NV4500 2wd to 4wd?

[dutchmanz]

I have a 94 NV4500 trans out of a 3500HD. Is it possible to switch it to a 4wd version? I guess it is possible, but what must be changed and is it worth it? I want to reuse my current NP205 also.

[duallyjams]

Well if your 205 is a figure 8 it requires a adapter so if you bought a AA adapter then you would have to change out the main shaft in the nv4500.Any way you look at it $$$$$$$$.

[jltait]

Dutchmanz,
You will need to replace the main-shaft and tail-housing at a bare minimum. IF you have a circular pattern np205 you can use factory parts with a spacer between the t-case/transmission(about 1" iirc). If it is not a circular pattern but instead a figure 8 style you will need to be looking at advance adapters kits.
JLT
PS ck5 site has some good information on this combination.

[DirtyLarry]

I wouldn’t recommend using a 10 spline 205 for this project anyway. The 10 spline 205 input shaft has a habit if getting extremely sloppy after years of use. This is a perfect time to get rid of the 10 spline. Get a 32 spline or at least a 27 spline 205. Ideally, a round pattern 205 with 32 splines would be best but they are hard to come by and then you would have a slip yoke at the rear of the tcase which sucks too. I ditched my 10 spline 205 and found a 27 spline 205 to use for the swap in order to get a finer spline tcase input.

The AA kit that I used is for a NV4500 to a 27 spline 205 is AA kit 27-0031. This particular kit requires a large section of the main-shaft be cut off anyway. You cut the shaft right behind where the 31 spline section of the shaft turns into the 32 spline (basically behind where the problematic 5th gear nut would be). With that, I wouldn’t think it would matter that you are starting with a 3500-HD trans or not.

Study all of available AA’s kits and instructions as main shaft cut off varies between different spline count 205 kits. I noticed the NV4500 to 10 spline AA instructions have a different cut off measurement and does say a 4x4 main-shaft is required. I would think finding a different 205 is cheaper than ponying up $500 to $700 for a main-shaft only to get stuck with a sucktastic 10 spline 205 in the end.



Here is the cut off for the 27 spline kit (AA kit 27-0031).

[jltait]

The circular pattern np205 did come in a fixed yoke style, but are hard to come by. I think they were limited to Crew Cabs and chassis cab trucks. I have one in the garage that came out of a Chassis cab truck IIRC. I can get pictures if anybody wants 'em. The Chevy style NV4500 main-shafts are $152 through most places.
like here for instance, that is where I got mine

http://www.tbtrans.com/transmission_...ev_truck_parts

For my 4x4 conversion (when I finally get to it)I will be using the nv4500 with the new 4x4 main-shaft ordered from the link above. I will use the nv4500 adapter from Advanced Adapters between the NV4500 and the circular pattern NP205 with fixed yoke. Here is a link to the adapter (It's $99.95 at summit racing). I have all the parts minus the transmission/t-case adapter/spacer.

http://www.advanceadapters.com/products/pn-50-6910/

I will also using a cast iron tail-housing that I picked up from the same place as the main-shaft. These are aftermarket parts, but any new NV4500 part will be, they have been out of business for quite some time now. Anything anybody says is new would be either aftermarket or NOS. With the np205 weight I thought the cast iron tail-housing would be a good idea. They do not advertise it on their web site but when I called they had 'em.

If your transmission has a lot of miles on it in a heavy duty application a new shaft is not a bad Idea anyway. The 5th gear issue is actually a function of the shaft and the way it supports (or lack of) the main-shaft 5th gear. there is a place (http://quad4x4.com/NV4500_Transmission_Kits.html) that sells a truly corrected shaft but only for the DODGE application. Why? because the GM design uses either a spacer (speedo ring/fixed yoke 2x4) or a dampener and/or sleeve (most 4x4's) in the tail-housing which prevents the nut from backing off when the wear between the Gear/Main-shaft on the Dodge would normally allow the gear to hammer the nut loose.
So the reality is the updated Nut is really treating the symptoms, not curing the ailment. Many Dodge guys that put their transmissions back together with old shaft/5ht gear and new "updated" nut find out 10k mile later it backs off again. IF you have your transmission apart and find the 5th gear rocks on the Main-shaft(it should be a light press fit) then it is worn. IF it is nice and tight on the shaft then it is probably fine. I can tell you mine with high 200k miles used as a water truck for a construction company behind a 6.5 diesel rocks loosely. REMEMBER MOST OF THIS APPLIES MORE DIRECTLY TO DODGE, Chev's may have a loose gear/shaft fit but may never have the nut come loose 'cause of the design of the tail-housing components.
This all being said I will use my 2x4 transmission as is with the worn shaft/gear cause the speedo ring and fixed yoke should hold it all together till it grinds the splines completely away, and I plan doing the 4x4 conversion with new shaft/5th gear in the next 2 years. This is why I bought the 4x4 shaft/tcase-housing.

IF I were putting an nv4500 together for the long haul (Dodge or GM)I would check the main-shaft/5ht gear fit, if tight I would not worry about it. IF 5th gear rocks on the shaft I would replace the shaft and main-shaft 5th gear.

The Quad4x4 guy has this information on his site, frankly I originally thought his information was hype and he was just trying to sell what I thought were overpriced shafts to the Dodge guys, but after having my transmission apart preparing for the Cummins/NV4500 conversion, I started to understand what he was talking about. Since his shafts are really a cure (Made in the USA with very specific guidelines and probably patented to boot) I guess I cannot blame him for his pricing.

Oh by the way I am using a GM NV4500 with a cummins (using an AA bell-housing kit) so I can run the circle pattern np205 behind it at a later date.
JLT

[DirtyLarry]

That is some good info there ^

Nice source of main shafts too. When I was looking, I was finding prices at $500 plus. $152 isn’t too shabby at all!

[jltait]

yes,
I thought the shaft was very reasonably priced. I was skeptical about the quality, but when it arrived it appeared to be a very nice piece. Same goes for the cast iron tail-housing. I have not checked these parts on a CMM or anything but the machining appears to be good quality.
JLT

[dutchmanz]

I'm not sure which 205 I have. It's behind a SM465, so I would trink its a fig 8. Would a 205 behind a TH350 be the round style?
The 4500 needs some repair, but I got it for free, so its worth the time.

[dutchmanz]

Guys, I really need to thank you for all the information. There sure is more to a simple transmission swap when it involves a transfer case. I guess I'll keep saving up and keep looking for a few more parts.

[jltait]

Dutchmanz,
An np205 with an sm465 can be either the 6bolt circular (late model '85 up) or the fig. 8, not sure exactly and I'm not sure anybody knows exactly. It may have been a rolling change not restricted to a specific model year. Anything in the 70's would be the fig. 8 for sure.

The later 6 bolt circular will be 32 spline if either attached to a th400 or sm465, in fact my understanding is they are common and interchangible the only differenece being some have fixed yokes some have slip yokes and of couse the factory adaptor between the th400/t-case. The late sm465 has a tailhousing the bolts directly to the np205 and has a mount for the shifter built into it. I can get picture of this part if anybody need 'em of this style. yoke style depends on chassis it came in and I do not know those specifics.

An np205 behind a th350 will be the older fig. 8 style, unless of couse somebody has used aftermark or hand fabricated adapters.
JLT