Caliper Rebuild

cmvasquez · 06-02-2013, 08:32 PM

Hey guys,

I am in the process of rebuilding my calipers for my 1988 911 Carrera. The problem I am running into is that I decided to split the calipers and one of the M9 (9mm) Caliper half bolts was stripped in the process. Of course I am now in the process of finding another fastener that works properly. Due to the rarity of the M9 bolt Porsche used on the 911 calipers I was thinking of either simply using an M8 bolt and setting it to the correct torque in assembly or should I get a M10 bolt and maybe bore out the cylinder the caliper bolts slide through. There is plenty of room between the bolt hole and any other bored out part so I do not see any harm if the job is done right and the surface is smooth. Any thoughts? Have any of you guys run into the same problem.

As always, Thanks for the help!

Cheers,
CMV

DRACO A5OG · DRACO A5OG's Garage

Why not get a used caliper and use the split one for a paper weight and this time, do not spli the rest.

Hodgey · Hodgey's Garage

Quote:

Originally Posted by DRACO A5OG

Why not get a used caliper and use the split one for a paper weight and this time, do not spli the rest.

what he said ^^^^^^^^

don't muck about with brakes or tyres........change em out and drive it like you stole it.

bobolsn · bobolsn's Garage

Since you split the calipers, I understand that you will need the o-ring (?) seals. From reading the forum, they are hard to come by, but PMB has them. Since they are very responsive and rebuild calipers, I would order the seals and a new bolt from them. Last thing I would do would be to bore the caliper.

Good luck

JohnJL · 06-03-2013, 06:44 AM

Contact PMB, they will get you the proper fasteners and seals. Dont fart around with brakes.

wolds · wolds's Garage

I did mine over the winter with PMB's help. Eric supplied the rebuild kits which include the o ring along with the ribe bit to break them apart. I needed several caliper bolts also and ended up buying a rebuilt one off ebay for $80.00. The reason I went the rebuilt route as a sacrificial caliper is that I reasoned it had already been split and that I'd be able to get the bolts out of it without difficulty which was the case. If you have gone this far find someone to yellow zinc them for you. It is worth the expense. Warren

Quote:

Originally Posted by cmvasquez

Hey guys,

I am in the process of rebuilding my calipers for my 1988 911 Carrera. The problem I am running into is that I decided to split the calipers and one of the M9 (9mm) Caliper half bolts was stripped in the process. Of course I am now in the process of finding another fastener that works properly. Due to the rarity of the M9 bolt Porsche used on the 911 calipers I was thinking of either simply using an M8 bolt and setting it to the correct torque in assembly or should I get a M10 bolt and maybe bore out the cylinder the caliper bolts slide through. There is plenty of room between the bolt hole and any other bored out part so I do not see any harm if the job is done right and the surface is smooth. Any thoughts? Have any of you guys run into the same problem.

As always, Thanks for the help!

Cheers,
CMV

cmvasquez · 06-05-2013, 06:40 PM

Thanks guys,

The guys at PMB have been awesome. They zinc plated the cores for me along with polishing the pistons and painting the top to prevent from rust. I purchased the o-rings from PMB, the bleeder valves, as well as the clips that secure the pad and they look awesome. I am just now waiting on the screw from PMB. They were kind enough to use one of their odd numbered bolts to help me out for my birthday this friday! What awesome service. Thanks for the request guys. Definitely worth it.

James Brown · James Brown's Garage

sweet stuff

DG624 · 06-17-2013, 02:25 PM

Since you split the calipers, I understand that you will need the o-ring (?) seals.

What else must be replaced when the claipers are split?

rusnak · 06-17-2013, 02:33 PM

I would never ever split the calipers, nor attempt to bolt them back up myself. That is the one thing that is beyond most home DIYers to do yourself and be 100% sure of. It's just not worth doing at home, and taking that kind of risk.

What we DIYers call "rebuilding the calipers" is usually replacing the pistons, o-rings, and dust seals. Not actually splitting them. If they leak, then buy a new caliper or a rebuilt one. Send in the core.

Eric_Shea · Eric_Shea's Garage

Splitting calipers is not rocket science. The internet "Myth" as probably started because they didn't want every Tom, Dick and Harry flailing away at something as important as brake calipers.

What's difficult is what Chris has experienced... the fasteners. As I mentioned in another post; THEY SUCK. Big M9 fasteners and tiny Ribe R6 heads. We order Ribe R6 bits 48 at a time SOLELY BECAUSE OF A-CALIPERS.

Splitting calipers is almost a must if you're going to rebuild them properly. Torqueing them is simple:

Number 1-2-3-4 (left to right looking at the bolts)

First Torque = 10lbft in the following order: 2-3-1-4
Second Torque = 29lbft in the following order: 2-3-1-4

Split your calipers, do it right, enjoy life...

cmvasquez · 06-24-2013, 02:27 PM

Eric,

Well said, After getting them all together and installed they are working great. I have to admit it was a little nerve racking at first after hearing everyone warn against this but in the end it all turned out great and with little work. Thank you for all you guys did to help me in figuring out this issue. I ended up just ordering another used caliper to strip for the bolts and torqued down in the order you mentioned. All good with no leaks so far but I guess the real test is yet to come...

As always guys, thanks for your time.