vibrating rear brakes

[nick]

i seem to be having all sorts of issues with my 850R recently and another has reared its ugly head today.

when braking (from any speed) there is a godawful vibration from what i think is the rear brakes. it vibrates the whole car. i assume this could be warped rear discs or possibly something else i haven't thought of - any clues ?.

i'll get this damm car sorted out soon i hope !!


thanks all

nick

[Ed.]

I had this issue when i first got my car. I got the front discs and pads replaced and this solved the problem. Though apparently rust can accumulate on the hub and cause the disc not to sit properly on the hub and hence cause vibration on braking and disc warp.

You could get the discs skimmed and the hubs checked at the same time. Would be cheaper than a new set of discs and pads. However, if you are running 280mm discs, this could be the perfect opportunity to upgrade to 302mm.

Ed

P.S. Something to read that may help http://www.stoptech.com/tech_info/wp_warped_brakedisk.shtml

[nick]

thanks Ed, very interesting read.

i'll check all the discs when its light enough to see them !!

nick

[iGGy]

I've experienced this and it really is quite disconcerting when it happens! The cause was going from genuine pads on the rear during a complete brake change. Going back to genuine ones fixed it.

[nick]

thanks for the reply.

it only seems to occur after some 'ahem' spirited braking. driving to work this morning with 'normal' braking and no issues at all - confused...

i think you might be right about the rear pads - perhaps they aren't genuine volvo items - i'll check later

nick

[Quicksilver]

I had the same problem with my car for ages and have just fixed it.

Symtoms with mine were judder under moderat brakeing once brakes were warm, getting worse under prolonged brakeing (i.e downhill).

Done all the usual stuff, new discs and pads and checked that the pistons wornt seazed, OK for a bit then it came back.

Well I checked the pistons again but this time looked at how far each one came out with one press of the peddle, on the n/s rear the inside piston came out but not the outside one, that required more peddle preasure.

I sprayed WD40 into the dust cover and worked the piston in and out a bit until they both came out at the same rate and bingo seems sorted.

Still got squeel though.

[nick]

that sounds like mine to a tee

i'll have a look at the calipers on the front & back and check the piston movement