While we're talking brakes...

phat46 · March 12, 2006, 03:01:47 PM

I thought i better take advantage of the situation while we are talking about it. I need to get better braking on my truck project since I hope to be driving it this summer. What i have is a '40 ford truck cab on a home built frame witha 429 Ford engine. The brakes work, but not like they should; what i have for componets are as follows: The M.C. is a mid seventies mid size G.M. non-power disc/drum. The front brakes are a Speedway kit with G.M. calipers on Mopar rotors, the rear is a '79 Ford pickup. the pedal is out of the '79 truck. All componets are new, lines, M.C., calipers, wheel cyl. etc, the only used parts are the rear drums which are good. The M.C. is mounted on the firewall. What it is doing is locking up the front wheels and and the rear don't seem to be doing much. I know the rears are working, I have had it jacked up in the rear and the brakes do function to stop the wheels. I need the rears to do more of the stopping as now it will lock the front on dirt and slide while the truck keeps plowing along when it's on fast idle; kinda hard to turn like that! I am thinking maybe I need a proportioning valve to provide more rear wheel pressure and maybe a hold off valve on the front. what do the experts think?

enjenjo · March 12, 2006, 05:20:58 PM

A poportioning valve can't suppy more pressure, only less. And a hold off valve only works for a split second. What calipers do you have on the front? I know GM, but are they the metric calipers, or the bigger ones use to 77?

phat46 · March 12, 2006, 07:32:36 PM

Metric

enjenjo · March 12, 2006, 09:12:01 PM

According to my books, you have 2.5" front caliper pistons, 1" master cylinder, and 15/16" rear wheel cylinders. The original Ford truck setup was 2.875" calipers, 1" master, and 15/16" rear wheel cylinders. Looks like if you change the master cylinder to 7/8", it will match the front brakes pretty good. Since there is a tire size difference front to rear, I think that may be enough. If not you can reduce the rear wheel cylinder size too. A hold off or combo valve would be good too, but not the root of the problem.

phat46 · March 12, 2006, 10:02:09 PM

Thanks for the info Frank, any suggestions on a M.C.?

enjenjo · March 12, 2006, 10:37:09 PM

79 Mustang looks good for bolt up, and the right size.

phat46 · March 13, 2006, 06:25:22 AM

Quote from: "enjenjo"79 Mustang looks good for bolt up, and the right size.

Thanks Frank

phat46 · March 13, 2006, 03:49:47 PM

One more question that I didn't see addressed, maybe it was and i missed it; which port on the m.c. goes to which end of the car, i have mine front port to front brakes and rear port to rear brakes....

enjenjo · March 13, 2006, 04:36:49 PM

Quote from: "phat46"One more question that I didn't see addressed, maybe it was and i missed it; which port on the m.c. goes to which end of the car, i have mine front port to front brakes and rear port to rear brakes....

That is typical for a 79 Ford truck. If there are two different size reservoirs, the larger generally goes to the front.

rooster · March 13, 2006, 05:09:46 PM

I got my sons master cylinder and bracket assembly for his 49 chevy after installing it we were wondering if it would be a good idea to change Ford master cylinder's to the kind that has the ports come out the opposite side to give some room for exhaust. Might be something to consider, I think truck master's and car master are opposite sides. There are some on ebay you could look at! May or may not work for you.