Changing rear pads I found the inboard passenger side piston to be VERY stuck. Wouldn't budge even with the large woodclamp I normally use for the job. Knowing it's probably toast and beyond rebuilding I used a small hammer and block of wood to drive it back. Off the car of course.

Then pumped it back out with pedal pressure. Still stuck. Tomorrow I'm hitting the salvage yard looking for a serviceable caliper. In the event I find one with a good inboard but stuck outboard piston, any problem splitting the caliper? I've already done it to mine twice and it holds presssure.

Also, just to satisfy my need to disassemble the unserviceable, what's the best way to remove my stuck piston just to see how bad the corrosion is?

Thanks,
Erwin
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Erwin in Memphis, '88 745t 190,000 miles, '95 855t 92,000 miles

I doubt it's worth salvaging, but if your determined to get it apart out of pure stubbornness (I get that myself quite often. the use of the part is no longer the point, it will come apart and I won't be beaten by a chunk of metal), I'd try a lot of wd-40 on it, drive it back in, then pump it out again. I suspect if you do this several times, stopping to clean it and add more WD every time you pump it back out, eventually it should come free.

since you where able to move it somewhat it's likely corrosion and debris in the uneven surfaces left by the corrosion. the WD and the friction of moving it in and out should break down any debris enough to let it come apart (eventually).

Check this link: http://www3.bc.sympatico.ca/Volvo_Books/brake1.html

Mine was very stuck- heat and screw drivers worked for me. I saw a rebuild kit on Advance Auto Parts web sight a while ago. I had already bought a new caliper and haven't tried to rebuild the old one.

The green books say NOT to split the caliper.

chuck

Thanks for the link. I've already done three things improperly. Use a prybar, hammer and split the calipers halves. Oh well it IS pretty well seized up. Before using drastic measures I'd accepted that a salvage yard replacement was in my future.

I'll still try and get the piston out with heat just to further my education.

;^)

Thanks,

Erwin
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Erwin in Memphis, '88 745t 190,000 miles, '95 855t 92,000 miles

Chuck's advice is good. I just threw away several good rear calipers. The size designation is shown in the picture.

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john

Thanks John and Chuck,

I found my Haynes and learned about the piston size difference after I'd put things back in place and mounted the wheel. I needed to roll the car away from the garage door.

From the pic it looks like I may be able to read the size through the wheel. If I don't find one salvage looks like I might be buying a rebuilt. I'd still like to get the piston out to see if mine is rebuildable.

Compressed air? That's what Haynes suggests.

Cheers,

Erwin
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Erwin in Memphis, '88 745t 190,000 miles, '95 855t 92,000 miles

compressed air seems like a really bad idea. once it passes the obstruction it would shoot out fairly hard I'd think. it won't come out, with hydraulic pressure from the brake lines?

you need to make sure the piston diameters are the same. 36, 38 and 40 are cast into the body of the caliper. get the same, otherwise, the rear wheels will brake different. splitting the calipers should be left to the builder. you won't find the orings in any caliper rebuild kit, only the piston seals. good luck, chuck.