[Richardw]

Hello all, I've researched all I can here regarding caliper rebuild and still have some questions:

For front (I plan to do the vented pistons upgrade):
Part No. 23242510 x2 (vented pistons + seal)
Part No. 19207044 x2 (dust boots)
Is the above correct?

I'm not able to find anything GM part no on the rears for pistons/seals/dust boots. Would appreciate some help here.

Thanks!

[carguy55]

Those are the correct numbers.

I rebuilt my fronts using vented pistons and RB high temp dust boots. Results are great so far and I no longer need to run with Ti shields and dust boots have not melted again.

The pistons are not packaged very well and I found a few very small scratches on them. Had to get an additional kit and returned the bad ones.

The downside to the Racing Brakes high temp dust boots is they can be damaged by brake fluid, which if you're careful during the rebuild is not an issue.

The service guide for Front Brake caliper overhaul (J6H, J6M) has some really great info, including making some required wood shims which add in blowing pistons out. You'll need compressed air to blow pistons out.

[RUQWIKR]

Mike (carguy55) did a nice job responding per above. The RacingBrake silicone high temp dust boots are nice, but the stock ones are cheap and easy to replace plus aren’t damaged by brake fluid. Either are a good choice.

If rebuilding a J6H / J57 front caliper (including the larger BCD J6H), the vented piston kit (per caliper) is 19207043. Those are 2mm longer pistons than the J56 vented ones (23242510) that work in a J6M front caliper.

[Mountain]

To add some additional insight: Regarding the boots, when I went to order parts a few months ago for mine, I could not source the GM boots easily. They were quite a bit backordered. Maybe they aren't anymore. It may actually have been due to the supplier, Hutchinson having some fire in one of their plants. So I ended up ordering the EPDM boots from RB (pieced together the seals, otherwise the entire RB kit is expensive and you get more than you need). I almost went with the RB silicone boots, but 1. if you get any brake fluid on them, it will destroy the seals and 2. the reviews I read on them, it didn't seem that they were an upgrade worth the hassle. To not get fluid on the boots, you not only have to be very meticulous on how clean your hands are and all surfaces, but if you aren't using the proper brake part lube, instead of brake fluid/regular brake assembly lube, on the pistons/seals upon assembly, it's nearly impossible to not get whatever assembly lube you are using onto the boots through piston assembly/insertion.

As far as ordering several sets of vented pistons. I had to do this as well. I actually went through three (3) places: RockAuto, GMPartsDirect and my local dealer. The set I got from GMPartsDirect came very well packaged. Maybe I have a picture somewhere... but every single piston had plastic wrap over it, the pistons sat in a plastic tray and all was enclosed in a plastic bag and tapped fairly tight. None of the pistons were damaged. The set I got from RockAuto was packaged similar, but the plastic bag wasn't tight and allowed the pistons to move around and one of them came out of their little plastic sleeves. I looked at probably 3-4 sets at my local dealer and none of them were well package - all were in various degrees and some actually looked like either people had gone through them, as well, or the parts department were using the sets as footballs in their spare time. Honestly, it was pretty appalling, especially considering you'll pay a PREMIUM to order these through the dealer. You CERTAINLY don't get a "premium product" at all. If I had to guess, over 90% of the pistons had fairly deep scratches or gouges in them and some had mis-matched or missing piston seals.. If I had to do it again, I'd probably just ordered through GMPartsDirect or RockAuto.

[Richardw]

Thanks guys! Any info on the rear? Also I have a tire pump is that enough to blow out the pistons?

[Richardw]

https://racingbrake.com/search-results-page?q=c7-42

I found this for the rear, but couldn't find any OEM part numbers. I don't understand what they mean by "external fit" and I'm not sure what the O ring is for. Any experience with this?

[RUQWIKR]

Rear J6M dust boots are PN 22968937.

[Richardw]

Originally Posted by RUQWIKR

Rear J6M dust boots are PN 22968937.

Thanks so much for this! Do they come with seals?

Also I got a pdf service manual from eBay and don't see these. Can you point me to a resource for part numbers?

Super helpful, thanks again (to everyone who replied)

[HD_ZLE]

following

[RUQWIKR]

Originally Posted by Richardw

Thanks so much for this! Do they come with seals?

Also I got a pdf service manual from eBay and don't see these. Can you point me to a resource for part numbers?

Super helpful, thanks again (to everyone who replied)

The piston kits come with the pressure seals.

[carguy55]

Originally Posted by Mountain

To add some additional insight: Regarding the boots, when I went to order parts a few months ago for mine, I could not source the GM boots easily. They were quite a bit backordered. Maybe they aren't anymore. It may actually have been due to the supplier, Hutchinson having some fire in one of their plants. So I ended up ordering the EPDM boots from RB (pieced together the seals, otherwise the entire RB kit is expensive and you get more than you need). I almost went with the RB silicone boots, but 1. if you get any brake fluid on them, it will destroy the seals and 2. the reviews I read on them, it didn't seem that they were an upgrade worth the hassle. To not get fluid on the boots, you not only have to be very meticulous on how clean your hands are and all surfaces, but if you aren't using the proper brake part lube, instead of brake fluid/regular brake assembly lube, on the pistons/seals upon assembly, it's nearly impossible to not get whatever assembly lube you are using onto the boots through piston assembly/insertion.

To add some insight as someone that is actually using the RB boots, it was not an issue during assembly if you follow the instructions and has not been an issue during regular use and doing brake fluid bleeds etc. The benefits are they have not melted. I have not tried changing boots like RUQWIKR mentioned so don't know what's involved there. Some of mine were melted so bad it was hard to get all the old dust boot material out.

[Richardw]

Originally Posted by RUQWIKR

The piston kits come with the pressure seals.

Is there a part number for the rear piston itself?

[RUQWIKR]

Originally Posted by carguy55

To add some insight as someone that is actually using the RB boots, it was not an issue during assembly if you follow the instructions and has not been an issue during regular use and doing brake fluid bleeds etc. The benefits are they have not melted. I have not tried changing boots like RUQWIKR mentioned so don't know what's involved there. Some of mine were melted so bad it was hard to get all the old dust boot material out.

On vehicle, you can change the boots without pulling the caliper, but, it's easier to pull the caliper bolts and use a dental pick type tool or flat blade to get the old ones out. They do usually come apart when brittle. You can loosen and plug the caliper and the banjo bolt and do it on a bench.

Mountain: I was able to get multiple sets of the fronts recently (19207044), not sure if lucky, or the backorder is done.

Richardw: PN 22968936 for the J6M rear pistons (with pressure seals), on kit per caliper. If you are having to change anything on the rears, you might have a serious brake temp issue.

[Christian1LE]

How often do people rebuild calipers? Is this something you guys do periodically, after a certain number of miles? Or are there obvious wear signs when it's time to rebuild?