The Stovebolt Site Forums The Shop Area Driveline Under cab disc m/c

I wanted to swap my front brakes to power disc and maintain the 6 lug wheels and under an m/c mounting location. My 50 3100 truck still has the stock manual trans, which seems to be an issue according to the kits I found online. Is there a disc/drum power m/c available?

I made the switch on mine but without the vac boost and it works great.

I went with one of these:
Under Floor MC

Was the manual setup For disc front/ drum rear? Any help with a link?

Mine was for 4 wheel power disc, but the kits shown are available for disc/drum or 4 wheel disc- you select which MC you want when you order the kit. My power boosted setup is a pleasure to drive.

I may not be understanding you correctly, but if you are looking to install a disc/drum manual MC, I would advise against it and get the power booster setup. The pedal ratio on the truck is probably not going to provide a very good pedal feel (high effort and/or very long pedal travel) for even a front disc only setup. Discs require more hyd volume and more pressure than drums.

Perhaps others here have gone with a manual disc/drum MC and they will post their experiences... manual drum/drum and manual disc/drum have different MC piston diameters and different MC piston pressure applied requirements... I am not a brake expert, but the results can be truly awful if you mix the wrong components.

Wish I could be more help, but I've only installed a 4 wheel power disc setup and a 4 wheel power drum setup on these old trucks...

You can order the MC only and select a 2 wheel disc setup: $285 master cylinder with booster & proportioning valve

Disc brakes take very little fluid volume, but generally higher pressure. The piston does not retract much at all.
Drum brakes the piston is retracted after braking by the springs on the shoes, more movement if not adjusted regularly or properly.

With the undermount m/c pressure valves are used to maintain the pressure against the discs in the front and the shoes in the rear.

IIRC the front uses a 2lb valve and the rear uses a 10lb valve.

Grigg, you're right. I remembered wrong... the caliper setup that uses more fluid volume over time as the pads wear, but not while actuating, correct?

Sounds about right.

Be cautious, you may need to modify the brake pedal due to a new angle with the new master cylinder.

Chris

The MC link that I posted uses the stock pedal pivot and has an adjustable pushrod with clevis so that pedal ends up in the stock location. It also installs at the stock angle.

Link to understand the brake components and their function:

http://www.hotrod.com/articles/proper-plumbing-pointers-making-installing-brake-lines/

In general.............Residual pressure valves on drums hold the wheel cylinder seals out not the brake shoes. On discs they stop flow back on certain installs, normally not needed. Pressure hold on discs can result in brake drag and lock up from pressure build hot with not allowing pressure release.

I used the CPP kit, power booster, disc front, drum rear, stock pedal and location.
Get the kit with the integral proportion valve/RP setup.
Plumbed the whole thing with CuNi tubing.
Contrary to what you may read, there is NO interference with the stock clutch and 3 spd on the tree linkage.
Check my 51Build page in my sig link to see photos.