My DD-3 brake chamber experience.......(1964 PD4106 GM Bus)....

[bwze]

Hey folks, thought I'd start a new post to show my progress with the removal and disassembly of my DD-3 brake actuator. I'll try to keep adding pics as I get parts from Luke for the rebuild. Let me know what you think....

Here's my blocking and cribbing technique....


Pics of the can before removal...


Push rod to slack adjuster connection....


Pin removed from yoke and adjuster...


Can unbolted from frame...


Ahhhh.....removed at last...


On the table in my shop, ready for disassembly...


Another angle...


Auxiliary clamp ring loose...


Auxiliary pressure plate and diaphragm removed...


Service clamp ring loose...


Service pressure plate and diaphragm removed...


Here's a look at where my push plate shaft exits the non-pressure plate....looks a little damaged huh...and yes, there is supposed to a boot here...


Had some trouble getting one of the mounting studs loose...


Here's a view with the spash guard removed.....nasty...


Lock cap unbolted...


This thing is in bad shape...


Here's what's left of the rollers...actually a few of them appear to be OK....


Here's a close up of the rollers removed....the one to the right is a good example of how they shouldn't look...


A view of the push plate and shaft from the inside of the non-pressure plate


Here's a shot of the collar removed with the piston still installed...the rollers fit between the two...


This is a close-up of one of the main reasons for not being able to get my brakes to release.....a special hats off to the previous owner for not keep up with periodic maintenance....


And last, but not least, my own version of an exploded view....


I've got my part list created and I'll be giving Luke a call tomorrow to see what the damage is. I've actually had fun (considering what I've had to do). It really wasn't all that bad. I would definitely recommend this approach to anyone who has the mechanical background and the tools necessary to get the job done. And I would like to thank all those who helped me in this post ----->http://www.busconversions.com/bbs/index.php?topic=18442.0.....without your help, I couldn't have made it this far....

[Rick 74 MC-8]

Great pics Is one of the diaphragms ruptured?

                                                        Rick 74 MC-8

[bwze]

Nah...the diaphragms looks good.....no dry rotting or cracks at all. It looked as if the can had been rebuilt in the past. I'm guessing that the roller condition was causing the whole problem....at least I hope so anyway.

[Rick 74 MC-8]

Didn't you have air escaping until it popped the parking valve




                                                        Rick 74 MC-8

[ArtGill]

Wow those pictures were great.  Thanks for taking the time!!!

Art

[bwze]

Yeah I did. It was leaking from around the rear of the can where the push plate shaft exited. As far as I can tell, when you push in the park brake valve, the lock port air line is pressurized which supplies air to the back of the piston to relieve the rollers and the mechanical lock they apply to the push plate shaft. I can only assume that the air was leaking past the piston sealing ring because the rollers were locked in place (due to rust and corrosion).



Edit: After posting and reading, I'm wondering, did that make any sense?

[gmbusguy1]

Great job Billy !!!!!!

keep up the good work

most of the damage that I can see in the photos looks like it is from moisture in the air system. of course sitting and no grease does not help either.

also you are going to need new airbags very soon as the front one in your pictures looks like it is frayed and could leak anytime they are very easy to r and r

keep in mind that everything you do to fix a bus is DONE for a very long time

Thanks for posting this work

Chris

[zubzub]

Excellent job documenting the job...I always get too busy wrenching and only think of pics when the job is done.  since you have the wheel off might as well change the front bag, rear looks good though.
Also to any following this post, while bwze's method is the best for pics and clarity, one can also remove the brake cans by driving the bus up on ramps/blocking etc...chocking the wheels and squirming underneath....

[gmbusguy1]

Billy, I think you should replace the Inversion Probably the leak you think is the can and replace all the rubber stuff you run into under there

Just my way

Chris

[bwze]

Thanks Chris. Yeah, I know the bags need to be replaced. Luckily, the previous owner had purchased a complete set for front and rear. I'm thinking that since I have the wheels off and I'm this far in, that I'll just go ahead and replace them. Seems like the best time to do it......

[longjohn]

Billy , Great job of documenting this procedure. You have made someones job in the future much simpler. as gmbus and zubzub both said the frayed airbag looks like its time. Thanks for sharing!

[Dreamscape]

A most excellent presentation! One of the best I've seen!

This should be an article in BCM for sure!

Great job!

Paul

[wildbob24]

Billy,

Very nice job! I second Dreamscape's mention of an article in BCM.

A couple of suggestions:

You might want to crib under the beam where your jack is. Cribbing under the end of the axle means you can't turn the drum when you adjust the brakes.

It's a good idea to mark the parking and service chambers before you remove them, so you can get them "clocked" correctly on assembly. You may have done this, but it didn't look like it. If you didn't, your excellent pictures should help  you figure this out.

I see some cracks in your service diaphragm around the circumference where it seals on the chamber. I would examine them very closely and consider replacing them.

In addition to the inversion valve, I would seriously consider replacing the relay valve, as well. There's a good chance the insides of both look like your brake chamber. You might consult Luke on this when you talk to him.

I also would encourage you to replace the airbags while you're there, especially if you have them "in stock".

Bob

[papatony]

BWZE:: the worst part of changing air bags is getting to where you are now I would change them now. you will be set for several years. Beats changing one on the road some where.      papa T

[bwze]

Bob and Chris, I do plan to remove and replace both the inversion and relay valve(unless they are in good condition and can be rebuilt).....and change all the air hoses in this compartment...

Chris, I do have it cribbed under the axle. You can't really see in the pictures. I blocked out on the end of the axle to give me some added feeling of security. Unfortunately, I'm working off of the ground and whatever this point of the bus weighs (I estimated around 6000#), it was enough to drive my jack, and the larger piece of 3/4" plywood beneath it, down about an inch. I ended up finding some larger pieces of steel to use as a bed plate for my jack, and all of the cribbing, to help distribute the weight evenly to minimize the sinking issue. I also decided to leave the jack in there for good measure too...

I sure hope this helps someone in the future. I plan to do this with all the big jobs I end up doing on the bus.....like replacing air bags.....