Wheel cylinder ears shearing off

[MacAaroni]

Im wondering what issue would cause the rear wheel cylinder ears that hold the brake pads, to shear off? I have a 2006 GMC Sierra 1500 2WD 4.8L with rear drumbrakes.

 

I replaced the rear wheel cylinders and brake shoes on both sides. After 5-10 minuets of driving, i had extremely loud squealing from the rear when braking to a stop. I took off the drums to check and saw that the passenger side wheel cylinder ears had sheared right off, but only on the outside of the truck, not inside ears. The shoe that is towards the front of the truck also was pushed out towards the inside of the drum and was rubbing on the inside facing where the hub sits so that must be what was causing the squealing. But i dont understand what would cause such a force to shear the wheel cylinder ears right off. Drum out of round? Before i replaced the shoes, both passenger and driver side shoes towards the front were almost to the metal shoe backing plate, so thats why i replaced them.

 

 

[MacAaroni]

Did a rear drum brake shoe and wheel cylinder replacement on my 2006 Sierra 1500 2WD.  After about 5-10min of driving i started getting very loud squealing when braking to a stop. I ended up checking the next day to see what the cause may be and noticed that the passenger wheel cylinder ears where the shoes sit had sheared right off. The shoe on the front side of the truck had also pulled away from the backing plate a bit and was rubbing on the inside of the drum face. That seems to be where the squealing is coming from, but what would cause the wheel cylinder ears to sheer off like that? It's only the ears that are facing on the outside of the truck, not the inside ones. In other words, it seems that the shoes were trying to pull off the backing plate and come out.

 

Besides all that everything looked good. I replaced the wheel cylinder and tried again... 10min after driving with the new wheel cylinder, i got the squeal again, i didnt drive around after hearing the noise as much as last time, i checked again but the ears are still there and everything looks good. I'm guessing it will shear off soon if i continue braking with the noise. 

 

https://ibb.co/mFHMmMb

https://ibb.co/tc900YM

 

https://ibb.co/YNB51qM

 

https://ibb.co/FgvFKHs

 

Edit: During this job i also had replaced the the wheel bearings and seals. 

Edited August 27, 2020 by MacAaroni

[Jsdirt]

Not sure where you live, but if it's where it snows and road salt is used, you'll have to grind the surface the wheel cylinder sits on smooth and free of all rust. Another thing that will cause that is overtorquing the bolts.

 

The 3rd thing could just be crap quality parts. I'm partial to Raybestos for all the brake work I do.

 

Also, make sure the bolts are correct, and aren't bottoming out before the wheel cylinder is tight to the backing plate.

 

Edited August 27, 2020 by Jsdirt

[txab]

Did you get the hold down "spring" (u-shaped) clipped in place at the bottom? It designed to keep the shoes pressed into the backing plate. Did you lube the the contact points on the backing plate? Got your shoes adjusted properly?  Your driver side doesn't have this issue?

[Doug_Scott]

You will also want to double check that the replacement brake shoes are the same width as the original ones.  Since only the passenger side did this carefully compare the sides to see what is different.  Look for things like others have suggested, is the wheel cylinder tight to the backing plate on both sides, or can you move the one on the right side, the big blue spring thing installed the exact same way on both sides, etc.  Also make sure you have primary and secondary marked shoes on each side, and not two primary on one side and two secondary on the other side(assuming they still have primary and secondary shoes).  Also make sure that the slot between the two "ears" is in the middle of the cylinder, and the brake shoe is also rubbing on the backing plate and not being forced in or out due to the shoe not aligning with the slot.

 

You are lucky one side is good, it should make it easier to find the problem on the other side.