10 replies to this topic

[eebee]

Hello folks,
I'm running a reshelled '66 Mini badged as a Cooper S. Looks great, but I have no history or spec for the car. It has a Metro engine and goes like stink. Various issues with it, but main current problem is slightly wobbly rear end when cornering at speed. All tyres good and at correct pressure; very hard lowered suspension. Could it be the rear trailing arm(s) need rebushing ?
Your help and comments will be greatly appreciate. Thanks, eebee.

[oltonlad]

jack up the rear of the car and check for play in the radius arms............thats the most likely problem.

[Stevie W]

As above,
Chock the front wheels and leave the car in gear.
Jack up and support the rear end on axle stands.
With the handbrake OFF gently grasp each rear wheel and pull towards you/push away from you.
Whilst doing this look for any movement and pay particular attention at the radius arm pivot nut.
What usually happens is either the bushes/bearings wear causing movement or the arm siezes on the shaft and the outer hole in the subframe bracket wears oval, again causing unwanted movement!
Cheers, Steve.

[Lsurt95]

are the tyres a good make and not some cheap and cheerful brand. also are you running radial or crossply tyres?

Edited by Lsurt95, 22 July 2012 - 05:50 PM.

[Tupers]

It's because you've no rear suspension travel............. raise it up and soften the suspension.

You shouldn't really suffer with wobble on hard lowered suspension, you'd be more like to see sliding and lift off oversteer.

Get the back end in the air and check the radius arms and wheel bearing for play.

[donjarr]

I would hazard a guess it going to more likely be the rear sub frame rubber bushes if it's not just sliding and lift off oversteer as mentioned. Also if the radius arm bushes were that worn, firstly I'm sure it would have failed its last MOT as to get enough movement to notice like that they are going to have to be really worn, and also I'm sure you would feel it just going straight when you make tiny steering corrections. However worn sub frame bushes can appear fine when going straight as they tend to compress under the weight of the car but when corning and loads are moved around and sideways forces introduced then the rear subframe can move around.

So as to check the rear arms as mentioned you are going to have to jack the car up anyway, jack it up on the body and get someone to watch the subframe bushes to see if there is any movement as the weight is taken off the wheels. If the car lifts a bit before the subframe does chances are the rubber bushes are knackered.

:)

[Cooperman]

The term 'wobble' is not exactly a technical description and could encompass a variety of conditions.
It could be a case of a lowered and stiffer rear suspension more suited to smooth race tracks causing 'patter' on bumpy corners on normal public roads.
But equally it could be the rear suspension is not toein-in the right amount.
Or it could be worn bushes in the radius arms.
Or it could be a road-holding issue due to in correct tyre pressures,
Etc., Etc.

[eebee]

Thanks to all. By wobbly, I mean the rear feels off balance on fast cornering; not sliding, just like something's giving up under load. Tyres are a mixture, including Camac. Probably need A008's again like on my old 'sticky' Cooper. Also, does light mayonnaise on oil cap mean doom/engine rebuild ? Thanks for all your help so far...

[Yoda]

Light mayo usually means someone is on a diet!


Sorry, couldn't resist that!

A Mixture of tyres definitely won't be helping, are they in pairs back and front or a complete mixture?

Edited by Yoda, 23 July 2012 - 08:25 AM.

[Cooperman]

It's probably not going to be possible to diagnose the problem without either seeing or driving the car.
If you have lowered the suspension, but you are using the car on public roads then it won't be as stable in bumpy corners as a car at standard ride height. Lowering is for the track, which is a smooth surface, and thus the suspension travel can be reduced without compromise. Hard damping is also detrimental to good road holding on normal roads.
There are so many factors which could affect the rear end road-holding, the handling and the general 'feel'.
You need to do the following:
Set the ride height back to standard all round, soften off the dampers to allow the suspension to work in the way it was designed to.
Check all suspension bushes for wear and replace as necessary.
Check the suspension settings to the following:
Front: Toe-out: 1 mm, Camber: 1 to 1.5 degrees, Castor: 3.5 degrees
Fit decent matched tyres.
Rear: Toe-in: 1 mm to 2 mm Camber: Zero to 0.5 degrees negative.

[eebee]

Thanks everyone. It's the nearside rear trailing arm bush; kernackered ! Tyres are a complete mixture too. Basically, a tired Min which needs a bit of time spent on it (by my 13 year old son).