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Adjusting Self-Adjusting Brakes

Mike Armstrong

Bronze Level Sponsor
Pulled the drivers rear wheel off, though from the looks of the puddle, I didn't need to in order to see if the cylinder is still leaking.

I'll pull the piston out again and see if I can re-seat the seal. Tomorrow I'll talk to Rick at SS about the physical size of the early series larger bore cylinders to see if using them in place of mine is a possibility.
 

Jay Laifman

Donation Time
I am a huge fan of the Motive power bleeder. Best bleeding I've ever done.

On the other hand, I hate the hand pumps. I was using one on my Alpine, not that long after it was repainted. These things have this hand pump attached to a reservoir. At least the one I had did not sit on the ground well. It wanted to tip over. And of course, that's exactly what happened once when I got up to check the level of the fluid in the master. I just picked it up and started pumping to get the suction up. Sadly, when it tipped over, apparently the fluid in it got into the valve and as I pumped up the pressure, it sprayed fluid out and all over my new paint!

Never used it again.

FWIW, I did get the speed bleeder valves for the Alpine. These have a little ball and spring or plunger and spring and let you just put on a hose, loosen and pump away. I've been very pleased with them as well.
 

Mike Armstrong

Bronze Level Sponsor
Just as a follow up,

As much as the the drivers side cylinder was leaking I would have guessed either the seal was installed backwards (taper away from the piston head instead of towards it) or the cylinder itself was too warn to seal correctly. As it turned out, the seal was correctly installed but sliding a finger down inside the cylinder I could feel roughness from deposits. I was able to use some 800 grit wet/dry sand paper rapped around my little finger to smooth out the cylinder wall. Once put back together the leaking has stopped.
 

Mike Armstrong

Bronze Level Sponsor
No leaks and good bleeding but still had weak breaks. I had the drums checked out by another shop and they were out of round. Re-installed the drums and the braking was better but really not effective, I certainly wasn't able to lock the brakes up, however, another forum member related that even after a full brake overhaul he was still not able to lock up his stock brakes.

I've been adjusting the rear brakes to the point I felt there was slight drag even without the brakes applied. Then I remembered a post a forum member made about getting his brakes to work effectively by adjusting the rear brake shoes to drag to the point he thought they would heat up, but they never did.

I've been turning the drum by hand, feeling for drag, then readjusting. On both drums there has been a part during turning the drum where it spins free but there is drag during the rest of the turn. I have stopped adjusting when I thought the part where it dragged was dragging hard enough. But, like I said, breaking has not been that great.

Well, thinking of the members post I kept adjusting till the 'free spinning zone' during the drum turn was eliminated to the point that there was a slight drag during the entire spin, not just a portion. Now, when turning the drums by hand there is a constant drag, not allot, through the the entire turn.

This has made a big difference in the braking, they are much more effective now. I don't know if having a bit of drag on the drums (or how much is too much) at all times is good or not, unlike the front rotors that spin freely, but it did do the job.
 

Thor 1211

Silver Level Sponsor
Brakes

I don't want to hijack the thread, but I have the exact opposite problem and wonder what I need to do to correct it.

When I first back out of the garage in the morning the braking is so tight that I really have to rev it up to move the car and the car will not roll down the slight slope of the driveway. Once underway it improves and the car will actually roll.

When I jack the car up and turn the wheels, I can hardly rotate the wheel by hand, so it's dragging pretty hard.

I blame the self adjusting and want to disable it. Does that make sense?
 

Bill Blue

Platinum Level Sponsor
I always adjusted drum brakes so you could hear contact and the wheel would have a slight drag, usually in one or two spots as the wheel was turned. Rear brakes that lock up are dangerous, as the rear end does not like to stay to the rear when the wheels are skidding.

Rootes took care of that problem by downsizing the wheel cylinders.

Bill
 

hartmandm

Moderator
Diamond Level Sponsor
When I jack the car up and turn the wheels, I can hardly rotate the wheel by hand, so it's dragging pretty hard.

I blame the self adjusting and want to disable it. Does that make sense?

I don't think it is the self adjusting feature. In my (limited) experience, the self adjustment fails to keep up with the brake pad wear and you have to manually adjust the brakes anyways. I'd pull the drums, reduce the wheel cylinder expansion until the drum spins freely, check the force needed to rotate the adjustment sprocket (and address that if you find an issue), and then adjust the sprocket until you just start to encounter drag on the drum. You can insert a screwdriver through the hole in the drum to rotate the sprocket (in the expansion direction) while the drum is in place. It greatly speeds up the adjustment process.

Mike
 

Mike Armstrong

Bronze Level Sponsor
I always adjusted drum brakes so you could hear contact and the wheel would have a slight drag, usually in one or two spots as the wheel was turned.

Bill

Hi Bill, so is it normal as you turn the drum by hand that there are spots with drag and others with no drag at all? As mine do. What is causing that?

If I hadn't had the drums machined smooth and round I would have guessed they had high and low spots. I have pictured the brake pads setting evenly inside the drum and the cylinder extending them evenly, but it seems maybe neither of those is occurring but maybe that is normal for these drum brakes,?

Maybe I shouldn't have adjusted the 'no drag spots' out, ?
 

Tom H

Platinum Level Sponsor
Mike, I think no matter how well machined the drums are there is likely to be a slight non-concentric movement resulting from less than perfect alignment of the holes and bolts in the axle hubs. - just my guess.

By the way as you tighten the adjustments, you should step on and release the brake pedal as a last step to set the brake shoes evenly. Then see how much drag you have.

Tom
 

Bill Blue

Platinum Level Sponsor
I don't know what causes it, but I don't recall ever seeing a drum brake that had the same contact 360 of the turn of the wheel. I think Tom's explanation is on the right path.

I have always found that when the brake is adjusted so there is 360 contact, they are too tight.

Bill
 

DanR

Diamond Level Sponsor
From the old school.....

My Dad used to do something to the shoes themselves because of them out of round. He had some kind of a lathe? He'd just lightly hit the high spots.

Sure don't remember what it was He used....

DanR

P.S. I just adjust to they are fairly tigh and run them like a test run, re-adjust several times until I am happy with them. Sure wish they were disc.....Next project.
 
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Mike Armstrong

Bronze Level Sponsor
Thanks guys, all good points to remember.

Speaking of which, I don't remember which forum member suggested it, but I was told to bring the shoes when I had the drums turned, which I totally forgot to do:rolleyes: Now it makes sense why.
 

Bill Blue

Platinum Level Sponsor
Maybe that's why there arced to the drum by some people?

I don't think so. A high spot is a high spot, whether is is 1/2" long or extends the circumference of the drum. If the drum runs true, the high spot will give even contact the entire revolution. Think of a dial indicator being used on a lathe.

I think the shoes are arced to fit the drum so there is maximum contact from day one, giving maximum braking effort immediately and extending the time to the next adjustment.

Bill
 

DanR

Diamond Level Sponsor
".....bring the shoes when I had the drums turned, which I totally forgot to do Now it makes sense why."

Ah HA! That is a must;)
 

Shannon Boal

Platinum Level Sponsor
Hand adjustment on Alpine V self-adjusting drum brakes, done through hole in drum with wheel removed: tighten them until tight. (Drum hard to rotate, about locked up.) Then, back off star wheel 5 to 8 teeth ... (A thin-bladed long screwdriver slid next to brake adjusting spoon will release self-adjusting lever if so equipped.) You should have a light drag. Most of the time you have some out-of-round in drum brakes. Make hard stop on dirt at 3-5 MPH, verify equal skid pattern in dirt. Do it again, while backing up. Drive it ten miles highway, and check temps at each wheel with your hand....they should be cool. Make reservations, and drive to SUNI VII......
 

Gordon Holsinger

Diamond Level Sponsor
Also note that the star wheel and pin are handed, one is r/h thread and one l/h. So when looking at the car from the rear, when the brake handle is pulled the l/h side would spin clockwise to tighten up the brakes, the r/h side counter clockwise. Get them on the wrong sides and they won't adjust. Also, the wheel tends to seize to the pin and doesn't adjust anymore. I suspect that's why the factory went back to the manual adjust so quickly.

Also note that the MGC appears to have used the same setup, pictures look the same to me. So it could also be a source of parts if Rick doesn't have something.
The MGC set up works on the sV
 

Shannon Boal

Platinum Level Sponsor
Have finished the rear brakes.....far more trouble to fix the self-adjusting feature than it is worth. Biggest things...the wheel cylinders have to move freely, slide with finger pressure in the backing plate. I filed burrs off the wheel cylinders and backing plates. I stoned burrs off the horseshoe clips. Furthermore, the levers have to hit the star wheel, mine were both bent. I straightened one, but broke the other!... I made a fixture and precision-welded the lever with nickel-silver-bronze alloy. The star wheel teeth were worn flat, I filed those and the lever edge nice and sharp. The star wheels did not fit in the wheel cylinder bores, one too tight, one too loose....I cleaned up the tight spots with a tiny scraper, and made a tiny spiral shim for the other, cut out of a beer can....
 
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