T-case removal problem

[Mario]

My truck is an '81 K20 upgraded to a Chevy NV4500 with a NP208.  I installed the transmission not fully knowing it's condition.  About 8k miles later it developed a loud whine.  So, I figured I better take it down and overhaul it before it disintegrates or I lose to many hard parts.  I had sealed most everything with Permatex The Right Stuff 1 minute gasket maker.  The problem is that now I can't separate the transfer case off the transmission.  I've tried prying with a scraper and screw drivers (broke the tip off one screw driver).  I've even pried with a long bar against the flange of the front output shaft.  I've also tried applying gasoline to the exposed bead of the sealant, to no avail.  One of the first problems I noticed with this transmission is that it had a slamming noise after coupling the transmission to the transfer case (like first releasing the clutch).  I'm thinking that the transfer case input coupler may be fused to the transmission main shaft.   I'm hoping someone can give me some ideas on how to get these two components separated.  Thank you!

[Captkaos]

Did it mount up flush and you just installed bolts or did you pull it together with the bolts.
Have you tried a dead blow hammer?  It shouldn't be sealed that well.  I thought the input for the 208 was different?

[Mario]

At first I had bolted up my old transfer case, but I quickly noticed that it had a crack in the front half of the case.  The SM465s and TH400s all had 32 spline NP208s.  So, I found a replacement that must have been mated to a TH350 because it had a 27 spline input coupler.  I ended up swapping all my original internals into the replacement case halves.  Both times the case slide over the main shaft and the faces made contact.  No, it wasn't pulled together with the bolts.  I haven't thought of a dead blow hammer, but I wouldn't know what to attach it to.  I'm leaning towards taking both units down, and dealing with this out in the open.  I may run into problems with how to secure each unit to even begin a tug of war.  By this point, I'm convinced it's the coupler that's stuck onto the main shaft.  Thanks for your reply!

[bake74]

      I am not too familiar with the nv4500, is there a way too take it apart while still hooked to the 208 to be able to see the shaft ?

[Mario]

I took both of them down together, and continued to pry on the two housings to no avail.  Unbolting the rear housing of the NV4500 would just create another gap to pry from.  The main shaft wouldn't be exposed.  I'm going to disassemble the NP208.  I can remove the planetary gear set and get to the input gear/coupler.  Maybe at that point I can attach a slide hammer.  Thanks for your responses! 

[bake74]

     If you can take some pics, would like to see how/what happened.

[Mario]

Give me a day or two, as I'm not too eager to jump on it.  More than likely previous owner loved to pop the clutch, and the transmission main shaft output splines raised up pressing against the coupler.  We'll see.  I'll post a couple pics.

[Mario]

I'm able to hook on to the NP208 input gear with the OEM 27078 puller attached to a slide hammer.  I use a piece of small inner tube to hold the jaws onto the gear as I slide the hammer, but it just doesn't budge.  After about 3 slides the jaws slip off the gear.  I tried the pressing bolt with the puller against a large crescent wrench bridging the front case, but it just bent the wrench.  I'm not sure what else to try.

[werewolfx13]

Use a 30lb pinch bar instead of a crescent for the pulling point? I'm not entirely sure what else you could try..

[81_Chevy]

have you tried heating it up? that always seems to work for me getting things un-stuck

[skinu]

seen this before ,one was installed crooked hence the wear mating(locking) together, take a come along and keep pressure on it while tapping around the case with a ball peen and piece of 2x4 ,place 2x4 against where you wanna strike, use what you got to get a straight pull and attach to rear or bumper just don't pinch off your brakes,wires ect. have a jack or something under ready to catch it when it comes free.
keep it in line or you'll snap something off good luck also
I had to hook one to another truck and we rocked the truck back against the the chain

[frotosride]

Not saying you don't know this but often times we forget simple things when it's to late but remember that the 208 case is aluminum so be careful bridging stuff across it for leverage...friendly reminder.

[Mario]

Thanks for your replies!  I drilled a hole through the "cap" inside the coupler that way the pushing bolt would press against the transmission main shaft.  Actually it was a 7/16" x 2" bolt that I inserted.  I restrained the rotation with a crescent wrench on the puller and against the case half.  I got it as tight as I could with a breaker bar, and then I left it alone for about a minute and it "popped" off on it's own.  I did add some heat to that "cap" inside the coupler, so maybe that aided the situation.  The splines on the transmission main shaft were raised, and being coupled to a different TC with a different wear pattern on the splines made it lock on.  Also, I had just pulled a load of hay up a steep incline in 4 low just prior to removal.  Had I driven it and gone between 1st and reverse a few times it probably would have freed itself.  Not sure though.

[bake74]

     So are you going to be able to fix them and use both again ?

[Mario]

I had already planned to replaced the Transmission Main Shaft due to condition of the splines.  I had to overhaul the transmission to address an increasing "whine".  So, it's kinda like a "two-fer" deal with the transmission.  I'll probably try to find a new or "used and in better condition" Transfer Case Input Gear/Coupler.  I'll have to check the fit prior to reassembling the transfer case.  I have a spare,  but it's high mileage and had been abused.  It does fit better than the coupler that I just removed.  In a pinch, I guess I would install that one.  Moral of the story is:  If you're buying something used and never overhauled, saved yourself the trouble, and just overhaul it before you install it.