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Author Topic: Maxi brakes failure  (Read 4452 times)
silversport
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« on: November 11, 2010, 05:40:59 PM »

Fired up the old girl (GM 4106) for a nice weekend in the wine country, when one of the back brake chamber sprung a leak. Went to DA Book but I have Maxi's, replace the diaphragm but air is still escaping from the push rod area. With out a schematic I am unsure on how to take the chamber apart ( are there O rings that need replacing?). Has two air hoses, a plastic cover on one side that has inside a self locking nut on a Allen head stud also a retaining clip holding a washer that the stud is going through ( I think this is to manual release the push rod but I am not sure how). There is a bolt on the bottom of the unit. Any help would be appreciated .
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jackhartjr
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« Reply #1 on: November 11, 2010, 06:16:35 PM »

Not trying to alarm you...however if you do not know what you are doing it could KILL you.  Get someone that knows how to handle this. 
Jack
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Jack Hart, CDS
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« Reply #2 on: November 11, 2010, 06:27:35 PM »

I would just get a new one. Your old one is probably rusty. Not worth fixing.

JC
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JC
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gus
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« Reply #3 on: November 11, 2010, 06:45:51 PM »

Amen to the other posts, maxi brakes are too dangerous to fool with. New ones are cheap in comparison to your head.
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PD4107-152
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« Reply #4 on: November 11, 2010, 06:52:28 PM »

I concur. If you want to mess with it. Do so after you've had it replaced.  ...Cable
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Sofar Sogood
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« Reply #5 on: November 11, 2010, 07:37:58 PM »

Don't mess with a spring brake without the proper metal box to put it in, or a properly equipped press.

The spring can knock a cement block out of a wall.

You'll never know what hit you, and those who find you will wish they didn't.

happy coaching!
buswarrior
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« Reply #6 on: November 11, 2010, 08:22:07 PM »

I am reminded of my Dad about 40 some odd years ago that tried to 'fix' an old tube type TV.  One second he was on one side of the room with a screwdriver in his hand...the next he was on the ther side of the room...wondering how he got there.  Those brakes can do that too...or worse!
Jack
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« Reply #7 on: November 11, 2010, 08:49:04 PM »

Just analyze how powerful that spring has to be to stop and hold 30-40 thousand pound vehicles.  You really don't want it jumping out at you.
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« Reply #8 on: November 12, 2010, 01:37:39 AM »

are maxis that different from regular spring brakes?  I changed the diaphragms in my spring brakes, no muss no fuss.  You need the  the bolt that holds the spring, you tighten it to capture the spring, take the can apart, change the diaphragm , and put it alll back together.  Sure a spring is a dangerous thing, but it's not that complicated.  Macpherson struts need spring compressors to be taken  apart for rebuild and that is more dangerous as the compressors are installed by the rebuilder.
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« Reply #9 on: November 12, 2010, 04:54:29 AM »

ZuZub, it's not that they are difficult...it's that if you mess up, it is REALLY, REALLY, REALLY BAD!  I was just suggesting that our friend that we want to enjoy this hobby for a long time get help the first time. Grin
Jack
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Jack Hart, CDS
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« Reply #10 on: November 12, 2010, 05:04:01 AM »

From my air brake course notes, the spring in a spring brake exerts about 60% of the force of a full brake application.  Say that is 100 psi into a 30 brake can, that is 60% of 3000, or 1800 lbs.  Looking at the diagrams, that's probably a 600 lbs spring compressed 3 inches or something similar, but the 1800 lbs of force is what the problem is.  Even with a caging bolt, that's a lot of kinetic energy waiting to do something to you.  I think of it as working in a 600 volt 3 phase panel, live...  Wouldn't do it on a bet!

Brian
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« Reply #11 on: November 12, 2010, 06:07:57 AM »

I just don't get it.  Brake cans are cheap and by the time you might start thinking of working on them they are obviously old.  They live in a bad place, covered with road salt, grime and often damp.  Why anybody would even think about servicing them is beyond me.  If it made economic sense the commercial guys would be all over it and they clearly aren't.  Look in the back yard at any truck shop and you'll find an oil drum filled with dead air cans.
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R.J.(Bob) Evans
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« Reply #12 on: November 12, 2010, 06:26:47 AM »

Bob, it's my impression that Maxi chambers are very old design, no longer in production and expensive when you find them.  They are smaller than spring brake chambers so swapping to cheap, new, available parts is hard to manage.  5 minutes with google brought up no links to Maxi chambers for sale, or kits for that matter.  Didn't check ebay.

edit: ebay found a single 30/30 maxi chamber for sale at $175.  http://shop.ebay.com/items/?_nkw=maxi+brake+chamber&_sacat=&_ex_kw=&_mPrRngCbx=1&_udlo=&_udhi=&_sop=12&_fpos=&_fspt=1&_sadis=&LH_CAds=

Brian
« Last Edit: November 12, 2010, 06:29:18 AM by bevans6 » Logged

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Joe Camper
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« Reply #13 on: November 13, 2010, 06:12:14 AM »

175 bucks for that chamber on E-Bay??

Kinda pricy we give 48 bucks a piece for them, new, and not piggyback but complete.
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Eagle Andy
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« Reply #14 on: November 13, 2010, 06:26:00 AM »

I have been watching this post as I have looked at mine and found I have Mini Max cans . Iam thinking I am going to change them out to a newer style. Mine are mounted on the engine side of the drive axle so I think Ihave room for the 30/30 . Like Brian I went on line and could not fined anything related to Maxi cans of mini Max cans .
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« Reply #15 on: November 13, 2010, 07:49:02 AM »

Some Mack Truck dealers still have parts and the maxis they were used on the B model Mack and are not that dangerous to repair,they have their clamping device built in


good luck
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« Reply #16 on: November 13, 2010, 08:01:59 AM »

I have been watching this post as I have looked at mine and found I have Mini Max cans . I am thinking I am going to change them out to a newer style. Mine are mounted on the engine side of the drive axle so I think I have room for the 30/30 . Like Brian I went on line and could not fined anything related to Maxi cans of mini Max cans .

Eagles are no problem, plenty of room far any type of brake can.  The 4106 does not have that luxury unless you make some significant modifications to the brake can mounting arrangement.  That would take some serious welding and fabrication skills, and most welders would be afraid of liability issues.

That leaves the Maxi or DD3's, both expensive and hard to find options compared to spring brakes.
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« Reply #17 on: November 13, 2010, 08:21:30 AM »

Andy, if your cans are on the backside of the housing the one on the drivers side has to be rotated to clear the transmission mounted on the front side it is not a problem.
Eagles have used the spring brakes since the 80's the last 05 had spring brakes

good luck
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« Reply #18 on: November 14, 2010, 06:03:05 AM »

The word "maxi" was a brand name that drifted into being used generically in reference to the parking brake system or components, depending on whether the speaker is a driver or mechanic.

The brand is long, long gone, the word lives on.

The collective busnut wisdom has been suggesting Mini-Max chambers have been pretty much unobtainable for as long as I've been on the boards. No one could find them in 2000 either.

I fear that the DD3 will drift into obscurity at a faster rate than we might expect. No business today can afford to stock parts that don't move. Shelf space simply costs too much, margins are too small, and new old stock rubber parts deteriorate too.

Grab and distribute to the busnut community all the DD3 you can find.

happy coaching!
buswarrior 
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« Reply #19 on: November 14, 2010, 11:08:05 AM »

This is all news to me, I thought "Maxi" is just a brand name for one type of spring brake and has become generic like "Scotch tape"??

As Joe says, the new can is so cheap it makes no sense to try a dangerous repair that might still leak or have another worn out part fail later.
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« Reply #20 on: November 14, 2010, 11:17:51 AM »

I was guilty of thinking that maxi was a generic name for spring brakes.  It's a rare day that I don't learn something here.
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R.J.(Bob) Evans
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« Reply #21 on: November 14, 2010, 12:17:09 PM »

This is all news to me, I thought "Maxi" is just a brand name for one type of spring brake and has become generic like "Scotch tape"??

As Joe says, the new can is so cheap it makes no sense to try a dangerous repair that might still leak or have another worn out part fail later.

When I was looking for spring brakes for my n'04 it was hard to find them with the necessary front end on them.  Not only is the push rod longer than most, but there is a built up area on the front of the can to clear the mounting bracket layout (stock bracket)  I looked around for cans like these, found some at +$100 each, without the spring brake. part.  So I just used my old can with a new diaphragm and attached some decent looking spring brakes that were available.  Come to think of it I guess I jsut changed the service brake dia., not the spring part, as the new spring brakes did not need messing with.
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« Reply #22 on: November 14, 2010, 02:12:39 PM »

I'm still not clear here, can spring brakes be mounted on a 4106 or 4107 or are they stuck with DD3s?
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« Reply #23 on: November 14, 2010, 06:52:20 PM »

Gus, ours works fine, but it required modifying the mounts and adding the parking circuit. Ours did not have DD3s from the factory.

I don't know how much modification might be required for parking circuit from DD3s.

Take care.

Tom Caffrey
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Tom Caffrey PD4106-2576
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