M923/M543A2 Axle Swap

[nf6x]

I've often wished that my M543A2 wrecker (part of the old multifuel 5-ton family) had air brakes with spring parking brakes, instead of air-over-hydraulic with a driveline brake. Yeah, I know that all of that air plumbing would be difficult, but I'm expecting to need to replace the air lines anyway even keeping the hydraulic brakes, because I get more rust than air out of the glad hands. And there's a leak somewhere in my hydraulic system that I haven't found yet... every time I want to use the truck (only moving it around on my property in 1st gear/low range), I need to refill the reservoir, pump for a long time, and then use 2-3 pumps of the pedal for every stop. Not good at all. Heck, I'm considering selling off the wrecker because I just don't have the time to give it the maintenance that it needs... but I still have need for a crane of some sort, so I'd probably just be selling one set of problems just to buy a different set of problems. Sigh.

Seeing the piles of M9xx axles in that Fontana boneyard got me thinkin' (yes, that's usually a dangerous condition!). So, I'm wondering if any of y'all are personally familiar with the different axles used in both the multifuel and M923 5-ton trucks.

Are there any air brake assemblies out there that would bolt on to the M543A2 axles without machining?

Would it be easier to swap out entire axles from M9xx series trucks?

Would M9xx axles mount in the same way as the M543A2 axles without any cutting or welding, using the original M543A2 suspension components?

Would I be better off selling my M543A2, using the proceeds to buy lottery tickets, and then buying an M9xx wrecker if I win?

Does anybody have a nice military rough-terrain crane that'll lift 5k pounds 18+ feet that they'd like to trade me for my wrecker?

Have I finally gone off the deep end into CARC-induced dementia?

 

[M1075]

You can bolt up M939 axles to older five tons with no problem. I have done it. They are the same housing. I believe you can also switch over the axles from hyd to air and vice versa.

 

[DDoyle]

Mark,
There is another way - I'll PM you.

DD

 

[nf6x]

BTW, if I had the money, I'd just sell off my deuce and wrecker, then get an M923A2 and put a big knuckleboom crane on it!

 

[redass73]

what is the other way DD ?

 

[nf6x]

Re: RE: M923/M543A2 Axle Swap

Mark,
There is another way - I'll PM you.

DD

DD directed me to email Joe Shannon to ask him what he did with his M62. Joe responded (and gave me permission to quote him):

I took out the lever beside the seat and ran the cable into the toolbox behind the driver. I then mounted a PTO valve where the brake lever used to be. In the toolbox I made a lever with a 30-30 spring brake chamber on one end and the cable from the parking brake about half way down the lever. The valve controls the brake chamber and the chamber pulls the lever and the lever pulls the cable.

I've attached the pictures that he sent me.

This isn't what I want to do... I want to have all four rear brake drums firmly locked up when my 34,000 pound wrecker is parked on a hill. Still, it's interesting and I can see clear benefits to Joe's modification over the regular hand-applied driveline brake:

• Uses less muscle to apply.
  
  Automatically compensates for minor wear (as opposed to the hand lever where the operator needs to adjust the knob manually).
  
  Applies automatically whenever the air is low or the truck is off.
  
  Can't be disengaged accidentally by bumping the lever while exiting the cab, or by curious little fingers when the truck is off.
  
  No more getting boofed by the brake lever on the way out of the cab.

 

[redass73]

RE: Re: RE: M923/M543A2 Axle Swap

that is pretty cool. but the air brake conversion on the axles is still better. woder why the military didnt ''upgrade'' the older trucks years ago. prolly still alot of 800 series trucks in service the could use it. i'm sure they have spend more for less.

 

[CGarbee]

Go to M Series Rebuild and see if Charles will tell you how he does the air brake conversion on five tons... He has photos on his website of a full air conversion that he did recently for a customer's M817...

See two photos from his website below...

His website is located at:
http://www.mseriesrebuild.com/

 

[jeli]

That's interesting that the conversion above is using the more popular S cam brakes not the wedge brakes the 900 series uses.

The spring brake on the std parking setup is functional but I'd want to mount the can directly onto the linkage and eliminate the cable. That might be challenging physically.

 

[DDoyle]

Memphis Equipment has on the shelf conversion kits for 5 tons - this is a stock item for them. They may have a similar kit for deuces - I dunno, I've never asked.

Interestingly, the government specs on these trucks say the parking brake must hold the loaded truck on a substantial grade (I don't recall the percent grade), although on a wrecker I'd be concerned that using the drag winch would overcome the parking brake - guess that is what the ground anchors are for.

DD

 

[NEIOWA]

Can anyone quote the mfg/model # for the M923 series rear? Milspec or is there a counterpart in civilian world.

What I'm looking for is what the a civilian GVW rating would be. Military rating does help. Working on a glider concept for Civilian Fire Dept tanker chassis and need donor rear axles. M915sereis would be the other likely source.