Brake wobble: what's the consensus?

Merlin3046

Merlin3046

Member
My '54 plate TDi 90 has got the pulsating brake problem that appears in many threads on the site. The default fix is to replace front discs and pads (there's no wobble if I pull the handbrake on whilst travelling, and I generally feel it through the steering, so it's not the rears). However, there are many stories about people doing exactly this fix only to have the problem come back shortly after. Others say it's fixed by replacing the front wheel bearings.

The thing that puzzles me is that my problem varies in severity. Sometimes, it's horrible and other times it's barely detectable. I don't believe my discs periodically straighten themselves out, and then go Pringle-shaped again all of their own accord.

I'm about to commit to the purchase of a dial indicator so I can get some evidence, but in the meantime I'd like to know how many have had this problem fixed by replacing the discs and pads, and how many have had to get wheel bearings replaced, or other fixes (suspension joints?).

One thought that occurs to me is that if a new set of discs and pads fixes the problem to start with, but it comes back after a short while, is the disc of poor quality so it's not been properly stress-relieved after casting? Add a bit of heat through use, and the stresses all come out via the warp. Alternatively, does the bedding-in process need to be better controlled and more rigorous? That way you heat treat both discs and pad in a prescribed way so it settles in properly.

I'm an engineer in the pharmaceutical industry so I appreciate the power of properly constructed statistical evidence. This sort of question is highly unlikely to yield that, but I'm keen to hear the success stories as well as the "it didn't work for me" stories. All replies gratefully received.

Thanks,

Mike
 
Wobble could be anything! I have had it on 2 cars and been frustrated when replacing disks didn't fix it, both those times it was a worn control arm / wishbone bush, this will manifest itself in twitchy steering usually also.

My understanding of disk warping is that it is usually caused by a pad dragging on a surface of the disk, check the thickness of all 4 front pads, is one / or two (on the same side) far lower than the others? The sliders / piston on the calliper may be sticking and that needs addressing before replacing pads and disks (or as above, the problem comes back).

Unless you are talking properly cheap crap disks, it's unlikely to be manufacturing problems... But I'm sure someone will correct me on that one!

A common one with automatic cars is people coming to a stop at lights, and putting very slightly higher pressure on the brake (to prevent creep), this can leave a pad deposit on the disk which builds up over time and can cause the vibration. Not sure this is particularly common, but a few good slams of the brakes (tickling the ABS threshold) from 60 - about 15, maybe 3 or 4 times in a row on a nice empty road, is the solution to that.... Again wouldn't put money on that!
 
Hi, I once had a car that needed front brake discs replacing every 12-18 months due to discs warping gradually over time (had around 4 or 5 pairs of discs before being cured) Eventually found front brake caliper pistons were slightly tight & not fully returning when brake pedal was released. This was causing brake pads to grip the discs slightly out of line when parking up after a run, the brake discs were obviously hot after a run & after a few months started to warp. This gave the slight juddering through the brake pedal that became worse the harder you braked until it got so bad that new discs were fitted. Once new disc were fitted brake judder was gone for a few months before returning. The slight tightness of front brakes was not enough for car to fail MOTs or even be mentioned.

Eventually cured by removing brake pads & repeatedly working the front brake caliper pistons in & out until they become easier to move. Obviously you have to be careful not to pop the pistons right out of calipers though. The other option is put new seals on caliper pistons by getting repair kits. Simple test is to jack up front of car & check front wheels spin without excessive drag from brake pads; there will be some resistance from driveshafts turning gears in gearbox through the oil.
 
I had this problem last autumn. I was pretty miffed when a local garage suggested the discs were warped as they were only a few months old.
Turned out to be the bearings. I had both fronts done and the wobble was gone. Interestingly the bearings weren't far enough gone to produce the typical droning sound, but worn enough to transfer some juddering through the brakes.
Hope that helps.
 
tch said:
Hi, I once had a car that needed front brake discs replacing every 12-18 months due to discs warping gradually over time (had around 4 or 5 pairs of discs before being cured) Eventually found front brake caliper pistons were slightly tight & not fully returning when brake pedal was released. This was causing brake pads to grip the discs slightly out of line when parking up after a run, the brake discs were obviously hot after a run & after a few months started to warp. This gave the slight juddering through the brake pedal that became worse the harder you braked until it got so bad that new discs were fitted. Once new disc were fitted brake judder was gone for a few months before returning. The slight tightness of front brakes was not enough for car to fail MOTs or even be mentioned.

Eventually cured by removing brake pads & repeatedly working the front brake caliper pistons in & out until they become easier to move. Obviously you have to be careful not to pop the pistons right out of calipers though. The other option is put new seals on caliper pistons by getting repair kits. Simple test is to jack up front of car & check front wheels spin without excessive drag from brake pads; there will be some resistance from driveshafts turning gears in gearbox through the oil.
Click to expand...
I had the calliper and pads freed up by A2Cars last November, but kept the old discs. This did seem to make it better for a while, but it soon came back. I'm beginning to think suspension joint or wheel bearing. The rubbers are 14 years old, so despite mileage not being enormous (100k), they're pretty old. Someone replaced the discs fairly soon before I bought the car, but based on what you're saying, it doesn't take long to knacker them. Will check the pads and Pistons for free movement. Thanks.
 
steve@cromford said:
I had this problem last autumn. I was pretty miffed when a local garage suggested the discs were warped as they were only a few months old.
Turned out to be the bearings. I had both fronts done and the wobble was gone. Interestingly the bearings weren't far enough gone to produce the typical droning sound, but worn enough to transfer some juddering through the brakes.
Hope that helps.
Click to expand...
No drone from mine either. Interesting. Thanks for this. M
 
Age destroys the rubber more than miles I believe. At the age of your car, you will not regret swapping the bushes, even if they aren't the cause of your judder! The difference will be noticeable. Especially the larger of the bushes at the back of the wishbones.
 
I have this problem too and have come to the conclusion it is the bearings. Having replaced disks a few times and both calipers.
 
Thanks, everyone, for your replies. So far no-one has said "I had this problem and new discs fixed it". That says a lot to me. I'm on the bushes and bearings trail. Work about to start.
 
I have suffered with this problem on a number of cars from Ford Anglia to Jaguar.
Do not assume it is both left and right. I was going to replace my discs a few years ago to correct but only had time to do the one. After the initiall bedding in I had perfect smoothness. . for a few months. Now I now only to replace the rhs one with one I have used before but filed flat (Im good with a file ;) ) every few months but getting fed up with it and did some more research.
I found that there are a few but growing number of garages that offer disc skimming on the car. It is called procut. I found out about it while looking at EBC pads. They recommend that even newly fitted discs should be skimmed. The hub runnout is then catered for.
Go to https://skimmingdiscs.co.uk I will be soon enough when my file wears out !
Martin
 
I had new front discs about eighteen months ago (supplied and fitted by Awesome). The judder was dreadful, I'm surprised the tech let the car out of the door, maybe the tea boy did the road test? Anyway, I left it a couple of weeks, in case it was a bedding in issue, but if anything it got worse. Took it back, and a new set of discs was fitted. These were OK for a few months, but then a judder crept back in (I'm very light on brakes, and the car freewheels, er, freely, so no drag on the calipers as far as I can tell). The front disc is visibly marked with a sort of stripe pattern radially round the disc, which suggests a warp to me. It's tolerable, so not done anything about it yet, but will probably look at replacing the discs again at some point. I'm not prepared to accept the same brand again, though, and will ask about alternatives. Does anybody have any experience with upmarket disks, eg TarOx? Worth a try, or not worth the extra?
 
I went through 4 sets of discs and pads, each new set would start juddering after about 1000 miles. It turned out both front wheels had flat spots on the inner rims caused by potholes. After getting the wheels straightened and balanced with new tyres, another set of discs and pads, braking has had been smooth now for ages.
Jack up a front wheel, spin it by hand and watch the inner rim to check for buckling or flat spots.
In my case I think the discs wore unevenly due to the tyre leaving contact with the road once per revolution.


Sent from my iPhone using Tapatalk
 
Interesting, thanks. I'm on the 17" Sport alloys, which I believe are more prone to road damage, so that's plausible.
 
BiggDogg said:
I went through 4 sets of discs and pads, each new set would start juddering after about 1000 miles. It turned out both front wheels had flat spots on the inner rims caused by potholes. After getting the wheels straightened and balanced with new tyres, another set of discs and pads, braking has had been smooth now for ages.
Jack up a front wheel, spin it by hand and watch the inner rim to check for buckling or flat spots.
In my case I think the discs wore unevenly due to the tyre leaving contact with the road once per revolution.


Sent from my iPhone using Tapatalk
Click to expand...
Good point well made. I have a slight wobble when running fast that's still there after a new set of tyres. Maybe non-round wheels. A very easy check. Thanks.
M
 
BiggDogg said:
both front wheels had flat spots on the inner rims caused by potholes.
Click to expand...

Interestingly, I've just been out and checked the rims on my car and I find that the wheel with the constant warping has indeed got a deformed inner rim. I'm going to try my spare in its place, when I change the discs again.
 
I got my 17" alloys straightened and refurbished at Letchworth Diamond Wheels (in Letchworth) but I expect there will be somewhere local to you that can do it. Seems only some of the refurb places also offer straightening in-house i.e. without themselves using a subcontractor.
 
I won't be going to that expense unfortunately. I'm actively looking for an i3 and the A2 will be going. if I'd have found out about it a few years ago I certainly would have remedied the problem. It also worth a note that the problem wheel also deflates slowly. It need air every week or so. I thought it was corrosion around the valve but now I realise it could be the wheel itself.
 
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