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MG MGF Technical - MGF Bad Handling

After an hydragas recharge I started to fell the car instable in motorways, specially at speeds above 120km/h, I get floating feeling from the back end, is like driving in heavy wind all the time. In fact, it feels dangerous and the only way is reduce speed to 100km/h.
I had the car re-aligned, but I don’t get any improvement, the ride height is 355mm , and the tyres are the same Michelin Pilot that I had before.

Any ideas on what might be wrong and how I can restore the fun to my motoring would be much appreciated.

cheers

Joao

98 1.8i mpi
Joao Barros Gomes

Are they new tyres ?

If so, new tyres on the rear only give this effect for about 500 miles until they have worn the initial skin off.

It's quite worrying, almost feels like a wheel is loose but like i say it soon goes.

It's not so noticeable on the front and when new tyres are fitted all around.

Stu
Stu Dickens

Hi Joao,
long time no speak.
:)
May be a similar problem that Neil reported in the current thread *nervous behaviour*

It's almost a worn bearing, or gone ball joint (upper or lower one) or may be wheel bearing.

Car re-alignement is of no use if anything has play and is _moving_ at higher speed.
Mind you, the re-alignement is only as correct as the rear wheels are rock solid mounted to the car.
Alignement will fail if anything is loose there. So that's it where to start investigations.
Rear lower arm ball joint and fixture i.e. and
did you get in the compliance washers to removing the play from the tie bar to lower arm bush ?

Upper Ball joints only could get checked if the suspension is de-pressurised.

HTH
Dieter
Dieter

Hi Dieter, In fact I have been away from the BBS for some time….
About the F, I didn’t check any mechanic components yet. Just notice that the car handling was weird since the last hydragas recharge on Valter’s garage. I talk with him, and we first thought it was the wheel alignment settings, because the new ride height… but after a new alignment, the ride was about the same.

Answering Stu, the tyres are not new but they are ok.
About the worn bearing or ball joints, is it something that you could check easily? What should look like a faulty joint?

Is it good idea replace the older rubber bushes for new Polly bushes and compliance washers or am I spending a lot of money on this?

I appreciate your help

Regards

Joćo
Joao Barros Gomes

Raise each corner of the car in turn and try to wobble the wheel horizontally and vertically - any play will indicate failure of ball joints or wheel bearings.

Another thought - could one of the dampers have become detatached at the rear? Standard dampers have been known to do this - especially on earlier cars. Worth a look. Also check the condition of the ARBs.

Do let us know what the problem turns out to be :o)
Rob Bell

Hi Joao
Agree with Rob and Dieter.....Wheel bearing....mine felt as though I was in an unstable rowing boat !

Paul
Paul Carugati (MGF and MGBGT)

hi
look at this for the work :
http://www.mgcars.org.uk/cgi-bin/gen5?runprog=mgoc&p=emg/bearing1.htm
regards
PAD Pascandrea

worn ball joint.
I've had this too. The behaviour on motorway was exactly as you described. The rear going sideways... not exactly a pleasant feeling !
Fabrice

Thanks guys, I will check this items next weekend.

Joćo
Joao Barros Gomes

Hi

Today I remove both rear wheels, and the right rear roller foot joint looks damaged, the rubber seal has gone and wheel seams to play in and out a little more than the left side.
I can’t find the roller foot joint in the parts catalogue, only on the MGF Manual workshop. Both upper ball joint looks ok. Could be this faulty element is causing the poor handling? While I am driving it seams to be the left side which is more affected. Is this a DIY job?

Regards Joćo
Joao Barros Gomes

I had the same problem - new tyres , poly bushes etc. It took my mechanic some time to find the problem. The culprit was a loose bolt which is inside the the chassis rail So loose that the nut was almost off - hard to find and not easy to tighten - will get some details for you am tomorrow. For me it was quite scarry as the body of the car would drift out to the right on a sharp high speed bend.. will be back wih more

David
David Richards

I apreciate all your help
tanks David

Joćo
Joao Barros Gomes

I have spoken to my mechanic. The bolt holds the bottom suspension arm to the chassis rail. The bolt runs from back to front and is deep inside the chassis rail -you can only just get to the head of the bolt
Hope that helps

Regrads

David
David Richards

The roller foot joint (better known as the knuckle joint) is a fairly easy DIY depending on current ride height - if the car is significantly lower than 'normal', or if the shorter lowering pins are fitted, you may be able to remove/replace it without de-pressurising the hydragas system. I would be surprised if this alone was causing the problem though :o/

The bolt David is referring to is accessed through a rubber grommet in the curved section of the subframe. With the right length extension bar and IIRC a 17mm socket I had no problems... I did however find that the bolt from hub to lower suspension arm could loosen itself in normal driving, which gave some very interesting handling indeed 8-0

IMHO replacing all the rubber bushes with poly is well worth doing - not actually as much work as you may think, and you get much sharper handling as a result.
Mike Hankin

Thanks for providing greater level of information with reference "the bolt"

Totally agree with your comments about putting in poly bushes -one of the better things I have done

David
David Richards

I appreciate the info. I let you know if I could find “the bolt”….
I agree with you about the polybushes, but is a considerable investment for a car that has only 75000kms.
First I going to fit compliance washers and replace the damage rear knuckle joint and find that “bolt”… and I hope that solves it!.... I will let you know

Cheers

Joćo
Joćo Barros Gomes

This thread was discussed between 01/05/2007 and 15/05/2007

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