Trailer bleeding brakes. Part 2

[Lou C]

getting back to brake bleeding, the way we did it in the old days was to start with a clean clear bottle, and tape a plastic hose to the neck, with the end almost at the bottom of the bottle, and then fill the bottle till the bottom of the hose was covered in brake fluid. Then pump the master while your assistant opens the bleed valve. You'd see bubbles and repeat this till you saw no bubbles. Usually you'd have to dump some of the fluid out of the bottle after doing 2 brakes so it would not overflow. Then Lisle came out with an easier way, that you can do by yourself, I have used this on the trailer and various vehicles, it has worked fine every time.
Note that the bleeder bottle is above the level of the brake caliper....

 

[Lou C]

While we are diverging from the OP’s issue, I will take a chance and provide my thoughts regarding Drum vs Disc. My understandings: (1) for a given diameter disc have move sweep area then drum and (2) drums have a mechanical multiplying (aka self-energizing) effect that increases the shoe’s pressure against the drums beyond what the hydraulic pressure is doing > the forward shoe, when rubbing against the drum tries to rotate with it, causing the bottom of that forward shoe to push against the bottom of the rear shoe (via the adjuster), which has also been pushed out to engage the drum causing it to also try to spin with the drum causing the top of the rear shoe to push against the cylinder which in turn causes the forward shoe to press even more against the drum (they are coupled b/c the hyd fluid is not compressible). For disc brakes, the only force pressing the pads against the disc is the hyd pressure. Note that there is a higher pressure applied to disc vs drum due to these design differences. This is why Lou has the experience he does with that 70’s auto and his trailer.

Yes drum brakes have a self energizing effect and they can provide more braking force with lower actuator pressures than disc brakes on a surge system. The other difference is that drum brakes have very strong return springs to release the brake, vs disc brakes have the square seal in the caliper to perform the same function.

 

[demarko210]

I tested the trailer out last Friday. I needed to pick up my boat from the marina and bring it back home. Done with that place. Trailer ride was nice and smooth. No issue with brakes locking up. Again I replace both calipers and pads. New bearings and seals on the brake axle. And on one new 24" brake hose. I did need to replace the caliper mounting brackets because they were stripped. I put new hubs on the rear axles.

Now after getting down to the marina, I got out and use the heat gun to see the temps. I dont remember what it was but it was not alarming by far. What I did see was some grease in the inside of 2 rims. One back axle and one front axle. From what read either I did not seat the seal good enough on the axle or the buddy bearing are over packed. Let me know.

Other issue I had that I did not expect. My plan was to get a rental to pick the boat up as my truck is waiting on a new rear end and transfer case rebuild. Rental company did not have a tow hitch so I took my truck which is still in good driving condition although I know I smell antifreeze steaming away from someplace. Coming back engine temps are normal then all of a sudden, high temp low oil light came on. I pulled over and steam was coming out my fill cap and flowing onto the ground. Lucky i had 1 gallon antifreeze in the truck. Waited about an hour and half on the side of road almost fell asleep. Got back in truck and went down the road. Got 9 miles from my exit and same thing. Engine temp normal, high temp light came on and engine temp just jump to H. More antifreeze after it cools a bit and I made it home. 2 hour round trip turned into 5 hours.

So worried if I did a good enough job on the trailer and my truck took a crap on me for the first time. YIKES.