ALL SUGGESTIONS APPRECIATED

I bought my new RST about 2 months ago with a braking problem and I still can't seem to solve it so I'm turning to the peeps of PF...please HELP as its doing my nut

The steering wheel / dash vibrates really badly when breaking.....It doesn't really do it at low speed mainly from above 40mph.....If I brake really hard it disappears (its just under light application of the pedal).

The following has been replaced with no change:

Wheels and tyres (all perfectly balanced up)
Suspension and springs
Rear brakes (changed to discs)
Front track control arms (all the bushes are tip-top as well)
The tracking has been done (The castor is out on the near-side 3.5 degrees)

The front brakes are ST170mm 300mm discs and calipers which have only done 2k and I really don't think they are warped (they are not Ford discs).

Has anyone got a set of these discs knocking/laying about that I could try to elimnate this (I don't fancy buying another pair on the off-chance).

In addition my mate (who I bought the car off) bumped into the kerb last winter pushing the off-side wheel back the following was replaced: the anti-roll bar (replaced), the off-side mounting point (replaced) and the TCA (replaced). He doesn't think the vibration was happening after these items were replaced it just suddenly started afterwards.

N.B. The drive shaft was pushed back far enough that it hit the chassis (where i comes through the inner wing) bending it slightly.

Can anyone suggest what could be the problem before I start replacing any more parts (or burn it )

Could there be something bent on the drive (i.e. shaft, C.V.s, hub etc...)

 

get it on a jig chassis may be bent or twisted frount end

 

Big hit then, geometry needs checked

 

The bent piece of chassis is only the lip (it just curled it over). I've had a look around the suspension mounting points and there doesn't seem to be any visable damage.

How do I go about having the geometry checked? What do they actually do??

The reason I didn't suspect its a geometry problem is that fact it still drives ok....and with it being a braking problem it seemed rotational. I was under the impression a bent chassis would just meant it pulled to one side under power/braking rather than vibrate?? (I'm no expert though).

My mate reckons this problem didn't start until a few months after the car was 'Fixed' after the accident.

n.b. There is no pulsing coming through the pedal under braking.

 

Sounds like the discs are warped, they dont have to be old to get warped it can happen on a set of dics a day old. (sorry if i aint read thru the post propperly & the discs have been changed).

 

you got dannyc old motor if so whats he driving these days

 

check the discs for run out with a dti, if there straight-check inside and outside though, then i'd look at a sticking front caliper.

Tricky

 

Calipers are pretty much brand new (could they be sticking?). There is no pulsing coming through the pedal....could it still be warped discs??

I'll have the discs checked this weekend but I'm pretty confident they are ok (I had a quick check done by a mechanic a few weeks ago and he said they were ok).

Any other ideas anyone?

Who do I speak to to get the geometry checked??

 

i used tto get very bad vibrations with my car whenn i first bought it when braking from high speed, changed the discs and pads at the same time problem solved.

i think its the disc mate

 

A company like ELITE will do a full test of angles of the dangles for ya.

www.elite.co.uk or summin like that

Have you checked the rack for movement in the joints?

 

If we are all making wild guess's i reckon disks. Where did you buy them from and were they new? If not why did the person who was selling them do so?

 

One side or both John ?

Jack the front of the car up and put it on stands. Replicate the braking to see if it happens off load so to speak. I know you have changed suspension but were the rubber mountings changed too ? But I too think it may be a disc problem. If its just one side swap them over for a sec and see if it follows.

Just an idea

 

OK guys thanks for the info..... I think the first thing to do is eliminate the possibility of it being the discs before I go any further

JANO - The discs (and pads and calipers) were bought second hand from Steve@RSX off here having covered minimal mileage.

NutsRS - Not sure what you mean by which side as its just transmitted through the steering wheel/car

I'll have the brakes/discs checked over the weekend and re-post

 

Is the front wheel bearing okay ?

 

Not sure how to check it? I had a quick shake of the wheel and it had a couple of mm play on one side and none on the other. Could a faulty wheel bearing cause the above symptoms?

Thanks for the help

 

My old XR2 Turbo used to do exactly that.

I replaced everything and it still didn't sort the problem.

One day though the drive shaft snapped and after replacing it the vibrating went away.

 

Mine used to do this and it turnde out that I had indeed warped my 300mm discs. New discs were fitted and the wobble has not returned.

Hope you suss it mate as I know how annoying these things are

 

99% sure it will be the disc, but just giving other things to check / rule out too.

To check a bearing jack the car up. Put your hands at 12 o clock and 6 o clock position on the wheel and rock to see if there is any play. Repeat at the 9 oclock and 3 o clock positions. There should only be a small amount of play, any more than a couple of mm and it can start to cause issues yes.

 

Get the discs checked.
The unipart ones we used to put onto rovers were always checked and usually always slightly warped.

May be worth checking what your disk is installed onto ie. state of the hub is it clear of rust and grot.

Get a 4 wheel track done some where also to eliminate any chassis damage.

Was the Drive shaft replaced?

 

Cheers guys...a few thing foe me to check at the weekend then

The drive shaft wasn't replaced but I got hold of a complete assembly including C.V.s and everything so I think I'll chuck that on and see what happens after checking the discs

 

John,

Replace the discs mate.

 

Does sound like discs to me

 

I don't want to there all new and shiney