Rear brake adjuster

[Linda]

Most people seem to have a frozen rear brake adjuster, that is not my issue. Instead I am wondering if the adjuster is working correctly because it turns as if on a cam...the 2 little pins” open then close then open. I can’t seem to adjust enough to stop the drum from turning in order to back it off for the correct drag. Been awhile since I looked at this , so now I wonder if the drums are out of spec or what. The adjusters had good grease and turn easily, but it seems that the “adjustment” is rather small. The rear shoes are good as the car is not driven too much. Anyone have this problem?
Thx
Linda

[itsa68]

Linda
The adjuster wedge bolt end should be sticking out 3/4 inches from the adjuster housing when it is fully retracted. The two adjuster tappet pins are butting ends when the wedge bolt is fully retracted.

As we both know, the wedge bolt cam clicks against the adjuster tappet pins almost immediately upon turning the wedge bolt in. The bolt torque will be the highest when the wedge cam passes the ends of the tappet pins and then clicks into to the next wedge flat spot. More torque will be required to get to the next flat spot in the wedge bolt when the shoes start seating themselves to the drums. The drums should lock up and not turn when on the final wedge flat spot. The wedge bolt is backed off for 1-3 flat spot clicks so the drum is free of drag to complete the adjustment.

Having said all that and since you only getting a rather small adjustment with out obtaining any brake drag/lock, I think that your adjuster bolt threads may be jamming in the housing and preventing deeper engagement. Those aluminum housings seem to bind up if a bolt thread is cruddy or damaged.
A good wire brushing to clean out the thread root may be be enough to get the adjuster bolt to thread in properly.

Cheers
Ray B.

[itsa68]

Oh ya, and another thing comes to mind.
It seems to happen every time I adjust the brakes, I forget to wrench the passenger side in the opposite direction and loosen instead to tighten.
Obviously the brake shoes will not engage when I do do that. Duh...

adjuster wedge bolt.jpg

brake adjuster.jpg

Cheers
Ray B.

[Curtis]

The amount of adjustment is dependent on the amount of brake shoe you have left as mine taught me early on. Gee, I wonder why they don't tighten up any more? Then there was the relined brake shoes that were too thick to even get on. I had to remove material.

I cleaned mine thoroughly and used silicone lube on them.

[Linda]

I thought of that Curtis. But of course I have not measured them yet.
Linda

[Curtis]

I thought of that Curtis. But of course I have not measured them yet.
Linda

My assumption was you did, I didn't. But it was in the 70s with my SPL310.

[theunz]

Linda, I can get one side to lock the wheel when adjusting, but not the other. Just put new shoes in. I don’t remember my emergency brake ever working really well, but then I could say the same for my memory The car seems to stop well however...for a fifty year old car anyway! I don’t think the rear brakes do a lot on these cars anyway. I remember a knowable race enthusiast telling me many years ago that the fronts would fade at the end of a long race, but the rears held up fine.

[Curtis]

These cars all seem to be quirky like their owner's.

[Linda]

These cars all seem to be quirky like their owner's

Are you calling me quirky??...
Sure, no problem

Linda

Mike , I think new rear shoes would be an idea. And I need to measure the drum diameter too. I think they are supposed to be 9”. And shoes should be 9” also which most 510 shoes are.

[Curtis]

Normal people don't own roadsters.... and who wants to be normal anyhow?

[Linda]

Wanted to come back around to this issue. I thought I was able to adjust the adjuster previously, but it was just sort of spinning in place, so I was confused. It was acting like it was on a cam, but not adjusting very far. So I took it off as was recommended, after some PB Blaster to the fasteners. After cleaning out the grease, which was good, and taking out the little pistons ,then cleaning the screw threads I could see that it could engage farther than what I had been seeing. Should now adjust better once back together.

CF5D5E41-8D9F-40E0-8745-A4FDF4CFE641.jpeg

Linda

[Linda]

So I am noticing the diagram posted by Ray, and it appears there is supposed to be a nut on the adjustment screw? Mine doesn’t have one on either adjuster Is it necessary to hold the adjustment?
thx

Linda

[Curtis]

No nut on the adjuster, internal threads. Just the two nuts to hold it on.

I am under the opinion that the adjusters should be removed periodically and cleaned and lubed. I put silicone lube on mine. I have never been able to remove the adjuster from the housing. I'm guessing they have a special tool to fit over the cone.

[Linda]

I could not remove screw adjuster out the front either. I sprayed alot of PB Blaster in there to clean, and then used the silicone brake grease as well.
Linda

[itsa68]

For some strange reason, sometimes the material at the intersection of the holes get raised and can prevent the adjuster head from advancing up to or past the side holes. (Probably the side pins rock a bit every time the brakes pads are actuated.)
In the past, I have fully backed off the adjuster and used a small needle file to remove the small amount of excess material around the adjuster clearance hole at the intersection of the 2 side holes. Only the adjuster head clearance hole bore requires the dressing.
(The adjuster thread not must be damaged or dirty or it will also prevent adjuster advancement.)
Once the adjuster clearance hole is relieved of the local excess material, apply some grease to the dressed hole surfaces.
Clamp the adjuster body in a bench vice and advance the adjuster bolt in and out to check if the hole interference area has been removed or you have obtained additional turns in.
If interference location is at same number of turns in, the hole must be cleaned and more material will have to be moved from the adjuster hole intersection area.

Hope this helps.

Cheers
Ray B.