Manual disc/disc master cylinders

[woody80z28]

What are you using?

I'd like a budget aluminum master cylinder for a Chevy with manual brakes and 4 wheel disc. GMs up to 84 have the standard fittings I want and most got aluminum masters in 81. I've looked at Camaros, Vettes, T/As, S10s, Cadillacs and still cant find what I'm looking for.

The cheapest aftermarket ones I've seen are about $200 (Wilwood & CPP).

I did find a 79 T/A master for manual disc/disc that will work, but it's an ugly cast-iron piece.

Anyone have a suggestion?

[Apogee]

What calipers are you running? Caliper bore sizes are going to determine your MC bore size requirement, which in turn will make any suggestions much more applicable to your situation versus someone else's.

Tobin

[woody80z28]

Front single piston calipers (2-15/16)
Rear single piston calipers (1-7/8)
Right now I have power brakes and a 79 Vette master with a 1-1/8 piston and a prop valve plumbed in the rear line.

General consensus on NastyZ28 seems to be a 1" master would be best for my application.

[Chad-1stGen]

You can get a 1" cast iron deal by using the vette manual M/C disk/disk from the late 60's early 70"s vettes. Can't recall the exact year range but it is the cylinder that many of the aftermarket conversion kits are based on.

I'm interested to see if there are any aluminum suggestions since I use the one above.

[Randy67]

The 1" master is from 67-79 Corvettes with manual brakes.

[woody80z28]

Ok, I found that one...
http://www.napaonline.com/MasterPages/NOLMaster.aspx?PageId=470&LineCode=TS&PartNumber=101371&Description=Brake+Master+Cylinder+-+Remfd

Could I make this S10 disc/drum master work by taking it apart and modifying it? IE, do drum masters just have a restriction in the rear line that could be drilled out?
http://www.napaonline.com/MasterPages/NOLMaster.aspx?PageId=470&LineCode=TS&PartNumber=101905&Description=Brake+Master+Cylinder+-+Remfd

[Skip Fix]

They did not make any 79 TA disc/disc that were manual. All used a dual diaphram power booster. Yes 79 used a cast iron similat 1 1/8" as the disc/drum power cars but without the RP valve in the rear.
80 or 81 they switched to the aluminum quick take up MC for the TAs and the new "low drag" front calipers.

All of the later aluminum MC even disc drums I've looked at don;t have a RP valve built in them like the old iron ones. Don't know if they did without them or moved it in the prop/combination valve. The aluminum ones have a shallow hole but appear to have enough meat to drill it deeper to retain the manual rod better.

[woody80z28]

If the aluminum disc/drum ones don't have a rp valve in them, maybe I can give that S10 cylinder a shot and at least see how it works.

[Apogee]

I would say skip the straight 1" bore MC options as you may have a lot of pedal travel with the calipers you're running. You should be able to use the stepped bore manual S10 MC by turning down the pilot register to 37.5mm [1.476"] and possibly slotting the holes a little as I don't recall if they used the standard 3.400" spacing or not.

Interestingly enough, the manual and power brake versions of that MC both have 24mm pressure bores but different primary bores at 31.75mm and 36mm respectively. If I recall correctly, both have shallow pushrod holes so you'd want to make sure that the pushrod couldn't fall out of the MC piston divot.

[35spline]

Does anyone know if the Wilwood 1" MC a straight bore or stepped bore MC? I have a similar disc/disc porject underway with a single piston 2.85" front caliper and a 2,125" rear. I am wondering if I can pull this brake upgrade off with a straight bore 68-76 corvette MC?