I have a brand new 71 master cylinder for front drum brakes. I need a master cylinder for a 77 with front disc brakes. Both have power boosters. They look the same from the outside. Can they be switched?

Thanks.

Jack

 

Highly unlikely, master cylinders are sized to the piston at the wheel. Different size pistons = different master cylinders.

 

Thank you. Makes sense.

 

Yea, Ecuri is definitely right... Disc brakes have a much larger resevior. If you notice on your current 77 Master cylinder there is a large resevior and a small one.. the large one is for your front disc and the smaller for your rear drums. If you look at the 71 Master cylinder, the resevoir sizes should be the same as the 71's had 4 wheel drums.

More often than not, when people do rear-disc conversions they never replace the master cylinder with a 4 wheel disc master cylinder. I mean the original drum/disc master cylinder will work - but you will need to keep adding fluid as the disc pads wear down...