Horse_Apple

Hello. I wrote a long intro but my 2 year old daughter cunningly slapped the keyboard!!!

I was pointed to the website by a colleague and I have a few questions to ask and I'd be very grateful if anyone can help.

I'm a big Rangie Classic fan having owned 90s ones and the last Overfinch 570 conversion carried out in 2005.

I currently own a 1972 2 door and am rebuilding it to be a fast and comfortable long distance road car. It won't go offroad unless I get a corner wrong

The logical route in order to get the power and ease of running above what a Rover v8 can deliver is to go down the LS route.

It is relatively straight forward to install a crate LS3, mate to an uprated ZF 4 speed and beef up the diffs with Quaifes along with the rest of the train etc.

However, I am exploring something a little different and this is what I need advice on:

Basically, I like the idea of using an L99 and a more modern/intelligent auto box.

While the L92 has lower outputs than the LS3 it still has more power than I am actually looking for but I like the idea of running DoD and VVT to try and eek out better range. The same logic lies behind looking at the 6L80 transmission.

Now, I know that the 4L80 mates strait to the LS engines and that you can obtain adaptors to connect them to the Lt230 trans. I know that it is a dumb box so easy to take control of. But I want to explore 6 gears. I know TCI do a 6 speed version and this would be a last resort.

The 6L80 is chunkier but the trans tunnel on Rangies just unbolts so if needed I can fabricate a new one to give required space.

What I am not sure of is whether you can, or if anyone has, mated this more modern box to the LT230 transfer box?

If it can't be done then the idea kind of dies at this point.

My very crude idea at the moment is to ship over a 2007- Tahoe or Escalade from the US and strip this of the engine, box and management system and also re-use the instrument clustre. I am obviously expecting various electronic issues with regards to removing the running gear from its original host and getting it to work independently, but if I can manage that side it seems to have more potential to being trouble free than buying parts separately and trying to get them to work together.

So, where I really need help is with regard to experience of trying to work with post 2007 Chevy 6.2L plus 6L80 box, whether this box can be mated to the LT230 (or if there is another solution) and whether there are obvious electric issues that will completely stop a factory set up from running properly outside of its original vehicle.

Thanks very much for any help or advice you can offer.

Tim.

91sonomast

If the 230 can't be used and since you aren't going to be using the truck offroad, why not use the t-case out of the donor vehicle?

71403

4l80e isn't a "dumb" box - needs PCM to control it. I would avoid the TCI unit since it needs it's own proprietary controller. And you'll never find one if it craps out far from home.

If shipping over a whole donor vehicle might as well use the xfer case and all unless there's an incredible reason not to.

Horse_Apple

Thanks. The main reason for trying to retain the LT230 is that over here you lose points as you lose originality in the build and you can reach a point where you can no longer retain the original registration. This is a risk on a 1972 vehicle as pre 73 cars are tax free. As a result, there are big value swings as you go from 72 to 73.

Also, I believe they are a different design in that the TB for the 6L80 has the rear out put inline with the gearbox shaft but on the LT230 the rear output is inline with the front output?

With the 6l80, I was wondering also, whether the output was on the same side as the ZF box, ie on the right?

On the TCI box, what is the general consensus as to it's quality/use ability etc?

Thanks again.

Tim.

Horse_Apple

A couple of questions re the 6 v 4L80:

Is it correct that the 6 is a few inches shorter?

Do the two boxes have the same rear fittings?

Ie could you fit a Marks LT230 adaptor plate for a 4L80 onto the back of the 6 and then mill up a simple adaptor extension to the LT230?

zuffen

Do some more searching.

From what I can see a few Aussies are using the Marks adaprter on the 6l80.

If I were doing the swap I'd look at using the engine/trans/transfer from the donor as it all works without mucking around.

I have a DAKAR with a Lexus engine and Nissan Patrol transmission and transfer and it works realy well. I lost full time 4wd but haven't noticed the loss.

I also have a 6l80 hooked up to a a patrol transfer (different vehicle) and it works realy well.

Horse_Apple

Thanks Zuffen.

My understanding is that the Transfer Box on the 6L80 from something like a Tahoe or Escalade is biased to the left, whereas the Rangie needs the output to be on the right.

Also, looking at some images of the 6L80 it looks to me like the TB doesn't have linear front and rear output but rather the offset is used for the front connection and the rear connection is actually straight through, linear from the trans shaft? Any info confirming or correcting that would be gratefully received.

The solution that I'm seeing at the moment is to use Marks' 4L80 adaptor but with an adaptor extension to ensure the LT230 and front shaft can clear the wider pan on the 6L80. This means replacing the front and rear shafts as the standard lengths will no longer fit.

91sonomast

No I'm sure your original shafts won't work. But yes, GM t-cases are offset to the left due to the exhaust system, the fuel tanks are also on the left. They offset them to the left as to no interfere with exhaust pipe routing, and the GM t-cases do have the output for the rear diff straight out the back.

Horse_Apple

Thanks. That's cleared quite a bit up.

It does look like the TCI 6X may be the solution here then. I'd much prefer the 6L80 but it does look like mating the LT230 is the core option and that will require setting back away from the tranny case so having bespoke drive shafts made, or the existing ones cut and adjusted.

So, settling on using the TCI6x and their controller, I'd still like to use the L92 opposed to the LS3.

However, depending on where you read the L92 has VVT but it's the L99 that has VVT and DoD (AFM), but some sources say that the Escalade runs AFM and has the L92.

Can anyone confirm this either way?