Nv4500 to np241

[Tomo]

I’m picking up a nv4500 out of a 02 silverado later today for my 70 k5. I have a passenger drop np241 out of a 1990 k5 to go behind it. I know I will have to make some changes since the nv4500 has 32 spline output and the np241 has 27 spline input. I’m thinking the only change is tcase input shaft, can anyone confirm I’m on the right track?

https://www.allstategear.com/NP241-I...ft-p/17118.htm

[kwmech]

That's it, just the input swap. There is however a different design input bearing and I can't remember what year this took place. I don't think it anything to do with the spline input though. You may also want to get a slip yoke eliminator kit and install that while it's apart, (Highly Recommended) AND install new shift fork pads at the same time. You'll probably find when it's apart that one side of them is pretty thin or missing. ALSO get new snap rings for the gear install

[Tomo]

Originally Posted by kwmech

That's it, just the input swap. There is however a different design input bearing and I can't remember what year this took place. I don't think it anything to do with the spline input though. You may also want to get a slip yoke eliminator kit and install that while it's apart, (Highly Recommended) AND install new shift fork pads at the same time. You'll probably find when it's apart that one side of them is pretty thin or missing. ALSO get new snap rings for the gear install

Thanks for the info!

The slip yoke eliminator kits I’m seeing are way more than I have in the tcase. Is there a more “cost effective” route than what I’m seeing? Hack and tap?

[Tomo]

Another idea for the tcase. I can get an np205 for less than the sye kit for the 241. Would that be a better route to go?

[b454rat]

In less have a sh!t ton of torque, a 241 is fine. In order to run the 205 behind the 4500, need to notch the adaptor for the t-case shifter. Not hard, just one more thing that needs to be done. Plus depending what was in front of the 205, might need to change that input too....

[kwmech]

Originally Posted by Tomo

Another idea for the tcase. I can get an np205 for less than the sye kit for the 241. Would that be a better route to go?

Stronger route for sure, but as 454 said....adapter notch and a custom shifter mount fabrication. 205 also needs to be specific (ROUND PATTERN) and also requires an input swap. Round pattern 205s the majority of the time did have a 32 spline input , but they were always a long input and needed to be disassembled to replace to the early short 32 much like the 241. AND they are very rare to find now-a-days. 241s are strong and have been reliable if there are no leaks and if there is a leak you need to take care of it right away. 2-1/2 qts of ATF can disappear pretty quick with a just a single drip. With the slip yoke kit, an input swap and a rebuild kit, you'll have close to 1000.00 invested into the case. Well California price anyways. I think when I was done I'm pretty sure it was at least over 900.00 in parts including shipping from various vendors. Then the rear driveline had to be redone. Be sure to get the slip elim kit with a yoke as they can come with or without. I procure from either Off Road Design in Colorado or JB conversions. Last kit I got from Ord, and it was a nice and complete kit

[Tomo]

Originally Posted by kwmech

Stronger route for sure, but as 454 said....adapter notch and a custom shifter mount fabrication. 205 also needs to be specific (ROUND PATTERN) and also requires an input swap. Round pattern 205s the majority of the time did have a 32 spline input , but they were always a long input and needed to be disassembled to replace to the early short 32 much like the 241. AND they are very rare to find now-a-days. 241s are strong and have been reliable if there are no leaks and if there is a leak you need to take care of it right away. 2-1/2 qts of ATF can disappear pretty quick with a just a single drip. With the slip yoke kit, an input swap and a rebuild kit, you'll have close to 1000.00 invested into the case. Well California price anyways. I think when I was done I'm pretty sure it was at least over 900.00 in parts including shipping from various vendors. Then the rear driveline had to be redone. Be sure to get the slip elim kit with a yoke as they can come with or without. I procure from either Off Road Design in Colorado or JB conversions. Last kit I got from Ord, and it was a nice and complete kit

Sounds like an input swap and sye kit will be worth it in the 241 since I only have $100 in it as it sits in stock 27 spline form.

I picked up my nv4500 yesterday (it’s out of an 02 silverado 3/4 ton). It has a sticker on the side that had a date of 3/23/2021. Did some digging and emailed Zumbrota Drivetrain, they confirmed that it is 1 of their remanufactured units from 2021. Very happy with my purchase.

[kwmech]

Originally Posted by Tomo

Sounds like an input swap and sye kit will be worth it in the 241 since I only have $100 in it as it sits in stock 27 spline form.

I picked up my nv4500 yesterday (it’s out of an 02 silverado 3/4 ton). It has a sticker on the side that had a date of 3/23/2021. Did some digging and emailed Zumbrota Drivetrain, they confirmed that it is 1 of their remanufactured units from 2021. Very happy with my purchase.

That's a cool find. The 4500s are getting hard to find even in decent shape

[Tomo]

After inspecting my parts after work today I found that the bellhousing has a 4-5” crack. What bellhousings are compatible? Do I need an 01-07 bellhousing for it to be compatible with both sbc & LS?

[franken]

I thought the early GM ones used the original GM bolt pattern 10.078" top and 10.394 bottom used by most GM transmissions. Later years ~96 used the Chrysler pattern.

I have an AA pdf file that says the 4x4 and 2x4 bolt patterns were different in the early years. I'm confused by this.

I'd measure the bolt pattern and research things.

I have a 96 NV4500 and a round pattern 205 I converted to a short input if anyone cares. I also have a 2.6 doubler to bolt between them for my K10, not that the diffs can take it.

[Tomo]

For all that have done nv4500 swaps what trans crossmember works best? Is there 1 that will work or is there 1 that works best to modify?

[kwmech]

There was a write up in here somewhere of one of the guys using a factory cast iron bell housing and making the 4500 fit it by redrilling some holes. It was a nice alternative. Either that, or purchase an Advance Adapter Bell or a good welder can fix a crack

[special-K]

I don't know a lot about the NV4500 and NP241, but I had a lot of experience with troubles in both K3500s I had with that combo, a '92 and a '95. One issue in both was the DMF flywheel, which I have three different works for that acronym to call the engineers that thought that was a good idea. Both trucks ended up needing a swap to the trouble-free tried and true solid flywheel.

In the '92, I had already replaced the NV4500 with a GM crate due to dropping 5th gear resulting in expensive internal damage. To add insult to injury, later on the rubber cushions in the Dumbass MF'r gave out. GM didn't even sell replacements, but they did sell the parts to swap back to the smarter design. Before I figured out it was the flywheel cushions I thought it was a bad input bearing and had one on hand. Got into it, found the problem, and got the parts to go solid flywheel and that required changing the input shaft and a different input bearing. I guess that is the difference in input bearings kwmech mentioned above. That is my guess.

[SunSoaked]

Originally Posted by Tomo

For all that have done nv4500 swaps what trans crossmember works best? Is there 1 that will work or is there 1 that works best to modify?

Stock Xmember in my 85. NV4500 bolts right in.