Need a break from these brakes... and help

[67chevy_hotrod]

Ok so. 69 chev longhorn c20. I ditched the eaton and put in a Dana 60 out of a 72 GMC(thank you randy500) Everything on both trucks was stock, stock. I just put power breaks on my longhorn and adjusted the brakes. Now one or the other on the rear will lockup at about half pedal. Regardless of adjustment, regardless of road condition, that same side will get smoking hot after a big hill even with minute breaking. However if you back off the pass. side brake the driver side locks up and visa versa. Now just recently ive replaced everything front rear and booster obviously. I even had the rear drums turned! ( new they where both over 12 thousandths out...) do I need a proportioning valve? Is the fact that the 72 (I thought was front disc), mean that the brakes on this rearend in stock form work properly with front discs only?? Has anyone encountered this issue? Thanks in advance!

[cleszkie]

Did you install the drum brake shoes correctly? Each pair has one shoe with a long lining and one with a shorter lining. If my memory serves me, the shoe with the long lining always faces the front of the truck. If you don't install in this manner, your drum brakes can be very grabby to the point of locking up occasionally. I hope someone will correct me if I'm wrong about which shoe goes forward. I had this same problem a while back until I made the correction. I run all disc brakes now so that bit of drum brake knowledge is fading.

[B. W.]

Originally Posted by cleszkie

Did you install the drum brake shoes correctly? Each pair has one shoe with a long lining and one with a shorter lining. If my memory serves me, the shoe with the long lining always faces the front of the truck. If you don't install in this manner, your drum brakes can be very grabby to the point of locking up occasionally. I hope someone will correct me if I'm wrong about which shoe goes forward. I had this same problem a while back until I made the correction. I run all disc brakes now so that bit of drum brake knowledge is fading.

Hate to correct but the short shoe is the primary shoe (goes to front) As far as memory goes, I work on cars for a living - when I enter mileage on the work order I can't remember the mileage between the car & the computer!

[HotRodRyan]

Originally Posted by 67chevy_hotrod

Ok so. 69 chev longhorn c20. I ditched the eaton and put in a Dana 60 out of a 72 GMC(thank you randy500) Everything on both trucks was stock, stock. I just put power breaks on my longhorn and adjusted the brakes. Now one or the other on the rear will lockup at about half pedal. Regardless of adjustment, regardless of road condition, that same side will get smoking hot after a big hill even with minute breaking. However if you back off the pass. side brake the driver side locks up and visa versa. Now just recently ive replaced everything front rear and booster obviously. I even had the rear drums turned! ( new they where both over 12 thousandths out...) do I need a proportioning valve? Is the fact that the 72 (I thought was front disc), mean that the brakes on this rearend in stock form work properly with front discs only?? Has anyone encountered this issue? Thanks in advance!

Going from non power brakes to power brakes almost always require of swap or adding a prop valve. Provided brake wheel cylinders have same volume and cross sectional area.

[67chevy_hotrod]

I've done drums a thousand times and never had an issue lol. plus they where even rebuilt by an actual shop after he said the same thing! I told him hey man I did them proper and he said "couldn't have"... welll well i did them exactly right! Like usual( probably just jinxed myself) any rate, I will try a prop valve and see what that does, and recommendations?

[gottattooz]

BOB or big on back for brake shoe configuration.

If you replaced your master and booster, verify the push rod between the two isn't too long. I did a rear disc swap along with booster and master cylinders from different vendors and my push rod was 1/4 inch too long. It keep pressure on the rear brakes and smoked the first set of rotors and pads until I figured it out.

- Josh

[67chevy_hotrod]

Originally Posted by gottattooz

BOB or big on back for brake shoe configuration.

If you replaced your master and booster, verify the push rod between the two isn't too long. I did a rear disc swap along with booster and master cylinders from different vendors and my push rod was 1/4 inch too long. It keep pressure on the rear brakes and smoked the first set of rotors and pads until I figured it out.

- Josh

Bob! Exactly that's what I was taught. How do you suggest checking said push rod? I believe mine is adjustable..

[gottattooz]

I inserted the push rod into the power booster and marked the depth with a sharpie. Then put the other end of the push rod into the back of the master cylinder and mark the depth with a sharpie. If the rod is too long, there will be a gap between the marks, and you'll need to cut off the excess, or if your rod is adjustable, shorten the length of the rod. The rod should be about 1/8 inch shorter than the total depths of the booster and master.

- Josh

[67chevy_hotrod]

Originally Posted by gottattooz

I inserted the push rod into the power booster and marked the depth with a sharpie. Then put the other end of the push rod into the back of the master cylinder and mark the depth with a sharpie. If the rod is too long, there will be a gap between the marks, and you'll need to cut off the excess, or if your rod is adjustable, shorten the length of the rod. The rod should be about 1/8 inch shorter than the total depths of the booster and master.

- Josh

Nice. Thanks man! Will look into it

[Myoldtruck]

I did the power brake conversion over the summer on my 70. If you still have 4 wheel drums then continue to use the stock brake line block under the master cylinder. Did you oil your emergency brake cables and confirm they are working, thats what started my problems with smoking brakes. I also had front brake pulling to one side.

Check for correct brake shoe installation, one short shoe and one longer shoe per side ect. Shoe linings have to be very clean, no finger prints of oil, grease ect on the linings. I used a drill with wire brush and cleaned all parts and backing plate. Take adjuster wheel apart and clean threads and sleeve and antiseeze it up, so it spins easy, make sure the adjusted wheel is installed properly facing the correct way. Anti seeze the high bumps on the backing plates so the shoes move smoothly in the drum. Replace all rubber brake lines, you have alot more system pressure now with power booster. Do your research on brake shoe quality, there is a difference, Im using napa ultra premium linings, dont go cheap.

My truck stops straight and well now.