These billet aluminum custom rear master cylinders feature one blind hole and one thru bore hole for clean mounting on the Softail type forward controls. The 3/4" bore is stock replacement for our billet forward controls like ZPN056150 but does not feature the ball milled grooves. The 5/8" bore version is stock on our forward controls ZPN 055101 & 055102. They can also be used, without any modification, on many other FL, FX and FXST forward controls as well as other custom applications.

Note: The new DOT 4 (as used in the late models Harley-Davidson) can be mixed with the old DOT 4 without any problem, even with the older DOT 3. The new DOT 4 CAN NOT BE MIXED WITH DOT 5. DOT 5 is a Silicon based fluid that has its own formula. This also means that DOT 4 can not be used in a system that has been on DOT 5 (and vice versa) unless the whole system has been taken apart and cleaned. It also needs new seals and cups before the DOT 4 can be used. Cleaning the parts with cloth or paper is also no option, the parts have to be very well cleaned with brake cleaner! (ZPN748043 or similar).