how do you adjust the brake ? I tighten the (don't know what they are called) nut with the lock collar until the shoes are barely touching the drums and even all the way around how about oil leaks around the axle ? Good point, I will look. We had a wheel seal out and changed. I wonder if some oil has that drum and shoes slicked up. Can oil ruin the shoes? is the shoes the right radius for the drum some times shoes have to ground to suit the drum if it is worn ? I don't know, but it seems the shoes fit the drum well. is there air leaking out when you apply the brakes ? No. do you have enough air pressure at the maxi chambers on the axle ? I don't know, how would I check? Tee-in a guage at the chamber? What is the Maxi chamber? Is that the canisters? I will have to look. How much should I have? As for 30x30 chambers, will that make the brakes more powerful if I switch to them? As for the service relay valve, I don't think that is the problem. The red and yellow buttons are inoperable and permanently pressed "in" on this truck. We only use the blue valve. We don't pull a trailer with air brakes. Could there still be a problem with the red or yellow buttons? Thank you all!