t-case question

[k5ontherocks]

where can i get some diagrams of the t136 tcase?
some exploded views,im new to this and have been searching forever and cant find what i want.
ive got a few questions that are probably too basic, i just need to read.
are there any exploded assembly views of these cases?
i am wondering about the sprag shifters.
i am also wondering what the threaded fitting on the front of my case near the front output is for....maybe speedo cable?
also wondering about the shift shaft coming from the same area...is it for 2x4 and 4x4
or fwd and reverse??
thanks in advance for any help and advice guys.
andy

 

[Barrman]

The TM9-2320-209 -20 manual in the TM section should have detailed correct explanation for all your questions. The -20P or -34P will both have exploded views.

 

[gimpyrobb]

The shift lever is for hi/low. The sprage you want to weld is for 4x6/6x6.

 

[m-35tom]

with a sprage case won't the front drive shaft turn slower than the rear even with the thing welded up. get an air shift case instead.

 

[k5ontherocks]

thanks for the ref to the tm...worked

so is the sprag case full time 4x4 and the air shift is selectable?
if so then what is the short shaft sticking out of the front lower cover on my case,is it just a spot for the upper linkage to bolt to??

i was understanding that welding the sprag would make the front and the rears turn at the same speed???

sorry for not understanding this all.
i have searched and read tons on here,just cant find exactly what i want.

if i do need an airshift case,anyone wanna trade???

 

[m-35tom]

sprag is linkage selectable and rear has to slip before front will pull. front shaft turns slower. air is, well, air selectable and both shafts turn same speed. throw sprag away and get air shift.

 

[Barrman]

One of the shafts out of the front is your range HI-Lo selector. The other tells the overrunning clutch which direction the truck is going.

The "automatic" front axle engagement is really pretty simple to think about. The front axle drive shaft is connected to gears inside the t-case. So is the rear axles drive shaft. Those gears are different sized with the front ones smaller. So, the front gears inside the t-case are spinning faster than those for the rear. When the rear axles loose traction, the rear drive shaft spins faster than normal. Once the rear shaft is spinning the same speed as the front one, the "automatic" parts comes into play and engages the front drive shaft. This gives you 6 wheel drive as long as the t-cases "senses" that the rear one is going as fast as the front shaft.

That is how it is supposed to work on a properly adjusted t-case. Mine works this way very well. But, what a lot of people have happen is the truck will basically stop with the rear axles bouncing/spinning, the front engages, the truck lurches forward a foot or so, the front dis engages, the rears start bouncing/spinning again, etc...

The air shift t-case leaves it up to the driver when to engage the front axle

 

[k5ontherocks]

ok,im getting this i think.lol

first,if using the sprag case,do i need to hook up a shifter to the lower rail or just leave it in forward all the time??

second,what would be involved in converting my sprag case to airshift,or should i just look for an airshift case?

if i need an airshift case,is my nice condition sprag case worth anything??

i really appreciate all the info from you guys,i am a service manager at a chevrolet dealer if i could help repay any favors,just ask.i would do what i could to help.

 

[gimpyrobb]

I forgot about changing the sprag direction! Yup, just get an air shift.

 

[Barrman]

Where abouts in Indiana? No problem on the questions.

An air shift would probably do you better either in an M35 or any other big truck. Just remember this. The t-case for a M35 is about the same size and weight as a SBC engine. They won't fit just anywhere.

 

[m-35tom]

The "automatic" front axle engagement is really pretty simple to think about. The front axle drive shaft is connected to gears inside the t-case. So is the rear axles drive shaft. Those gears are different sized with the front ones smaller. So, the front gears inside the t-case are spinning faster than those for the rear. When the rear axles loose traction, the rear drive shaft spins faster than normal. Once the rear shaft is spinning the same speed as the front one, the "automatic" parts comes into play and engages the front drive shaft. This gives you 6 wheel drive as long as the t-cases "senses" that the rear one is going as fast as the front shaft.

sorry but i do not agree with this. the front output of the transfer turns slower that the driveshaft so that when the rear looses traction and the vehicle slows, the front catches up with the driveshaft and powers it. same in reverse but it has to have a different sprag clutch decause of direction.

in any event this was a poor design and would be worthless for rock climbing etc.

 

[emr]

Sprags are worthless, ive seen air shifts for 250 to 300, with not the hoses,and such, as for U saying its full time its not the sprag is a clutch and as said there is one for foward and one for reverse, when they work they work very well, they can be adjusted most dont know how to, and say they cant because they dont know how to, there is info on this site on adjusting one, but an air shift is the way to go , although i have loved the performance for many years in my first deuce with a sprag, worked flawlessly for 9 years and some pretty tough running, as for having one U need to understand it and use it properly like everything else. they go in gear and people dont know how to treat them and they bang and ruin tires, as 99% of things i see its driver error, Randy

 

[k5ontherocks]

hey guys,thanks again.

i am in summitville indiana,just about an hour north and east of indianapolis.

i think i forgot to mention this is going in a mud and trail rig.a 1970 chevy k5 blazer.aprox 450 hp,plus 200 n2o shot!!16.9x24 vtread tires.2.5 rockwell toploader axles.
i am aware of the size and weight,the pics above are of mine in my garage.ive got the mounting handled.
i was originally gonna run a np200,but have seen a few of thiose breaking.

some mud bog guys are welding the sprags and clutches,im still trying to get some more info on that subject,but i wonder if that takes care of the clutch and 2 shafts turning at 2 diff speeds???i guess i would still have to have a 2 stick shifter ,one for hi-low,the other for fwd/rev???

i guess one reason im trying to use the sprag case is to save some $$..already got this one for a good deal..its got a tag that shows military rebuilt in 1974,then never put back into another truck.but....if its junk....its junk

 

[JasonS]

I don't agree that they are junk. Folks have to realize that the sprags are constantly wearing. You can't fairly judge a design with a worn out component. The forward sprag wears first. You can most likely take two rear sprags (they interchange) to make one good assembly. It will be obvious when you take it apart which is which. You can also service the sprag without removing the whole transfer case.

I replaced my sprag with Memphis's kit. It replaces the sprag clutch assembly with a solid hub and two gears are replaced to correct the drive ratio. Cheaper than an air shift xfer case for me; out here in this wasteland.

 

[jatonka]

Transfer case

Yes JasonS, that is a reb kit and they took care of the problem, I have one in my M35A1 wing plow. It is great.

 

[m-35tom]

RE: Transfer case

holy crap!

 

[clinto]

RE: Transfer case

jatonka, I believe there is a locomotive somewhere that wants it's snowplow back

 

[k5ontherocks]

wow,that snowplow is massive...awesome.

ok,the reb kit from memphis eq. is no longer avail.

any other options??

any chance (since mine was overhauled in 1974)that mine had been updated by the military ???
i guess i can pull apart and find out.

 

[jatonka]

So, you guys wonder if the old Deuce can push the plow and wing? Oh, it really does. It is singled, flipped rear hubs for in line tracking. Mud and snow tires, tire chains on front axle and front rear axle. Hydraulic power steering, live hydraulics of the front of the crank pulley. Body shortened to 10' to make room for the wing tower. Had to put a head gasket on her last month. I'm getting a V blade for it so I can open drifted roadways easier. Back to topic, I doubt the military updated your sprag transfer case, unless you see an air cylinder sticking out of it on front cover. JT

 

[gringeltaube]

I don't agree that they are junk. Folks have to realize that the sprags are constantly wearing. You can't fairly judge a design with a worn out component. The forward sprag wears first. You can most likely take two rear sprags (they interchange) to make one good assembly. It will be obvious when you take it apart which is which. You can also service the sprag without removing the whole transfer case.

I replaced my sprag with Memphis's kit. It replaces the sprag clutch assembly with a solid hub and two gears are replaced to correct the drive ratio. Cheaper than an air shift xfer case for me; out here in this wasteland.

If anyone really wants to fix his sprag T-136-21 let me know, I have about a dozen brand new OEM clutch assys laying around and no use for it!

G.