Uneven wear on drives brakes

Google how to adjust. Your truck brakes .for year model .it's usually going foward or backwards at 15 mph and locking them down to stop repeatedly.not letting off till stopped.

 

Or a wrench

 

Could be a multitude of things:


-Brakes could have been replaced on axle 2 more recently due to a blown wheel seal.

-Weight distribution on the drives during braking. ABS keeps wheels from locking. More weight transfer to an axle means it can brake harder without locking up.

-Mix match of shoes between the 2 axles. Softer friction material will wear quicker.

-Possibly a difference in cracking pressures of the drive axle relay valves. Cracking pressure is the amount of PSI from the pedal that is needed to overcome the spring in the relay valve.



There is a bit of a misconception with slack adjusters. Yes everything modern is required to have auto slacks. They adjust the shoe to drum clearance and keep it constant. However, due to the design of the chambers, they produce the same amount of force per PSI of application through out their entire stroke.

 

That's for certain types of hydraulic drum brakes. Hitting brakes in forward or reverse does nothing to adjust heavy truck drum brakes. The shoes are anchored solid on the brake spider. Adjustment is done solely in the slack adjuster. The auto slack wants to see a 90° slack to pushrod angle.

 

Does your truck have piggy back, spring parking brake, chambers on both axles?

 

Do you ever go under your truck to inspect your brakes?

 

This is perfectly normal. Internationals do this. Our company has 2019 and 2020 internationals and the 3rd axle drive brakes wear before the number 2 axles do on every International in our fleet.