Power brake Master Cyl question

[crews]

When switching from a 68 power drum truck to a 72 disc set up, you obviously need the 72 master cyl for the greater fluid capacity for the calipers. Is there any difference in the rod depth/ length between the two or is it a straight swap? Any help would be greatly appreciated.

[Eichorst69]

I put a 72 disk/drum master on my 69 power drum when converting to disk and had to shorten the rod a bit.
If I remember, I think it had to be shortened a couple of inches.

Rob

[BurnoutNova]

i think the proportining valve is more important than the fluid capacity, as disc brakes take WAY more psi to be effective. the surface area is much less than with drum brake shoes, and most drum brake setups are self- energizing, becasue they kind oif wedge them selves into the drum


but to answer your other question, once the system is full, it shouldnt matter how big the master cylinder is, as long as its full.

[Longhorn Man]

you should go with both the master cyulinder and prop valve forr a disk/drum system.
Going from manual to power, you will need the pedal pushrod off a power brake truck, they are not the same.

[crews]

Ok- Thanks for the input. I already have the discs on it but the PO did not change anything else. I just got a disc master cyl but I did forget about the prop. valve being different.

Thanks for the help....