Transmission Swap

I'm planning on putting an automatic in my 95 Chevy K1500 project truck, which has a trashed NV3500 5-speed. Currently 2nd, 5th, and reverse are out, and it is very hard to shift. I've always had automatics, and am going to a 700R4, and have read that the transfer case input shaft is different. I will need the 27 spline input shaft, and my question is how hard is it to change this part? I seen where one member had posted several good pictures of the breakdown of the NP241, but there wasn't a good shot of the input shaft. Anyone have any experience with this?

Thanks,
Aaron

I've never gottin into transfer cases the closely.
That would be awesome if you could take your own pictures and post them.
This way you could be our source of information here at Truck Source.

If the transfer case is already out, it will be a lot easier.. The reason being you have to open up the transfer case to change the shaft. I know Fasel will know more about this then I so I will PM him the link to this thread.

you could just get a 700r4 4wd with a np205 or np208 transfer case and make things a whole lot easier.. it depends on where your speedo output is and whether its drivers or passenger drop

Thank you merlin for the PM!!! Aaron I'll gladly elaborant on my post with my pics in. I did have a pic of the input shaft it was the one infront of the yellow battery... However on with the show!



The NV3500 has a 30 spline output shaft and you are correct in saying you needed a 27 spline input. Now if you have the 241 out of yor truck then swapping the input shaft is easy! First the case has to be out of your truck then the 241 has a 2 peice tailhousing so take the first half off because there is a bearing inside there and there is snap ring that has to be removed first. Once the snap ring is removed the second half can be removed once the second half is off you'll see the the VSS gear the is a snap ring in front of and behind the gear to hold it into place once they are removed the gear slides off the end of the tailshaft after that is off you'll be looking into the case you'll see the pump now that pump is connected to a small rubber hose that connects to the oil pick up now that hose will disconnect from the pickup tube but reconnecting it later is a PITA!!! Actually it's virutally impossible... Ask me how I know!!

So what you do to make things easier is take that case half bolts out and break the seal on the halves and take the half and slide the pump and the halves off all at once the pump will just slide off the tailshaft after that the chain needs to be removed now this can be done one of 2 ways way number 1 is walk it off the gears by hand which if you have alot of patience and a strong hand then this is an option... But way number 2 is quite a bit easier. Spin the case around half take off the frontdrive shaft output nut off and the yoke will come off with some work. After thats off the chain and both chain cog gears will pull out with some wiggling. Now your looking at the shift fork and gear take those out I can't remember if there are any snap rings but if I recall everything will just slide apart.

Once you have the tailshaft out the shift fork will slide off the rod and the low range shift fork will come out with some wiggles now if you have to take out the gear seletor be very careful there is alittle spring in there that will pop out along with the little metal piece that rests on top of it. However once the low range gear fork is out you'll be looking at a planetary gear that planetary hear is the back side of the input shaft that piece will literally twist and slide out because the gears are curvedonce that's out you'll see right through the case and all you do then is slie the new input shaft in and reassemble the case which is opposite of disassembly.

Be careful though with that pump because it can be PITA it get it lined up and don't get mad if your trying to get it on and the tubes disconnects just pull it off and reattach it now the pump has to go on a certain way because if not the tailshaft won't sit on all the way and you'll have to pull it off and move it to fit... Now the gear inside the pump does move back and forth so take an extra minute and get everything lined up before you set it on.


P.S. Good luck with your project and keep everything clean and lay it out as you take it apart so that way you don't get confused with what goes where. If you have any questions pm me and I'll answer it ASAP!!!

Ummm... Yeah I just noticed that your truck is a 95... Are you sure you have a 241? It could be a NP243. Easy to tell though is it push button 4wd or is the shifter on the floor? I ask because there are internal and external differences between the 2. If it's on the floor then you have the 241 but the puch button is a 243

Hey Fasel, Thanks for the detailed reply! I saw your other thread on here showing the breakdown of the T-case and the picture of the input planetary set. I have the manual transfer case and am fairly certain it's the NP241. I'm planning on pulling the case saturday and begin disassembly to see what I've got. Hopefully it won't need much more than the input shaft changed, we shall see!

Yeah sure no problem man... If you have the manual tcase then you have the 241 there is a little circle tag on the back of the case it'll say new process on it and it'll say the number of the case on the top and the ratio on the bottom it'll say 241 on top and 2.62 on the bottom. Now if your 4x4 works then you won't have to change anything inside the case. Of course eveybody always says "change all the bearing and seals and bla bla bla" Man fudge that! You'll rarely ever blow a tailshaft support bearing or a front driveshaft output bearing! Unless you drive it with no fluid in it! You have a better chance of blowing the front end before you blow out the 241! So break it apart change your input shaft and put it back together everything else will be just fine. Good luck man like I said before if you have any questions just ask I'd be more then happy to help!!

Got everything removed last weekend but have a question about the flywheel. I got the bolts all removed but am concerned about the weight of the flywheel when I go to remove it. Are they very heavy?

its a decent amount of weight.. probley 40-50 pounds.. auto flywheel is alot lighter though.

Like Joe said, its a decent weight. 40 ish pounds for a manual, autos are around 30 lbs.

Yeah I agree it's not that heavy but certainly not something you want to let fall on you.

Got a question about the transmission cooler - My truck was not originally equipped with a tranny fluid cooler in the radiator. Do I need to get a new radiator with a tranny cooler, or will an aftermarket cooler work by itself?

aftermarket cooler willl work even better then the stock one.. i put an aftermarket one in my jimmy and c10 when i had to do tranny work to them.. you can eather get one that accepts AN fittings and steel braided line or use high pressure fuel line and some hose clamps. both work the same but i like the look of the AN and braided line

So I won't have to change the radiator?

I was thinking a good large capacity cooler and steel braided lines. That would be cheaper and easier to install than another stock radiator.

Its really up to you Aaron. You can change the radiator out or buy an aftermarket one. Both will work well. A cheaper option would be to pickup a factory trans cooler out of a 3/4 or 1 ton GM truck.

yeah either will work just fine! I have 2 trans coolers on my truck! The feed line come from my trans into my rad. then out to the secondary cooler then back to the trans!!

Never mind - found my answer in the Haynes manual...

haynes ftw. be careful on some stuff though. they like to leave out steps sometimes.