M105A2 brakes... Now FIXED!

[emmado22]

All,

When the brakes are applied on a M105A2, should they "lock up", or come to a rolling stop? I hooked up the M105A2 to the M35A2C. jacked up one side of the trailer axle, and hand spun the wheel. I had a buddy hit the brakes ont he deuce.... The tire came to a rolling stop. I was kinda expecting a sudden stop. Same thing with the other side... I'd say they "kinda" work, but not as well as I'd like.. But, I've never checked M105A2 trailer brakes, so I dont know what they should do...

I guess I need to check the M105A2's master cylinder, see if it's topped off with fluid and then bleed the brakes...

Air is getting to the trailer brake system. The trailer's air tank filled up, and I could bleed it down thru the drain on the bottom.

I pulled the hubs when I first got it, the brake shoes are in excellent shape, wheel cylinders not leaking, etc.. Perhaps I need to adjust the shoes, now that I think about it..

Any other checks I should do?

Thanks!

 

[Recovry4x4]

RE: M105A2 brakes... HELP!

Off the ground they should lock up pretty quick. I'd do a thorough bleed and if that doesn't fix it, pull the drums and have a looksee. May also be adjustment but it would be good measure to pull the drums anyway.

 

[acetomatoco]

RE: M105A2 brakes... HELP!

Whole system probably needs bleed and refill and exercise..sometimes they sit for years and the whl cyls get varnished in or even rusted. A slow stop could indicate a stuck piston maybe water in the trailer air system from glad hand being open to the rain for years, too.. Get a double ended glad hand hose and hook it up to the emergency side of your truck and blast a bunch of air thru it... You will probably find orange mud in the Trailer MC, too...cuz they always seem to miss out on the PM.

 

[WillWagner]

RE: M105A2 brakes... HELP!

Mine did that too. Pulled it apart, only 1 shoe was moving, the front. Everything was in good shape, but the BFS had just solidified. I just honed and cleaned everything up and put it back together and gave it a good adjustrment. The tires lock up now if you romp on the brakes, even loaded.

 

[emmado22]

Ok, all fixed now.. Problem was a bad relay valve.. NSN 2530-00-021-2366

It's the gizmo that is the "brain" for all the air on the trailer. It has the service line and emergency line going in, and an out to the brake actuator. It's held in place by the air tank.


Seems the just go bad after sitting unused for awhile.. I also filled up the master cylinder with BFS, and am now able to lock up the brakes on the trailer.... Saftey is a GOOD thing...

The replacement was manufacturerd by Excel 2000, Info on the sticker on the box says: EM36350 VALVE OEM-REF# 5396-KN30300 6123

 

[Recovry4x4]

Mark, where did you find the valve and at what cost?

 

[emmado22]

Cost was $66.00 at http://www.autobrake.com/


It did take the lady a few minutes to crossreference it, as it is an older Midland product, but she found it..

One small detail. On the original, it has a 90 degree fitting that goes out to the brake actuator. On the new one, with the new style DOT fitting, I had to add a 1 inch long piece of pipe, and a double female adapter so I could screw in the new 90. Yes, I could of tried to get the old one out, but it was easier to get new stuff. Also, you'll need 3 plugs (or attempt to salvage them off the old valve) and also the 2 fittings that come from the service and emergency air lines.. I just got all new fittings as I in my experience, the old ones always get screwed up somehow on the removal process....

My advice, get new fittings and plugs, and save yourself the headache of removing the old ones.. Also, see how many layers of paint are on your air brake lines, the paint needs to come off to make the fittings snug down correctly. Might be a good idea just to get a few feet of 3/8 inch air brake line and be done with it..

 

[jasonjc]

All this info is great and I do appreciate it all. But, I still most do this

 

[emmado22]

Here is the new valve installed. Seems lack of use and old age kills the relay valve. Add moisture from the ambient air if you dont put the glad hands on the mounts, wasp nests in the air lines and dirt in the actuator pancake, and general old age of the trailer, and your valve is gonna check out early bcause thats how they are. Seems like the valves across the board are short life items.

Also, check the airtank for gunk in it (you do drain it, dont you??) and blow out the tank, and make sure the drain valve isnt clogged with dirt/gunk/rust/water.


In the first pic, the 2 lines on the top are the service in and emergency in from the galdhand lines. The line going out the bottom is the line to the brake "pancake" actuator.


Here is my little "trouble tree" for diagnosing the M105A2

Hydraulic side:

1. check hydraulic master cylinder for fluid THIS IS #1 cause for no braking action!!!!!!!!!!

2. check wheel cylinders for leaks/function

3. check brake shoe operation/ adjustment

Air side:

1. detach lines from valve and blow out all airlines (from gland hand back to valve)

2. detach actuator air line and hook air source to the actuator line.. Check for operation of actuator (blown actuator pancake is #3 cause for no brakes)

3. if actuator actuates, then the relay valve is bad. Replace valve. Bad valve is #2 cause for no brakes

The actuator is another "probable fail" part, so if your getting air THRU the relavy valve, and your MC/hydraulics is good, thats the problem.

Personally, I'd check for fluid in the MC, then go to the air side if you know your wheel cylinders and shoe adjustment is good.

Is this the correct TM way to do check everything, no. But in trying to figure out whats wrong, I'll say
#1 cause is lack of BFS (DOT 5 brake fluid) in the MC
#2 cause is bad relay valve
#3 cause blown actuator pancake

 

[hippiedude]

Thanks for the info. and pics ....


Tim

 

[jasonjc]

YES YES pic are great why don't you do a write up on this and send it in to MV mag.?.?

 

[emmado22]

Jason,

Not a bad idea.. I'll have to get some more pics of before, but thats not a problem.