To Split (calipers) or not to Split, that is the Question

[jbeach]

Dear Brake Experts:

So I finally delivered my front calipers to my local Midas shop to have them rebuilt. I asked whether they could split the calipers and replace the O-rings. They said if the calipers are not leaking (they are not) don't even think about splitting them, as to do so is just looking for trouble.

I'm perfectly fine with this approach, unless any of you more mechanically-knowledgeable folks believe I should insist this be part of the rebuild.

Many thanks!

John

[mbell]

The main reason for splitting them is to make it easier to remove the pistons. If they are happy to remove the pistons with out splitting it should be fine. That's how I did my calipers, as ever probably just making life harder for myself...

[collins_dan]

I had no need to split to remove the Pistons. No leaks before or after. Dan

[europatek]

I've split a few pair to rebuild and never had any trouble. Just make sure the rebuild kit contains the o-ring for the passage between the halves before you discard the old one. I've had kits with and without it.

[fasterbyelan]

I've split a few pair to rebuild and never had any trouble. Just make sure the rebuild kit contains the o-ring for the passage between the halves before you discard the old one. I've had kits with and without it.

Paul Matty supplied me with the O rings when I re-built my calipers. I have never seen a kit with this part included (here in the UK).

[Elan45]

Not so much of a problem with the front calipers. The rear ones, if stuck, as they usually are, I've always had to split,them, then use an internal pipe wrench to remove the pistons. I would source the O rings at some one like RD Ent, Dave Bean or one of the Triumph specialists. Never tried any of these suppliers for them, because I have a local source I've used since the mid-70s.

Roger

[john1180]

For stuck pistons, try adapting a grease zirc to the hose inlet and pump grease in to pop the pistons. I bit messy, but always works!

[Elan45]

I knew someone would suggest the old grease gun method of removing pistons. My father taught me some 50 years ago, to never get any petroleum based solvents inside any brake fluid surface. I always use denatured alcohol or spray :"Brake Clean" to clean the cylinders so as not to contaminate them. I suppose some newer brake fluids may not be so susceptible to petroleum, but why take a chance..

Roger

[StressCraxx]

I knew someone would suggest the old grease gun method of removing pistons. My father taught me some 50 years ago, to never get any petroleum based solvents inside any brake fluid surface. I always use denatured alcohol or spray :"Brake Clean" to clean the cylinders so as not to contaminate them. I suppose some newer brake fluids may not be so susceptible to petroleum, but why take a chance..

Roger

Roger,

I agree about the grease as a questionable choice. The grease may attack the o-ring, causing it to swell and eventually leak. Most of the caliper rebuild and o-ring kits now use EPR or EPDM elastomers. They will swell and fail with the oil in the grease.

Regards,
Dan

[UAB807F]

I used to leave them assembled and just remove the pistons until I got one pair that were very rusty. When I split them I found a "gooey mess" in the passageways, after which I've always split calipers. I have no idea where it came from, all I can add is that it had been hanging around unused for a while before I started on it.

Some of the UK Ebay sellers do the complete kit which includes the small square section ring you need.

[lotocone]

Not so much of a problem with the front calipers. The rear ones, if stuck, as they usually are, I've always had to split,them, then use an internal pipe wrench to remove the pistons. I would source the O rings at some one like RD Ent, Dave Bean or one of the Triumph specialists. Never tried any of these suppliers for them, because I have a local source I've used since the mid-70s.

Roger

I agree with Roger about the rear ones. I rebuilt mine a few years ago and splitting them helped a lot with the reassembly also.

[dgym]

I've just done this job and was recommended by several experienced people to split them.
The rebuild was a lot easier, I am yet to re fit the calipers to see if i've ruined anything but it all went back together hassle free.
-Jim

[jbeach]

Thanks everyone. VERY informative, as always!

I'm going to let my guys make the decision whether they'll split, but they've ordered the o-rings just in case.

I'm more inclined to just do it all now, but I'm trying to avoid getting sideways with my brake specialists before we even get started.

I'll give a report with some photos when they're done.

Best,

John

[elanner]

Rotoflexible hasn't been around for a few weeks so I'll steal his thunder.....

I went over to his place last year to watch/learn how he was refurbishing his calipers. He had a neat setup to remove the pistons. He'd cut a bicycle valve from an old tube and fashioned it so that he could jam it into the bleeder hole. Then a few strokes with a bicycle pump and out they popped.

Nick

[potleyu18]

I Recently split the rear caliper to replace the pistons and seals without any issues and to do this without doing so requires a great deal of patience.

Steve