front brake repair

[Sexagenarian]

the carb synch went great and I have been enjoying the ride tremondously. I just replaced the front brake pads and noticed that my left front brake pad, on the inboard side, was almost 6mm while the outboard side was less than a half of a mm. Further investigation revealed the inboard pistons were no longer moving. I am going to order a new seal kit for this caliper and replace the seals. Changing out the brake pads was a first for me and rebuilding the caliper will be another first for me. For those of you who have gone through this before, can you give me some advice on what to notably be aware of or any other helpful advice on front caliper seal replacement? Thanks all.

[Squidley]

Make sure the bores are clean enough to eat off and smooth, the pistons the same way. Your biggest issue will be getting the pistons out of the bores. The way I have done this in the past is to keep one side pistons locked all the way into their bores, like with a small clamp and an old pad. The I blow air into the caliper through where the brake line hooks up. This will pop the free pistons out with a bit of force so watch for that.

 

I clean and inspect that side and install the pistons back in with the new orings and plenty of lube to make them slide in easier. Do just the opposite for the other side and reconnect, fill, bleed...

[Sexagenarian]

.....I clean and inspect that side and install the pistons back in with the new orings and plenty of lube to make them slide in easier. Do just the opposite for the other side and reconnect, fill, bleed...

What type of lube do you use Squidley? Or do you apply some of the Dot4 brake fluid around the piston as a lube for re-seating the pistons?

[MiCarl]

Use only fresh DOT4 for assembly. You don't want anything else in there.

 

I remove pistons the same way Squidley described. Only difference is I will stack strips of corrugated cardboard, blow air, remove a strip and repeat. That way both pistons advance. It also limits the speed so you're less likely to send a piston flying.

[Jimbob66]

The way I have done this in the past is to keep one side pistons locked all the way into their bores, like with a small clamp and an old pad. The I blow air into the caliper through where the brake line hooks up. This will pop the free pistons out with a bit of force so watch for that.

 

 

One word of advice .. catch those pistons in an old rag stuffed up in the caliper and do NOT have a finger (or thumb!) anywhere near the area. Don't ask me how I know.

[Squidley]

What type of lube do you use Squidley? Or do you apply some of the Dot4 brake fluid around the piston as a lube for re-seating the pistons?

 

Yes sir, the same brake fluid you will use, sorry about not putting that in there. Carl caught my CRS nicely....thanks Bud

[Hazenson]

i had some ruff spots around my pistons too- near where the seal rides. I used 1000 grit and wet sanded it-- only going across ( or around the piston) to clean these-- never sand oppisite way of a seal- ya dont want any little scratches passing under where seal will ride. I also used a light film of greese on seals to place them in there pockets- but just enuff to make em slippery and wiping all excess off

[Sexagenarian]

was wondering if anyone ever used a metal polish on the pistons? If so, what kind?

[Ben Rollins]

I just received new seals from skydoc-17 and there are small pacs of pink lube with them, I take it this is for the seals. This will be my first rebuild on the venture, I rebuilt my 74 cb once but that is a different monster in its self.