Member Since: 13 Apr 2014
Location: Aberdeenshire
Posts: 122
brake judder, warping discs and correct fitment
I keep getting brake judder, despite new calipers and probably my 4th set of discs.
I've just had it in with Kwik Fit to get a puncture repaired and they have said that either the discs are warped and/or they have been fitted incorrectly.
what IS the 'correct' way of fitting the discs? generally, I clean up the faces, offer up the disc to the hub, install the wheel nuts to centralize the disc around the studs, tighten the disc retaining screw, back off wheel nuts, and then install the pads/caliper and wheel etc.
anything I'm doing wrong?
I have V8 style brake caliper brackets installed and have wondered if it's something to do with these?
Thanks
Matt
21st Feb 2017 12:36 pm
mike23118
Member Since: 01 Oct 2010
Location: North Wales
Posts: 1028
I had the same problem , changed discs and pads but still the same. turned out that the bottom bushes were goosed, got new set of bottom arms of advanced factors and problem solved
Hope this helps
Mike
21st Feb 2017 1:26 pm
mattm
Member Since: 13 Apr 2014
Location: Aberdeenshire
Posts: 122
Did you find that the brake judder went away for a short while after changing the discs pads or just the same immediately after?
21st Feb 2017 2:01 pm
Disco_Mikey
Member Since: 29 May 2007
Location: Dundee, Scotland
Posts: 20807
As other mike says
I went through 3/4 sets of front discs, and a new hub in an effort to cure my wobble.
Always went away for a short while, but would return same as ever
Then went for the 6 pot upgrade, new discs, pads and calipers. Still wobbled
There was a slight clunk from the front end, so lower arms were replaced for it's MOT, and the wobble stopped
Alas, it has returned again, but the current discs were Delphi ones I had lying around, so they will be replaced in due course when the pads are worn out, which won't be far awayMy D3 Build Thread
Would I right to assume that my front discs may need changing ? I am getting brake wobble when i brake quite heavy from 70. I have checked paper work and they were changed shortly before I bought the car in 2015 at 139,000 and the car has now done over 154,00.The happiest of people don't necessarily have the best of everything;
They just make the best of everything they have.
17th Mar 2017 12:24 pm
mattm
Member Since: 13 Apr 2014
Location: Aberdeenshire
Posts: 122
Mikey,
I forgot to thank you for your input. Im not totally convinced that there still is something brake related that is causing the issue, however, I also think that my lower WB bushes are probably at least partly to blame.
Weirdly the brake wobble seemed to come on after I changed a wheel bearing, even though I was careful to try and re-center the disc when reassembling everything. which is why I asked about some specific method of brake disc mounting/assembly/centering etc.
17th Mar 2017 2:30 pm
Alphamale
Member Since: 28 May 2014
Location: Belfast
Posts: 497
I can never understand why, when there is 'brake judder' everyone seems to jump to the conclusion that the problem lies with the discs. Even after fitting new discs and the judder is still there, the blame is put on the discs.
Discs don't warp, that's not to say that you won't get one that has been poorly manufactured, worn badly or not been fitted properly to clean mating surfaces, but the steel in the disc won't warp even when driven aggressively, instead, they can wear unevenly. This uneven wear is caused by the brake pads themselves as they intermittently touch an out-of-true disc i.e. disc not seating property on the hub.
mike23118 mentioned, what is probably, the first area to look at if you get a judder (unless the brakes are defective, callipers seize or in need of refurbishment or discs very badly worn), suspension components. Bad performance from worn and deteriorating bushes and/or upper and lower ball joints, will cause juddering. As the brakes are applied the suspension knuckle/s try to rotate. Normally the ball joints and bushes will counter this, but if any one or more of these is worn the knuckle might move resulting in the juddering observed by some owners, as the knuckle/suspension components bang around in their mounts. Oh, and don't forget the dampers or the brake calliper guide pins.
If you get juddering you should really check the discs for runout with a dial gauge before concluding they're at fault or you could miss the real problem. For the cost of a set of discs, that you maybe don't need, you could invest in a dial gauge, but make sure the discs are properly seated before testing or you'll get a false positive caused by dirt or rust between the disc and the hub.
17th Mar 2017 3:18 pm
mattm
Member Since: 13 Apr 2014
Location: Aberdeenshire
Posts: 122
Im not inferring that it's the discs themselves that are at fault, but more possibly could be mounting issues**, warped or incorrectly fitted caliper carriers, swelled/burst brake line, blocked lines in one's side etc.
Ive had brake judder to some degree for quite a while, The PO changed the Lower bushes just before I bought the car, I have changed the Upper bushes, upper ball joints, inner and outer tie-rods, AR links, AR bushes, drive shafts, bearings so it's not like I haven't explored a lot of these avenues at various points.
It seems odd that it's a reoccurring issue and last time I thought I had fixed it, it was then exacerbated by me changing a wheel hub (bearing) which made me think maybe I was doing something wrong during mounting.
My last set of discs were not too bad runnoutwise, however, new calipers and discs fixed the issue for a fair while. I don't disagree that it may be bush related, however, that's a reasonably expensive option and I would like to ensure that I'm not throwing anything else into the mix if going down that route.
M
** My current method for brake disc mount is as follows; After removing current disc (after loosening wheel nuts as evenly as possible), clean hub with wirebrush and brake cleaner ensure no grit etc on the hub or the threads. Get new disc and clean thoroughly with brake cleaner and rags until no evidence of oil or grime is present - clean hands. carefully mount disc onto hub making sure not to get finger prints on disc faces. using wheel nuts makeup disc onto hub and centralize. locate disc locking screw and screw into place using recommended torque.
remove wheel nuts and continue with brake/wheel refit.
17th Mar 2017 3:50 pm
RBP
Member Since: 29 Aug 2012
Location: N Yorks
Posts: 1936
Aerialmark wrote:
Would I right to assume that my front discs may need changing ? I am getting brake wobble when i brake quite heavy from 70. I have checked paper work and they were changed shortly before I bought the car in 2015 at 139,000 and the car has now done over 154,00.
Hi Mark,
Discs should last longer than that in my experience. I change the pads every 20000 miles or so and plan on changing the discs every 40000 (both whether they need doing or not - was plenty of meat left on pads but I only do 10000 miles a year).
A relation had a D3 and seemed to need new discs and pads every year. Either she was driving like a dangerous lunatic or something was not right....
Could be bushes. Either way it's not that bad at the moment so it will have to wait. Thanks Richard 👍The happiest of people don't necessarily have the best of everything;
They just make the best of everything they have.
17th Mar 2017 5:17 pm
L319
Member Since: 14 Dec 2013
Location: Herefordshire
Posts: 2081
Alphamale wrote:
Discs don't warp, that's not to say that you won't get one that has been poorly manufactured, worn badly or not been fitted properly to clean mating surfaces, but the steel in the disc won't warp even when driven aggressively, instead, they can wear unevenly. This uneven wear is caused by the brake pads themselves as they intermittently touch an out-of-true disc i.e. disc not seating property on the hub.
This phenomenon is called Disc thickness Variation (DTV). Whilst a Dial gauge can be used to check run out it wont in itself measure DTV, a micrometer is needed as well to measure this. Run out or wear in the hub will set up this wear and sticking pads/ pistons not fully retracting from the disc will as well . The seal in the piston has designed in a degree of roll back to retract the piston when the pressure is released. Vehicle used for long journeys with little brake application are more prone than frequent applications such as town driving.
17th Mar 2017 6:24 pm
Alphamale
Member Since: 28 May 2014
Location: Belfast
Posts: 497
Just found this and think is will be of interest to everyone. http://www.mossmotors.com/SiteGraphics/Pages/brake_discs.html I found the section on bedding-in to be particularly interesting and worth taking note of. Won't mean you should discount other problem areas, but may go some way to explaining why new discs 'warp' if not bedded-in properly.
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