I have a 93 Civic DX.
I replaced the rear drums with DA rear discs.
The stock M/C size is 13/16th. Will that M/C be ok, or
should I switch to the 15/16th unit?
The front calipers are stock.

Also, should I run the 40/40 prop valve?

Thanks in advance for the help!

 

you should be fine untill you upgrade the fronts, then I would do the 4040 and master cyl.

 

92-95 Civic SI non ABS came with the 13/16ths master cylinder with rear discs.

I upgraded mine to 15/16ths and GSR front brakes and it felt MUCH better