4l80 2a np205

[SquareRoot]

Contemplating replacing my Th400 with a 4l80. Have a round pattern 205 ready to drop in. I've heard the 4l80 is basically a 400 with od. Will the two bolt together or is it going to require some special adapter?
TIA

 

[rpcraft]

They can but there is no real reason to stick with the np205 because the 4l80e has a super tall first gear and the np205 has a crappy low range so if you combine the two your effective crawl ratio will be garbage compared to what it can be. If you really want to chase that down you can check with advanced adapters and they can set you up. Alternatively you can look at a np208 that came off a th400 and it will bolt up using the adapter from the th400.

 

[climb-101]

i did a 4l80e/np205 for my truck. depending on the 205 that you have, you might need to swap input gears in them so they have the right spline count to match the 4l80e. if it’s a 205 that came off a th400 you should be good but those seem to be kind of hard to locate. advanced adaptors has them and so does off road designs

http://offroaddesign.com/catalog/TransferCaseAdapters.htm

 

[CSFJ]

i did a 4l80e/np205 for my truck. depending on the 205 that you have, you might need to swap input gears in them so they have the right spline count to match the 4l80e. if it’s a 205 that came off a th400 you should be good but those seem to be kind of hard to locate. advanced adaptors has them and so does off road designs

http://offroaddesign.com/catalog/TransferCaseAdapters.htm

The later (post '85) m465 manual switched to a 32 spline output, and the round adapter pattern also. I don't recall if the input snout on the 205 between the one behind the 465 and 400 was a different length or not.

 

[shiftpro]

They can but there is no real reason to stick with the np205 because the 4l80e has a super tall first gear and the np205 has a crappy low range so if you combine the two your effective crawl ratio will be garbage compared to what it can be. If you really want to chase that down you can check with advanced adapters and they can set you up. Alternatively you can look at a np208 that came off a th400 and it will bolt up using the adapter from the th400.

What other transfer cases can be set up with twin sticks? This imo is well worth it. Also, just to say, and auto can get away with taller crawl ratios than standard. Your torque converter gives a lower range from start, plus the slippage.

 

[SquareRoot]

My 205 has the 32 spline long input and fixed rear yoke. The best t-case for strenght and reliabilty IMO. I've already added the ORD twin sticks. I am just looking at ways to add an OD. The 4:56 gears and 1:1 high gear are killing me. I have everything needed to convert from auto to NV4500 but have run out of time & energy to see it thru. Gear vendors is too pricey for what it is. Thinking about an LS drivetrain swap but want to retain my 205 setup.

 

[bucket]

My 205 has the 32 spline long input and fixed rear yoke. The best t-case for strenght and reliabilty IMO. I've already added the ORD twin sticks. I am just looking at ways to add an OD. The 4:56 gears and 1:1 high gear are killing me. I have everything needed to convert from auto to NV4500 but have run out of time & energy to see it thru. Gear vendors is too pricey for what it is. Thinking about an LS drivetrain swap but want to retain my 205 setup.

What size tires? I run 36's with 4.56 and th400, imho it's a wonderful combination for all around driving and towing. Highway mileage is similar to the 33/3.73/700r4 combo I used to run in my Burb.

 

[SquareRoot]

I believe the tires are stock size. Maybe like 31-32? Here's a pic.

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[bucket]

Ah, I see. Yep, OD could be beneficial. Nice truck too!

 

[Craig Nedrow]

Here are a couple good resources.

https://www.700r4transmissionhq.com/ls-engine-swap-transmission-guide/
https://www.700r4transmissionhq.com/th400-vs-4l80e-differences/

The 1-3 gear ratios are the same with the OD having a .75 ratio. I have one that will be installed in a 73 K20 this winter, and will do a build thread when I get to it. My truck runs 4:11 Dana 60 rear, Dana 44 front. Have a set of 33, and wish for a little less rpm, but it tows great. Also have a set of 35 that I run in the summer hauling hay, they too work good, but still want the OD.

 

[SquareRoot]

Here are a couple good resources.

https://www.700r4transmissionhq.com/ls-engine-swap-transmission-guide/
https://www.700r4transmissionhq.com/th400-vs-4l80e-differences/

The 1-3 gear ratios are the same with the OD having a .75 ratio. I have one that will be installed in a 73 K20 this winter, and will do a build thread when I get to it. My truck runs 4:11 Dana 60 rear, Dana 44 front.

I had a built 700r in an El Camino with 3:73 gears and it worked well. I would not put one in a truck, especially a hd truck. Guarantee it wouldn't hold up if it was used as a truck.

 

[rpcraft]

I had a built 700r in an El Camino with 3:73 gears and it worked well. I would not put one in a truck, especially a hd truck. Guarantee it wouldn't hold up if it was used as a truck.

Depends a lot on the builder and heat management to be fair. I have seen some stump pulling big blocks backed up with 700r4's and they had a long and happy lifespan

 

[4WDKC]

What are you guys doing for the support bar of the tcase when switching to the 4l80?

 

[SquareRoot]

Was there ever a 4l80 4wd that came from the factory with support rods? I've never looked under a newer truck to see how things were laid out.

 

[rpcraft]

Was there ever a 4l80 4wd that came from the factory with support rods? I've never looked under a newer truck to see how things were laid out.

Pretty much no, not now. May as well Ditch the rod anyways though because it will no longer be long enough. The 4l80e is a few (or more) inches longer than the standard trans or a 400 that would have come out of it. You'll also need to plan on relocating your cross member back some (no problem, just drill 4 new holes) and then also shortening your driveshaft.