5 ton sprag question

On my 813 A1 the frontend wont engage in forward. But it does every time
in reverse. I was wondering if i could put a manual air switch on it like a deuse
has to engage the transfercase. Thanks Brad

The Transfer case is alway engaged whenever you have air pressure. The 5 tons have notoriously lazy sprags. You need to be sure the air switch on the tranny is working right and that the shaft in the forward - reverse section of the sprag in the xfer is moving fully when you shift the tranny from forward to reverse.. You should hear it clunk...My usual advice is to drain the xfer and fill it with diesel fuel or kero and run it 50 miles or so to clean out the crud and then put the GO (GL1) back in...

Ace is right. Had issues with our truck, so filled TC with fuel oil and ATF. Drove around the block a few times, cycled the shifter between neutral and reverse 50 times and drained out the mud. Installed new 85-90 gear oil, and no problems.

Remember, the TC is in forward sprag when transmission is in neutral or any of the forward gears (so don't roll backwards in 1st or neutral) and only goes to neutral when there is no air to the shifter valves on top of the transmission.

Thanks ace and m139 i will give it a try. How do i find out if the air switch
on the tranny is workin right?

BMS07 said:

Thanks ace and m139 i will give it a try. How do i find out if the air switch
on the tranny is workin right?

Click to expand...

If you hear "ka-thunk" when shifting into reverse, its working.

I love learning all the technical terms!!!!thanks David!!... Randy

Thanks DDoyle for the info.

"Ka chunk" is just about right varies a little based on 80 or 120 psi.. Drain air tanks daily..

ok so what happens if i t in to the main supply line cap the to lines coming out of the to of the switch going back to the t-case, and from the t i run a line up to a two way air switch on the dash then take both the new lines coming out of the air switch on the dash down to the t-case? will the trans still go in to nuetal? and then will i be able to contral the in and out on the front axle line the 2.5 tons?

This will work as long as you don't have the dash switch in forward while going in reverse and the other way around, and

yes if the air switch has a position that cuts the air off to both sides, will put the sprag in neutral, this is used for towing (reason for the MWO), will NOT act like a 2 1/2 in or out front drive because the sprags will still work as on demand front wheel drive (conditions demanding. not driver) if air goes to the xcase

ALSO, if spinning the rears with the air cut off putting the sprags in netral, SOMETHING will go BANG and most likely BREAK if the air is turned on, engageing the front drive. The sprags are designed for a very little over run to cause engagement.

P.M. sent to 73m819
O.k. I'm lost.

Ok so I have run into the same issue with my M-61. I have front axle engagement in reverse. I have the air "kinch" when I shift into reverse but not into any other gear. It does do it when I go from reverse to neutral. I pulled a tree down a few weeks ago in reverse and the front end was locked and digging. Then we had a good bit of snow and I tried moving around it wouldn't go anywhere. Even with 3,260lbs bolted over the rear axles of concrete in a steel mold. I got it chained up on the rear axle alone and I was able to move a little bit around but nothing like i can in reverse. Should i do the flushing it out deal? or just go right to tearing into it and think its something more? I have never noticed the "ka chunk" when going into reverse or forward since I owned it. It is also hard to find someone around here that is willing to work on this thing.

Anyone have a copy of the sprag air cutoff MWO manual?

sigo said:

Anyone have a copy of the sprag air cutoff MWO manual?

Click to expand...

all it is is run the trans valves air feed line though a deuce air shift switch instead straight to the valves, this allows the cut off of the air to the trans valves, and the quick dump of the air in the transfer shift cylinder, with NO air going to the transfer case, the sprag stays in neutral, trust me you can get stuck with the sprag air OFF
any more questions, drop me a line, or a number

I have never seen the mwo in person, saw it YEARS ago in MVmag, it seems that it was put out military wide, BUT it was a unit by unit if it was implemented or not, some did, some did not

What does MWO stand for? My son's 5 ton M51 has a little triangular tag attached to the driver's door opening that says "MWO applied" and a number below the text.

Maintenance Work Order (a upgrade or change that the military thinks need to be done), every MWO has a number, not sure what MWO that number applies to

I had a feeling that was what it meant. So somewhere in the vast military land there must be a list showing what number meant what.

Close... it's Modification Work Order. What's the number and date on the tag?

When you go from reverse to forward do u hear the air leaking out the poppett valve/ trans? It should still go into forward sprag with and air leak. I would rebuild the air cylinder on the transfer case.
I know the air switch conversion but I just can't figure out how the piston is going to stop in the middle. Seems like without air it would be in the last pisition when shut down. Don't want to disagree but I think I will allways stay with rebuilding the air cylinder/ poppetts. If you do just the cylinder do make shure u tighten all 8 of the bolts holding the poppetts on the trans and together. Everyone I check has been loose. Also to add if you hear/feel air comming out the transfer case breather then you have a bad shaft seal so if you do the sprag cyl. you should do the shaft seal.