My rear brakes vibrate, but only occaisionally. I put new pads on a while back and that is when the problem started. I replaced the pads with Volvo pads. It is a 94 850. It almost feels and sounds like the ABS system is kicking in. Has anyone experienced this problem before?

I'm having the same problem. I had it a while back - my independent Volvo shop said it was warped rear rotors and replaced rotors & pads. It went away for a time but now is back doing it again. It happens only after I've been driving for at least 20 minutes or so (i.e., after the brakes are hot) but the whole car shudders like mad and makes an awful noise. Anyone in the car would freak out for sure.

I took it to a different shop and they said the only thing to do as Rx is replace the rotors and pads. They said when the whole car shudders, it's usually the rear brakes. When the vibration is through the steering wheel, then it is the front brakes.

Any comments or thoughts? Sounds like a number of folks out there have had this happen. Anyone replaced their own pads and rotors using the Bay 13 instructions? If so, how easy is it (for a novice) and did the shudder problem go away?

Thanks,

Steve (94 850 N/A, auto, 105K)

Is it a light vibration or really bad shudder? I replaced my pads with OEM and when I brake hard they'll start to shudder so bad the whole car shakes. I think it's because the brakes get hot--if I brake gently I never have any problems. It kinda feels like it's from the front though.

When they shudder it is a really bad one. I took to my regular Volvo mechanic and he said it was the pads and changed them out and turned the rotors. The problem went away for a long time, but has returned. It seems to happen after the brakes get hot. If I brake hard they shudder. If I break easy, no problem. I checked the on board computer and it gave me a code for a bad/shorted ABS sensor and for heated brakes. I pulled the sensor on the left rear wheel and it was caked with a thick hard grease. Cleaned it checked the pads on both sides and hit them with emery cloth as the pads appeared to be glazed. Have only driven the car a few miles since, but no problem so far. Will know better this weekend as I have to drive some 50 miles through heavy traffic.

>>>I pulled the sensor on the left rear wheel and it was caked with a thick hard grease. Cleaned it...<<<

How easy was this to do ? Where are the sensors located ??

TIA

Hi ha kahuna,

you have warped rotor/discs i am afraid to say.

mark in leeds/uk.

How long does it take for rotors to warp? I tried the seasoning method described here and scrupulously keep my lugs torqued correctly. How could they have warped after a week?

migt be bad ABS sensor on one wheel

hi ya,

ABS sensor rarely fail to be honest if i recall correctly, but its worth anyway. Check the cableing as this may give you a intermittent short, and clean them up if you can.

Mark in leeds/uk.
uk 94 850glt 2l 20v 173k.

Hi ya,

Well you have one of three things i can make out:-

You should have shims installed behind the pad do you have them, this will elimate brake shudder and vibration. You also will need an application of copper grease on shim and pads do you have either or both installed ?

The shims cost about $15 to $20 i think for a pair one on each.

You may have a sticking caliper on one side

You have have warped discs/rotors and if serious enough will fell like the hole rear window is going to fall out.

Hope this helps.
mark in leeds/uk.
uk voc 94 850glt 2l 20v 173k.

Thanks for all the tips. It looks like it was the ABS sensor. I pulled it out and it was caked with a thick black greasey substance. Cleaned it off and have been running the car for about four days now with no recurrence of the vibration. I hope that was the problem.