BOLT ON brake master

[EricB]

Hi all


I thought I read in someone's brake / build thread that the Australian Protex master cylinder that is sold by Greg at 4WD in Australia was bolt-on?
Well it isn't, I just received one and the center to center dim on the flange bolt holes is approx 60mm.
The center to center dim on the firewall studs for the stock single circuit MC is approx 65mm.

Unlike the Wilwood MC, there is SOME meat in the Australian MC to open up the holes, but not much.
I measured the Aus MC and there's 5mm between the OD of the top mounting hole and the edge of the flange,
and only 4.5mm between the OD of the bottom mounting hole and the edge of the flange for the bottom hole.

Do-able yes, but admittedly that doesn't leave a lot of meat...
I just wanted to put this out there.

Also (not that it matters) the outputs for the brake hard lines are metric FYI



So is getting a old Chevy truck MC like what Rob came up with the only true BOLT ON MC ?

[RiverPatrol]

After seeing the eBay listing, I was wondering how much difference, if any, you noticed after installing this MC? And what type of proportioning valve did you use?

[EricB]

Hi Leslie

After I drilled out the ears of the ProTex MC flange to match the bolt spacing on our firewall, I built up the outside of the ears with several layers of JB weld to get it back to a similar kind of material thickness. I used washers on either side of the flange and a bolt going through the hole as dragging/profile guides to makes something that is nice and round like stock. It came out great.

As far as feeling, I'm not sure the comparison is a fair one since the stock MC I removed is sorely in need of a rebuild, and I replaced it with a brand new one... So yeah the new 77+ Australian Patrol ProTex feels better. Is it day and night though ? No, probably not ... But there is something to be said from a peace of mind standpoint about now having dual circuits instead of just one ... I guess that helps me sleep better at night.

In all the other threads I read about MC swaps, I never saw mention of a prop valve so I actually haven't used one.
I ran a brass T inline with the rear circuit to operate the same kind of brake light switch that is on the stock MC but nothing else beyond that.

The trip to the muffler shop, the last fun run I did off of Angeles Crest, and the trip to the tire store to install the new KO2s all happened without any drama.
The brakes felt good and I had no complaints.

-e


(On a side note, the 4WDParts Australia Protex clutch master IS BOLT-ON - no mods needed there ...)

[RiverPatrol]

Thanks for that detailed explanation.