Frustrating 809-series sprag!

[73m819]

it was on the truck when i got it, i could not tell any difference on the road, though off road is another story, in realitly this mod was done in the military to keep the front wheeles from turning with a front end lift recovery i would guess in case of front end damange ect. i would think it would work with eather forward or rear lift tow. this is the only reason im going to leave mine hooked up

 

[jwaller]

the answer is yes, and i can say without a doubt you can get stuck if you have the air cut off which means forget to check the flip valve

just as a side note , the flip valve is a old mwo from m54 series days, though not many have it, it seems that it was done only here and there, the idea was that when lift towing, the front wheels would not turn

So, you did this mod? How did it work for you? My trucks are on road 90% of the time and this would be a great addition to them. Overall, would you recommend it?

yes his truck has this mod. and I'm going to do it to the 818 next tim eI get a chance to see it and how it's done. I cant find the MWO so I'll have to use his truck as a blueprint.

 

[73m819]

the air supply line to the trans air valves is cut, then air line to the flip valve, that back to the supply line, you could do the cut anywhere but i would do it under the trans cover floor panel, this will give a lot of room to work

 

[AMGeneral]

Chris,

I just finished rebuilding the air actuator cylinder on the M62 t-case,not a hard job at all.
Basically just pull the 4 bolts holding the air cylinder on,there are 2 copper washers sealing the ends of the cylinder to the t-case and end cap.There are 2 cup shaped seals on the piston and 1 on the sprag shifter shaft,that's it.Just clean,replace parts,lubricate and re-assemble.

Hope this helps

 

[steelsoldiers]

Thanks Brandon. I pulled the 4 bolts off of it and removed the end cap. I couldn't get the cylinder off because the front output shaft flange was in the way. Did you remove the front case to get to the sprag shifter shaft? Where did you buy the seals for it?

 

[AMGeneral]

Whoops,forgot to mention you have to pull the front flange,but the seal for the sprag shaft is on the outside,not the inside.

I ordered my stiff from Memphis Equip,it got here in 2 days!!

 

[steelsoldiers]

Well, I got my parts kit from Memphis and installed it last Sunday. I am happy to say that my sprag seems to be functioning normally again. No more drive-line wind-up or banging and lurching in the forward gears. Woop-woop!

 

[acetomatoco]

The sprags themselves get lazy and remember that they are in fact operated by an overrunning clutch so that the rears have to be spinning to get the fronts engaged...All you are doing by shifting the main tranny is telling the sprag which way you are going. (That is why it is taboo to roll backwards when you are in a forward gear!!) The air pressure on the 5 ton and the linkage on the deuce are just changing the direction in which the sprag will engage the front axle if the overrunning clutch tells it too....Those clutches get lazy and you can run diesel fuel in the xfer instead of oil for 50 miles or so to free em up, or use atf or kerosene... drain and refill with the gear oil when you are done. The air shift deuce case is a different story, it is a real shift in or out for the front drive, at the same ratio as the rear so you do not get so much driveline windup as on the other ones which drive the wheels at different speeds until the friction loss on the ground releases the windup. Do not jack up the truck with the drive line wound up or you will be in for a big surprise, especially if you left a lug wrench on one of the wheel nuts. The sprag system probably needs a sticky up top here and all the other posts on the subject merged into it as it is about as much of a mystery as the charging system on the M1010. Be careful.

 

[acetomatoco]

Yes, you have all wheel drive in both high and low range and for reverse and all forward speeds if the sprag setup is working correctly, and with the air shift deuce, too.

 

[jatonka]

5 ton sprag transfer case

I was talking to Memphis Equip Service man the other day and he told me every 5 ton that gets sold by them gets the dash mounted air cut off switch to kill the ait to the transfer case actuating cylinder and that puts the transfer case in a no front drive condition. I have a transfer apart in my garage right now and for the life of me I can't feel a neutral in the sprag between reverse and forward but it is there. The reason I had to take it apart was because it falls out of high range. Anyone have a 5 ton transfer for sale in the North East? One that worked good. John Tennis

 

[m139h2otruck]

John, our 5 ton Mack powered tractor has the same problem, you can't pull it up into high and have it stay there. The last owner(?) drilled a hole in the shift lever and had a rope rigged up to hold it. Any idea why it won't stay? Looked at the book, but can't seem to see what would prevent the shifter from moving into high and locking. Even took the detent ball and spring out and looked into the hole to see if the shifter was messed up.

 

[jatonka]

5 ton transfer

Hi M139H20, well, in my case the shift fork and the shift collar that set it in high range are both worn and don't move the gears all the way into position, so they walk apart as you drive. I need to get both pieces built up and re machined. If it works, I have another transfer that does the same thing and I will be able to fix that one too. Most likely it is your problem too. I thought the shift fork might have slid on the shaft but that wasn't the problem at all. John T

 

[98hd]

Re: 5 ton transfer

Hi M139H20, well, in my case the shift fork and the shift collar that set it in high range are both worn and don't move the gears all the way into position, so they walk apart as you drive. I need to get both pieces built up and re machined. If it works, I have another transfer that does the same thing and I will be able to fix that one too. Most likely it is your problem too. I thought the shift fork might have slid on the shaft but that wasn't the problem at all. John T

I'm having the same problem w/ my M818. I was talking to a guy that thinks it's because the lever is in a bad spot and hits the seat, not putting it completely into high range. After being like this for awhile it gets worn.

I need to either get a new one, or find a way to fix mine.

 

[msgjd]

Have been a mechanic and driver of 5-tons for many many years. Yes, when properly working, the front axle will kick for AWD regardless of what gear or range you are in. The air valve is supposed to shift the sprag into forward operation the second you pull the shifter out of reverse into neutral.

 

[GIJoeCzar]

M818 Sprag

AMGeneral and steelsoldiers,

OK, I finally took my sprag apart today; pictures are at:

http://czarnik.net/joe/My_Stuff/Mil...9 M923 M925/Truck Repair Progress/M818 Sprag/

I found the two copper washers and the two large cupped seals, but I can't find the other seal that you were talking about - where is that seal?

Did both of you take the locking nut off of the sprag and actually remove the sprag assembly from the transfer case? I've got the four long bolts off and the case off, but not sure if I'm actually supposed to remove the nut that holds the sprag assembly onto the transfer case (lase picture in series).

Also, what did Memphis charge for this kit??? Can you find these parts elsewhere?

Thanks much!

GIJoeCZAR

 

[73m819]

RE: M818 Sprag

that looks like the air piston assembly that is used to shift the sprag into reverse, that is not the sprag clutch

 

[steelsoldiers]

RE: M818 Sprag

The other seal is the shaft seal. It is behind the piston. The nut holds the piston to the shaft. I couldn't get my piston off so the seal didn't get replaced. My problem was the 2 piston seals were dried out and loose. I can't remember what the price was from Memphis. I think it was around $40 shipped.

 

[steelsoldiers]

Here's the blow up from the parts manual:

The copper spacers are #17

The piston seals are #22

The rubber shaft seal is #30

 

[GIJoeCzar]

M809 Sprag

73m819 - Roger, I meant to say "sprag actuator".

steelsoldiers - Thanks very much for your feedback and help. I'll let you know how it turns out.

Joe

 

[GIJoeCzar]

M809 Sprag

Gentlemen,

I tried getting the locking nut off that holds the sprag actuator cylinder, but couldn't get a socket on it. Can you tell me what size that nut is (1/2", 9/16", etc.). As you know you can't get line of sight on the nut when the cylinder is installed.

Thanks much,

Joe