Rebuilding calipers on an '03

[Kevin Kurtz]

Guys, Everything went well, disassembly, buying new seals, etc. But for the life of me I cant get the piston back in with the new seals.
There is no rust, corrosion, etc. The old seals were is good shape when I took them off.
Since I'm doing a rebuild with added supercharger, I thought, well why not make sure everything about the brakes is known good.
Now I cant get the piston back in using the old seals. I've tried a C clamp, but no go.
Any ideas?
Thanks

 

[Mustang5L5]

Which Caliper? Front or rear?

The fronts are easy. Lube the seals up well with a good synthetic grease (not petroleum based) and insert them into the bore. Install the piston boot on the bottom of the piston. Then install the wide end of the boot into the Caliper. Then slide the piston in.

If you are using a c clamp something is wrong. The calipers should assemble by hand.

If these are the rears...different story

 

[Mustang5L5]

Some pics of a recent rebuild I did. It’s a PBR Caliper just like in the GT

Mustang5l5's Progress Thread - misc stuff

Realized I never unboxed this either. Figure I should inspect it. Really nice quality stuff. I imagine as some point I'll change out the flowmasters. prob gain some power with the new heads

www.stangnet.com

 

[Kevin Kurtz]

Well, both front and rear. All 4. As luck would have it, I started on the rears.
I made a simple rotation tool out of a socket and tried twisting as I applied pressure...no go!
I'll go at the fronts today, but any help would be appreciated.
The pistons are phenolic I think.

Beautiful job on your rebuild! Love the white mustang.

 

[Mustang5L5]

I personally never did the rear, but this might help

Brakes - Complete Disassembly/Reassembly Of Rear Calipers (w/ Integrated Parking Brake)...

Well I have yet to find a single post on any Mustang forum about taking these puppies apart so I figured I would take some pics and post up. And there is probably a reason for this... they're going to be a bitch to get back together and secondly you can buy new ones for a reasonable price...

www.stangnet.com

 

[Kevin Kurtz]

5L5,
Thanks for your help.
I finally got it. Gonna need some touch up paint!
The key was the initial alignment of the piston as it enters the bore and hits the inner seal. It must be perfectly centered/squared in the bore. Then the applied force used to seat the piston all the way must also be square into the bore.

The caliper itself doesn't afford any square surfaces for a c-clamp to sit on, so when using a C clamp, the seating force gets cattywampus and everything stops.

A nicely sized piece of wood (the end of a 2X1 I think) put on the piston square (with the caliper held by a bench vise) and then hammered gets the piston past the seal, which I imagine is being compressed a decent amount into its seat and against the circumference of the piston...which I suppose is absolutely required.

Thanks again!
-KK