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I need info on selectable 5 ton locker's

cerial0411

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For the last 4 years I have been getting parts around for a expedition vehicle. Originally the design and gearing was for 2.5 ton axles. But after doing lots of late night searching, talking to people about what is here and what is to come I have decided to go with 5 ton axles instead. From the start I decided whatever the cost I would have a selectable locker. It is simply needed for the street and offload use this will endure. This was not a concern with the 2.5 ton.
Because no one makes a aftermarket selectable air locker for the 800 series 5 ton that I know of I went looking for one. I found it in the 900 series and found everything different. For the most part the 900 series axles will work. But, the aftermarket focuses on the 800 series currently and that is where things such as stronger knuckles, hubs, and so on.

I like the 800 series it gives the possibility for upgrades in the future while giving a very low upfront cost. Like I said though I need the selectable locker. My first thought was to take a 900 center section and graft the 800 outer sections onto it. What I think may be easier is simply using a 800 housing and modifying to work with the 900's mechanism that en-gauges the splines on the shaft. Either way I will need to have shafts made to work with the 800's smaller bearing diameter that taper up to work with the 900's air locker mechanism. Where I am at right now is considering just using the stock 900 series axles and making my own knuckles. The only issue with doing this is that the hubs for the rear axle need to be flipped inward. I will need to cut and weld the rear axle to make it in a "moonbuggy" style and have new shafts made no matter what. Still if someone has any experience or write ups on what needs to be done to flip the rear air hubs inward on the 900 series that would get rid of one major issue. The front axle can remain stock if I use a complete 900.

The parts availability of these "rare" axles is what has me a bit concerned. The fact that I really don't know much about the locking mechanism or what would be the best selectable locker 5 ton axle to choose has me typing this post. I need some advise onto what selectable 5 ton I should look for. The more popular the better due to the once again mentioned parts availability.

Sure there are going to be a couple of questions here is a bit of info to try and crush those upfront. The total vehicle weight is going to be between 6200 and 6400 lbs. I am using lug mounted 22.5 rims and 40" tires. I have 12 speeds with 3 practical overdrives, they are .90, .75, and .54. The breaks will be a lug mounted 2 piece rotors with F-550 calipers. Steering is done with a axle mounted power steering box out of a semi with custom linkage to prevent suspension binding while giving control in the event of a pump or line issue. I am using a propane powered 1968 Cadillac 472 motor that is mostly stock.

I was planning on the 6.72 ratio in the 2.5 ton. But, a 6.44 ratio will work or up to 7.40 if there is a more "popular" 5 ton selectable top loader out of a crane or something. I did the math and a 8.8 ratio will simply not work with the motor's oiling system and there is a high chance will have me going up steep grades at 55 mph. A 6.4 to 7.4 ratio is what I need to work with.

What is a good air selectable 900 series to look for, what issues can I expect, recommendations on flipping the hubs, what should I do besides the knuckles as far as upgrades, and any non military options out there?

Thank you for reading
 

Warthog

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I always thought it was the transfer case that was selectable and not the axles themselfs
 

quickfarms

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Some USMC trucks gave Detroit Lockers in the axles.

I have never seen a 5 ton with air lockers.

Air lockers do exist, I used to drive a mack that had them
 

porkysplace

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Look for some Rockwells out of a FWD Tractioneer , they are the same design as military . But they are air over hydraulic to engage the posi and will have full air brakes .
 

jdknech

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just a FYI, the "800" and the "900" (if your talking about the M939 trucks) are the same axles with the exception of the brakes, the 939 had air brakes, and the m809 (800) has hydraulic brakes.. the center chuncks are interchangeable.. that being said, i have been looking for 5ton lockers, and detroit is all i have found.. and they are a auto engage.. the air switch that you are talking about is for the 6x6 engagement... the 800 trucks had a sprag transfer case, and didnt have the switch...
 

cerial0411

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I am talking about the axles in this thread.

http://www.steelsoldiers.com/showthread.php?61719-5-ton-air-lockers

This link was within that thread has a broken link.
http://mudboggers.net/threads/here-is-some-5-ton-axle-tech-and-differences.9734/

As stated before they look similar to a 5 ton in dimensions. I am trying to get more info on reliability, parts availability, how exactly the locking mechanism works, and if there are inherent flaws that I can fix with any tricks learned over the years. If they have a super rare hub or hard to find bearings then I will simply use the more common 800 series hydraulic hubs and bearings then taper the shafts up to the larger size at the carrier. If the locking mechanism is known for poor reliability or is simply a bad egg in general then I will shy away from this axle. Although I really want a selectable locker, if this axle is going to cause more headaches then it is worth I will simply go with a 800 axle and wait till someone builds a ari locker for the 5 ton.

If ARB made a 5 ton locker I would not even consider using these axles. I would use the common 800's, install the ARB, some stronger knuckles, and be done with it.
 

cerial0411

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I did find the axles I was describing. I was told they are out of a forestry/fire truck. They are a 240 series 5+ ton Rockwell's from the 70's with a 5.81 ratio. I will be switching these to the 10.24 ratio later on which will bolt right into the 3rd members.
They have half round 1710 u joints which I will try to reuse.





Here is the cover for the locking actuator. It is nothing more then a air piston. All three are broke due to improper movement during removal of the vehicle which is about the only way to damage these. I will tear them apart and replace or fabricate air pistons using parts from similar air actuators used on Loader style top loaders. Worst case I will use a aircraft cable and 2 position lever to lock/disengage.


One of the three axles has an inner axle differential lock using the same style of air actuator to engage/disengage the rearmost axle



 

cerial0411

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Update

Update:
I found a set they were out of a forestry and fire truck. The id tag shows 240 series from Rockwell. They have 5.81 gears which I will be swapping to 10.26. They came with half round 1710 u joints which I will try to reuse. All three have damage to the locking mechanism in someway. But, it is simply an air piston and can be rebuilt or switched to a cable. Despite having air suspension I will most likely switch these to a mechanical operation with a spring engage, parking break pull disengage, using aircraft cable to avoid any issues.

0608131100.jpg0607132058d.jpg




Locking Mechanism
0609131529b.jpg

The Middle one has a inner axle Lock using the same simplistic air piston design. It also has a locker on the housing.
0609131534a.jpg0609131535.jpg
 

porkysplace

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It's not a LSD or "posi" which are the same. It's a locker. Totally different.
LSD and posi are not the same , limited slip differential is just that it allows the wheels to turn at different speeds in turns . A "possi" turns at the same rate all the time . When you egage air to those axels the will not rachet like a detroit locker , they lock-up solid , both tires will turn at the samr rate in a turn .
 

Mercunimog404

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LSD and posi are not the same , limited slip differential is just that it allows the wheels to turn at different speeds in turns . A "possi" turns at the same rate all the time . When you egage air to those axels the will not rachet like a detroit locker , they lock-up solid , both tires will turn at the samr rate in a turn .
A lsd and a posi are the same thing. Posi is GMs name for its LSD. A locker turns the wheels at the same rate.
Even eaton says they're the same.

http://www.eaton.com/Eaton/Products...utomotiveAftermarket/Differentials/PCT_221429

Dodge called there's sure grip
Ford called there's tracklock
And gm called there's positive traction

All limited slips. There is tight lsds and loose ones.
 

Recovry4x4

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If I recall, here's how they work. One axle has 2 set of splines on it. The inner of course goes to the axle gear but the outer is outside the carrier. The carrier extends past the carrier bearing and has a gear (of sorts). There is a collar that the air mechanismslides back and forth. When it slides towards the carrier it engages the outter set of splines on the axle and the gear (of sorts) coming out of the carrier. Locking both together in effect, locks the axles.
 

Mercunimog404

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If I recall, here's how they work. One axle has 2 set of splines on it. The inner of course goes to the axle gear but the outer is outside the carrier. The carrier extends past the carrier bearing and has a gear (of sorts). There is a collar that the air mechanismslides back and forth. When it slides towards the carrier it engages the outter set of splines on the axle and the gear (of sorts) coming out of the carrier. Locking both together in effect, locks the axles.
And that is a locker. Not a posi :)
 

cerial0411

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Hey cerial that was a good find. Do you know what year and model of a truck those axles came out of?
Here is all the numbers I could pull off them
Here are the tag numbers.
Steer:
Model: FM 240 HX 19
Cust: EE40437
Series: 255106
Plant: NY
Date: 1107731
Ratio: 5.81

Drive w power divider (parts axle)
Model: MD 240 HX 1
Cust: EE34376
Series: 142101
Plant: NY
Date: 1306741(the 0 might be something else)
Ratio: 5.81

Drive rearmost
Model: M 240 HX19
Cust: EE34377(the first 3 might not be a 3)
Series: 228104
Plant: NY
Date: (could not read)
Ratio: 5.81

Meteor does sell parts for the 160 and 180 series. But, they list the 240 series as an inactive axle.

The M stands for Meritor(FM front, M normal, MD is power divider). The HX stands for hydraulic breaks.

There are also numbers stamped into the top of the 3rd member
The first one says
A73E473MY2
58192678
Another one says
A72E478MY 10
58111878
The third one is really hard to read I believe it says
A17R512MY14
581?3?12?78
These look to be stamped by hand so they could be missing number's. I am guessing they are the dates 9/26/78, 1/18/78, and 3/12/78 making the 3rd members around 1979. The tags say Rockwell International placing these post 73 supporting that theory they they may be from 1979.
That's all I know up to this point. To the best of my knowledge they are a civilian axle so that makes nailing down an exact model nearly impossible.
 
Last edited:

350TacoZilla

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You might want to get ahold of Adam from adams offroad, he runs the air locker axles in his mud bronco and has dealt with them for years.

http://adamsoffroadperformance.com/contact/ he might also be able to help you on parts and interchangability.

my suggestion would be save your air lockers for the front and use detroits for rear(s) since rears are always driven and parts are easier to come by (not that you will be breaking them)

if you do start breaking shafts http://www.gearharteng.com/assets/images/oversize-axle-front.jpg http://www.gearharteng.com/assets/images/oversize-rear-axle-kit.jpg
 

cerial0411

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Talked with Adam's offroad he has been a great help. The abuse he puts these through under his bronco is why I wanted a set. Gearheart is very close to where I live and they will take these axles further strength wise(knuckles, hubs, shafts, shorten, truss) once I am ready. He actually told me where to find these through another local supplier(on another forum)who was within an hour of me. I will be more then happy to have Gearheart work on the stuff beyond my skill level such as the housing and gear change. I have a single speed transfer case designed by me and built by the great folks at SCS for this making it full time 4wd.
 

Stevepala

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I have a set of these air locker axles also, but I believe they are 6.44 ratio in my set. I was told they have larger axle shafts and bearing then a standard 5 ton. I'm not sure of the original application of my axles but a mud truck would be fun.
 
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