Donor Brake master cylinder

[RickGT40]

I am using the brake master cylinder from a 1994 Mustang GT and I need to know if I should keep the distribution block, or go directly off the master to the front and rear?
Rick

[steno]

The general school of thought is to dump the valve body, and go right for the wheels. Do a search though...TONS and Tons of threads and opinions.
Good luck, Sten

[RickGT40]

Thanks for the reply. I did a search on what I thought would be good terms but "proportioning" didn't come to mind. Searching that yielded results with similar suggestions - eliminate the valve.

[Walt]

What would the difference be with and without ?
Thanks
Walt

[CraigS]

The block, if plumbed as it was originally, reduces the amount of rear brake. This is the last thing an FFR needs.

[OVCobra]

I would not recommend just plumbing directly from master cylinder to brake calipers...brake bias/balance needs to provided. While the stock proportioning valve was set up for a mustang (and not ideal for the kit) it would be better than rear wheel lockup. IMO, install an adjustable proportioning valve (eg. wilwood) so that the brake bias can be set up as required.

Dave

[RickGT40]

After doing further research I have concluded that I should keep it in the system. If it causes issues I can disable or bypass it later.
Rick

[CraigS]

I disagree w/ keeping it in the system. I have done this on two different FFRs so am talking from experience not theory. Both cars started as I bought them w/ standard Fox front discs and rear drums. I gutted the valve on the first one and it definitely helped the braking but it came nowhere close to causing too much rear brake. On the second car I was doing some other mods and it was easier to remove the block completely so I did. Same result. There is absolutely no way, w/ the stock calipers and drums or, w/ the stock calipers front and rear, to end up with too much rear brake. I know because my next upgrade on the second car (my current MkII) was the Mustang cobra rear discs. Still not enough rear brake. Then I went to a CNC dual balance adjustable MC setup. Finally, w/ different sized MCs, and, by running the balance about 90% as far as it would go to the rear, I was able to get rear lockup.

[RickGT40]

Craig,
Why would you want "too much rear brake"? What is the consequence of more front brake than rear? Wouldn't that produce understeer, which I would think is more desirable that having the ends swap around if the rear locks up first?

[MPTech]

RickGT40, after reading many posts and talking to previous builders, I did not install the OEM proportioning valve either. (easier, cleaner install, better performance, and 1 less thing to go wrong. Keep it simple). I think my "donor" brake setup (Front: ’95 Mustang GT Disc Brakes, Rear: ’92 Lincoln MK-VII disc brake calipers, Hawk HPS Pads) are about as good as they can be for stock, and more than adequate for Street use. Next upgrade will be aftermarket.

I also highly recommend that at a minimum you replace the Master Cylinder (and booster) with a new or re-manufactured one from the get-go. I used the donor unit and it went out in the first 2k miles (no telling how long it sat before I used it on my build). After replacing the M/C on a built car with a booster, I can tell you it is a PITA! DON'T DO IT! Save yourself the headache and install good / warrantied units during go-kart! (you can change the calipers later if needed, but the M/C and booster and very difficult to access under the fenders and more so if you have remote reservoirs.) I upgraded this to a ’95 Mustang Cobra 1.00” bore (Dorman Master Cylinder M390125), based on forum recommendations.