Brakes that grind/grab on 1993 850 GLT

vmo67 · Post by **vmo67** » 23 Feb 2008, 07:44

Hi guys,
Please read the sob story first to tell you how frustrated I am with volvo repair shops and chain repair shops that do nothing.
My dearly beloved 93 850 GLT 4 has 135,000 miles and I got the shaft treatment lately.

So, let me describe to you the noise in detail. I press the brakes when I am about to stop and it seams to grab and push up the pedal with the grinding noise. When I stop aggressively it won't do it. It feels good and tight.

This is my favorite car and would like to drive it for much longer and not sell at a big loss. God, please is there anyone out there who can give my advise on where to start my search for the mystery grind?

The guy that worked on the car to begin with put new rotors on the front, new aftermarket pads and the noise only did it sometimes but has gotten worse.

I got the service manual the other day to start from step one again but I don't know much about Volvos brakes, only chevy cars, VWs and Subarus.

I went to the only reputable Volvo dealer around for 50 miles (Volvos Only) in Bellaire, since I am not a regular there and he came back with a list so long of problems he found with my car he made it out to seam my car was not worth messing with. Not good.

At the Brake Check service center here in Houston, TX off 610 North, the guys at the shop suckered me into a life time membership warranty and totally did nothing for my problem. They replaced the pads again. He got really defensive when I told him nicely that even though I had an idea what was going on (pads?) he wanted me to understand that they could find nothing wrong with my brakes and could hardly make the noise when he test drove it.

Post by **Ozark Lee** » 23 Feb 2008, 08:24

Describe the noise a little more. Could it be described more as a buzzing noise than a grinding noise and does the brake pedal pulsate?

It sounds to me more like an ABS issue. Normally the ABS light will come on if there is a problem but read the codes from port A-3 and post them back, you could have a dirty or bad wheel sensor.

...Lee

vmo67 · Post by **vmo67** » 23 Feb 2008, 08:54

Ok
If I drive with hard braking it doesn't do it at all the brakes grab fine with no noise at all.
Any time I am stopping slowly at about 1/2 mile an hour, as I am about stop, the pedal grabs and is forced up and at the same time the brakes make the noise.
I know what pad to disc grind sounds like, it's not a rotating scrapping, If I let off it stops completely and the pedal resets itself.

More like a firm grind with a push up of the brake pedal but I don't loose brake force. At 1 mph speed I just come to a stop. If I'm slowing down the car to stop 20 ft ahead it does it again.

I don't know how to read codes but I can learn. I saw where my old volvo mechanic was doing it. The service light is always an issue to reset.

Post by **Ozark Lee** » 23 Feb 2008, 09:18

I don't know how to read codes but I can learn.

Reading the codes is easy. Here is a link that shows you how to do it:

http://volvospeed.com/CheckEngine.php

That link is specific to the fuel system but it works the same way for the ABS if you plug the flywire into socket A-3.

Give it a shot and post back what you find.

...Lee

vmo67 · Post by **vmo67** » 23 Feb 2008, 10:10

OK Ozark Lee I will let my friend look into this tomorrow he can probably figure it out better than I can. Do I need some special tools to do this procedure? Duum question: What's a flywire, any thing like a firewire?

Post by **Ozark Lee** » 23 Feb 2008, 12:33

What's a flywire

I don't know if that is the official term for it - I kinda made it up - but it is the wire with a plug on the end of it that you plug into the socket to read the codes.

...Lee

vmo67 · Post by **vmo67** » 23 Feb 2008, 13:27

OK
I got a 1-1-1 code out of it. the Haynes book says that's normal.
As I read my book with little knowledge of what to do, I see 3 things that make up the system. the wheel sensors, the electronic control unit, and hydraulic modulator assembly. It says one sensor is installed to each wheel, and someone mentioned that earlier today. However the book says that the front sensor ring is a press fit on the driveaxle constant velocity joint and a special tool is needed for removal. I have a hunch it's this. The car was in simi high water when my wife drove it and I have had to replace the AC clutch, soon afterwards. Wet is not good for electrical

Post by **Ozark Lee** » 23 Feb 2008, 13:41

The problem can often be just dirty sensor rings - the ones that are on the CV joints. They have magnets and they tend to collect the steel off of the brake rotors as they wear down. Try cleaning the sensor rings with brake cleaner and a toothbrush on all four wheels. If it was an electrical problem the system would have set a code. You are correct that 1-1-1 means the system itself is happy.

...Lee

vmo67 · Post by **vmo67** » 23 Feb 2008, 18:18

final post for Saturday.
I got a RHand rear wheel sensor error message 2-1-4 and 2-1-3 Lhand.
Now I can try to clean them as you say if I can get under it.
I went through the entire set to seek out others if any and got a few non related issues. Most of all though Thanks for the help today, I really learned allot about that car. New appreciation for it.

vmo67 · Post by **vmo67** » 24 Feb 2008, 15:13

Sunday efforts for not??
Don't know if this was the right area to clean but I went around on all 4 tires and brushed off the dirt and cleaned the inside of these connectors. Anything else was probably over my head. I took the pictures for future reference. The noise only happened in reverse a few times while testing them. I believe they have not made the noise again. If it goes OK for a few days do I then reset the computer? Q: What happens when I push the ABS button on the dash?