Brake judder, warped discs?
 

Hi!
I've have a little problem with my brakes. Whenever I hit the brakes at high speed my front brakes start to vibrate and sort of shake so that I can feel it through the steeringwheel. If you brake with no hands on the wheel you can see the wheel vibrate from left to right.
But whenever I hit the brakes hard the vibrations stop and it feels like normal. It only appears when I brake in small amounts.
Do I have warped brake discs?

Johan

Or may be play in the steering rack joints? :shrug:

Yes, sounds like some slight disk warping and the fix might be an easy no effort, no cost one.

Take the car on an open, but little used fast road, where you can safely get it up to 70 mph and brake very hard (just short of the ABS being triggered), several times in succession.

The idea is to get the disks good and hot, but not come to a complete stop, then rapid acceleration again to 70 and repeat. Do it two/ three times and it may just fix the issue at no cost. Remember you must not come to a complete stop with hot disks, because that will cause distortion.

Brake/steering judder
 

Hi Johan,

I had identical symptoms on my 05 diesel Tourer. It turned out to be the front suspension lower arm rear bushes. I did both sides and the problem was completely cured. I also blamed the discs, which may be your problem but I would strongly suggest either checking or getting the bushes checked before investing in new discs and pads?

Russ :shrug:

The brakes are fluctuating. This condition is down to the discs. If the discs look good from the outside and free from corrosion, check the inner surface. If rust has contaminated the surface, this will give the symptom.

Check this first, cheapest and easiest option before exchanging the item.

When has the brake fluid been replaced?
If old and too much water in it, it will do funny stuff and could be like you are experiencing.

Rob

discs
 

I had this problem also. lower arm replacements made no difference and the discs looked good. Traced the problem to the nearside disc not seating very well; the single securing screw pulled it slightly off centre. Cured by not tightening that screw too tight (the wheel studs hold the disc on) and fine after that.
BTW - I'm sure there is no need to worry too much about warping discs if you brake hard from a fast speed and hold on the brakes. I race cars and have never had such a problem after getting the brakes/discs nice and hot and holding on the start line for some time.

Do you feel a slight judder when braking at low speed?

Sometimes discs develop a rough/smooth area that feels like judder but has nowt to do with warped discs.

Mine recently decided to shake the steering wheel out of my hands when lightly braking from 70-ish mph or so.

Also had a, ever so slight, vibration in the wheels when normal driving.

Had the car checked and balanced at Imperial in Swindon, using the Road-Force balancer.
They found that my front wheels are slightly buckled and did all they could to sort it out.

End result is that the shaking when braking is gone, so the discs were fine, and I now need to find a new set of rims.

Moral is that judder is not always the discs, but can be tyres, wheels or steering as well.

Ok thanks guys for all the tips! I have a couple of things to check for but I think I will start with checking the bushes and the brakefluid because the discs seems too be in good condition. I will definitely try the road braking test and see if that cures the problem.
And yes it only appears at higher speeds, can't feel it at all at lower speeds in towns for example.
I'm installing polybushes all around the car soon with new wheels, new springs and balancing all the four wheels. Hope that will sort it out!
I've heard that some bushes are a pain in the **** to change and some are easier to get to, which ones are the hard ones?

Cheers

Johan

As already said, warped discs, lower rear mounts (front arm) etc will give you a judder.

I've got a BMW in next week for the same issue.

On checking the lower arms, both rear bushes are shot, a huge amount of play in the O/S lower ball joint & slight play in the N/S.

Checking the run-out on the front discs, they are borderline.

The BMW's (this is a 3 series) have a very similar setup to the 75.

You'll soon know if the lower bushes are gone:

Put a socket/bar on a wheel bolt & pull the bar towards the back of the car, you'll see & feel excessive back & forth movement (this BMW has a good 1 1/2"-2" !!)