Brake shoe arcing

A

azandy

Member
Is there a material I could use similar to plasti-gauge to do a static check on brake shoe to drum gap? I think it would give me a rough idea on where to remove material to arc the shoe to the drum.
 
Years ago some cars had slots in the brake drum into which you could insert a feeler gauge to check the clearance between the drum and the shoe. There is no plasti-gauge for brake shoe clearance as it wouldn't be practical or possible to get reliable and accurate measurements.

Adjust the brakes as prescribed in the manual and you will be "good to go".
 
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When I did mine, I used old fashioned black board chalk. I scribbled lines on the shoes and spun the wheel/drum while my helper pressed on the brake.

I would then pull the drum and the spots where the chalk was removed were the high spots on the shoes.

I sanded those spots down and tried again. It doesn't take much to knock down the high spots. Once the lines were all smudged, I was happy with the fit.

As 19Fordy mentioned above, follow the adjusting procedure to the letter and you should be good to go.
 
Tim Ayers said:
When I did mine, I used old fashioned black board chalk. I scribbled lines on the shoes and spun the wheel/drum while my helper pressed on the brake.

I would then pull the drum and the spots where the chalk was removed were the high spots on the shoes.

I sanded those spots down and tried again. It doesn't take much to knock down the high spots. Once the lines were all smudged, I was happy with the fit.

As 19Fordy mentioned above, follow the adjusting procedure to the letter and you should be good to go.
Click to expand...

This is about as good a method as you are likely to utilize without the proper equipment. Just keep in mind as you adjust the shoes, the radius changes in relation to the drum. A little, but it does change.

Getting them close by this method will help you a lot.
 
I picked up a strip of 36 grit sandpaper from the automotive paint store that measured 3" X 17" for doing body work. Then taped it to the inside of the drum and slid the shoe back and forth until I had the same radius. Yes, I used a particle mask.
 
Kube said:
This is about as good a method as you are likely to utilize without the proper equipment. Just keep in mind as you adjust the shoes, the radius changes in relation to the drum. A little, but it does change.

Getting them close by this method will help you a lot.
Click to expand...

Kube,

What I left out was the shoes were riveted "organic" linings that were NORS and placed on mint cores. The drums were NOS and measured out at a perfect 12". The shoes were allegedly "arched" on a proper arching machine.

When I went to check them, I found the contact issue.

I agree with you regarding arching, but this was a home fix after paying a "pro" to do them "right".
 
I have two of those Ammco brake shoe grinding machines. When I first became a mechanic at the phone company, we still ground brake shoes. Then because of asbestos dust the state made it illegal to grind shoes, it was a big fine if they caught one in use or even found one in the shop. They don't use asbestos anymore but that's not to say that the new brake materials are healthier. The phone company packaged them up and took them away. Over the years I've bought two of them at local estate sales, but I've never used them. But I have them in case I need them.

New brakes shoes are ground from the factory to fit the diameter of new drums shoes. Just lay them in the drum and you can see how the material contacts the drum. If the drum has been ground larger the shoe will be tight in the center and then have spaces towards the ends, until the center of the shoe finally wears into where it makes full contact and that could be a long-long-time on a collector car that is hardly driven. It wasn't a problem on newer vehicles with front disc brakes but on older ones the car might not stop straight until the shoes wore in. The front drums should be ground close to the same size to keep the vehicle stopping straight, I think the specs used to be within .005 of each other but I could be wrong, that was over 40-years ago. I suppose you can set the shoes in the drum and see how they make contact and then carefully sand them until that fit.
 
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Tim Ayers said:
When I did mine, I used old fashioned black board chalk. I scribbled lines on the shoes and spun the wheel/drum while my helper pressed on the brake.

I would then pull the drum and the spots where the chalk was removed were the high spots on the shoes.

I sanded those spots down and tried again. It doesn't take much to knock down the high spots. Once the lines were all smudged, I was happy with the fit.

As 19Fordy mentioned above, follow the adjusting procedure to the letter and you should be good to go.
Click to expand...


X2 but no helper
 
tim ayers said:
kube,

what i left out was the shoes were riveted "organic" linings that were nors and placed on mint cores. The drums were nos and measured out at a perfect 12". The shoes were allegedly "arched" on a proper arching machine.

When i went to check them, i found the contact issue.

I agree with you regarding arching, but this was a home fix after paying a "pro" to do them "right".
Click to expand...

i think what you did was a great home fix :)
 
As a kid with no money for pro help, I would install and adjust shoes close, take a drive and ride the brakes, adjust once again and good to go. The last time I used that method was one time too many, those drums were so worn out I fried the lining and had to buy another set.
 
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