hi,

I just put new front brake pads and rotors on my `95 850 glt with 102,000 miles. That was about 1 month ago. Today I was driving around town and about 20 minutes after i started driving when i stepped on the brake, the pedal and the whole car pulsated and shook pretty hard. It continued until i got home about 30 minutes later. About 2 hours later, i got in the car and everything was fine. The brake fluid levels look ok so i`m thinking it might be the abs. any ideas?

Hi all,

I've colllected some data about brake judder.

Maybe it is interesting also for the Volvo 850 owners.

Have look at:

http://home.planet.nl/~annevelink/brakes.html

Some other interesting links

http://www.thomdejong.nl/Opbouw.htm

http://www.thomdejong.nl/Foto850.htm

Have fun,

Jan-egbert Annevelink, Holland

I had a sticky rear caliper piston that caused a strong "front end" shudder every time I applied the brakes. It took a little while to figure out, but as soon as I changed out the caliper, everything returned to silky smooth. If it is the rear caliper, you should not feel the shudder too strongly in the steering wheel, if it's in the front end, you'll likely feel it in the steering wheel.

If it is the ABS, your dash warning light should have gone on, and there should be a code registered in your "code box"

claude

Have seen this problem time and time again. Usually happens shortly after front brake repair. The problem is with the rear brakes. Visit your dealer and ask for a set of modified rear brake shims. They are stainless steel, and have 1 corner cut out. Smear both sides with anti squeal grease and install betweet rear pads and calipers with the arrow pointing up. Don't know exactly why the problems arrise but do know 99% of the cases are cured by adding the rear shims. They cost 10-12 bucks. Good luck.

hi mark, not to worry, it's a "somewhat common" occurence. quite a number of people on the board have experienced the same thing, one of them even set up a website on the subject! sorry i don't have the URL offhand, but try doing a search.

i did a coupla posts on BB too, that was just after i started getting the same slow-speed shudders on my T5 once in a blue moon, sumthing like once a week, and only happens in town driving.

i brought it into the dealers, they confirm it wasnt warped rotors, they SUSPECT my Rr rotors needed new brake shims (i don't agree), but the main things was it took some 20mins of plodding around at start-stop speeds just to get that shudder to resurface, and only once.

i find if i regulate pedal pressure, i can actually stop the shudders as it's just about to start. well, either that or brake to the point of coming to a stop, which obviously may not be the safest thing to do in many circumstances.

on my ride - Fr oem pads are almost new, Fr oem rotors worn, Rr Brembo rotors and Axxis Metal pads new.

saying all that, Barney may have a good point, but if the calipers were actually sticky, my/ypour rotors would be long warped by now.

still a mystery ...

good luck on finding the anwser n keep us posted

rgds

jeff

95 855T5A SAM chip

Hi Mark,

Did it only happen when you pressed on the brakes, and not constantly (even after letting up on the brake pedal) after the initial pulsating/noise? I would think if it was a sticking caliper it would make the noise even after letting up on the brake pedal. The reason I ask is that my 95 T-5R did a similiar thing that I can not figure out why. It was an Extremely loud scraping/pulsating noise. It did it about 4 times, each time when I was hitting the brakes. That was about 4 months ago, and it has not done it since. The only thing I could figure is something got stuck in the pad/rotor and then disappeared/disintegrated, or the abs was doing nuts. If it was the abs wouldn't the light or some sensor go on?

Let us know if you find anything out.

I'd guess that you have a sticking front caliper as they'll often start siezing only when hot (after driving a bit) but then not stick cold when checked cold later. Look at both front rotors as if that's the case, you'll see one discolored (dark to blueish). Unfortunately, when that occurs it'll usually warp to new rotor requiring yet another new rotor.

Short of changing (flushing) brake fluid as advised in your owners manual, there's nothing more that can be done to prevent the problem or predict when and if it'll happen. When checked cold, it may look and function normally.

If it happens again after driving and you're close to your garage, lift both wheels off the ground (or whichever has the discolored rotor if so) and try spinning the wheels. If the caliper is sticking, you won't be able to turn the wheel and that wheel (etc) will be VERY hot.

Worn ball joints on 850s is also becoming very common (higher mileage typically) but most people never seem to notice that driving and they have to be very loose to cause vibrations.

Barring an edpisodic event (like a stuck caliper or other oddity) I would suspect a front end thing, like worn torque rod bushings which can be sensitive to temperature. (When it's warm, you'll feel vibration in the brakes, but not when it's cooler.)