32 spline NP208 is not mating up to NV4500... what am I doing wrong??

[Farm Shop]

I could really use some insight as to what I am doing wrong here. I did a TON of reading on here, pirate4x4, etc, and thought I had all my ducks in a row, but apparently not.

I'm swapping out the SM465/NP205 in my brother's '72 K20 for an NV4500 from a 1996 GMC 1 ton. I got a 32 spline NP208 transfer case since everything I read said it would bolt right up to the NV. Long story short, it doesn't.

Please excuse the nastiness, I was just trying to verify fitment of everything before cleaning and painting.


Output shaft of NV4500


NP208




When I install the TC to the trans, this is all the further it will slide into place


After some measuring and head scratching, I put blue marker on the aluminum casting of the 208 and verified that the portion of the input shaft bearing support contacts the large damper on the output shaft, keeping it from fully seating. You can see where the marker is rubbed off due to contacting the damper in the trans.


Where did I go wrong? Thanks in advance for any help or recommendations on where to go from here.

-kyle

[b454rat]

Looks like you need a small spacer.

[kwmech]

http://www.advanceadapters.com/tech-...modifications/


The damper was meant more for the diesel applications

[snj8198]

Originally Posted by kwmech

http://www.advanceadapters.com/tech-...modifications/


The damper was meant more for the diesel applications

ya, two piece design fly wheels. From what I understand, the two piece design created enough harmonics that, without the tail balancer, would vibrate and destroy the mainshaft. I have a buddy with a '95 6.5L Diesel this happened to twice. Expensive learning lesson.

[franken]

The AA conversion guide and other sources mention cutting the 4500 output shaft. You could also make a spacer from aluminum using a gasket as a template. Make sure all the bolt holes line up.

[kwmech]

You shouldn't have to cut the shaft if the damper is removed. And change the input seal on the 208, looks like it has cracks in it

[special-K]

Originally Posted by snj8198

ya, two piece design fly wheels. From what I understand, the two piece design created enough harmonics that, without the tail balancer, would vibrate and destroy the mainshaft. I have a buddy with a '95 6.5L Diesel this happened to twice. Expensive learning lesson.

Ah yes, the DMF (dual mass flywheel) folly. I figure DMF better describes who's idea these were. Had the snubbers go out on one and another cracked almost all the way around the center. GM didn't even supply replacement DMFs. Instead, they offered a conversion to tried and true solid flywheel, which made for an involved and expensive conversion. Really sucks when it happens after you install a fresh GM crate NV4500 and Centerforce dual friction made for the DMF. Had to get another clutch and break into my new transmission. Not to mention dropping all that out of the truck again.

[Farm Shop]

Originally Posted by kwmech

You shouldn't have to cut the shaft if the damper is removed. And change the input seal on the 208, looks like it has cracks in it

I'll have to look into removing the damper, I guess. I'm just really surprised to run into this after everything I read about the 208 and early 241 being a bolt-on part for the NV4500. This trans was behind a 350 in a 1 ton dually.

And good eye on the seal. It will be replaced along with several others after the parts are cleaned and painted.

[Farm Shop]

So after some more digging, it seems like this trans is a bit of an odd duck. The damper (big steel drum counterweight) apparently started in 1995 behind the 6.5 diesel to fix the 5th gear nut loosening issue associated with the hammering harmonics of a lugging diesel. The weird thing is that this truck has a vortec 350... but it was a 1 ton dually, so maybe all 1 tons got the same trans?

I don't know. Regardless, the damper has to come off. Behind a mild big block that won't ever tow much to be a problem, eliminating it shouldn't be an issue. Now I just need to find a trans shop with the correct spanner/socket to do it for me... spending $170 on a production socket is not a great option right now!

[snj8198]

Dang, I just read an article somewhere that you can drill a hole through on each side of the nut and just chisel it in half saving the cost of that expensive spanner socket. Most replace that nut anyway. I'll dig a bit

[CrewCab59]

The nut is the same as a Dana 44 spindle nut socket, I have one that I made long for the shaft .

Thanks

[Farm Shop]

Originally Posted by CrewCab59

The nut is the same as a Dana 44 spindle nut socket, I have one that I made long for the shaft .

Thanks

That is great information! Thanks!!

[CrewCab59]

A socket will be needed any ways to reinstall so get a spindle nut socket cut it in half and weld a section in. That way you can still use it on the hubs and Trans.

Just a thought.