TR2/3/3A A type tr3 calipers

[sp53]

I am rebuilding some A type tr3 calipers and hoping to getsome feedback. I rebuilt a set some time back and cannot remember which way was the easiest to get the rubber boot on. Is it best to put it on the piston first?I remember Art suggesting that glass beading is fine and these could use a good cleaning. The inside bore is nice with no rust, but the grove where the boot goes has some rust. I think I will duct tape the bore and blast that little groove out. I might leave the bridge pipe in place and blow air through to make sure everything is open. Anyways, all suggestions are welcome.
Steve

 

[bertl]

I just rebuilt mine and I installed the boot to the caliper first. Smearing a little (very lightly) red grease on 'O' ring and piston helps lubricate the process. I have an awl with a right angle tip on it which I used to "roll" the boot over the piston. A little tricky due to the configuration of the caliper but with a little patience it can be done. I bead blasted my calipers and painted before I installed the new seals, (definitely mask off the bore before blasting). I still had to use a probe to clean out the groove on the caliper body though as the bead blasting did not thoroughly clean out the groove. A good flush with brake cleaner before blowing out with compressed air before assembly is a must.

Bert

 

[TR3driver]

The bore is not involved in sealing (although the groove is). So I don't see any point in masking the bore if you are going to bead blast.

IIRC, I put the boots partially on the pistons first, after lubricating both of them with brake fluid, only far enough that the lip for the caliper was still hanging off the edge. The piston served as kind of a handle while maneuvering the boot into the caliper groove. But that was a long time ago and I may have it wrong.

 

[Geo Hahn]

I, OTOH, fit the boot to the caliper, sit the piston on top of it (lubed) & with the opposite side of the caliper blocked with a plain piston (clamped in place) I use a blast of low pressure air into the caliper. This has the effect of inflating the boot and makling it 'want' to go over the piston.

I use a little hook tool made from a length of 12ga copper wire (house wiring) with the end rounded off to hook the boot and help it over the piston. Sounds fussy but once you get the air and timing right the boot pops on it a second. Easier if you have an assisatant who can operate the air gun.

 

[sp53]

geo you are the poop

 

[Geo Hahn]

Nice set-up -- glad it worked and you thought to get a pic of it in action.