roadrunner
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| posted on 3/11/11 at 09:11 PM |
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tin top brake judder
I have had a slight knocking sound at slow speeds over the last month or so, then the brakes started to feel that they where on then off ,on, off
under very slow and steady braking, until tonight when travelling at 60ish then braked the hole car went it a massive judder, even when the speed was
scrubbed off the bad judder was still there.
Any ideas before I have a look tomorrow.
Brad.
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HowardB
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| posted on 3/11/11 at 09:13 PM |
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pads worn out?
Howard
Fisher Fury was 2000 Zetec - now a 1600 (it Lives again  and goes zoom)
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roadrunner
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| posted on 3/11/11 at 09:15 PM |
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No, there is plenty of meat on them.
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britishtrident
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| posted on 3/11/11 at 09:26 PM |
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If your description is accurate I would suggest it points straight to a warped brake disc but brake vibration and judders can have other causes
for instance premature ABS activation due split ABS reluctor rings or particularly on Fords worn suspension bushes.
[Edited on 3/11/11 by britishtrident]
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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roadrunner
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| posted on 3/11/11 at 09:31 PM |
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If my discs had a slight warp before, then surely they wouldn't get severally warped during a twenty minute drive.
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focijohn
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| posted on 3/11/11 at 09:41 PM |
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Loose wheel? and as above check the ABS ring for a fracture.
Anyone going slower than you is an idiot. Anyone going faster than you is a maniac.
Too many targets but too few bullets.
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roadrunner
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| posted on 3/11/11 at 09:43 PM |
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Were do I look for the abs ring.
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phelpsa
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| posted on 3/11/11 at 09:46 PM |
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Sounds like something coming loose! I'd have a good check over all the suspension fixings before driving again.
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britishtrident
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| posted on 3/11/11 at 09:53 PM |
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Strange as it may seem brake discs warp when cooling down after being hot, when stationary the bit of disc covered by the calliper stays hot
while the rest of the disk cools quickly. If you have changed the discs before it might be an idea to check if the caliper retaining bolts are
tight.
ABS rings are easy enough to visually check as long as you don't have the more modern active wheel bearings which use a ferro-magnetic ring
built into the wheel bearing.
With old style reluctor rings just clean and examine the rings looking for cracks, splits and missing teeth. However with active wheel bearing
the only way to check the ABS rings is to use an Oscilloscope when the car is being driven at constant speed.
Some Bosch ABS are very prone to problems if the multi-plug on the ABS modulator control unit gets damp due to callipary action.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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britishtrident
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| posted on 3/11/11 at 09:57 PM |
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Reluctor rings
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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RickRick
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| posted on 3/11/11 at 10:02 PM |
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bm's the brake reaction arm, or the forward part of the wishbone bush wears and gives a judder at any speed replace with powerflex unless your
bothered about the road noise, gets slightly more noticable with PF's fitted
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coyoteboy
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| posted on 4/11/11 at 01:12 AM |
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For what it's worth, brake discs actually warping is *incredibly* rare. Far more likely is that you've stopped with hot discs and left
your foot on the brake which has caused an uneven deposition of pad material. The more braking you do from this point on the more pad material gets
deposited in that spot, the worse the judder gets. Looks like a warp as the uneven wear creates a high spot, but careful examination is more like a
swelling. A surface skim should sort it but the only cure is not leaving your foot on the brake when you stop.
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britishtrident
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| posted on 4/11/11 at 08:26 AM |
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quote:
Originally posted by coyoteboy
For what it's worth, brake discs actually warping is *incredibly* rare. Far more likely is that you've stopped with hot discs and left
your foot on the brake which has caused an uneven deposition of pad material. The more braking you do from this point on the more pad material gets
deposited in that spot, the worse the judder gets. Looks like a warp as the uneven wear creates a high spot, but careful examination is more like a
swelling. A surface skim should sort it but the only cure is not leaving your foot on the brake when you stop.
"*incredibly* rare2 --- That particular bit of misinformation started on one website and has been floating about the web for a three or four
years, a warped disc is less common than it used to be because brake discs are thicker (hence more rigid) than they were in the 1960s and modern
floating callipers tend to an extent mask kick-back through the brake pedal.
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tomgregory2000
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| posted on 4/11/11 at 08:28 AM |
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just a thought.......
but would a fecked damper on the front cause this?
as the wheel would be bouncing down the road so as the brakes were applied the tyre would grip, lock up because its bouncing, the abs kick in, the
wheel then grip agen and the cycle begins.
like i say its just a thought
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tomgregory2000
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| posted on 4/11/11 at 08:29 AM |
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yes brake discs do warp, i had the brake discs on my motorbike warp, now thats scary 
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Dingz
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| posted on 4/11/11 at 08:35 AM |
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I have had Vented discs warp, as have others I know. They are prone as the thickness varies, they 'dish' in where the vents are and once
they start they seem to go quite quicky.
Phoned the local ramblers club today, but the bloke who answered just
went on and on.
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coyoteboy
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| posted on 4/11/11 at 10:10 AM |
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quote:
"*incredibly* rare2 --- That particular bit of misinformation started on one website and has been floating about the web for a three or four
years, a warped disc is less common than it used to be because brake discs are thicker (hence more rigid) than they were in the 1960s and modern
floating callipers tend to an extent mask kick-back through the brake pedal.
It's not misinformation - it's confirmed by several brake manufacturers that almost all cases reported are pad deposition causing disc
thickness increases in a localised spot. I never said it can't happen, just that it's very rare, and people automatically jump to
"warp" incorrectly. Actual rotor warp usually comes with low quality of excessively worn rotors which either have residual stresses after
manufacture or have started to reach the material limits (worn so thin it's a joke) The problem is it requires the person doing the diagnosis to
actually take the disc off and measure what's going on and virtually no-one ever does, they just make an assumption and replace the disc. Must
admit I've not run any calcs on it, but I suspect it's very hard to get plastic deformation in a disc from thermal variation alone (not
impossible) and would require glowing rotor temps - not something that occurs very often in tin tops on public roads.
[Edited on 4/11/11 by coyoteboy]
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roadrunner
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| posted on 4/11/11 at 06:56 PM |
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I have just replaced discs and pads, and I am glad to report all is well.
The only reason I questioned the disc fault was because it went from a small hardly noticeable judder to a really nasty one within a mile of
travel.
Thanks fellas.
Brad.
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