5 ton doing donuts, question about sprage transfer case

[davesgmc]

Well, after watching the video of the deuce doing donuts in the snow the other day, i just had to do it myself in my bridge truck. I have the 16x20 tires on it singled out so i wasn't sure that it would even spin the tires in the snow. it snowed about 4-6 inches of real powdery snow last night and it was slick as snot this morning. took me a hour to make a drive that normally only takes me 20 minutes. I went out and started the 5 ton up this morning,,,and wow, it cranked right up on the first try! i let it warm up, blew some snow off it, aired up the tires, and proceeded to drive it around in the snow. first thing i did was put it in 2nd and dump the clutch. WOW! those xzl tires can throw some snow! The Detroit engine spooled up would certainly spin those tires, through second, 3rd and fourth gear. and no, no one wanted to stay behind me on the street, snow was flying everywhere! I went to the bank to make a deposit and get some spending money for the weekend, then went to a vacant parking lot with lots of room, stopped an put it in second, dumped the clutch, turned the wheel and started doing donuts!! They were more like long johns! took lots of room to spin the extra long wheel base truck weighing 20,000 plus, but once it did it was FUN!


OK, the technical part......

the sprag in my transfer case.......???? i didn't ever notice that the front tires were ever spinning in the snow,,not in any gear above 1st. it did seem they would in first, but not if taking off in second. is this right? do i have a problem with my transfer case and its not going into full lock once the rear wheels are spinning? or does it only lock in in first gear?

kinda confused,. i know it works, i moved the truck around this past summer with the rear drive shaft completely out, just moved it out of the driveway and parked it, thats it.

sorry guys no cool video or pics, i was having TOO MUCH FUN doing donuts to have someone video it!

 

[Chevytruck]

I was told the sprague engages in first and reverse only.

or the sprag could be worn out?

 

[Nonotagain]

My concern with doing "Donuts" is breaking an axle.

I've seen a lot of oil delivery trucks getting onto side streets for deliveries in snowy conditions only to snap an axle when the spinning wheels finally got traction with the now uncovered pavement.

 

[bulldog_mack13]

Hopefully someone ansewers that

 

[BKubu]

I am not sure, but I could have sworn that Winslow told me that the 5 ton sprag works in all gears while the deuce sprag only works in first and reverse. My memory is a bit foggy on that but this is what I recollect.

 

[hvann]

The below info is from a previous post where I was testing my transfer case. All I can attest too is that my transfer case has the forward axel engaged at all times no matter what gear when there is air on the system. When in reverse the sprag is in the reverse position and when in any other gear including neutral the sprag is in the forward position. With no air the front end is not engaged.
Van

I have an 818 that is MO with my brother and he said the front wheels were not engaging in either forward or reverse. I have an 813 here in VA with me and I wanted to know if the front wheels would engage. I have just recently purchased both trucks. I don’t have tags on the 813 yet so I needed a way to test the functionality of the t-case without driving it somewhere.
I have been researching ways of testing the T-case on the site here and a lot of people talk about jacking up the wheel and checking that way but I was afraid that there may be enough resistance to keep me from turning the wheel but not enough resistance or engagement of the sprag to drive the truck forward. So I came up with the following way of testing the sprag for popper operation.
On my 813 I disconnected the drive shaft from the rear end and kept it in a rope sling so it could turn a little without causing any damage to it or anything else. (See the images) I wanted the shaft to rotate freely on the rope so it would not try to climb it or try to wrap in it, so I put some grease around the shaft where the rope would be in contact with it. I fired up the truck and put it in first and started easing out on the clutch. I could hear the clutch start to engage and almost immediately I heard the sprag engage and the truck started to move forward. I repeated the experiment in reverse and the front wheels would drive the truck backwards. There was an added benefit in adding the grease on the shaft. I could tell that the rear drive shaft only turned about a quarter turn in either direction before the front engaged.
I almost started putting the drive shaft back on when I started thinking about the questions about a neutral position on the T-case so I thought I would do some more experimentation.
I insured that I had air pressure and shut the truck off. I used a 2X4 between the clutch and the steering wheel to keep the clutch depressed. By depressing the clutch I was insuring the engine would not be keeping the drive shaft from turning.
When I talk about clock wise or counter clock wise you should envision looking from the rear of the truck to the front. So with the drive shaft disconnected from the rear end I was looking at the disconnected end of the shaft.
Here are my findings.
Air on system transmission in reverse, drive shaft will turn CCW but not CW
Air on system transmission in forward, drive shaft will turn CW but not CCW
Air on system transmission in neutral, drive shaft will turn CW but not CCW
No air on system, transmission in any position, the drive shaft will turn both CW and CCW
So this tells me that there is a neutral position on the T-case only when there is no air to it. So needless to say I will be putting the air selector valve in the cab so I can control air to the T-case.
I hope this makes sense and helps with the sprag T-case questions.
Van

 

[bevanet]

hvann, Did you test any other forward gears besides first? There seemed to be some question about the front wheels engaging in first but not the other forward gears. Did you also test with the transfer case in low and high range? If anyone else knows these answers it would be nice to have them here.

 

[spicergear]

Did you put a Detroit in that?

 

[davesgmc]

Ya, it has a 6-71 in it

 

[bambambam22]

DavesGMC,
Can you tell me what the tires are you have on the 5 ton that are awesome and I want to see if I can find some that I can afford
Thank you
Rick

 

[Squirt-Truck]

The front drive......sprag....The M-39 and M-800's use the same set-up. THe air selector is on the first/reverse shift rail. Front axle is under sprag engagement for reverse when transmission is in reverse. The sprag shifts to forward went the shift rail moves to netural. So....the drive is in forward for ALL forward gears and netural all the time (except reverse).
Transfer selection does not affect sprag operations.
Removal (or loss) of air does put the sprag in netural, but netural is NOT available in ANY transmission position. A front axle disconnect like the M-35 uses (with air shift) will give you a netural for the front axle drive.

 

[davesgmc]

DavesGMC,
Can you tell me what the tires are you have on the 5 ton that are awesome and I want to see if I can find some that I can afford
Thank you
Rick

they are michelin 16.00x20 xzl tires

 

[OPCOM]

So, what this means very simply is that to freewheel the front drive shaft from the transfer, remove the air from the transmission.

Then the transfer will not spin the front drive shaft.

The front drive shaft will be driven by the front axle.

Assuming lockout hubs were available, then the front axle and driveshaft could be completely shut down.

Nice. I have never seen a lockout hub for a 5 ton.

 

[SuperJoe]

is there a lock out for the 5 ton?