Brake port confusion


Spotter Required
Staff member
Oct 20, 2010
Las Vegas
So, I've been fighting the brakes on my FJ40 with D60 front and 14 bolt rear (3/4 ton D44 disk conversion). Existing master setup is a 79 Dual diaphram booster with a 1" FZJ 80 series master cylinder, but I'm about to add a 86 GM 1 ton master cylinder.

My main question right now is which port goes to the front brakes. I was working this through with @woody and @Lil Rich who both were of the opinion that the rear port goes to the front brakes and the front port (furthest from the firewall) goes to the rear brakes. I was convinced that it was reversed instead, but trust them.

Just recently I found this brake diagram (stolen from

Rear port goes to the rear brakes. Front goes to front.

Reading up on GM junk, there are apparently masters with both designs. I guess I need to go grab the master cylinder I'm gonna use and see which reservoir is larger. I would assume that the disk front circuit would have a larger vol reservoir, which looks to be the rear res on this master.

It seems the answer is "it depends"...


eternal noobie
Staff member
Oct 12, 2010
Toquerville UT
Yep, the bigger res is front surprise that masters are not consistent across all brands :)
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