe haven't scrubbed in yet

What were the old ones
 
only time ive seen an FWD car oversteer was in the hands of matt neal at the VXR track day.

i asked what modifications they did to the handling but was told (predictably) that it was standard and due to his (very) aggressive drying style that provoked it.

To be fair, he did flick the car first to unsettle it before getting it to slide sideways.

Still not entirely convinced however.
 
MrLOL said:
only time ive seen an FWD car oversteer was in the hands of matt neal at the VXR track day.

i asked what modifications they did to the handling but was told (predictably) that it was standard and due to his (very) aggressive drying style that provoked it.

To be fair, he did flick the car first to unsettle it before getting it to slide sideways.

Still not entirely convinced however.
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It's not that hard to get a fwd car to oversteer. In my old Focus I only needed to let off the throttle quickly to provoke the rear to step out.
 
MrLOL said:
only time ive seen an FWD car oversteer was in the hands of matt neal at the VXR track day.

i asked what modifications they did to the handling but was told (predictably) that it was standard and due to his (very) aggressive drying style that provoked it.

To be fair, he did flick the car first to unsettle it before getting it to slide sideways.

Still not entirely convinced however.
Click to expand...

Giovanardi was doing the same a couple of years ago, spent the whole lap in a Astra sideways :) He was just flicking it as you mention to unsettle it before sliding it where he wanted.
 
saitrix said:
It's not that hard to get a fwd car to oversteer. In my old Focus I only needed to let off the throttle quickly to provoke the rear to step out.
Click to expand...
I remember losing the rear end around a corner on my old XR2 and span around by 180 degrees ..But i was very Lucky that time as i didn't hit anything.....
 
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