After a rotor/pad change on a recently bought 98 V70XC with 80k, I noticed severe vibration at 55+ MPH. Previous posts told me to look for a sticking brake caliper, and sure enough, the RH front rotor was steaming hot and the LH was fine. So what do I need to do to fix the problem? I fixed a similar sticking caliper problem on my 740 with the guide pin set, but what about on this car?

Bill
93 945T 175K
98 V70XC 81K

Who changed the rotors and pads?

How were the pistons pushed back?

Can you find out if these were the car's original rotors?

Perhaps the pistons were pushed back into territory that they probably have not seen since the car was new. They could be sticking on some goop that was deposited in the bore a long time ago. Or, the pistons may have scored the bores when they were pushed back.

If you can, how about doing an autopsy on the calipers? If you or someone else take them apart, perhaps your findings could be of use.
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96 855R, 95 855,854, 90 744 Ti - 310,000 miles driven

James,

As you know, I just got the car. I forced the seller (indy dealer who bought it off 5 year lease (yes, I verified-a 5 YEAR LEASE!) to have his service guy do a rotor and pad change, so the are not the originals, nor are they Volvo parts (BREMDO (regular, not drilled) rotors and MINTEX pads). I understand the old rotors were way thin, and were probably original. I agree that the pistons have not been that far back in a while, accounting for "why now" (my wife also drove through a lot of standing water a couple of days fbefore we noticed it). The "what broke" autopsy from the dealer is that the internal seal was comprimised (as Frank thought would be the case). Waldo at Carolina Volvo did not mention any scoring from improper work, and he is the type that would have if it was there. Perhaps some improper technique could have caused the seal to break. However, it probably could not have been avoided in this situation. The rotors just should not have been left that long (past specs I'm guessing) which meant the piston and seal were extended to their max for some time. I have seen a similar situation happen on 7/940 guide pin boots-they break during the change due to what I call "rubber fatigue" (or cheap French parts), water gets in, and they start to seize a couple of weeks later.

Sorry I wussed out of the caliper job (and thus no personal autopsy)-we are moving to England and need to ship the car, and are running out of time.
Bill

I would like some edification on sticking calipers. Say, i had that problem too, what would i do to verify that i have that problem other than a hot rotor? what if it sticks just a little bit? How do i test under those conditions?

Andrew

When ones brakes either seem to act up (vibration, noise or pulling) and if a wheel seems hotter than usual (burnt smell too), sometimes a rotor turns bluish if too hot, jack up the front wheels after driving the car (brakes hot) and if a wheel doesn't turn, that's it.

The two ways I know to check for a stuck caliper are 1) checking for a hot rotor after driving the car (steam and near-glowing metal made it easy for me, but you could also try a laser thermometer for more precision since you say your's might only be sticking a little) or 2) put the car up on jackstands and try to spin the wheel, noting the differences. Method 1) seems best, because the caliper may not stick under all circumstances, and may not stick at all before it warms up a little under speed. If not a laser thermometer, perhaps a oven thermometer to see if one is hotter than the other.

Bill

Just replace the caliper and bleed it. From a dealer they're $150 for a reman Volvo OEM caliper.
Hopefully your rotor is also now warped from the heat.

Frank,

Thanks for the info. $150 is not too bad. So is it usually the caliper itself on 850s/70s vice the guide pins problem I saw on 740/940s? And what goes out on the caliper?

Bill

On FWD calipers the piston (seals) themselves that sieze in the bores. One could rebuild them if you had a seal kit but no one does that anymore and it's easier to just replace the caliper.

Well, it was the caliper itself and not the guide pins. I am having the dealer put in the remanufactured caliper since I am short on time these days. As a note of curiosity, they tell me the caliper was made for the newer cars (01-?), and so needed a different mounting bracket (which they did not have on hand for some reason).

Thanks to Newbie and Frank for thier responses.