Odd Brake Shoe Failure. Any Ideas?

[TucsonJim]

Since I'm retired, I like to keep busy and help family and friends with RV maintenance items from time to time. This time, I volunteered to inspect the brakes on my son's 12 year old pop up and repack the bearings for him. He had the brakes replaced about six years ago, and has maybe put 3000 miles on it during that time.

When I inspected the brakes, there were cracks running parallel to both rear brake shoes. I've seen brake shoes crack laterally before, but never radially like the ones pictured here:





I inspected the drums and they were within size tolerance and there were no hot spots indicated. Since they were okay, I don't think heat was the issue.

I've ordered replacement brake assemblies and will be installing them as soon as they arrive. BTW, the assemblies I ordered were self adjusting and not the cheap manual adjusting brakes he had.

Have any of you ever seen a similar failure? If so, is there a likely cause?

As a side note, I'm also going to replace his bearings, races and the cheap brake wire connectors you can see pictured in the photos.

Jim

[Lynnmor]

While I would replace them, this is what Dexter says:

Usually, light cracking of the surface of a brake lining can be expected under normal use. This is not cause for replacement. However, if the lining is deeply cracked to the shoe surface or is missing chunks, your brake linings will require replacement.

[Gdetrailer]

Ozlander wrote:

time2roll wrote:
Typical of bonded shoes. Run them another 12 years.

X2
And check them again in 6 years.

No, not "typical" of "bonded" OR "riveted" brake shoes and in PA ANY CRACKS in the lining results in an IMMEDIATE FAIL for the annual trailer inspection.

I suspect the backing plate of the shoes is substandard (IE to light of a gauge) and was flexing considerably due to the fact that the crack happens to be right smack dab in the CENTER of the brake shoe which happens to be right where the most pressure will be..

I would bet that the backing plate of the shoe is bent and if you measured the thickness across the shoe it will have LESS brake material in the center!

[Huntindog]

I would not call that a failure. It is pretty common for those cracks to appear. They have probably been there since shortly after they were installed.... And if you get new ones, they will likely do the same.

[joshuajim]

My guess would be that the metal backing plate on the linings was too thin. When the brakes were applied the center fully engaged, but the outer part of the shoe bent back just slightly causing the crack.

Just for jollies, measure the backing on the old shoes and the new ones.

[Chum_lee]

Ozlander wrote:

time2roll wrote:
Typical of bonded shoes. Run them another 12 years.

X2
And check them again in 6 years.

I agree with this but maybe inspect again in 1 year. Seen it many times. (not the second picture with lining material missing) If cracks bother you and it gives you piece of mind, you can have a brake shoe rebuilding shop (usually a facility that caters to trucks) make a set of rivited shoes for you. That's the old school way. Or just replace with new bonded shoes.

If there are portions of the shoe with unbonded/missing lining, then replace the shoes.

Chum lee

[Ozlander]

time2roll wrote:
Typical of bonded shoes. Run them another 12 years.

X2
And check them again in 6 years.

[bucky]

I've had bonded shoes laying in the bottom of the drum when I pulled the drums to see what was wrong. Adhesive just let go. Front axle on one side, rear axle on the other. Only one of the shoes at that.
Way cheaper to replace the whole assembly also.

[westend]

Chances are, the dealer that offered the "lifetime" package was using the cheapest shoes possible. Replace them with name brand product, clean/lubricate parts, and adjust accurately, there shouldn't be an issue. At 3000 mi/year on a PUP, you're looking at a lifetime maintenance procedure.

[time2roll]

I poked around a bit... trailer shoes seem to all be bonded 😞

Did read some that the bonding has been far improved.
Definitely heat that cracks the material. Could they have been adjusted too tight?

[TucsonJim]

time2roll wrote:

TucsonJim wrote:

time2roll wrote:
Typical of bonded shoes. Run them another 12 years.

Not with my grandchildren in the car he won't! Not to mention the safety of motorists around him.

Nothing wrong with new shoes, hardware etc.
Can you get shoes that are riveted instead of bonded?

As long as you are replacing most of it have you considered disk brakes?

He was griping at me about a couple hundred bucks for brakes and new bearings. He takes after my wife (his mom), so he's a tightwad. :R

[TucsonJim]

All I could afford wrote:
How about these shoes on the back of a 1995 ford 150. Truck had 120,000 miles and still had retaining clips keeping drum on studs. I was checking/cleaning/adjusting the rears for the owner about 6 months ago! Believe it or not, he declined replacement.

All I can say is OMG!

Jim

[All_I_could_aff]

How about these shoes on the back of a 1995 ford 150. Truck had 120,000 miles and still had retaining clips keeping drum on studs. I was checking/cleaning/adjusting the rears for the owner about 6 months ago! Believe it or not, he declined replacement.

[Old-Biscuit]

Bad bonding

[TucsonJim]

Old-Biscuit wrote:
This only occurred on the secondary shoes (rearward ones) and NOT on smaller primary shoes??

Primary shoes get most of the heat due to being first to make contact and that contact force has to increase to activate rear shoe engagement


Were dust caps missing on bottom of drum?
Does your son do much dirt road/off road driving?
Seen similar scoring from dirt/grit but it was on ALL brake shoes.

Otherwise.....HEAT causes most cracking.

DId you have to back off adjuster a LOT to get drum off?

Yes, just the secondary shoes. The others were in great shape.
Dust plugs were in place.
This is not "scoring". It's king of hard to see in the pics, but the cracks appear to go all the way to the base metal of the shoe surface.
And he does drive down a dirt road from time to time, but most travel is on paved surfaces.
I did not have to back of the adjuster at all to get the drums off. The brakes were snug, but not too tight.