Shift lever for the sprag

[kurtkds]

I think the air shift transfer case in an M800 series is solid as it. The shift mechanism from forward to reverse is a very simple well thought out design. To see if it works, start truck, build air, shut truck down, move shifter from any forward gear to reverse. You should notice a nice pffft of air and a nice solid clunk. If you're not hearing both, you have some work on your hands. With the M818 in my yard, I oiled the "sprag shifter" via the airlines and still have a problem. I took the transmission tunnel sheet metal off and noticed somebody had plugged the vent line on the transmission poppet valves. Removed the bolt, Transfer Case pffting and clunking as it should and no further issues with this truck.

I've asked this question before but.. When shifting from neutral to Reverse I can hear the cylinder clunk and the puff of air. Shifting from reverse to neutral same thing. This sounds normal, now when shifting from neutral to forward I hear nothing, same with going from First to Neutral, nothing. I have heard that the forward sprag could be disabled to prevent the truck from getting "really stuck" and reverse was left alone so that the truck could be backed out..

Any truth to this?

 

[73m819]

If you have air, there is NO neutral, REVERSE puts the tcase into REVERSE, taking the trans OUT OF REVERSE puts the sprag into forward,

 

[ReoRider]

Actually, back in the day, Memphis Equipment had available a manual control to correct the problems with the early non-air assisted sprag units. They would not engage the front axle drive until you were slipping the rears a little and thus about to be stuck. It was called the REB sure shift and was available for the 2 1/2 and maybe(?) for the 5 ton as well. The air assist system, when it came into production, gave the needed positive engagement of the front axle and conventiently, when equipped with a shut-off, provided a neutral for the system when the air was cut off. This allowed for installing front free wheeling hubs as I did on my early M52 for highway use.

 

[73m819]

Actually, back in the day, Memphis Equipment had available a manual control to correct the problems with the early non-air assisted sprag units. They would not engage the front axle drive until you were slipping the rears a little and thus about to be stuck. It was called the REB sure shift and was available for the 2 1/2 and maybe(?) for the 5 ton as well. The air assist system, when it came into production, gave the needed positive engagement of the front axle and conventiently, when equipped with a shut-off, provided a neutral for the system when the air was cut off. This allowed for installing front free wheeling hubs as I did on my early M52 for highway use.

A part of this kit took away the over running clutches (8% over run) and made it 1 to 1 with the direct drive, by LOCKING in the 8% over run full time, you WILL BREAK something, it will be like running a different size of tires on the front and the rear of a 4x4

 

[seano11]

So the kit would take away the 8%?

 

[73m819]

so the kit would take away the 8%?

yes,

 

[seano11]

Hmmm wonder if they still have this

 

[cx65083]

I'd be interested in that kit myself...still dont have my 6x6 working right. Grrrrr.

 

[wdbtchr]

Memphis stopped making this years ago and I think it was only for the deuce and a half.

 

[BARROWCANYON]

I have a bobbed 5 ton that does not engage the front axle in forward gear. So, is there a way to permanently lock it up for permanent 4X4? This truck will only be an off-road vehicle up here in the Arctic, we plan to use it in the oil fields. Is there another T-Case that will work in place of the one in there now?

 

[BARROWCANYON]

Or are there spring upgrades that will ensure that when my rear wheels slip that the front axles get engaged?