4l80E to Atlas

RebelRider · Jul 23, 2014

I posted in the wanted section looking for an Atlas II to 4L80E adapter.

A couple of members said I might not need to buy one from advanced adapters ($200+). They said the stock adapter for an NVG261-3 will bolt to my atlas. Is this correct? Now, my 4L80E is a 2wd but that shouldn't make a difference with the tail section removed and the output shaft cut down, correct?

TBItoy · Jul 23, 2014

You'll lose the vss sensor on the tail shaft, unless you have one on the atlas.

The $175 kit from AA is for a 4wd 4l80e anyway. It lets you put the vss on the tail shaft of the trans, so you don't get skewed readings from the tail of the transfer case.

The factory ECM tells the TCM when the case is in low range and adjusts shift patterns accordingly.

RebelRider · Jul 23, 2014

Thanks for the reply. The vss on a 2wd 4l80 isn't in the tail shaft. It's in the trans. The AA adapter will work on the 2wd with the tail section removed an the shaft cut down. The VSS is sold separately from AA and is to be used in conjunction with the adapter.

TBItoy · Jul 23, 2014

RebelRider said:
Thanks for the reply. The vss on a 2wd 4l80 isn't in the tail shaft. It's in the trans. The AA adapter will work on the 2wd with the tail section removed an the shaft cut down. The VSS is sold separately from AA and is to be used in conjunction with the adapter.

Cool, didn't know that about the 2wd 4l80.

Search "4l80 241 adapter" on eBay . That is usually the cast iron version and an aluminum version of the adapter

If you search 4l80 261 adapter it will mostly bring up the aluminum version

RebelRider · Jul 23, 2014

I'm going for the iron one, right?

TBItoy · Jul 23, 2014

RebelRider said:
I'm going for the iron one, right?

Pick yer poison ( or metallic alloy in this case )

I'm not 100% on any of this, just recalling some of the research I've done

Np231/241/etc share the same bolt pattern with all the other round pattern cases (205,208,d300,atlas)

99.9% sure you'll need a clocking ring to get the case at an angle you can use.

Neal3000 · Jul 23, 2014

Clocking is built into the atlas

TBItoy · Jul 23, 2014

Neal3000 said:
Clocking is built into the atlas

Ah, I see that now. My stak was the same way.

RebelRider · Jul 23, 2014

Thanks for all of the info. I think ill give the gm adapter a shot. I found one for $60, so I'll take a chance.
I'll still have to give AA cash for my 32 spline input. It's 27 spline at the moment.

ALLJ · Jul 25, 2014

Its easier to use a 2wd version of the 4L80 in a swap because of the sensor I learned this the hard way when I did my 6.0 in my jeep I bought the 4wd version and had to end up swapping the internals to 2wd to move the sensor I used a Novak adapter and put a 241OR behind it the engine ECM thinks its still a 2wd vehicle shifts like a dream we actually done more tuning on the transmission than the motor to get the shift points where they needed to be

RebelRider · Jul 25, 2014

I'd like to say that I planned ahead for that very reason, but that's not the case. I bought an entire GMC pickup to swap the 6.0/trans into my toyota. It just happened to be 2wd.

I initially contacted northwest fab to see what I needed. They tried selling me the adapter and sensor which would have been $400. They then told me I'd have to swap outputs on the trans. That would require complete disassembly. I then contacted machinewave off of pirate and he cut through all the BS and told me the 2wd would not need the additional VSS adapter.

I did some measuring today and the OEM adapter should work once I swap my 32 spline input into my case an cut down my trans output.
I'll report back with the results.

ALLJ · Jul 25, 2014

good luck with it you should be ok mine was very simple to do

InDaShop · Jul 27, 2014

I responded in the Wanted thread, but this might get more people the right information.
4l80 to Atlas or 205 or even Stak and Hero, can be done with a stock GM 4wd adapter on the 4L80 (currently $49 on GmParts Direct)
A 4wd trans this is a bolt up. On a 2wd you just have to upbolt the tailhousing and bolt this up, as well as shorten the output shaft.
Its not real scientific, we machined mine off when we did the initial rebuild, but it ended up 1/16" too long, so I hit it with a cutoff wheel and dressed it with a flap disc. On the next rebuild we just cleaned it up on the lathe,

InDaShop said:
GM PN# 15724745

http://www.gmpartsdirect.com/
type in that PN.

Google images for what it looks like.
https://www.google.com/search?q=GM+PN%23+15724745&source=lnms&tbm=isch&sa=X&ei=JF7VU6ieIKLV8AHakoHgAg&ved=0CAgQ_AUoAw&biw=1600&bih=799

I run it in my racecar, 4l80 to an Atlas, I bought 3 when I ordered just to have the spares.
Dont really have a good pic of mine, but heres the few i got.

RebelRider · Sep 23, 2014

Just an update for future reference. The adapter fits good. The output shaft will have to be cut down 3 1/4"s.

InDaShop · Sep 23, 2014

That seems about right. I know it was a long ass chunk.

RebelRider · Mar 11, 2015

Bringing this back up.
My front shaft is binding pretty bad at full droop. I'm going to have the clock the atlas down a little. What are my best options for a clocking ring? Will a dana 300 clocking ring fit my setup?