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Need help - NP208 speedo gear removal (read last post)

andyblack

andyblack

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Experts, I need to tap into your exrerience and wisdom. I have an '85 GMC half ton pickup with a 305/TH700R4/NP208. Saturday I was out wheeling down by the river. After shifting in and out of 2Hi, 4Hi and 4Lo several times, I noticed that it was slightly harder than usual to shift the transfer case into 4Lo, but not too bad. Anyway, everything was working fine. I drove up on top of a tree that had fallen and then backed off it because the trail ended. I backed up and turned around and started going forward. When I got off the throttle, I heard and felt a pop like the transfer case had slipped out of gear and then the truck wouldn't move forward or backward. I couldn't shift the transfer case out of 4Lo. Even when I put the transmission (which was still going into gear like it was supposed to) in neutral, I still couldn't move. I couldn't make the truck moved by pushing it, so I unlocked the hubs and hooked my winch line up to a tree and winched the truck forward. The back wheels were locked up. I jacked up the rear axle so both wheels were off the ground and they both spun by hand like normal. I crawled up under the truck and examined the transfer case linkage and it looked fine. I tried to pry the linkage with a pry bar, but no luck. I was forced to undo the rear drive shaft and have my wife tow me out of the woods with her Jeep.

What do you think the problem could be? Currently the truck is sitting at a boat ramp several miles from my house that is prone to flooding. It snowed last night and there's ice all over the road, so I can't do anything with it any time soon. Hopefully I'll get some good advice from some guys on this forum that will allow me to fix it out there without having to try to tow it home or call a tow truck. Thanks for the help in advance.
 
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You definitely have a problem with the drivetrain. The rear wheels turned when off the ground because you don't have a locking rear end.
When you turned one, the other one turned backward through the spider gears, but the driveshaft did not turn.

Unless someone else chips in who has seen this problem before, I am going out on a limb and guess that one of your shifters has failed internally and the transfer case is in two gears at the same time.

It might be worse. One of the gears may have broken and the pieces are binding the other gears.

Either way, I don't see much chance of getting it home under power.
If you can tow it, I would crank it up so that you have power steering and brakes and let someone tow it home so you can pull the transfer case.
 
Worse come to worse, pull both driveshafts, crank it, and tow it home.

You'll have to get the driveshafts out when you pull the case anyway....
 
This is just a guess, it sounds like the chain popped and is bound up in the case. If this is the problem, you can get it home.

drain the t-case fluid
chock the wheels and remove the rear d-shaft
remove the tailhousing
remove the rear t-case half
pull out the chain and loose parts
reinstall the shafts without the chain
reinstall the t-case half and tailhousing
reinstall rear d-shaft
hopefully the t-case shifter will let you get it into 2wd to get home, cause 2wd should align the input with the output shaft bypassing anything chain driven.

But, like I said, this is if the chain inside is broken/bound up. I would be messing with that t-case shifter (engine off trans in N) trying to find a gear first.
 
I like the two gears at once suggestion. I would think that if something had broken inside the case, I would have heard some grinding or something right? I was driving on flat ground at about quarter throtlle when the truck stopped. I think maybe I'll just wait till the ice and snow melts and try to pull it home. It will roll with the front hubs unlocked. Has anyone out there had this specific problem before?
 
496truck said:
This is just a guess, it sounds like the chain popped and is bound up in the case. If this is the problem, you can get it home.

drain the t-case fluid
chock the wheels and remove the rear d-shaft
remove the tailhousing
remove the rear t-case half
pull out the chain and loose parts
reinstall the shafts without the chain
reinstall the t-case half and tailhousing
reinstall rear d-shaft
hopefully the t-case shifter will let you get it into 2wd to get home, cause 2wd should align the input with the output shaft bypassing anything chain driven.

But, like I said, this is if the chain inside is broken/bound up. I would be messing with that t-case shifter (engine off trans in N) trying to find a gear first.
Click to expand...

I'll try this. Thanks. Hopefully the river won't rise and sweep it away before I can get out there.:doah:
 
andyblack said:
I like the two gears at once suggestion. I would think that if something had broken inside the case, I would have heard some grinding or something right? I was driving on flat ground at about quarter throtlle when the truck stopped. I think maybe I'll just wait till the ice and snow melts and try to pull it home. It will roll with the front hubs unlocked. Has anyone out there had this specific problem before?
Click to expand...

It will roll with the front hubs unlocked? Will it drive under it's own power with them unlocked?

Either way, this info point to the shift forks being worn and like previously mentioned the t-case is trying to be in 2 gears at the same time. Time for a rebuild or swap. I was just driving down the street in 2wd on the way home from work when my t-case started grinding away for no reason. No power to the wheels, just grinding. Pulled into a lot, shut it down and messed with the shifter till it felt like it was in a gear. Started it up, put it in D and it clunked into gear like normal. I made it home, pulled the case and brought it to a rebuilder. Cost me $600 but I got it back the next day along with a guarantee. He even thanked me for bringing in something so simple and straight forward compared to the stuff he typically works on with the newer cars/trucks. He told me something about the shift forks hanging up and dragging in the NP208s was a common problem back in the day. And he replaced them with new and did some mod to prevent it from happening again and of course all new bearings and seals throughout the unit.

Why didn't I swap it out for a used one? Because I did that already and got a year out of it. And, before anyone asks, I couldn't find any 241s local that I trusted and would've had to have that rebuilt anyways just for piece of mind. And I needed the truck back on the road cause it's my only vehicle right now.

rant off. carry on.
 
Hopefully it won't cost me anywhere near that much to get it fixed. I know a guy who offered to sell me an NP208 out of a military Blazer. Will this used t-case bolt right onto my TH700 trans? I'm pretty sure the military Blazers used a TH350. How hard would it be for me to rebuild the thing myself? If it's going to cost $600, I may just look into getting an NP205 put in there.
 
No, if the mil t-case was behind a TH400 it will have a 32 spline input and will NOT mate to a 700R4 which requires a 27 spline input. Look for an NP208 that came from behind a TH350 or a 700R4. Or look for an NP241 from a speedo cable truck (88-89 only I think) again with 27 spline input.
 
I am going to say the mode fork in your t-case just broke 208's are bad about this especially without warning but yours gave warning with the harder than normal force needed to go between lo and hi. If you are curious drain the oil to look for metal and plastic at the drain plug. If all it ate was the mode fork than all it will cost is seals, new nylon wear pads, mode fork, collar, and maybe a chain so for about 150 for parts without the chain with you doing the work.
 
All right, they called off work again today because of the snow and ice, so I waited until the ice was gone off the roads and went down and hooked up the truck with a 30' tow strap to my V-6 Ford pickup with a manual transmission and no receiver hitch. Not the ideal tow rig, but it's all I have. I made my wife sit in the 4x4 to steer and brake it. It was so much fun, let me tell you. All the jerking around and going slow. Good times. When I got home I drained the t-case, but I didn't see any metal shavings or plastic pieces or anything. I proabably won't have time this week to mess with it, but I have next Monday off for MLK day, so hopefully I can get the thing out and apart then and find out what I need to do. I'll post up when I find out something in case anyone wants to know. If anybody wants to drop any more advice or anything in the meantime, then feel free to do so. Thanks for the responses.
 
How much snow did you end up getting? My inlaws live in perry and I never did hear. The father in law works at Robbins AFB, so I'm guessing he got a few days off. Good luck with the truck. If push comes to shove, let me know and I can find you a cheap replacement case up here and ship it down. Heck, if you aren't in a hurry, I'm swapping my 208 for a 241 and would let it go very cheap. Not sure when it's going to warm up enough to do the swap on this end Though.
 
If the case is bound up, can't you just pour Metamucil in it?
 
JeffsJeep04 said:
How much snow did you end up getting? My inlaws live in perry and I never did hear. The father in law works at Robbins AFB, so I'm guessing he got a few days off. Good luck with the truck. If push comes to shove, let me know and I can find you a cheap replacement case up here and ship it down. Heck, if you aren't in a hurry, I'm swapping my 208 for a 241 and would let it go very cheap. Not sure when it's going to warm up enough to do the swap on this end Though.
Click to expand...

I think I saw about three inches in the back of my truck. Not sure what the official measurement was. It wasn't regular snow though. It was really hard and icy. Real slick too. I almost busted my butt twice this morning trying to step off my porch. I work at Robins too. Not sure why they decided to close for two days. I got paid though.

P.M. me when you get ready to sell the NP208. Hopefully mine will be fixed soon, but I may need to get a replacement. Thanks.
 
Hey, I've got two friends who regularly rub WD40 into their arthritic knees.

They both swear it helps. So, who knows.......

Funny part is, they both buy it in the gallon can. They said they didn't that propellant in the spray cans on their skin.
It might be toxic.........
 
Fordum said:
Hey, I've got two friends who regularly rub WD40 into their arthritic knees.

They both swear it helps. So, who knows.......

Funny part is, they both buy it in the gallon can. They said they didn't that propellant in the spray cans on their skin.
It might be toxic.........
Click to expand...

Well I sprayed liberal amounts of WD-40 on the linkage just in case (I got a huge can in my stocking for Christmas) and it did no good. Let me tell you, it doesn't taste good when it drips in your mouth either. Kinda makes your lips and tongue go numb for a while. I've involuntarily tasted just about every kind of fluid/spray you could possibly use on a vehicle over the years. The best tasting is probably antifreeze. Tastes like syrup! Yum. The worst is probably the WD-40 or motor oil. It's been several years since any motor oil got on my lips, but I seemed to remember that the partly synthetic stuff isn't quite as bad as the full on dino juice. Brake fluid will make you spit and cuss too.
 
I finally had time yesterday to take the t-case out of the truck. Thing is, I've never taken one apart before. How hard are they to disassemble and reassemble properly? Should I try to take it to someone who knows what they're doing or is it something that the average joe can handle pretty easy? Do I need any special tools or anything? Any tips, tricks or pitfalls I should know about? Common problems to look out for? I have tomorrow off from work so I'll probably try to take a look inside it then.
 
andyblack said:
I finally had time yesterday to take the t-case out of the truck. Thing is, I've never taken one apart before. How hard are they to disassemble and reassemble properly? Should I try to take it to someone who knows what they're doing or is it something that the average joe can handle pretty easy? Do I need any special tools or anything? Any tips, tricks or pitfalls I should know about? Common problems to look out for? I have tomorrow off from work so I'll probably try to take a look inside it then.
Click to expand...
Never had a 208 apart, but I've taken a bunch of np231's. The only special tools to have for them is a 12 point 13mm socket and a good pair of snap ring pliers. They are dead simple, you won't believe it when you get inside there. Take the front yoke nut off before you remove the case from the truck or it's a bit of a PITA to get loose. Still can be done, just more of a 2 person job at that point.
 
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