4wd vs 2wd transmission for 4x4 Blazer

[shenk10]

I have been searching and haven't found a definite answer to whether I should buy a 4wd or 2wd 4l80e transmission. The plan is to use the advance adapter to mate the 4l80e to my np205 so does it matter whether I get a 2wd or 4wd transmission?

[mongocanfly]

http://www.advanceadapters.com/produ...h350-or-sm465/ it says designed specifically for 2wd trans if this is what your looking for

[shenk10]

Yes that is what I was looking for. Thanks.

I would like to run a 6.0/4l80e but keep the transfer case in the stock location, but after looking at dimensions on the 4l80e it seems a 4l80e transmission would be roughly 4-5" longer than the TH350 and the 4l60e is roughly 2" longer.

I have seen 5.3/4l60e swaps where the engine sits almost exactly in the stock location, but if I want to run a 6.0/4l80e it seems I will have to move the transfer case/trans mount back a couple inches.

[franken]

A round pattern NP205 may bolt to a 4x4 OD automatic for a fraction of the price of that adapter. Even if you have to get a short 32 spline input for the new NP205.
The trouble is, they aren't too common.

[shenk10]

Yea I thought about that option too. I also saw that someone ran a TH400 to NP205 stock adapter and just had to machine down the indexing ring, but with that wouldn't you still have to swap out the input shaft on the NP205 from the 27 to 32 spline?

Actually I just read that he used a 1982 NP205. Would a newer NP205 already be a 32 spline? If that is the case it may be cheaper to try to find a newer NP205 and TH400 to NP205 stock adapter. In the end it may come out to the price of the advance adapter though.

[72MARIO]

I haven't done this myself but from what I have read round pattern 205 and a 4wd 4L80 with this spacerhttp://www.northwestfab.com/4l80E-to...acer_p_98.html It should bolt together.

[shenk10]

I saw that, but I would think you would have to make a custom trans/tc mount then.

What about this? You can get a TH400 to NP205 adapter new for $260 here
http://offroaddesign.com/catalog/Tra...seAdapters.htm

To my knowledge this would allow me to bolt up a 4l80e or 6l80e to my old style 8 bolt transfer case (would just need to swap the 27 spline input for a 32 spline which may require boring the input bearing hole on my NP205...http://www.offroaddesign.com/catalog...rcaseparts.htm) correct? This would then let me bolt up a 4wd trans without modification to the output shaft perhaps?

What about the VSS then? If I understand correctly there are 2 needed. One is internal to the transmission on the input side and then one would be on the output side of the transfer case and I would just have to machine the speedo housing on the outside of the NP205 like this....http://offroaddesign.com/catalog/NP205VSS.htm

[shenk10]

Okay did some more research. I am going to call Offroad Design to confirm all this, but this is what I found. http://offroaddesign.com/4L80ETech.htm

That concludes that you can use a 4wd 4l80e. In order to do so, this is what you'll need (4wd 4l80e to 8 bolt pattern NP205).

1. Start with a TH400 to NP205 Adapter - ORD P/N GU4032 - $260 (+$100? to machine down index to 4.8") I'm going to see if they will do this at ORD and cost. http://offroaddesign.com/catalog/Tra...seAdapters.htm

2. NP205 32 Spline Input Shaft - ORD P/N GU4037 - $293 (Need to see if this comes with the bearing as well. I already purchased an NP205 seal and gasket set) http://www.offroaddesign.com/catalog...rcaseparts.htm

3. NP205 Input Bearing Bore Machined to 90mm to Accept Larger Input Shaft Bearing. - $100? (Estimating, need to get an estimate)

4. VSS Modification for the NP205 - $125 (roughly $50 for sensor) Due to the 4wd transmission only having the VSS on the input side, an output VSS is required and can be done in the stock location on the NP205. http://offroaddesign.com/catalog/NP205VSS.htm


So in total to use a 4wd 4l80e to old style 8 bolt NP205 you are roughly looking at $928

[shenk10]

If you start with a 2wd 4l80e and are using an old style 8 bolt NP205 you would need.

1. Start with a TH400 to NP205 Adapter - ORD P/N GU4032 - $260 (+$100? to machine down index to 4.8") I'm going to see if they will do this at ORD and cost. http://offroaddesign.com/catalog/Tra...seAdapters.htm

2. NP205 32 Spline Input Shaft - ORD P/N GU4037 (shorter one, same part number) - $135 (Need to see if this comes with the bearing as well. I already purchased an NP205 seal and gasket set) http://www.offroaddesign.com/catalog...rcaseparts.htm

3. NP205 Input Bearing Bore Machined to 90mm to Accept Larger Input Shaft Bearing. - $100? (Estimating, need to get an estimate)

4. Cut 1 1/2" off the transmission output shaft (must be the fully splinned 2wd output shaft that sticks out of the housing 6 1/2" inches)

Wouldn't have to worry about the VSS since the 2wd has an output shaft VSS on the transmission. So you're looking at roughly $595.

With the advance adapter you're looking at $617 from Northwest Fabworks and would still need to machine the NP205, so roughly $717.

[shenk10]

And from more research it appears the same would apply to a 6l80e (not a 6l90e, the output spline is not 32). I am not sure if the adapter would require the same machining to 4.8" (would assume so since the bolt pattern is the same, but would need to double check). I haven't been able to confirm differences in output shafts yet for the 6l80e; I know it is the same for both 4wd (4l80e and 6l80e) versions, and it appears 2wds match as well (4l80e and 6l80e) therefor the 2wd would require the trans output shaft to be cut down as well.

The 6l80e is actually very similar in length (I think slightly shorter than a 4l60e) so I believe the transfer case could mount in the stock location and the engine would only have to move forward max 2 inches. With the 4l80e being longer, the trans/tc mount will have to move back.

[NorCalAnthony]

Just curious why not get a NP241 out of a 90-91 Blazer or Suburban? I found one pretty easily out of a 90 3/4 ton Burb that was originally mated to a TH400 (32 spline) and it bolted right up to my 4wd 4L80E and has the VSS in the tail shaft for the PCM. It only ran me $180 which is a lot cheaper than some of the options for trying to keep the older NP205...