Author Topic: Air brake chambers  (Read 4416 times)

Offline Nel

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Air brake chambers
« on: June 02, 2016, 06:55:43 AM »
Ok found the air chamber to be leaking on the passanger service side. It is a 30/30 2.5 stroke unit with spring brake.
found a date on it from 2005. I looked in the chamber weep hole an it does look like the diaphram is dried out.
Question , I am going to change both rear chambers,how long do they normally last and I am seeing cost from 45.00 to 120 dollars a piece , don't want to cheap out on the parts, but what should I look for when shopping for one and are the qualities that different?    Thanks, Nelson
4104-4519
West Nyack , NY

Offline luvrbus

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Re: Air brake chambers
« Reply #1 on: June 02, 2016, 07:16:54 AM »
I use nothing but the MGM brand of spring brakes they cost a little more but are a higher quality than the knockoffs and they are American made
Life is short drink the good wine first

Offline chessie4905

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Re: Air brake chambers
« Reply #2 on: June 03, 2016, 04:59:21 AM »
Make sure that the overall length is not longer than the ones you have. Clearance is fairly close on a 4104.
GMC h8h 649#028 (4905)
Pennsylvania-central

Offline Nel

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Re: Air brake chambers
« Reply #3 on: June 03, 2016, 05:38:47 AM »
Thanks Guys, Chessie,you are right very little clearance also no way to cage the spring brake if need be
4104-4519
West Nyack , NY

Offline chessie4905

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Re: Air brake chambers
« Reply #4 on: June 03, 2016, 12:30:03 PM »
Ours had an auto/manual level system....you could raise the rear enough to use the caging bolt, although we never needed to.
GMC h8h 649#028 (4905)
Pennsylvania-central

Offline Nel

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Re: Air brake chambers
« Reply #5 on: June 08, 2016, 04:49:37 AM »
I am installing the 2 new 30/30 chambers with air hoses, found that I had to trim/cut about 3/8" of metal around the mount area to clear the canister, so far so good, also inspected the driver side brake shoes and noticed the spring must have broke, that's why the slack adjuster felt weird on that side , the lower shoe is not following the cam but was able to move it with a screw driver,the top shoe is moving with cam so wheels have to come off and last but not least , the dash pop up valve is not working right , do they go bad? 
Got the pressure up with a compressor to 100 psi to test,will stay down if i hold it , but spring brake not releasing and if i pull it up , no air rushing out like it use to. So a lot of brake issues all at once , here we go, besides good luck any advice , thanks,  Nelson
4104-4519
West Nyack , NY

Offline Oonrahnjay

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Re: Air brake chambers
« Reply #6 on: June 08, 2016, 08:13:07 AM »
... So a lot of brake issues all at once , here we go, besides good luck any advice , thanks,  Nelson

      Individual checks and repairs, just move down the list.  My only piece of real advice is to leave the valve-button issue until last.  It may be that resolving the other items will make that work right.  But if you need to fix that, it's an easy repair.
Bruce H; Wallace (near Wilmington) NC
1976 Daimler (British) Double-Decker Bus; 34' long

(New Email -- brucebearnc@ (theGoogle gmail place) .com)

Offline TomC

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Re: Air brake chambers
« Reply #7 on: June 08, 2016, 09:49:33 AM »
Sounds like you have the air lines switched
Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.

Offline chessie4905

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Re: Air brake chambers
« Reply #8 on: June 08, 2016, 08:27:35 PM »
While you are in there, make sure to check over everything. Especially camshaft surface that rides in the bushings. Being that old, they may need to be spray weld and returned to correct size if your can't locate new ones. Luke would know or have what is needed. They make shims to remove excess end play. Download or read pertinent info on Bendix website for rebuild info if you don't have factory manuals.
GMC h8h 649#028 (4905)
Pennsylvania-central

Offline Nel

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Re: Air brake chambers
« Reply #9 on: June 09, 2016, 04:17:49 AM »
Ok update, got both air chambers mounted and adjusted, so far so good, went to dash pop up valve, still would not hold or release air right but air pressure was getting to it , result, the exhaust tube for the valve was clogged by mother nature, stuck a wire up it and all kinds of dirt and larvae of some insect came out,amazing how it was able to hold back a 100 psi, talk about unrelated stuff happening all at once, so now that works fine, last is taking rear wheels off on driver side to repair and inspect broken return spring and cam  wow, Nelson
Thanks for advice , Bruce, Chessie and Tom
4104-4519
West Nyack , NY

Offline buswarrior

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Re: Air brake chambers
« Reply #10 on: June 09, 2016, 10:45:44 AM »
Don't under-estimate the power of mud daubers and the like.

Their spit and mud can seal up every drain and vent hole in an air system. Particularly nasty is sealing up the atmosphere side of a valve. The pressure side will only move so far against the now plugged and sealed other side, robbing that device of full motion, or full strength.

As part of a busnut PM, this doesn't get written down properly anywhere, every vent hole needs a piece of wire poked into it, if your coach is parked where these beasties like to roam.

I've seen 'em seal up the exhaust line for a tractor trailer hand valve, no small opening, and fill the tank drains solid.

happy coaching!
buswarrior

Frozen North, Greater Toronto Area

Offline Nel

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Re: Air brake chambers
« Reply #11 on: June 09, 2016, 07:06:40 PM »
inspected the rear brake and the return spring is definitely not working but brakes are adjusted correctly , I can see the top shoe moving with the brake cam but the bottom shoe in sitting on the drum and with brakes released I can move it up with a screw driver easily . I may not have time to get it fixed before a 150 mile trip, do you think it will be ok to drive it like that for now?
4104-4519
West Nyack , NY

Offline buswarrior

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Re: Air brake chambers
« Reply #12 on: June 13, 2016, 08:56:25 AM »
NO!

Lazy bottom shoe will set fire to the tire.

happy coaching!
buswarrior
Frozen North, Greater Toronto Area

Offline chessie4905

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Re: Air brake chambers
« Reply #13 on: June 13, 2016, 10:12:32 AM »
No. Fix it first.
GMC h8h 649#028 (4905)
Pennsylvania-central

Offline trucktramp

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Re: Air brake chambers
« Reply #14 on: June 13, 2016, 02:04:43 PM »
Listen to BW and Chessie.  I have seen hot brakes start a tire fire and the trailer it was on burnt to the ground.  A tire/brake fire is tough to put out.  It would be a shame for you to have a bad fire like that.
Dennis Watson
KB8KNP
Scotts, Michigan
1966 MCI MC5A
8V71
Spicer 4 Speed Manual