Master cylinder for four wheel discs

[DaveB]

My son scored a Tera Flex rear disc kit at the Pull n Save and I am putting it on my Scrambler. I know that I need a new proportioning valve and have one from a ZJ. The front calipers are from a chevy truck. I need to find a master cylinder for a disc/disc vehicle since the one I have is for disc/drum and the rear reservoir is small. I have found online that you can use the master cylinder from a P30 Chevy van however it has a large 1 5/16 bore which may be overkill for the smaller Tera rear calipers. I have a modified S10 dual diaphragm booster in the jeep and a ZJ booster in the basement. I don't want to re-do the custom brackets to use the ZJ booster so I would like to find a GM master cylinder that would bolt up. Any suggestions ?

 

[flexyfool]

You can just remove the disk/drum proportioning block. Then, compare the bore diameter of the rear output with the front output of the OEM master cylinder. This is where the brake lines screw into it. If the rear hole is smaller than the front, drill it out to the same size. Now you have an equally balanced "disk/disk" system. If the rear locks up before the front, buy an adjustable proportioning valve from Summit, et. al. It will probably not lock up -- especially with a long scrambler with weight in the back. The size of the reservoir has nothing to do with the functionality or performance. The 1 5/16 master cylinder will not work for you.