Brake shoes cracked

[czechsonofagun]

This year to pass the VA safety inspection I had to replace drum brake shoes. Since I had quite few miles on drums I did the whole works - hardware, drums and shoes.
That was in August and few days ago I felt there was something wrong - like on a small hill I could take my foot of the brake and it would not start rolling. When I tried to push it - CJ7 is not heavy and to move it around I usually just push it without starting the engine - the right rear wheel felt like the brake is still on. Today I took both rear wheels off and tried to spin them - the left was ok, the right one would not turn. Taking the drum off I found both shoes are cracked sideways in the middle pair of rivets. Since I still had old shoes in the pile of the scrap metal, I just put them on to keep the truck on the road. I will take those shoes back to Autozone tomorrow. Is it safe to assume it is a problem of those shoes riveting? I done brake jobs more times than I care to remember in my life and never had it happen. What do you think?

 

[AlanB]

Did you arc the shoes to your drums before installation?

I am betting bad fit, and when applied you overflexed them.

 

[czechsonofagun]

I am afraid I dont understand. Shoes came from the store with lining just to be installed. If there is a way to change the arc of them I am not aware of it.

 

[kenmac]

Heat will also cause shoes to crack

 

[ToadHill]

If I have the choice I would buy bonded shoes. The holes drilled in the linings just invite the weak spots to crack.

 

[tallyho8]

If the drums had been turned too much for the shoes to fit properly, then they could crack in the center.

I would remove the other drum and check those shoes also.

 

[czechsonofagun]

Actually drums were new too. The left side is not cracked.

Took them to Autozone today and they gave me a new pair. The guy said they had somebody else show up with the same problem, I quess it was just a bad day in the factory

 

[Egon]

All brake shoes and brake disc's are not created equally. Most places have a range of types/quality/effectiveness and asking may get some answerers. Usually you get offered the cheapest if you do not ask.

 

[jinman]

Actually drums were new too. The left side is not cracked.

Took them to Autozone today and they gave me a new pair. The guy said they had somebody else show up with the same problem, I quess it was just a bad day in the factory

I think you are onto something Prokop. The machine doing the rivets was probably misadjusted and set them too tight causing stress cracks in the pad material.

 

[tallyho8]

It may be possible that 2 of his 4 shoes were factory defects. But the shoes usually come 4 in a box, 2 front and 2 rear. This would mean that he happened to pick out the front defective shoe and the rear defective shoe and put them on the same wheel and put the 2 good shoes on the other wheel. This is possible, but I think there is more to it.

 

[czechsonofagun]

It may be possible that 2 of his 4 shoes were factory defects. But the shoes usually come 4 in a box, 2 front and 2 rear. This would mean that he happened to pick out the front defective shoe and the rear defective shoe and put them on the same wheel and put the 2 good shoes on the other wheel. This is possible, but I think there is more to it.

Yes, I know. As of now, I have the new pair in the right rear wheel and will see what happens.

 

[AlanB]

I am afraid I dont understand. Shoes came from the store with lining just to be installed. If there is a way to change the arc of them I am not aware of it.

Arcing brake shoes is the matching of the brake shoes to the drum.

They will naturally do it themselves, but it used to be that the proper way (I guess that is a relative term) was to put them on a machine and custom fit them.

http://model-a-wis.com/brakearc.pdf

I doubt many folks do it now.

That said, one of the first things I do, when purchasing new brakes drums etc is flip them over on the parts counter and make sure they "fit" ie, and I don't know if you have the old parts or not, but put your shoe inside the drum against the outer edge, and look at the fit, the shoe material should be touching the drum pretty much all the way around.

If it is not, it is possible, that when you applied the hydrualic pressure too it, that the shoe bent more then the wear material would allow and it cracked at the weakest point (the rivet holes)

Could be wrong stuff, could be things at each end of the tolerance spectrum, could be a bad day at brake shoe reliners are us.

New shoes, and new drums, you would like to think they all fit together well, but that is just not always the case.

 

[czechsonofagun]

Well the replacement shoes are not cracked, but I noticed one thing. The drum centers on the axle flange (Dana 44) and on the right side, it takes bit of a persuasion. It seems the drum center hole is a fraction of an inch off center. I tried the left drum and it seems to fit better, I will run it like that for a while.

Tallyho8: That may be the reason for the one side problem only, I have no way to precisely measure drums (only caliper). Will try to find old drums and see how they fit.

 

[tallyho8]

Well the replacement shoes are not cracked, but I noticed one thing. The drum centers on the axle flange (Dana 44) and on the right side, it takes bit of a persuasion. It seems the drum center hole is a fraction of an inch off center. I tried the left drum and it seems to fit better, I will run it like that for a while.

Tallyho8: That may be the reason for the one side problem only, I have no way to precisely measure drums (only caliper). Will try to find old drums and see how they fit.

You can always try putting your left drum on the right side and your right drum on the left side and see if they fit better that way.