Brake caliper Re-build question

[makaio]

I'm in the middle of re-building my front calipers at the moment, and think I hit a snag .

They seem to have some pretty good rust build-up in the barrels (I think that's what you call them). I managed to get most of it out with some 600 grit wet-dry, lubed with brake fluid. But some of it is just standing it's ground and mocking me.

Am i just wasting my time? If the rust isn't coming off, should I just purchase new calipers?

[slakjaw]

if you are talking about the barrel as in the hole the piston goes in,

the best way to clean them up is to go to a napa or an independent auto parts store and buy a brake hone use a little brake fluid and hone them out, thats what i did on mine it cleaned them up pretty fast

if you are talking about the pistons all you can do is keep sanding

after you get the caliper halves back in one peice make shure thay are not leaking from between the halves. some pplz have leaky calipers after a rebuild


hope i could help


kyle

71 911

[makaio]

Thanks Kyle,

I was hoping to not have to split the calipers.

I went ahead and ordered a new set from Pelican just a few minutes ago. I guess the sun roof repair, and the Rs America carpet set will be put on hold another month.

Maybe I'll try spliting the old ones later, and trying to fix them.

[slakjaw]

if you are gonna sell your old ones



let me know

[Montara22]

Matt-

I recently rebuilt my calipers.. I ran into the same situation. I had a 100psi air hose on mine and they weren't moving. The way I got them out was by squeezing the pistons all the way into the calipers and using a bead blaster on the ridge of the cylinder. Worked great! You can get your own enclosed bead blaster at harbor frieght tools for around $65.

[spinner]

I always thought that the calipers were not supposed to be split. Am I wrong on this?

Paul
87 Carrera

[Dan Owens]

Paul,

You're not wong, you should split the calipers unless you have to. As for replacing them I believe Vertx has a good price on rebuilts. Minor "sanding" can be done on the pistons but it really should be more a polishing than sanding or you'll leak past the seal inside and the piston if you sand off too much material. The caliper barrells can be honed as mentioned in an earlier post.

[Early_S_Man]

The surface of the bore in the caliper is not very critical ... compared to the piston, since the rectangular cross-section seal has to 'work' on the piston rather than the bore. If there is any significant pitting of the chrome-plated pistons in the 'working area' of the piston surface ... they will have to be replaced or you are wasting your time trying to rebuild the caliper! By 'working area' I mean the outer half closest to the pads, since the inner half never 'sees' the seal.

Splitting the Ate caliper halves is no big deal ... except for the fasteners used and obtaining the proper Ate replacement seals. The procedure used to be included as a routine item in the brake section of the air-cooled VW Bentley manuals, and also is in the Clymer 912 book. The bolts are often rather rare and odd, such as 'RIBE' spline, and will be mangled or destroyed if XZN or Torx bits are used in the attempt to loosen them! The proper Ate rectangular cross-section seals used to be sold at VW and Mercedes dealers, and the Porsche part for 'M' calipers is 901.351.928.10 (same as VW pn 311.615.277) ... though I can't seem to find the part number for the 'A' calipers, and there may be a problem getting the 'M' caliper replacement part, too at dealers! Stoddard still lists it at $1.28, though. Silicone grease, which VW and Ate call 'brake paste,' should be used on ALL of the rubber seals when reassembling calipers! A very tiny 1 gm tube of unlabeled silicone grease with the same color & consistency as Dow Corning 4 or 4X ... used to be included in the Ate rebuild kit for 911 master cylinders!