'66 Non-power brake master cylinder gasket

[Rob A.]

Anyone know if the master cylinder to firewall gasket can be found without ordering it through the usual corvette part suppliers?...I'd rather not wait a week for it. Maybe I can just make one, it looks like it's a thick, felt-like material.

[Joe L.]

Re: '66 Non-power brake master cylinder gasket

Rob------

A 100% functional, if not absolutely "correct" gasket for this application is easily made from gasket stock which can be purchased in an auto supply store or some better hardware stores. I've made these before, myself.

[Rob A.]

Thanks...that's what I'll do... *NM*

[Mike M.]

Re: '66 Non-power brake master cylinder gasket

Old Trick - When manufactured gaskets are not available - I make my own.
Pick up the appropriate "Factory Appearing" flat sheet gasket material at your local auto parts store. Pre-formed gaskets never seem to be thick enough anyway.
In your case, cut-out a piece larger than you need for that surface.
Place the material over the end of the MC, keeping it secured so it does not move.
Lightly tap around the inside opening with a ball peen hammer.
Then inside the bolt/stud openings.
Then around the outside.
The machined edges of the casting are sharp enough that the hammering will usually cut-out a perfect fit gasket (Scissor Effect). If it is a little rough or does not release completely, you can trim to fit.
For example, I just finished detailing one of my engines. The only thermostat gasket available locally was a $13.00 combination Metal/Blue Plastic that didn't fit any way and I couldn't wait for a cross-country delivery.
So,
I spent $4.00 on a piece of gasket material about two-feet square. Formed all the gaskets needed and have enough left over for several more cars.
Hope this helps
H. a. N. D.

[Rob A.]

Re: '66 Non-power brake master cylinder gasket

Thanks...the original gasket does appear to be thicker than the material used in the current pre-formed.

[Joe L.]

Re: '66 Non-power brake master cylinder gasket

Michael-----

The method that you described works perfectly; I have used it many times. However, in this case, there is one small problem with it. The original gasket slightly "overlapped" the edges of the master cylinder mounting flange. If this method is used to cut the gasket, then the gasket will exactly duplicate the configuration of the master cylinder mounting flange. It will be 100% functional, though. The "overlap" on the original gasket serves no functional purpose.

[John H.]

Re: '66 Non-power brake master cylinder gasket

Michael -

GM has a relatively new thermostat housing gasket that's the same as the old ones, except it has a silicone bead molded on both sides, won't leak, and can't be told from the old one when installed - P/N 10105135