Caliper Rebuilding

[GR-124]

Hi guys, This is my first post on this forum.
Recently landed myself a 76 Alfetta GT. Been out of rego and sitting for a number of years. So the idea is to get her to a driveable state for club rego.

First things First,,, making sure the thing will stop. Have ordered kits for the front and rear calipers, but I know they only come with the piston seals.
I have split the front calipers, I did this because when cleaning I wanted to do a good job. So here come the questions.
The O-rings are square in profile see pic. these (used) measure at 1.95mm thick
The recess in which these fit is 1.5mm deep.

what are the thought of using a standard circular O-ring as a replacement?
The ones I have are 2.5 thick, would this be too thick? I would imagine they would squash the 1mm just fine.

[Neil Choi]

Thought someone would have replied. 

I have always just reused the o-rings.  Never had a problem with reusing them.  Changed the piston seals and the rubber boot  seals.  Rubber boot seal lasted not long but then I operated them at the extreme end of conditions.

You can pop into a brake parts supplier and see if you can get some new square ones.

Make sure your new o-rings are brake fluid or hydraulic compatible.

[GR-124]

Thanks Neil.
I was thinking about checking out the local brake mobs or if there is a (alfa) supplier with them, just get them posted.
OR ,,,getting back to the circular profiled O-Rings, maybe getting some at 2.1-2.3mm would be more suitable??

hope I get some other responses

[MD]

The key issue apart from sealing is the brake fluid compatibility. If the material is not compatible with brake fluid, it may break down and fail to seal. I think the idea of the square seal is to introduce the two faces of the seal so that there is good location to prevent any "pinching" between the metal caliper faces thereby introducing a "foreign object" where there should be none and ensure a flat and complete contact.

If the "pinching" can be avoided for sure and the material is fluid compatible, there is every likelihood that a substitute  O ring will work provided there is sufficient tension on the seal surfaces.