rear brake lock up

[stranman]

I replaced almost all the brake lines on my truck as well as both rear wheel cylinders. Shoes and drums where in good shape. I was re-bleeding the system yesterday because the brakes where still pretty soft. Re-adjusted each brake as well using the star adjuster. My neighbor a heavy equipment mechanic was assisting. My problem is that my driver side rear brakes locks up before the 3 other brakes. It was doing this a bit even before I re-bled the lines.
We played with the adjusters for a while, but could not fix the problem. Neighbor feels it is a pressure problem, uneven brake fluid pressure to the two rear wheels. The brakes seem so simple, could this be the problem?
One thing very odd, on my brake line from the rear passenger side to the T block on the axel, the metal brake line goes into a rubber type line which loops and then goes into the T fitting. This looks odd and does not show in the parts manual. I also looked on my m725 and this line run directly from the wheel cyl into the T block? Is my m715 odd or should this rubber line be there? That line is also the only one I did not replace because it did not come with the replacement set. Any suggestions on problem resolution is welcome.
Brakes feel great except the one wheel keeps locking up.

[amphi]

It is acting an out of round or misaligned drum. It has been posted here where the drum position on the axel flange is critical.

Try removing the three countersunk screws holding the drum to the axel.

Remove the drum and rotate it 120 degrees and reinstall. If it still lock up try another 120 degrees and see what happens?

If you still have the problem at least we have eliminated this possibility.

Good Luck

[amphi]

It is acting an out of round or misaligned drum.

should read:
It is acting LIKE an out of round or misaligned drum

[brute4c]

That rubber line is wrong...no telling where it came from.

I had a problem bleeding the passenger rear because the line from the T on the rear axle to that side was plugged...sounds like yours bleeds ok though...

If the line just a rubber line, it isnt good enough for brakes. ..you probably know that.
If it is old, it may be swelled up on the inside and be restricting flow to the passenger side rear.

Get rid of that flexi line and make it all metal and see if that does it.

The drum, as amphi has said, may also be the problem.

The stock brake system should provide equal pressure to all brakes at the same time.
If one wheel is locking up, then it **should be** because that one is overadjusted...all the rest of the system being correct.

I know several have posted this before...it might help with aduting your brakes...maybe you already know it:

(Copied from one of Barrmans GREAT posts!)

Spin the wheel while you are turning the star wheel with a brake spoon. The manual says to adjust them all the way to no wheel movement and then back off until you can make it turn with "minimal" resistance. I have found it is easier to adjust until I get a dragging noise but no drag while I am spinning the wheel. I then push the brake pedal a few times to get the shoes settled and spin the wheel again. Normally, you will have less noise than before you pushed the pedal. At least for the first 2 or 3 times at each wheel. Once you get the dragging noise, you are close. Do that to all 4 wheels and see what kind of pedal heigth you get. The pedal is all you are really adjusting from this point on. The tighter the shoes, the higher the pedal. Of course, if you go too far, you will be dragging the brakes and burn them up so don't get too agressive. I was playing with mine the other day and one push with a spoon at each wheel raised my pedal almost an inch. I was showing my students how just a little bit can be too much.

Seems to help me get them equal a lot faster than trying to set each one individually by feel.

[george walker]

After a recent adj. now my r.r sometimes locks up on light braking, im sure its part out of round drum an more to tight on the shoe clearance.

[stranman]

It did seem like the drum may be slightly out of round, when adjusting the brakes it seem to grab a little unevenly, will try the rotation of the drum as suggested.

I will also remove rubber brake line, it does seem to be a brake line, like those on front tries, but regardless it is not stock, it is old and I will remove.
Thanks for the feedback

[brute4c]

There is a statement in one of the manuals that we are to mark all the drums so that when they are removed, they can be put back on the way they came off...properly indexed to the hub...it does seem to make a big difference.

An easy way to do this is to remove one of the drum holddown screws and put a little paint or whiteout or something on the drun and in the flanged part of the screwhole...the end is beveled outboard of the threads.

[stranman]

Still have the problem.
Rotated the drum, checked that the shoes where on correctly and checked that self center anchor block was in correctly. Even pulled the t-fitting (on rear axel where lines meet) from my m725 and use in place of the one on the m715. Of course that is because I stripped the one on the m715 when re-installing lines. Why do they make those things out of brass? that is the second one I have stripped, I stripped the one on the front last year.
Driver side rear brake still locks up. Seems like driver side is getting more pressure than passenger side.

[amphi]

Well that's too bad!

How badly does it lock up? – Just grabs first? -- Will it skid on pavement?

Does it still seem like it might be out of round after rotating to the other two positions?

If the shoes happen to be contaminated with oil or brake fluid they will grab. One would think they would be slippery but it doesn't work that way – they will grab.

[stranman]

It skids on pavement. The out of round does not seem as noticeably now.
I assume I use brake cleaner to clean the shoes, to be honest I just wiped them down with a dirty rag, did not really clean, and they are probably dirty due to leaking wheel cylinder. Maybe it is that simple.