Brake judder - opinons please

[General Fluff]

I have significant brake judder, noticeable at speeds of 60+. The brakes are fairly fresh and look ok to me, though I don't know what make they are. I'm pretty sure it's the rears since there is no vibration in the steering wheel.

The pics below show a front disc versus a rear. The markings are continuous on the fronts but the rears have what look like definite start and end points. Rears are in the top pic.

Any thoughts before I replace them?

[HustleRussell]

Just as likely to be a suspension problem rather than a brake problem. Discs look normal. Lines of investigation;
-worn suspension bushes or ball joints
-disc runout (measure with DTI)
-sticking brake caliper

[helix402]

Discs in second pic look worn out. Not necessarily the cause the off the brake judder however well worth measuring and comparing to minimum thickness to check.

[anonymous-user]

A lot of times discs aren't actually warped it's just pad deposits. If you brake really hard repeatedly 3 or 4 times, leaving 20 secs between each and not stopping, does it clear? If a disc is warped you'll generally feel it at all speeds.

[LuS1fer]

What car is it? Sometimes the pistons stick or the handbrake lever on the rear caliper can stick, causing the pads to stay on or wobble. Some pads can even detach from the back plate.

May just be warped discs if you drive fast.

Discs have two sides so posting half won't necessarily help...

Edited by LuS1fer on Sunday 20th August 17:28

[NDA]

Last time I had brake judder it was warped discs.... this was on a new car too.

I had the discs replaced under warranty, but you can have them skimmed.

Have you jacked the car up and tried to rotate the wheels to feel for anything sticking?

[General Fluff]

helix402 said:

Discs in second pic look worn out. Not necessarily the cause the off the brake judder however well worth measuring and comparing to minimum thickness to check.

I see what you mean but think the angle is misleading. They're fairly new.

It's a 335i if it helps. Suspension problems are unlikely since the shocks were all replaced not so long ago and it all looks fine. Just gone through the MOT.

I was considering getting them skimmed but the cost isn't that much less than replacement. May still be the best option though I guess.

[HustleRussell]

Disc & pad replacement may prove a very temporary solution if the root cause isn't diagnosed

[Hungrymc]

I've had judder develop on an Evora, discs looked healthy, no issues found in anything else. Read so much about "warped discs" being a myth and it all being about pad material deposited on the discs (you can't see it, but can measure it).

I decided to have the discs machined and go through the pretty serious bedding in process that I've always previously ignored (10 hard brakes 60mph to 5mph, just inside ABS kicking in, accelerate back to 60 and do it again straight away). They have been perfect ever since.

May be worth the bedding in / cleaning up cycle before having the discs skimmed.... it feels a bit abusive, brakes got hotter than I've ever got them before on this car..... Worth a try.

[anonymous-user]

It's worth doing this anyway to see if you can clear the deposits. What is there to lose?

[Ransoman]

Make, model and age of car + Age of brakes would be usefull to know.

[Wait Here Until Green Light Shows]

Pop the disks off and check all the mating surfaces are clean and flat.

[james_gt3rs]

Hungrymc said:

May be worth the bedding in / cleaning up cycle before having the discs skimmed.... it feels a bit abusive, brakes got hotter than I've ever got them before on this car..... Worth a try.

Italian tune up the first thing to try (and free fix hopefully)

[r11co]

General Fluff said:

It's a 335i if it helps.

Check the caliper piston isn't sticking. I had a similar problem (330i) after rear pads were changed and it turned out to be dirt having crept into the piston bore when it was wound back to fit the new pads. Leads to all sorts of weird brake behaviour because of the 'self drying' feature that automatically applies the brakes gently periodically.

If the piston is sticking don't bother faffing about trying to clean it. Good quality re-furbed calipers are cheap if you source them properly.

[M-SportMatt]

I'd go through the bedding in cycle, see what happens then have them skimmed on the car if there's plenty of life left in them.

[jeremyh1]

I agree with warped discs too
Had it a couple of times now everything looks OK but they are actually out of shape

[KevinCamaroSS]

Far and away the most likely cause is a light amount of pad material deposited on the disc, likely caused by failure to bed in new pads properly. The LEAST likely is warped discs because this is as rare as hens teeth, most cases of 'warped discs' diagnoses is actually brake pad deposit. To warp a disc would require temperatures far higher than that possible on road cars.

Given that the OP has said they are nearly new this also backs up the brake pad deposit theory, also given the newness of the suspension.

[M-SportMatt]

KevinCamaroSS said:

Far and away the most likely cause is a light amount of pad material deposited on the disc, likely caused by failure to bed in new pads properly. The LEAST likely is warped discs because this is as rare as hens teeth, most cases of 'warped discs' diagnoses is actually brake pad deposit. To warp a disc would require temperatures far higher than that possible on road cars.

Given that the OP has said they are nearly new this also backs up the brake pad deposit theory, also given the newness of the suspension.

Could be run out on the hub if the suspension has been messed with

Agree its unlikely to be warped discs per se, but skimming will definitely cure it if its warped or pad deposits :-)

[r11co]

KevinCamaroSS said:

The LEAST likely is warped discs because this is as rare as hens teeth.

Not true. It's quite common on certain makes/models of cars where the brakes are on the limit of spec for a vehicle of that weight/performance.

[Pica-Pica]

r11co said:

KevinCamaroSS said:

The LEAST likely is warped discs because this is as rare as hens teeth.

Not true. It's quite common on certain makes/models of cars where the brakes are on the limit of spec for a vehicle of that weight/performance.

If people here think they are hard drivers, they should see what manufacturers put cars through. All these types of components are put through extreme use on
Component rigs
System rigs
Vehicle rigs and drives.
But warped discs must exist, I guess, because there is a name for it!