Brake caliper piston seized

[rpiereck]

Today I was doing the front brakes on the 900, did the left side first, took me a bit as there was some rust to clean up, as well as learning how to work on theis style brakes (my 900 is an early 87 car with the old school type brakes, parking brake on front axle). I got the left side done in an hour and a half, new rotor, pads and hardware.

Once I got to the right side things were harder. The inner brake piston was seized, and bang as hard as I could with a rubber hammer, the thing didn't budge. I had a huge C-clamp on it, cranked it as much as I could but the metal bracket under the clamp was bending. So no matter how much I tried, I could not get that piston to move. I ended up installing all the old stuff back in the car and drove it home slowly, new brakes on the left, old brakes on the right.

I will be ordering new brake calipers for the front, both sides, and redoing the whole thing soon. Looking at a few sites I see that there are "loaded" and "unloaded" brake calipers for this car, what does that mean?

[euromobile900]

Loaded means that the caliper comes with pads and hardware. Semi-loaded means it only comes with hardware. Unloaded means it may come with none of those things.

Be wary of rebuilds. See my tutorial on brakes for some advice on this subject. When you say the "inner piston", which one do you mean? You did screw the piston in by turning it, didn't you?

[rpiereck]

Yes, I screwed it in by turning with the original Saab tool. By inner piston, I mean inboard piston, the one that poushes the yoke towards the inside of the car.

[euromobile900]

The inboard piston and outboard piston are connected via a rod, which has threads on it; these are the threads that you are screwing the outer piston on when you turn it to move it in. If you squeeze and only the inner piston moves, try pushing against the caliper body, not just squeezing the two pistons together. If this doesn't work, then you will need to disassemble and move forward as I suggested in response to your post in my tutorial thread. Good luck!

Also, I wouldn't be worried about driving on one good brake and one bad brake for the time being. I have done it numerous times, for various reasons. There was even one time I drove an ABS car with one front brake entirely disconnected from the system. A friend asked me to fix his car, but the garage space he lent me was not his, and I got kicked out by angry property owners halfway through the project.

[rpiereck]

I tried pushing on the inboard piston, tried a c-clamp, tried banging with a huge rubber mallet, but it wouldn't budge. I think rust is the culprit as the entire assembly shows the brown stuff. I ordered a new caliper from Eeuroparts, hopefully it will be here this Friday or early next week, as I have to have the car inspected and re-registered before the 15th or I gotta pay some stupid fines. I looked at buying a caliper here in Germany, but Skandix wants 190 Euro for one, to which I said bollocks. The Eeuro part cost me $85, and that's with a $15 core charge.

[euromobile900]

I assume you'll have to eat the core charge given shipping costs to Germany, which is well enough. I'd make sure the "rebuild" is good in the sliding-yoke department. Also, a friend of mine got one that leaked (!)

Shame about the fines. Vermont is bad enough. I cannot imagine trying to grapple with the TÜV there. Do they even allow rust?

[rpiereck]

Well, the shipping charges are to the US not Germany so not too bad. The car is also TÜV exempt as it is registered with the US Army.