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.
pads worn out?
No, there is plenty of meat on them.
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]
If my discs had a slight warp before, then surely they wouldn't get severally warped during a twenty minute drive.
Loose wheel? and as above check the ABS ring for a fracture.
Were do I look for the abs ring.
Sounds like something coming loose! I'd have a good check over all the suspension fixings before driving again.
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.
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
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.
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.
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
yes brake discs do warp, i had the brake discs on my motorbike warp, now thats scary
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.
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.
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.