68442CONVERTCO

I was wondering if I can reuse my manual drum brake master cylinder to convert my 1968 442 to manual front disc/rear drum?

I am planning on using the '68 proportioning valve by the master.

Any other tips/suggestions for this swap?

Thanks,

Tony

67442HT

You cannot use the existing master cylinder that is for 4 wheel drum brakes. Drum brakes have a small check valve in the outlet of the master cylinder that holds a little pressure on the wheel cylinder cups so that they will apply faster. If you use the old master cylinder for disc brakes, the check valve will hold the brakes on a little all the time.

However, you can use the original master cylinder if you know how to take the check valve out. To do this you would need a master cylinder rebuild kit as you will damage the outlet port seat that the line seats on. So.....it is better to just buy a master cylinder that is for a disc/drum setup.

RAMBOW

New "correct" disk/drum MCs are cheap...
Order one for a 1970 442 w/ disk brakes. 1 1/8" bore large/small pot unit.

Reman ones are like $20 from autozone or oreillys. New ones are $40-$50

Not worth fighting with an incorrect one.

I would also convert over to a modern prop valve and mount it down on the frame rail to clean up the engine bay, but thats just my prefrence.

68442CONVERTCO

Thanks for the info!
Guess I'll be replacing it after all.

Allan R

Just curious. If you're going to convert to front discs... Why not convert to power front discs/rear drums? If you're changing to discs, you'll need different MC, proportioning valve, backing plate/bolts, spindle, knuckle, caliper mounts, calipers and pad, discs, brake hoses and lines. Power brakes are more effective than manual - I'd add the brake booster, proportioning valve and go power. You're already changing the spec of the car from as built anyway.
Have a look at ILT's Olds catalogue (page 25) It has the complete conversion to power front disc/rear drums http://www.inlinetube.com/PDF%20cata...dsmobile02.pdf

68442CONVERTCO

Trying to keep my options open, not sure if the 455 I'm buliding is going to have enough vacuum to support power brakes. Also it's a four speed and I'd like to keep as much room as possible for headers.

I already have the spindles,rotors,calipers,brackets,etc. I just need the proportioning valve, hard lines, and master cylinder. Looks like summit and autozone have a 1" bore for manual disc/drums. p-n m1479.

Thanks again for all the info.

RAMBOW

i would still go with a 1 1/8" bore mc, even with manual brakes.
I HAVE manual disk brakes and farted around with several different MC's. the 15/16 & 1" bores both felt mushy to me. the 1 1/8" is the same as the power disk MC, but it "felt" the best to me.

Don't forget that manual brakes, the pusrod must be in the 2nd hole on the brake pedal.

I prefer manual brakes to power... I like the direct feel of the pedal, vs the boosted pedal.

68442CONVERTCO

Ben,

Thanks for the info, I was wondering if you could feel the difference between the 1" and 1 1/8" masters.

mpolds

AS indicated countless times all over the * C O * Website -- DRUM and DISC are two very separate entities -- and the two use very different parts....

Don't use those redicously dirt cheap rebuilt Master Cylinders -- think about it -- if a Master Cylinder is $ 20 --- what can you get for $ 20 these days ?????????? Don't trust your life -- or your front bumper and grille being destroyed because you can't stop in time to a $20 Master.....
(Know the expression "penny wise and pound foolish"????????)

I have NEW DELCO MAster Cylinders (it is 1 1/8" Bore) for $ 49..........

Best always to call me --- Craig -- 516 - 485 - 1935.... New York