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brake help

Carnut

Member
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7:35 AM
Joined
May 9, 2019
Messages
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Location
Woodbury MN
Need your expert help. I am having trouble adjusting my power drum brakes on my 66 Belvedere. I can see the front shoes moving roughly a 1/4 inch inside the drums when I have someone apply the brakes and someone rotate the tire. You can hear them clank around a little sometimes. I do have new shoes and wheel cylinders, re-used the hardware. If I adjust them up higher and take it for a drive, they are way too tight and hot as hell. In the records that came with the car someone wrote on a work order back in 2005:

Checked and found valve stuck inside booster. Could not get new one. Removed and made rod for master cylinder . Bled system mounted master cylinder.

I thought maybe the rod was a little long going into the master, holding the wheel cylinders out and not letting me adjust them properly. What I measured was the hole in the master is roughly .915 deep. I took an aluminum block I had lying around that was 1.005 thick and dropped a hole in it so I could put it over the rod and measure the distance down to subtract the two numbers and find out how far out it protrudes, which is roughly .885. I say roughly because it is a rounded end and I did my best to be accurate. That leaves .030 clearance which I am assuming is ok? It has been a while since I have adjusted front drums and never on a mopar, but the slop just doesn't seem right. Stops great though. Any guidance would be greatly appreciated.
Thanks,
Tim

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I think you are safe with the .030" clearance. Did you adjust the shoes out to the max and then back the adjuster of until the wheel rotated with a slight bit of drag? Every thing looks normal in your pictures. Were the drums machined?
Mike
 
is there a proportioning valve ? when i adjust my drum brakes i run the auj up till i cant turn drum by hand then back off 1/2 to 1 turn where the shoes just light drag . or call doc diff he knows a fair amount.
 
I did try adjusting them that way one time and when I came back from a test drive, I could hardly turn the wheel, it had really tightened up. I could just keep doing that ( drive, back down, drive, back down) and see where it ends up, but it seems like whenever I get them so they spin with a slight drag after a drive, they are moving that 1/4 inside the drum. The drums were new from summit last year, although they didn't seem to press on to the hub real great. The drum raised slightly around a couple studs (see pictures) when I pressed them on. Measurement wise, the ID of the drum measures pretty consistent at 10.005 wherever I measure.

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You sure you dont have the self adjusters on backwards? They have different threads from left to right side of the car.
Also, what about the flex hoses? Are they new? I once had a problem on a Dodge with old hoses that looked good on the outside, but were deteriorated on the inside. They would swell up internally. When I applied the brakes, the fluid would force through, but then the old hoses would not let the fluid back off to release the brakes.
 
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is there a proportioning valve ? when i adjust my drum brakes i run the auj up till i cant turn drum by hand then back off 1/2 to 1 turn where the shoes just light drag . or call doc diff he knows a fair amount.
No proportioning valve that I can see, I think you don't need that if they are all drum or all disc, but I am not sure.
 
You sure you dont have the self adjusters on backwards?
I don't think so, when I adjust them I am turning them up, and the adjust is pushing down on the inside, so it seems like they are moving the correct way, unless I am missing something.
 
You sure you dont have the self adjusters on backwards? They have different threads from left to right side of the car.
Also, what about the flex hoses? Are they new? I once had a problem on a Dodge with old hoses that looked good on the outside, but were deteriorated on the inside. They would swell up internally. When I applied the brakes, the fluid would force through, but then the old hoses would not let the fluid back off to release the brakes.
The adjusters are stamped L and R on the end.
Mike
 
No proportioning valve that I can see, I think you don't need that if they are all drum or all disc, but I am not sure.

on a single stage master i did not think it would have a proportioning valve but a duel master uses a prop, valve as the rear has to work first [ build pressure ] only a quick sec to stop/ less nose dive under hard braking and a disk/drum use them also. that single stage master is a death system if it leaks you can loose all brakes if the car is all o/g then you have to play with adjustment with that system . if it were my car i would up grade to a duel master and install a prop, valve.
 
The adjusters are stamped L and R on the end.
Mike
i just bought new auj kit from o-relies and they weren't marked know that the teeth point down for the adjuster arm to catch and move out as you apply brakes in revers..
 
The adjusters are stamped L and R on the end.
Mike
I believe I have the left and right on the correct sides, L is on the drivers side. Last year I put new hoses on when I did the drums, I didn't want to take any chances with them. I have quickly had to replace darn near every piece of rubber on the car, all of it looked like it was ready to fall apart. Just had the drivers side motor mount fail last month! I did think about upgrading to a different master cylinder but right now I just wanted to get it running and driving. I live in MN so I was hoping to make that a winter project...
 
is there a proportioning valve ? when i adjust my drum brakes i run the auj up till i cant turn drum by hand then back off 1/2 to 1 turn where the shoes just light drag . or call doc diff he knows a fair amount.
I took your advice and turned them up to where the wheel didn't turn, marked them, and then backed them off 1 turn. It sounded like the shoes were moving around a lot when I backed out of the stall but I took it for a drive and did a couple of hard reverse brake stops to self adjust and it seems to have worked. They stop straight and smooth, and no noises. I will put some miles on it and see what happens. Thanks for the help!
 
I took your advice and turned them up to where the wheel didn't turn, marked them, and then backed them off 1 turn. It sounded like the shoes were moving around a lot when I backed out of the stall but I took it for a drive and did a couple of hard reverse brake stops to self adjust and it seems to have worked. They stop straight and smooth, and no noises. I will put some miles on it and see what happens. Thanks for the help!


glad to hear . they will make some noise but should get better with miles.
 
Just a quick update, I found two things with the brakes on my car.

First, the springs on the top holding the shoes to the center pin where reversed. Shorter one goes on the front. I could not figure out why they kept adjusting up. Turns out the one spring was not holding the front shoe tight against the pin and the whole shoe assembly was moving, causing the adjusters to keep adjusting up. One of my coworkers noticed the spring coils were tight together after I was at my wits end. I was positive I put everything back the way I found it, and based on the other issues I have uncovered, there is some probability someone put them on wrong before me, but I can't verify it was wrong when I started so I am going to take the blame for that.

Second, I bought new Raybestos 2915R brake drums and pressed them on (see picture in #4). Turns out, they were not pressing on all the way flat against the hub, and I was getting a vibration when I braked at freeway speed. I mounted the drum on the hub and tightened it down, and put the assembly on an extra front spindle I had. I measured the run out with a dial indicator and it was way out of wack. The measurement at the bottom of the wheel studs where the drum would sit is .640 and the lug holes in the drum are .625. A .015 press over 5 holes, it will never sit flush. Be aware if you buy these front drums. I am drilling the lug holes out to 41/64 so they just slide over the bottom of the wheel studs.

Just thought I would convey in case someone else experiences the same issues.
 
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