Dave E

Any benefit to swapping from the old cast iron reservoir master cylinder to a newer style plastic? I happen to have one from a 98 2500 truck I parted out that is in excellent shape. Assuming it will bolt to my 86 W250 booster will it be any advantage over the old?

TVLynn

NO benefit. Cast MC is probably 4 bolt too...

Dave E

Actually the old cast one is two bolt and the pattern looks almost identical... I have a rudimentary understanding of hydraulics and I know that if the bore and stroke of the piston is different you could drastically affect the force generated at the wheel cylinders (for better or worse). I may just hold on to the one I pulled from the 98 and in the event my cast iron takes a crap I will swap it in and see.

moe7404

i have been told that the aluminum cyls cant be rebuilt. but dont know for sure. the hydraulics works like this . i had a heavy duty d250 1982. it had 1 ton brakes. i changed the rear cyls from 1" to 7/8 and the rear stopped locking up. I.E. less power. if you change the front master cyl to a smaller size you will put less power to the wheel cyl, reducing over all lock up.