850 rear brakes

Rich · Post by **Rich** » 12 Nov 2009, 09:00

I had a look at the brakes on our 97 850. There is aprox. 20k on the pads and rotors. The fronts are about 1/2 inch thick yet but the backs are maybe 1/8 inch?????
Any ideas what might cause this?
Braking when driving feels normal, no grabbing or shaking.
The TRACS ABS light is on intermitantly.
Would this be the reason?

Post by **misha** » 12 Nov 2009, 09:54

The reason for intermittent abs/tracs light could be a faulty abs module.Don't worry...if you know how to solder,it's easy job.90% of mvs members,including me,did that job ourselves.There is a great detail write up on this forum about how to do that,including pictures.

About differences in brake pads wearing....usually,rear set of brake pads needs replacement after every other(every 2nd) front brake pads replacement.Meaning...two sets of front brake pads=one set of rear brake pads.That's is some kind of rule.

So....maybe the front brake pads are allready replaced 2nd time and now,the rear ones needs replacing.

FCPEURO · Post by **FCPEURO** » 12 Nov 2009, 10:15

That sounds like the case misha. How many miles on the car?

Rich · Post by **Rich** » 13 Nov 2009, 09:08

Thanks for the info on the ABS module.
The car has 207000km on it about 130000 miles. But like I said we just had the brake pads and rotors replaced 15000 miles ago.
To me that seems a little quick. If thats normal than I guess thats normal.
Thanks for the reply guys.

Post by **jblackburn** » 13 Nov 2009, 09:28

That does sound quick...my pads have over 40,000 miles on them, and still have plenty of pad left all the way around. I have no idea what kind they are, they were on there before I bought the car, and aside from squealing under light braking, they work just fine. I haven't exactly been nice to them either.

I wonder if your calipers are sticking. Have you ever flushed your brake system?

Rich · Post by **Rich** » 13 Nov 2009, 09:42

No I have not flushed the system......its on "the list".
I was thinking maybe there is rust bulit up on the caliper where the pads are suposed to slide? Not allowing the to fully relax when released keeping them on just slightly all the time.
Does this sound possible or am I totally out to lunch??

Post by **jblackburn** » 13 Nov 2009, 09:53

Could be. Or old brake lines. Jack up one side of the car, then put it in neutral WITH THE PARKING BRAKE ON, and try to spin the front wheel. Next, park and turn the parking brake off, and try to spin the rear wheels. They should spin reasonably freely; otherwise, something is sticking. If the caliper itself is sticking, spray some PBlaster around it, grease your slide pins, and the piston itself. Let it soak a while, and give it a couple good whacks with a hammer. That should help them release fully if they're sticking.

Rich · Post by **Rich** » 13 Nov 2009, 10:17

Thanks for the ideas...........I also have 2 other issue that I've been trying to locate answers for here in the forums.
1. Reverse lights.........work sometimes, car is a standard and once in a while they work(very rare). I've tried to "wiggle" and move the shifter in the revesre position but nothing. They only come on when they want and just for a quick flash.
2. Where do we find how to fix our own ABS module?

Post by **jblackburn** » 13 Nov 2009, 10:27

ABS Module:

https://www.matthewsvolvosite.com/forums ... hp?p=46827

As far as the reverse lights, I'm thinking you have a bad or out-of-place reverse light switch that is depressed and tells the lights to come on when the shifter is moved to that position. Pop the shifter boot off and have a look.

http://www.eeuroparts.com/Main/PartDeta ... id=9442728
^^Here's that part.

Rich · Post by **Rich** » 13 Nov 2009, 10:29

Thanks!!
I just found the tutorial on the Abs Mod.
The switch is under the shifter boot?