24 October 2014

Bus Brakes Round Two

So a while ago we replaced the brake lines on the front brakes.  After we got those done the only major work we had left to do was fix the exhaust leak.  When Kyle's car died, we started rearranging our priorities and having a functional bus became a little more important.  So while we were in Michigan we hired the professionals to fix the exhaust leak.  On the way home from the shop, Kyle hit the brakes pretty hard when someone slowed down unexpectedly in front of him, and my vantage point in the chase car allowed me to observe the cloud of smoke that emanated from the rear driver's wheel.  Okay.  More brake work.
Actually the shop had let us know we had a problem with brake fluid leaking in the rear wheels so it was already on our list.  So right after we moved, instead of unpacking boxes we spent our days out in the garage.  The shop had torqued down the lugnuts with power tools so it took Kyle at least an hour to loosen all the lugnuts.  After that, he promptly bent the jack trying to get the rear tires off the ground.  That was a frustrating day.
We bought a new jack and went in for round 2.  Progress at last - the bus on jack stands and the rear wheels off.  Since everything had just been disassembled by the shop it was pretty easy to get it all apart.  Everything got sprayed down with brake cleaner and scrubbed down.
The good news is that there seemed to be plenty of material on the drums and shoes - they weren't too worn down.
The bad news is that the replacement shoes that Kyle ordered came with four of the shoes on the left and zero of the shoes on the right in the photo below.  They look pretty similar but the shoe on the right has an arm for attaching the parking brake, which is a pretty crucial detail.  As I write this Kyle tells me that they actually did ship us the correct shoes, but this is a new style.  So we'll have to drill out the rivet so that we can install that parking brake arm on the new shoes.  Gah.
Kyle replaced the wheel cylinders - they were the cause of the brake fluid getting into the drums (that's bad!).  We ended up just cleaning up the old shoes and reinstalling them.
We also replaced the rear brake lines.
Mechanics eye view of the old vs. new lines.  Then we had to bleed and adjust the rear brakes (so that each shoe was engaging the drum at the same time). 
And lastly, we replaced the parking brake cables, which run from the rear brakes to the front of the bus.  This was a pain because I had to evenly tighten the square nuts that you can barely see in the photo.  One of them I could get a quarter turn on, the other an eighth of a turn.  I was down there for a while.  Kyle was running around the back of the bus so that he could tell me when the brake was fully engaged (per the manual, we were to pull the parking brake out six clicks then tighten the cables until the rear wheels could not be turned).  The vice grips are to prevent the cables from twisting.
Some of this stuff was new to me, so for the sake of others I'm including some pictorial clarification.  Click the photo to make the text readable.
This project was drawn out over several days, so it was nice to have it back together even if we did have to use the old shoes.
We took it for a test drive around the neighborhood and everything seemed to be working fine.  Then we took an extended trip at higher speeds and heavier traffic and the braking didn't seem to be consistent.  Then it felt like something shifted and it was breaking evenly again, although it is apparent that the drums are out of round (ie it feels a little bumpy when braking).  So yay, more bus parts to buy.  Even so, every project means we get to know the bus a little better, get to trust our skills as mechanics a little more, and get more excited about the adventures we can start taking!

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