Rear Caliper Rebuild

[SierraMCoupe]

I decided to replace pads and upgrade to brass bushings this weekend, also rebuilt the front calipers. The rear calipers looked fine when I installed my last set of pads but looks like things got a little toasty since then I'd like to rebuild the rear calipers now too just to be on the safe side. From what I've found the rear calipers sound like a little more of a pain and might require a special tool to install the dust boot (although my copy of the TIS says otherwise). I've also read that the dust boot isn't really required for track only cars.

Anyone out there have experience rebuilding the rear calipers? If so, have you used the special tool or compressed air to instal the dust boot...or should I just leave the boot out altogether? Thanks in advance!

Here's a great thread on rebuilding the rear calipers:
http://www.bimmerfest.com/forums/sho...d.php?t=488615

And here's what my TIS shows:

[dschultz]

I just did front and rears a few weeks ago. I don't know about eliminating the dust boots. I don't see how that can be good. Perhaps if you replace the pistons regularly too. Front boots are fiddly but doable. I didn't have the special tool for rears. I found a spray can top that was just the right diameter but too flimsy to really do the job. I ended up doing a lot of swearing and tore one of the boots in the process. I have the tool now. Hoping it's easier when I go back in.

[The HACK]

If you plan on rebuilding the calipers (because race car) every season, you probably don't have to worry about the dust boot. If not, I would probably put them back on.

I've been told (and have seen this) that you can get a pipe cap from Home Depot that's just the right size to put even pressure all around the dust boot to push it in. $1.50 solution for a $150 problem.

[SierraMCoupe]

Thanks for the replies! I'm going to give bootless a shot...from what I've seen so far it will most likely melt/crack within a few events anyways and I do plan on servicing the calipers after each season. I'll report back if I run into any issues.

[dschultz]

I know this thread is a bit stale, but I just got around to replacing my rear caliper boot and thought this might help someone. I had originally attempted this without the special tool and struggled to get the boots on, tearing one in the process. So I ordered the special tool described by Jim Millet and Ron Stygar in the thread mentioned above. I pulled the caliper off, disassembled it, then discovered that the "special" tool is the wrong f***ing size! $50 bucks down the drain. The diameter is too small by 1 or 2 mm and just doesn't fit properly. So in desperation I headed off to Home Depot to find something that might work but I couldn't find any pipe that was the right size.

So back home and staring dejectedly at my work bench I spy a box of shop vac attachments under the bench. I have a collection of hose and attachments that looked about the right size. I grab one, and the boot fits into it *perfectly*. Bingo! I cut about 1" off the end of one of the attachments and presto, the perfect tool.

Here are some pics. Note that the bmw tool comes with two cups. One is way too big, one is too small. Note the pic where I put the bmw tool inside the pipe that works... shows the inside dia. of the tool that works is the exact outside dia. of the bmw tool.

BTW, the vac pipe is about 2.5" OD so if you can find some fairly thin-walled plastic pipe of that size it should work as well.

[StickMon]

So you need a piece of Shop-Vac hose and one of these.

[dschultz]

Yep. The piston compressor is cheap and easier than messing with a C-clamp.