how do you check master cylinder in junkyard

[Canon_Mutant]

Not to hijack the OPs thread but thought perhaps this question might be pertinent. I am pretty sure I have 24mm on my 442 but Wilwood only offers 15/16" or 23.8mm. Anyone use a Wilwood 15/16 for this or do you have to buy a SAE 15/16 booster?

Going to a prop valve on my big brake front and drum to disk rear conversion so want to upgrade the M/C too. They have a nice kit that does it all.

 

[TURNA]

Are you trying to upgrade or just replace what you have?

 

[Canon_Mutant]

It seems to be a [?] on whether the factory M/C will suffice for a rear disk conversion AND going from a 2 to 4 piston setup? Now, I am certain Wilwood could answer all of these questions but has anyone here EVER got through on their phone system? I am beginning to think there is like one dude there and he takes like 1 call per hour.

Anyway, rant aside, I know I need an adjustable prop valve to dial the new rear disks in, and they have this really nice MC/Prop Valve kit I want to get. But I "assume" I have the metric 24mm bore so just trying to find someone that has put a 15/16" MC on the factory booster? Or, new booster required too?

 

[TURNA]

The factory double diaphragm booster master say from an 85 Cutlass or Monte SS will work with 4 wheel disk brakes.

If you want to "upgrade" the master use one from an 81 Firebird. Dorman part # M104458

As for the valve the factory GM disk/disk works as well and fits in the stock location.