Need some help with master cylinder issue in my 58

[ScottH]

Recently purchased a 58 Chevy Apache pickup that has had a camaro front clip and rear installed (believe its from 70s or 80s?). I would like to replace the master cylinder but not sure what to get as a replacement. I've never seen the one that is currently in it (see pic) so could use some input on what to get. Right now the fronts are doing all the stopping (front disc, rear drum). It does have a stock proportioning valve, I'm assuming it came from donor vehicle.

Any info or suggestions would be appreciated.

Thanks
Scott

[mr48chev]

I think you are on the right track. I'm not sure what year they went to aluminum master cylinders but you should be able to narrow it down. Some snooping on the net seems to show that they started with aluminum master cylinders in 1981 when they changed the body style on the Camaros and Firebirds.

With that you are probably going to have to match it to the replacement with bore size and the depth of the hole in the piston that the pushrod from the booster goes in. Also the replacement may have a single reservoir rather than two reservoirs.

[ScottH]

Thanks for the info. I suspect that the master is newer than the rest of the donor parts. I would actually prefer to go to a single cast, the aluminum looks too "new" for the truck, if u know what I mean.

I'm tossing around the idea of buying a 77 camaro master and seeing how that works.
Just a little concerned if it will work with the 8" booster, lines, proportioning valve, etc.

[72Mountaineer]

That is the same MC as on my '81 Camaro, first year (I believe) for the aluminum ones.

[mr48chev]

Originally Posted by 72Mountaineer

That is the same MC as on my '81 Camaro, first year (I believe) for the aluminum ones.

Come to think of it I think my 81 Berelinta (sp?) six cylinder had that same master cylinder setup.

Scott, probably the best thing is to pack that one to the parts house and see if an 80 or earlier master cylinder will work.

You need to look at three things:
The depth of the hole in the piston that the pushrod from the booster goes in.
The holes that the brake lines go in and the fittings that they use. Somewhere right in there they changed the fittings to a different style from the regular double flared fittings.
The bolt hole pattern. I don't think they changed that but it will need to match the booster.

The angle that it sits at should work good for the cast iron cylinder if everything else works.

[1project2many]

If the front brakes are doing all the work I'd also check the master cylinder bore sizes and the rear wheel cylinder diameters. Larger diameter wheel cylinders will make the rear brakes do more work and so will a smaller master cylinder rear bore or a larger master cylinder front bore. Many of the brake books will contain mountains of information for doing these swaps. There's always "cast iron look" paint to cover an aluminum master.

[OrrieG]

As long as you have the lines apart and have to bleed it take a look at an adjustable proportioning valve so you can fine tune the front/back balance.