Troubleshooting big air brake leak

[luvrbus]

If the rears brakes haven't been upgrade to DD3 on a 4104 you will the ICC system a single chamber no parking brakes unless it stays aired up or the driveline brake if it works

[brmax]

Hey nice ramp build, I also have some similar and like you realized, those work just great.
Sounds like ya got a nice project in the works to check and kick start your plan.
I found a big aluminum bakers sheet pan can be beneficial for Scraping and parts washing off some of those adjusters and other parts in certain places.
That way I don't blame the dog as much for empty grass spots hahaha


Have a good day

Floyd

[buswarrior]

Re the port-starbord slop of slacks

You see there are big washers/shims on the shaft, either side of the adjuster. Add to reduce slop.

I would also be a loud voice saying simply on principal, a tear down of the wheel ends is mandatory on a new-to-you bus. Brake issues are a big reason buses get sold, previous owner used up  the capital and isn't investing anymore, you have no idea what preventive maintenance has, or has not been done.

Experiential learning, when it comes to lack of brake performance... there may not be a second time to apply what was learned under terror the first time...

Happy coaching!
Buswarrior

[Nova Eona]

Thanks all - one of my early plans here is to bring the bus by a heavy truck shop I know which said they would work on it for a professional check of the brake systems, but I'm not taking it anywhere with a blown chamber!  It's only my passenger side leaking at the moment, but I'm going to replace both chambers and lines while I'm at it.  The adjustor slop is only the adjuster itself moving side to side, so additional washers sound like just the ticket.  Stopping by today to try pulling the chambers, I'll let you know how it goes!

[luvrbus]

Washers are not always the ticket, the splines get worn on the s-cam and the gears and splines wear out on the slack adjusters but they are cheap too,the S-cams can be a little pricey   

[Nova Eona]

Success!


Thank god for breaker bars, wasn't sure if impact tools were safe to use (have read they're a no-no on the rears at least).  I'm leaving the slack adjusters and the rest of the brake system as-is for now, I'll have those professionally checked over once I've got new tires on.  Going to swing by Napa tomorrow to see if they can just match the chamber and hose for me, I was fifteen minutes too late to catch them today.

[Jim Eh.]

Oh, and a small detail, just something that can be done better. Replace your cast pipe thread elbows with brass.
Don't forget to get new cotter pins to put in those clevis pins. Check for wear in the slack adjuster bushing by putting the clevis pin back into the slack bushings and check for play. A little dab of never seize onto the clevis pins when reinstalling would not hurt.

[buswarrior]

X2 anti-seize on clevis pins.

Duty cycle on bus conversion, they sit alot, seized clevis pins are a popular problem for us.

Effects smooth release the most, something you won't know well from driver's seat until smoke comes out... can lead to dragging brakes, as the return spring in chamber not strong enough to pull back thru the corrosion, what the air pressure powered thru.

Lack of clevis pin maintenance can burn your bus down.

So little, so important...

Happy coaching!
Buswarrior

[Nova Eona]

Behold the new and old!


In stock at Napa for a bit over $50 each, plus another $10 or so for the lines.  Thanks for the advice on the clevis and the elbows, I had already picked up an adapter for the line (new chamber and hoses are both 3/8) but I was going to leave the bus-side elbow in place, I'll swap that out instead.  Now, question - is there a reason why I can't use the alternate air port (on bottom in picture) instead of putting a new elbow in the central connector?  I figure the fewer connections the better, but there may well be a reason why things were done the way they were.

[freds]

Make sure the throw is the same, it appears that the new has a longer shaft!!!

[chessie4905]

Hope that it doesn't  need that hump where the studs are.

[Jim Eh.]

Best to use the original port. The air line/system is designed such that the hose will not rub on the tire or stationary bits. Unless there is clearance during the full travel of the wheel from lock to lock and zero strain throughout the suspension travel it is probably worth the extra fitting.

[richard5933]

For future reference, Luke carries most of these in stock and can ship same day. I know it's not as handy as getting something when you need it locally, but if the part has to be the exact one it usually works out best.

[Jim Eh.]

Hope that it doesn't  need that hump where the studs are.

It's actually not a "hump" but rather a relief around the edges opposite of the mounting studs for mounting clearance. A newer design but in that size it is not really a benefit. Probably just cheaper to manufacture.

[buswarrior]

Fittings, lines, diameter, lengths, elbows...

All effect the speed and rate of power application with which the brake chamber will perform.

Symetrical both ends of axle is really important, you don't want the brake on one end to be snappy and quick, and the other slow and lazy, the coach will pull to the side under heavy/panic stopping.

The designing engineers selected every little bit of it. Now, whether previous owners have been faithful...

The crap the hobby has seen on these forums in this regard is epic. Strokes cut too short, hoses fittings just stuffed in there on a whim, total ignorance, but a handyman attitude, can fool the next owner.

As always, refer to the books, not what is typed online...

Happy coaching!
Buswarrior