How to compress REAR brake piston

[Taz]

What's the secret to compressing the piston on the rear calipers so that I can put on new pads ? The front pistons compress using a C clamp no problem, The rears are another story. I know the piston screws into the caliper, I rebuilt one last year. When I looked up changing rear brake pads in my repair manual it said treat the rear as same as the front I removed the bleeder, tried compressing with a C clamp and also tried screwing the piston back in, WON'T BUDGE

[Hvnfn]

I havent done the rears without rebuilding the caliper yet.

[narfire]

I think they only compress a little, most of the retraction is from screwing the piston in. Perhaps you picked up on it, but the line on the piston has to be towards the top/bleeder screw.
I have used a file to turn the piston in, but be carefull as they are brittle and can break if you push too hard. A piece of 3/4 inch wide flat-bar 1/4 inch thick works well. Last time I did the rears, I don't believe they retracted as far as the fronts. The pads have a tab that goes into the slot on the piston.

[maytag]

and if you;re like me, you may have missed that the rear pads are thinner than the fronts.

[bobplyler]

You have to screw the piston in. I use a tire iron to screw it in.

[Marmeister]

Anybody have some specific instructions on rebuilding rear calipers? I've posted ("The infamous rear caliper challenge question, again") with more details about my confusion and my service manual shops 2 "disk" washers and a "thrust" washer, the "miafior rear caliper" article shows 3 "disk" washers and a thrust washer, and the caliper I removed had 3 disk washers and no thrust washer

And neither the service manual or the miafiori article show how the threaded plunger, the pawl (funny shaped wedge), etc, fit together !!

If any of you guys have already rebuilt rear calipers, please help !

Thanks
Adham

[81SPIDERMATT]

You have to screw the piston in. I use a tire iron to screw it in.

brilliant

[RRoller123]

Is it normal for it to take a really large force to screw the rear calipers in? I can barely get them to budge more than about 30 degrees. So now I am forced off the road until this is resolved, dammit. There is prior evidence of a vice-grip or huge pliers being applied to the pistons, and I basically can't get them to move at all. Unhook the hand brake cable? Bleed off some fluid? (probably buy new calipers?) Any help appreciated.

Pete

[rlux4]

They are very hard to turn if they haven't been done in a while. I use a large file that just fits the slot. I use it lengthwise, giving me plenty of leverage. After a couple of turns it gets easier.
Ron

[RRoller123]

Thanks, I will have at it in the morning. Was worried that there was something major wrong with it, but some brute force may convince it.

[RRoller123]

Man what a chore. I can't even guess what torque it took to turn the pistons in. A flat file, as suggested, worked really well. It remains to be seen if these calipers are ok; I will know when I get back on the road hopefully later today. Thanks for the input!

[rlux4]

If you lined up the notched side with the brake hose inlet you should be good. If they weren't leaking before they're probably OK, but did you change the seals and check the condition of the pistons and cyliders? If the pistons have been extended for a long time you can get pitting that will cause a leak when they're back down in the retracted position.
Ron

[RRoller123]

Yep, no leaks, they look ok, and the slot is lined up. I was just amazed at how much torque it took to get them to turn. It took about 6 full revolutions to clear enough width. The rubber piston boots are ok, no tears so re-using them. The new pads came with thin stick-ons that look like carbon fiber stickers; I assume these are anti-squeal pads and I should install them? (I did).

From the looks of things down there the rear brakes may have never been done. Unlikely but only 69K so possible? Hopefully back on the road today and all will be well! Want to make Cars and Coffee on Saturday!

Pete

[RoyBatty]

This may help. Sorry I didn't post sooner.
http://www.fiatspider.com/f08/viewtopic ... brake+tool

[RRoller123]

Oh man I gotta get one of those! That will do the trick.