Allison Transmission Swap

[David Kennedy]

I'm looking to do the unthinkable... but not the impossible. Does anyone have any ideas what inputs an Allison 1000 needs for it to execute its shift schedule? I have a 2wd version of the Allison 1000 series from an 8.1-liter 2001 3500, and would like to try to addapt it to something other than an 8.1-liter or Duramax engine.

I assume that "Big Al" would be my "Obi-Won"
in this situation. How about it? Am I crazy Big Al?

Out of curriosity, are any of you intested in reading about a swap like this?

[BigAl]

You're not crazy..........just ambitious! tongue.gif
Presuming you aren't trying to put it behind some behemoth of an engine (in terms of HP and Torque), your first "opportunity" is going to be the adaptation between the engine and tranny. The converter housing on your particular tranny is designed to match the butt-end of both the 8.1L Vortec and 6.6L Duramax. There are other engines the tranny will bolt up to, but in virtually every case, it requires a different converter housing, and different flexplates/adapters.

If I knew what engine you were working with, I might be able to help a little better! ;)

[Dmax son]

In the May 2002 Petersen's 4wheel and off-road, they did a write up on putting a 8.1 liter in a 2001 suburban. They used a turbo 400 transmission. The 8.1 came with the allison 5 speed. In the article is said that "chevy hasn't changed the 90-degree V-8 bellhousing pattern on the new vortec engines."So I would guess that the allison would bolt up to any internally balanced engine.

Bryan

[David Kennedy]

Al,

My current engine is a 6.2-liter Diesel in an '82 GM truck. I doubt very much that the the current 8.1-liter converter will work behind the 6.2, but I believe the 6.2 will bolt up to the Allison bellhousing. Is there a torque converter available to work with the Allison and the 6.2? Or would I be better off swapping in a gas engine with the Allsion? Are there many internal differences between the gas and diesel Allisons?

Also, the transmission I have is a 2wd version. Can I convert it to a 4wd version with a new output shaft and a new tailshaft housing? Any chance the output shaft is the same for both versions?

And as far as controlling the Allison... I beleive I have every bit of the original vehicle's wiring, including what looks like a stand alone TCM. If I get the transmission to bolt to an engine, where do I begin with the electronic controls?

Thanks Al,

David

[77TransAm]

You've got your work cut out for you, it sounds like... smile.gif

Bellhousing: will bolt right up, so you shouldn't have any trouble there.
Converter: the gas converter is a TC210, the diesel converter you'll want is probably the TC211. That is an easy swap and no other parts are required to complete it.
Internals: with the exception of the torque converter, there are no hardware differences between a gas and a diesel transmission.
2WD to 4WD: you'll need a transfer case adapter (rear cover), an output shaft, a spacer, an output nut, and a new gasket. The big problem will be that I don't think any of the earlier t-cases will fit the back of the Allison; you'll have to get an NP261 or NP263. Then you'll need a t-case output yoke for the rear driveshaft, and possibly one for the front (I can't remember if that is the same size as the GMT400 yoke).

Other minor things to consider: you'll have to relocate the rear crossmember and insure that the installed angle of the engine and trans stay about what they were. That will mean raising or lowering the trans mount on the crossmember. Also, the Allison requires larger cooler lines than the 4L80E, so you'll need to make a set of those. That may mean bypassing the radiator, cause I don't think you'll have much luck getting the in-tank cooler size changed.

The electronics are a whole different story - with the old engine you're going to need an external Throttle Position Sensor (available from Allison) and a calibration for a generic diesel, since that's the only thing available that uses a TPS. I don't know if one of those is available with 4WD and the other stuff you'll have cobbled up, though, so that is probably going to be the sticking point on that project.

[David Kennedy]

Thanks for your help... I agree that the only t-case that will bolt up dirrectly is the NVG 261 or 263- both of which have front outputs on the Driver's side and I would want a passenger's side front output. The Older NVG 241 can accept the 261's input gear but would require a custom adapter... maybe I'll talk myself into a divorced t-case- but I don't want to.

As far as parts are concerned...
Where would I get the new output shaft, spacer, nut, etc that you list to convert to a 4wd configuration? Are there sources for these parts besided the GM dealer (they don't list any avaible parts yet at my local retailer).

Any idea how much a new converter would cost me? Thanks again.

[David Kennedy]

Another Question for you Big Al... does the 1000 series transmission have a "terminal RPM velocity"... I have heard rumors that there may be a RPM limit to itssafe opperation.

My email address is:
kennedyd@primediacmmg.com

Thanks for the help

[mark45678]

posted on allisons site....5000 rpm max