M809 series t case sprag replacement

[Trango]

Hi Folks,

Does anyone know if there is (even the concept) of a permanent sprag replacement for the M809 transfer cases? Or, are there any pics out there that detail what the sprag looks like?

I'd love to see if there's a hardpart that could replace the sprag in function, but not have the same modes of failure.

Best,
Bob

 

[KsM715]

There's a few threads floating around that discuss welding the sprag but I have yet to find any definitive "how to" on how to do it.
You can also put a valve in the main airline going into the trans. to basically disable the sprag. So you could weld it and go full time 6x6 or put in the air valve and have a "part time" case.

Try reading thru these threads see if they help you out any.

http://www.steelsoldiers.com/5-ton-up/41459-sprag-gear-transfercase-question.html

http://www.steelsoldiers.com/5-ton-up/47520-i-need-some-help.html

 

[Trango]

This is what I was looking for. Many, many thanks!

 

[Floridianson]

Guess I'm lucky mine has a air shift just like the Deuce transfer. Just puts in engagement when in reverse or first high or low range. Was thinking about a an air switch on the dash and remove the one from the trany. Then again first high range in a 5 ton might be all the faster you want to go in the nasty stuff.

 

[bbf]

my went out and i just replace the t case did not want to go threw trying to fix the t case and then put it back in to find i still did not work

 

[militarysteel]

yeah the sprag is just a totally bad idea, they should have just went with air engagment from the start. full time all wheel drive is not needed, you only need the front end when you need it, other wise the wear and tear plus worse millage then what you are already getting. not a fan of the 5ton.

 

[BKubu]

Guess I'm lucky mine has a air shift just like the Deuce transfer. Just puts in engagement when in reverse or first high or low range. Was thinking about a an air switch on the dash and remove the one from the trany. Then again first high range in a 5 ton might be all the faster you want to go in the nasty stuff.

James, either you have something that I have never ever heard of in an M809, I misunderstood your post, you did not describe what you have well, or you are wrong. I have never heard of an airshift in an M809 series truck. John Winslow, Jeff Symanski and others have installed an airshift lever, but that just disables the sprag as stated above. With that set up, you flip the switch when you want to put things back to stock (rear wheels slip, front wheels pull). If you are referring to the air sound when you shift to first or reverse, the sprag is not engaging at that point, it is just switching from forward to reverse engagement (but nothing is engaged yet). As I said, perhaps I am not clear on what you were saying. Can you clarify, please?

 

[jasonjc]

Keep in mind that in the 5 ton or 2 1/2 ton sprag t-cases the front and rear out puts DO NOT HAVE THE SAME GREARS. You can not "make" it full time. Unless you put new grears in the case.

 

[Trango]

Jason,

Do you know if there are gears available to make the 5 ton M809 case a full time case? I understand that the front is overdriven by about 7% - are there gearsets readily available to eliminate that overdrive?

Best,
Bob

 

[BEASTMASTER]

why does anyone buy one of these trucks if the first thing they want to do is change it???????????

" IF IT AIN'T BROKE DON'T FIX IT "

 

[BKubu]

BEASTMASTER, I have often thought the same thing. The conclusion I came to is a lot of guys are not really military vehicle enthusiasts. Instead, they are big truck or off-roading enthusiasts. There is a difference. Sure, there is overlap, but there is a difference. For this reason, those guys who simply like the trucks because they are fairly cheap, big and tough don't care about modifying the trucks. They don't care what was correct in the military. As this site has grown, it has swayed in that direction. The old mil-veh list included very few guys interested in modifying their trucks. Over there, you had guys who were into restoring or fixing their trucks up to motor pool standards. I am not saying one is better than the other for the guys on this list. That is up to them. I know which way I lean and I will continue to pursue my goals. I skim this site and only really read the threads that pertain to my interests. I am not saying that guys should not bob or otherwise modify their trucks. Do what you want. You paid the price of admission.

 

[cundupa]

why does anyone buy one of these trucks if the first thing they want to do is change it???????????

" IF IT AIN'T BROKE DON'T FIX IT "

Because they don't understand how they work.

 

[Trango]

BEASTMASTER, I have often thought the same thing. The conclusion I came to is a lot of guys are not really military vehicle enthusiasts. Instead, they are big truck or off-roading enthusiasts. There is a difference. Sure, there is overlap, but there is a difference. For this reason, those guys who simply like the trucks because they are fairly cheap, big and tough don't care about modifying the trucks. They don't care what was correct in the military. As this site has grown, it has swayed in that direction. The old mil-veh list included very few guys interested in modifying their trucks. Over there, you had guys who were into restoring or fixing their trucks up to motor pool standards. I am not saying one is better than the other for the guys on this list. That is up to them. I know which way I lean and I will continue to pursue my goals. I skim this site and only really read the threads that pertain to my interests. I am not saying that guys should not bob or otherwise modify their trucks. Do what you want. You paid the price of admission.

Thanks for the post - I couldn't have said this better myself; although, of course, I will append some details .

From what I've learned via hard trial and error, military drivetrains are incredibly performant for the cost, and offer tremendous functionality compared to any other available axle / transfer case capability, along with excellent spare parts availability and documentation. It's not so much that I'm buying mil trucks and parts wishing they were something else - I'm buying them because they are such amazing value.

Don't get me wrong - I respect vintage- or application-specific restoration.
I got into the military truck game knowing my interest lies elsewhere. To pull a metaphor from modern classic vehicle restoration, I consider both my deuce as well as this next build to have what is essentially a medium-duty-truck version of the "pro tour" ethos - think of it as a base of classic sheetmetal, modified via unique bodywork and the transplantation of modern underpinnings.

I see parallels between my mentality and that which led to the addition of your air cut-off switch... both involve the addition or modification of items that help performance or increase vehicle satisfaction. Obviously, I'm taking it to another level. It's not everyone's cup of tea, but it suits me just fine.

But, I really do I hope my attitude is acceptable to this group. I was once part of the old mil veh list, and I definitely realized that this mentality wasn't germane to that community. That's totally ok - I will only want to be a part of a group if I can both be appreciated and also give back as possible. As an aside, I see the harebrained and truly poorly thought out ideas that now permeate the deuce modification forum, and I inwardly sigh.

Thanks for all the assistance with this sprag question. I'd really like to use the M809 case I already have for this next build, so I really value the information and assistance.

V/R,
Bob

 

[Trango]

Because they don't understand how they work.

For my own sake, I hope that my past experience rebuilding manual trannies (including the Spicer-supplied 5 ton 6855), Auto trannies, motorcycle gearboxes, passenger car awd boxes, detroit lockers, mack-style double reduction axles, arb air lockers, truetracs, Posi-tracks, Gov-Locks, light duty transfer cases, and setting up hypoid gears themselves can prepare me for the complicated mechanical test presented by the M809 transfer case.

Hey, with full humility, I'm no mechanical genius. I'm just looking for the best advice on dealing with the sprag. I want to build another bulletproof truck that I can drive around in terrible conditions without fear of failure. I think alot of people understand the weak link and why it may be desirable to eliminate.

Best,
Bob

 

[emr]

yeah the sprag is just a totally bad idea, they should have just went with air engagment from the start. full time all wheel drive is not needed, you only need the front end when you need it, other wise the wear and tear plus worse millage then what you are already getting. not a fan of the 5ton.

Are U saying they are full time because they have a sprag? they do not, U are also not correct about the sprag in the 5 ton, they are robust and work, the deuce sprags worked well also, but were not as long wearing as the 5 tons, the upgrade to the deuce was needed , there was no upgrade ever needed to the 5 tons, they work fine, these are facks, just an fyi....Randy

 

[emr]

Bob, I am really not sure the weak link is the sprag, It usually is the driver..LOL....but I understand the want for an air shift, but have to say i have alot of time with my 809 series, and it works very well, U are probably going to do more than me though, good luck, if there was an easy mod, I may still not do it, My sprag in one of my deuces worked so well for 10 years and 40,000 miles i have a ton of mud time for years ...and towing other vehicles for a weekend in some of the best mud ever,'Aberdeen past""" and some were heavy i mean heavy trucks, It was flawless and sooooo smooth, i also love the sprag in my 5 ton too, just sayin, an fyi, from having some time with it....Randy

 

[BKubu]

Bob, I like to think, and I am sure others will agree, that you are more than welcome here. I don't think guys like me or guys who mod there trucks are any more or less welcome to post and contribute to this site. I can appreciate the work put into re-engineering a truck or part. I have watched in admiration for the work that Bjorn, for example, has done. The same goes to John Tennis for the work he has put into everything that he does.

 

[D'cheat]

why does anyone buy one of these trucks if the first thing they want to do is change it???????????

" IF IT AIN'T BROKE DON'T FIX IT "

Thats like asking, "Why buy a jeep if the first thing your going to do is swap in stronger axles and a lift kit?"

You would hate me. Heck, I swapped in a 351W and unimog 406 axles into a bronco II.

Everything can be improved. If you buy a truck that you have always wanted, but find that you want a better performance, would you buy a new truck? No, you would tune your truck to run better.

Sorry, off topic here... Back to being on topic!
If worse comes to worse, find a newer model semi truck transfer case. They are all divorced cases. Most are manual or air actuated. Fabricate a new x-member, mount it up and have your drive shafts cut to fit. Problem solved. There are even locking hub assemblies out there for a 5-ton front end.
Best of luck to you!

 

[cundupa]

Bob, I see by the list of items you have rebuilt my smart a$$ remark does not apply to you! I just got a 5ton dump truck last fall and knew nothing about how the front axle engaged. I plan on using the truck in my excavating business, so I read everything I could find on the sprag system and how it worked. I even took things apart and cleaned and tested. I'm not an expert, but now I know whats going on in there and why. Now when I read about people that want to add a switch so the front axle stays engaged in all the forward gears...that's where my remark came from.
I used the truck yesterday on a wet site and the front end worked just like it should, engaged when spinning, out of gear on the hard road. I even had my 15 year old son driving it with no problem.

 

[Floridianson]

James, either you have something that I have never ever heard of in an M809, I misunderstood your post, you did not describe what you have well, or you are wrong. I have never heard of an airshift in an M809 series truck. John Winslow, Jeff Symanski and others have installed an airshift lever, but that just disables the sprag as stated above. With that set up, you flip the switch when you want to put things back to stock (rear wheels slip, front wheels pull). If you are referring to the air sound when you shift to first or reverse, the sprag is not engaging at that point, it is just switching from forward to reverse engagement (but nothing is engaged yet). As I said, perhaps I am not clear on what you were saying. Can you clarify, please?

Yea thanks Just changed out the trans and saw the outher air line in back of the air cyl so yes sprag for me. Guess i should read the TM's before I get the tools out.