The brake thrashing BEGINS!!! Toooo much go and not enough whoa

[special-K]

Have you pulled the rear drums yet? Not trying to sway you from discs, as I can read and can see you are staying with a plan. But, first thing that came to mind with rear brakes locking up is you probably have oil on rear shoe r shoes from leaky wheel seal. This is a very common issue with full floating rears. I change that seal each and every time a drum comes off for that reason. Those factory brakes when in proper working order won't lock up the way you describe. Guys who want to stay with rear drums on an 8-lug truck, but want even more brakes, go to the larger dually brakes, like are found on cube vans in the junk yard. There is a thread on this swap in the 4wd section for anyone interested.

[Bigdav160]

The guy wants disc brakes, let him do it. It's his truck.

But I'll agree. There's no benefit except in looks.

To the OP, yes, use a 1 1/4 inch master cylinder for power assist brakes. Smaller diameter MC's are for manual brakes

When shopping for a proportioning valve make sure it's for disc/disc. Summit sells them.

[Orange67]

Hi Phil, good to see another Utahn on here. I can't wait to see more progress on this, as this is one thing I've toyed with doing to my 67 C20. I've got the front spindles and another set of control arms, just getting parts when I can. Good luck, and let me know if you ever need a hand with anything.

[davepl]

I thought drums were actually BETTER when heavily loaded because it helps their self-energizing action. But I'm not a brakemeister, I could have that backwards for all I know.

I will say if they're locking up it's possible you have a wheel cylinder leaking, which will definitely cause that.

Replacing the rears will certainly fix that though!

Be really sure when you install these that you get the bleeder screw UP. It's trivially easy to swap them side to side so that you wind up with the bleeder screw on the downside, but you'll never bleed them fully that way, they've got to be oriented with the bleeders up.

I found the 1969 Corvette has a disc/disc master cylinder that I've used when trying to preserve factory appearance.

[ranger danger]

I put a disc brake conversion on the Dana 60 in the rear of my 69' C20 Suburban about a year ago. I'm replacing the rear diff with a 14 bolt 3.5" x 13" drum setup. No more disc's on the rear for me.

P.S. the Dana 60 with disc's is for sale.

[s_nova69]

Thanks orange 69

Interesting comments. Others

[s_nova69]

Orange67