Air Brakes sticking on M923A2...

[JamesH]

Well I had this problem with the air brakes during my recovery when I hit stop and go traffic. I took it for a drive yesterday and had no problems but then today when I took it for a spin, I got a 1/4 mile from the house and when I stopped at a stop sign, they didn't want to release. I gave it a little power and they released. I got to the next stop sign and they locked up good. I powered through to a vacant field across the street and tapped on them with a hammer and went from forward to reverse a few times and they eventually released. I got her back home and when I felt the rear drums, 1 was cold, 2 were warm and 1 was too hot to keep my hand on at all......I had traveled about 1 mile total.
I can't find anything in the TM's about this....anyone have any advise?

Thanks,

James

 

[Artisan]

What happens when you do a C.O.L.A.S. test?

 

[Floridianson]

Yea thats the problem with wedge. If they get rusty or stick because of a hard brake they will stick. You will have to find out which chamber stuck. The double or single. Then you might be able to remove it and try and get some lube up the cylinder. Then you could try and pull the hub. When you are looking at the brakes you will see the actuation unit and there will be two nut looking thing on it. Two on each actuation unit. You remove the nut and gain axcess to the workings. Then try and lube that up with something. Be carefull as one of the nuts is the slack adjuster and the nut thing can only go in one way. The best thing I might do if the actuation unit is bad PM Steve aka Steve 6x6x6 and see if he has a whole spyder that is a good take off and just replace you whole spyder. Pm me if needed and I will give you my cell.

 

[Csm Davis]

What was the air pressure? Did it go down as you continued?

 

[Floridianson]

Here is one link to show parts. Yea thought about it more and did you have any air leaking on the double brake chamber?
Like I said if the problem is a dirty or gumed up assembely then you might get lucky and free it up with some work. The parts can be hard to find but as said you could also just changed the whole spyder. You don't realy have much to change as just drop air lines off chambers and leave the brake shoes alone just unbolt the spyder fron the axle housing. Bolt on used spyder and hook up air lines. The mud guys unbolt the spyders and don't use them so if you need one they are out there for maybe cheaper than the parts to rebuild.ftp://38.106.177.129/gopettibone/fo...topmaster heavy-duty brakes manual no. 4p.pdf
Here is another good link.ftp://38.106.177.129/gopettibone/fo...-rockwell/stopmaster brakes manual no. 4r.pdf

 

[Floridianson]

If you do find you need a whole spyder believe the front left rear and rear rear right are interchangeable. Then so would be the right front rear and the left rear rear.

 

[country]

we have the part you need

(5T-661) Inversion valve for brake system- (NAP) NEW- $265 each

Dave
www.easternsurplus.net

 

[JamesH]

Thank you all! I got buried in work all of a sudden but as soon as I get the time I now know where to look!

James

 

[JamesH]

Well Dave I was really hoping it was the Inversion valve....thanks for getting it shipped out so quickly....unfortunately that didn't fix the problem.....Looks like I'm going in....

James

 

[country]

Sorry to hear

this fixes your condition about 99% of the time

dave

 

[Floridianson]

As I said before there might be a frozen assembely in one of your chambers. You will have to track the spyder that is locked up. Might be easer to jack up all axles one at a time if you have to and see which one is jamed. Then you will have to find out if it is the double or single chamber that is locked. Then you can eather try to get it to release or as said try and find all parts to rebuild or replace whole spyder. Pm me if you want my cell and I will tell you what I do in worse case.

 

[Tow4]

You can pull the dust covers off and check to see which brake shoe(s) are not releasing. I would check the wheel that was too hot to touch. You will probably end up pulling that one apart.
The are a couple of wedge brake videos on YouTube. Also Google meritor brakes or axles. You should be able to match them up. I found an on line catalog and was able to match all the parts but I don't have it handy now.

 

[Floridianson]

Ray did you order any parts from them and did they have them?

 

[Floridianson]

Sorry to hear

this fixes your condition about 99% of the time

dave

50%

 

[Tow4]

Ray did you order any parts from them and did they have them?

I didn't order anything. When I got mine apart, I didn't need anything, just clean and lube. It was a current catalog (only a year or two old) so I would think parts are available.

 

[Floridianson]

5 bucks say they won't have the 4 seals and roller assembely we need to rebuild.
I don't know what tools he has or even knows what drums is haveing problems. Yea he could pull dust shields and look. Myself I have a 30ton air floor jack that can lift one compleat axle quick so I would just jack up one whole axle and see what drum is stuck if it still is. The drum that is sticking is going to have to be removed to service. So in my case I do not need to remove the dust shields to quickley find which axle/drum has the problem. Also I found when doing an axle / bearing service with my wheel dolly it helps to have the whole axle level so I lift the whole axle and set it on jack stands even if I am only doing one side.

 

[Baradium]

If one drum was incredibly hot, that would indicate the sticking one in my mind. Just saying... Even if another one is sticking some, that one difinately is.

 

[Tow4]

I had to service the brakes on my M929 because of a dragging brake. I borrowed a wheel lift from RAYZER and pulled the wheels,hub,drum as one piece, much easier. Here's what you will see when you pull the drum/hub assembly.



One side has an adjusting plunger (on left), the other is a anchor plunger. The adjusting plunger has a pawl assembly and the anchor plunger just has a plunger guide The seals are different so keep track of them for reassembly. Look in the TM, there are also better guides on-line. Clean everything and make sure the adjuster is free and works correctly.



Clean up the bores of the spider and check to see if the wedge is in the proper position. Put some grease on the wedge and in the plunger bores and then reassemble. You don't need a lot of grease.



The 5 tons have regular oil seals on the back of the hub and since mine was already full of oil (as you can see), I put it back together that way. The hubs on this truck run cool at 110~120 degrees. I didn't use a keyway seal and you can leave the outer grease seal off. (Disclaimer: this is what I did, I don't care what anybody else does).

 

[Artisan]

Do I see evidence of overheating on that, is it the "Spindle" ?
See the discoloration? Did you replace bearings?
THANX for the pics !

 

[Tow4]

Do I see evidence of overheating on that, is it the "Spindle" ?
See the discoloration? Did you replace bearings?
THANX for the pics !

The bearings looked new and may have been replaced in the past. The hubs have never been hot since I've own the truck.