Old vs new calipers and pistons

[John_Mc]

I think I may have already found my answer, but I need a confirmation from the BCF Collective...

I just removed the old pistons from my calipers (16P) and am installing the new pistons I ordered from BPNorthwest. My new pistons are the "old" style and my old pistons were the "new" style. The rubber sleeves had clips on them before, but am I to understand that the sleeves for the old style do NOT require clips and instead just rest on the piston themselves (vs. clipping on to the rim of the caliper)? Here's a pic. I found on Buckeye Triumphs page:

Also, to install the pads, I've had to push the piston essentially all the way into the caliper and it appears that it will probably need to remain like that while I fit the caliper back over the rotor. How can I keep those sleeves on through that process?

 

[martx-5]

Are you talking about the rubber boot shown in that picture?? If so, the lip on the right side of the boot shown goes into a groove that is machined into the top of the bore of the caliper.

 

[PeterC]

John, The pistons and kits are NOT interchangeable between early and late. Get the correct stuff. The caliper castings themselves are different where the boots are retained, and the pistons are different because of the size of the groove for the boot.

Be safe. It's "only" brakes.

Peter C

 

[John_Mc]

My calipers are the 16P style (early) but the pistons I removed are the later style. I think my commission # would indicate that originally my car was equipped with the 16PB calipers. So maybe there was a switch of the calipers but a PO installed new pistons based on the model year? The article on Buckeye Triumphs website states that the two pistons are the same as far as diameter and width, so I'm guessing the main difference is the type of boot to use? My caliper has a raised lip but no groove for the clip to fit in. When I removed the old pistons, two of the clips were already loose. Soooooooo, in summary, as near as I can tell, my brakes should have been fitted with the early pistons but someone switched.

 

[PeterC]

John,
The earlier style casting will have a thin groove machined in the bore to take the outer lip of the dust boot.It is toward the top of the bore. (Of course there is another groove lower into the bore for the piston seal.)
The later casting has only the piston seal groove in the bore. There is a raised lip for the inside of the boot to sit on, and be clipped.

The picture in your original post is of an early style boot. The bit of the boot lip under the grimey thumb is what would go into the upper/outer groove in the 2 groove bore of the early casting. The earlypsiton has a very narrow groove as per that picture.

Hope this helps. Peter

 

[Geo Hahn]

In other words... the boot goes into that groove before the piston is offered up to the caliper. It may look like an impossible sequence as the boot will not want to go over the piston w/o popping out of the groove... but it can be done.

Here (and elsewhere in the archives) is mention of the method using compressed air:

https://www.britishcarforum.com/bcforum/u...true#Post155032

 

[martx-5]

I work for an automotive rebuilder, and one of the items we handle is calipers. We put together hundreds of these a day that have the boot with the lips. At first, it can be a bit tricky, but once the procedure is mastered, it goes very quickly.

The biggest hang-up in getting the lip into the seal is because the groove in the caliper IS NOT CLEAN ENOUGH. Any dirt or rust in that groove will be a big hinderance in geting that boot lip to seat in. We shot blast everything, so the gooves are very clean. Glass beading will work very well, but these things aren't available to the DIY'er. I would suggest using something like PB blaster and a sharp pick to dig out all the crap in the groove. You want all of the rust and dirt ou of there. Once it's really clean, you should have no trouble getting the boot in there.

The method we use is to slide the boot onto the piston as shown in the original poster's picture. Then continue to slide it down further until the lip section is below the bottom of the piston. Now take the piston and boot and kinda wiggle the lip into the groove. Then start to push the piston into the bore. If you have trouble getting it to go down, then the lip isn't in the groove all the way. Try again. If everything is in place properly, the piston will slide into the bore without a problem, and the lip will be in the groove as it should be. Lubrication on all these parts helps considerably. We use a brake part assembly lube which is very slick and compatible with all brake fluids. You could use brake fluid, but it is not as slippery as the stuff we use. If you can find some brake assembly fluid in the part store, use it.

The other method mentioned is compressed air. That's also not available to some DIY'ers, but I'll go over that one anyway. In this method, the boot is installed in the groove first. Then the piston is held down on the top of the boot. How hard to hold it down will be trail and error. Air is then slowly blown into the inlet of the caliper (the bleeder must be closed). The air forces the boot up and around the piston. Then you can just push the piston into the bore. Of course, you run into the problem of not having the other piston in place on TR calipers, so the air method would need to somehow close off the other bore.

EDIT: Another thing that makes it much easier to put TR and other multi piston calipers together, is to seperate the halves. I know you've all been told never to do this, but we seperate all of them at work. They clean more thoroughly, and are easier to assemble. The big problem, is that the O-Rings between the halves are not readily available. Most of them are square cut, similar to the piston seal...just smaller. I've been known to re-use those seals without any problems, but use your own judgement on that, as I'm not condoning anything here regarding your brakes.

 

[PeterC]

Art, I've done it your way many times, but I've found an easier way for me. I install the boot in the (you're right) VERY clean groove, then hold the piston on the boot and move it to one side, and take a dull right angle pick and pull one section of boot up on the side of the piston while moving the piston toward that section. Once one bit of boot is up, a little wiggling and the boot is up all around the piston, and then just push the piston in. Takes me a minute or so per piston.

Peter

 

[John_Mc]

I'm not seeing a slot inside the bore for the lower lip of the rubber boot. Am I missing something?

Nelson Reidel indicates in his article that the lower lip of the boot just rides on the cylinder. Looking at the diagram in the Moss catalogue, it shows the lip in a groove inside the cylinder as others have mentioned above. I'm not sure what's going on with my cylinder, but I don't see how I can fit that lip inside without that groove.
I'm baffled /bcforum/images/%%GRAEMLIN_URL%%/crazyeyes.gif

 

[PeterC]

That's a later caliper.

 

[John_Mc]

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]That's a later caliper.[/QUOTE]

Hence my confusion. The calipers are clearly stamped "16P" and not "16PB".