Here are the clues…

I knew my brake pads were wearing thin in the rear… on a long drive, I came to a point where the whole rear end would shudder and rattle. At first, it was not that severe, and I mis-interpretted what I heard as though it were a grind of the pad metal against the disc.
Then my Brake light came on in the Instrument Panel…
The shudder was getting a bit worse…

I ordered and replaced the pads…
But when I drove it, the Brake light was still on, and I still got the shudder…

It seems fine when cold, but after driving for a while, perhaps 30 minutes, if I come to a hard braking point it begins, and then repeats thereafter.

It turns out my Brake Fluid reservoir was WAY low… filling that up turned off the warning light.

Underneath the Pressure Reducing Valve, there is a good deal of moisture which I first thought was coming from a different connection, but now think may be the Valve dripping down… (see pics , ,

My first inclination is to think the Discs may have become too hot and overheated.
I had to replace the Front Discs in January, and I did not replace the rears at that time.

However, I wonder if the Pressure Reducing Valve is failing and there is more pressure going to the rear than ought to be which might cause it to skip…
OR if the reservoir being so low got some air in the system or something….

Because it works fine until it has been driven a while, and because the front discs were recently replaced, and because I just replaced the pads (although it did this just before replacing the pads), I am thinking the discs/rotors need to be replaced, but before I drop the money on that, I wanted to know if with the symptoms described I could have a different problem.

BTW, I replaced the rear shocks just a couple of months ago, but I would not think that is connected in any way.

--
1995 850T Wagon 120k

have rear discs machined if thick enough or fit new discs, this will fix your problem, shims have no efect on shudder they help regarding brake squeal

Hard to tell from the pictures but it is probably just the typical brake proportioning valve leak. I've done quite a few of them on the 850's. The racket you are getting from your rear brakes can probably be fixed with a set of "drawbridge" shims. They look like a normal shim only there is a square cut out of them. Do a search for them and you should find plenty of info on them.

Mark

Mark,

Here is a pic of the teflon shims I installed...

I think the ones I threw away were the shape you discussed.

If I am not mistaken, this problem started just before I changed my old pads and threw those shims away... I did not mention earlier, but when I got in there, there was no metal to metal grind, and there was still pad left without the mounting pins poking through.

I used the PBR/Axxis metal/masters on the rear and applied Plastilube Anti Squeal Grease between the back of each pad and it's respective shim.

If you still think this is it, I will pursue accordingly...

Thank you both for your replies.

--
1995 850T Wagon 120k

I just checked FCP Groton, and their shims (pictured here) are identical to the ones I installed...

Mark, can you please comment as to whether these are the Drawbridge Shims you were discussing??

From your description - particularly the arrow being etched out, I do not think so, and it was that arrow part that I recall with the old shims... If I am not mistaken, they were almost more of a triangle due to how much material was cut away in the corner.

Thanx
--
1995 850T Wagon 120k

Nope those are not them. Those are good shims but the ones you want have a square cut out of one corner and an arrow stamped in them. Those appear to have a square stamped out of the middle. Try again :)

Mark

Did you also replace the rotors? Many recommend replacing rotors and pads as a set to insure proper mating...

FCP Groton carries them in teflon..

Pic #2
--
1995 850T Wagon 120k

Pic 3
--
1995 850T Wagon 120k