M54a2 front axle engagement

[Slim]

Can anybody tell me how the front axle engagement would take place in a M54a2 with the multifuel engine? I was told by the last owner(jackass) that it did not work properly and they jammed something in there to keep the front axle locked.

Also, I assume the lever on the floor in the center of the cab is the transfer case shifter? Is it just engaged or disengaged, or is there a low range -high range selection?

Hoping to have this truck running tomorrow, and this is my next project. The previous owner said when he drove the truck with the axle locked like this it seemed like it was under extra heavy load(had to shift extra fast between gears).
Is this normal with the front axle engaged?

Thanks

 

[area52]

Have you looked at and read the TM's? Or searched on here? This has been covered quite a few times.

The transfer case is a sprague (sp?) type which means the rear wheels have to spin slightly faster (slip) in order for the clutch in the TC to engage the front drive shaft. The lever is only for high or low range. There are air valves on the transmission to "tell" the transfer case which direction you are going, other wise the case will bind up and bad things will happen.

 

[Squirt-Truck]

Area52 is correct, it is important to review the TM's. This topic has been covered and continues to be mis-understood.

Summary, the lever you are refering to has three positions, low, netural, and high. None of these settings has any influence on the front axle engagement. (Do not operate the engine with the transmission in gear and the transfer in netural, it will kill the bearings, again, refer to the -10 TM.) The trasfer case has a sprag system for front axle engagement. Actually it has two, lne for forward and one for reverse. An air cylinder shifts between them according to the air signal from the shift rail switch on the transmission. Reverse on the transmission uses the reverse sprag, netural and ALL forward gears us the forward sprag. Low or high range makes NO difference. If working properly, the rear tires will have to slip 6% to make the front axle engage (about one cleat on the NDCC). THe tront axle will remain egaged till the front axle propeller shaft equals or exceeds the speed of the rear axle propeller shaft.

Now....if there is no air on the transfer cylinder then the front axle goes into netural. There is NO stock operation that ever places the sprag into netural.

If they have placed air full time on the forward position of the transfer then you have front drive avaiable all the time, unfortuunately...backing up or even rolling backward will wind-up the system and can damage the sprag or worse. If they have full time air on the reverse position, the truck will be a BEAR to drive , and again can (will) wind up and can damage something. Does it feel like the brakes are dragging??? THis should be very apparent on hard surfaces, but much less so on dirt.

A quick test, with full air, shift the truck from first to reverse, there should be a hiss and the sound of metal shifting each time the shifter is moved, if not you have part of your problem already identified.

Hope this helps.

 

[rizzo]

Area52(Do not operate the engine with the transmission in gear and the transfer in netural, it will kill the bearings, again, refer to the -10 TM.)

how would you operate a t-case PTO? all the wreckers have them.

 

[Slim]

Area 52- I'm having trouble opening the TM's right now, been trying to access them for days. I have searched the forums for info on this with no luck in finding out what I'm looking for.

Squirt-truck- Thanks for the explanation, it makes good sense to me now. It sounds as though. It sounds like they have full time air going to one of the positions, I believe he said they used a hose clamp to achieve this.

I got the truck in non running condition and hope to have it running in the next day or two. this will be my next obstacle to tackle.

Thanks for your help.

 

[Squirt-Truck]

Rizzo,
The trucks with transfer case PTO's have an oil pump that circulates the lube when the T-PTO is operational.

I was wondering if someone was going to ask that........

 

[rizzo]

Rizzo,
The trucks with transfer case PTO's have an oil pump that circulates the lube when the T-PTO is operational.

I was wondering if someone was going to ask that........

right, that is why they have the oil tube on the outside right? I remember that on the 2.5 ton I had. bought it in a bucket and sold it in the same bucket, never used it.

 

[rizzo]

Area 52- I'm having trouble opening the TM's right now, been trying to access them for days. I have searched the forums for info on this with no luck in finding out what I'm looking for.

Squirt-truck- Thanks for the explanation, it makes good sense to me now. It sounds as though. It sounds like they have full time air going to one of the positions, I believe he said they used a hose clamp to achieve this.

I got the truck in non running condition and hope to have it running in the next day or two. this will be my next obstacle to tackle.

Thanks for your help.

try right clicking on the link and selecting "save as" or "open in new window"

 

[rizzo]

Rizzo,
The trucks with transfer case PTO's have an oil pump that circulates the lube when the T-PTO is operational.

I was wondering if someone was going to ask that........

I was just thinking too that the winch instructions always say to drive the truck while winching and NOT to use the winch only.

now I know why.

 

[fasttruck]

Reference above: As front winch drives off truck transmission, not transfer, it can be used anytime with or without the wheels assisting. Salient point is that with winch in low, transfer in low and trans in 1st gear cable and wheels move at same speed.