.....

 

The specs for a 2002 GMC Yukon Denali XL are:
Max Towing 7800 lbs
Gross Weight 7000 lbs


It came with a 4L60E. Sounds like enough capacity to me.

 

Okay... then why did shortly after that they start using the 80? It doesn't matter man, believe whatever you want to believe. I've seen enough failed 60s to know. They aren't good transmission. For what you'll pay for a rock solid 60 you could have bought an 80 rebuilt it with a standard overhaul kit and had money left over.

 

Look up connector C0637 pin 17 it's on the ECM



From the Rave,


Engine Control Module (ECM)
The ECM provides an engine speed signal on a WS wire to header C0291. From the header
the signal is passed on a WS wire to the instrument pack for tachometer operation. A second
WS wire is connected from the header to the SLABS ECU pin C0655-10

Engine speed signal
The ACE ECU receives an engine speed input signal from the ECM.
On V8 engine vehicles the signal is passed from ECM pin C0637-17 on a WS wire, via
header C0291, to ACE ECU pin C0647-19.

 

After much searching and head scratching, I finally decided to see for myself why the LT230 won't work behind the GM 4L60 - 65. For some reason no one I asked would come right out and say "It won't work...give up trying to find an adapter kit". From my own very crude mockup shown below, I would say "It won't work... give up trying to find an adapter kit!" The guys on Pirate 4x4 seem to think it would be child's play to divorce an LT230, I'm not sold on that idea yet (doesn't look so easy to me..in a Discovery anyway), I think it might be easier (not cheaper) to backup and swap the 4L65E for a 4L80E which has an adapter kit available.

 

Why do you want to go back to the LT230 mate?

I've been given approval to start mine soon. I'll be going down a different path though. We never got the 5.3 LS1s but we have plenty of 5.7s around here. I have a manual in my disco 2 and I'm going to adapt that to the ls motor.

Does your new motor have plenty of torque down low compared to the rover V8?

 

excited to see this. good luck

 

Just seemed like the "Rover" thing to do. But really it's because my choice of transfer case has been disappointing so far. The two GM cases that I have are both LEFT side drop and therefore have to run upside down. I do not think this will work reliably in the long run. (One of the main reasons to do the swap is for increased reliability). The rear driveshaft angle is also too extreme to be reliable. I will address the options I am considering in another post.



Way better power and torque and no random code throwing ... just crank it up and go.

 

My advice is to keep the manual trans. and LT230, adapt that to the LSX. Using the 5.7L is no problem, very few differences. Hopefully there is an adapter for manual transmission available. I don't know how the adapter you plan to use is configured, but if it is a bell housing swap then everything should be spaced in the stock location. If it is a plate style adapter, then you should push the engine as far forward as necessary (move the radiator and eliminate the cooler) to keep the trans. and transfer case in stock location. Be aware the front propshaft will very close to the bellhousing, it may have to be modified.

 

I have been losing sleep at night (and during the day) struggling with transfer case options. It really shouldn't be this hard.


OPTION #1: Current config.: NP(XXX) not sure which one, but its AWD, no levers or switches with automatic locking. It's a left drop running upside down.
Problems with this are: No low range. Builds up pressure inside the case and spits oil out any opening when it is run over 55 mph. Very noisy (can't be good) during wrap up (when you let off the gas). Extreme angle on the rear propshaft.
Below 50 mph it is very quiet and well behaved.


OPTION #2: NP241C Late '80s and '90s Blazers and 'burbs, right side drop aluminum case. Low range is 2.72:1, weighs in at 160 -170lbs. Later ones were probably mated to 4L60E, so if you find the right one, it will bolt up with 6 hole adapter (I have) and everybody is happy once again. They have two different input shaft stick out lengths (on the "C" model - Chevy) so you have to pay attention. NP241C of the right vintage will have the proper VSS connector. This is still gonna have the bad rear propshaft angle! This would also require some custom TC shift levers and rods and a place in the cab to mount them.



OPTION #3: Divorce mount the LT230 'cause it will NOT bolt to the back of a 4L60E with any kind of homemade adapter. (See my post above) You will need a 25 spline shaft welded to either a 4 hole flange or a u-joint. You will also need a 2WD transmission of your choice, a xx spline slip yoke and a custom built very short shaft. The case will have to be mounted on custom mounts and will also most likely have a very long front propshaft that wants to occupy the same space as transmission cross member, exhaust crossover and front cross member. Shorter rear propshaft should not be a problem other than 'mo money. This config. would also restore on demand TC locking, low range and parking brake. Yeah!




OPTION #4: Purchase a 4L80E 4WD transmission and a Mark's adapter for the LT230. Custom mounts for the transmission and transfer case. This option introduces another problem. Best I can tell, the Mark's adapter does not have a provision for the VSS sensor. I believe Jags that Run has some sort of kit for this, but I got a headache reading all the different shaft and gear combinations to make it work. But it is very doable.




Of course there are infinite combinations out there and all will have their own set of problems. All of these conversions will require custom built propshafts and most will require custom transmission and TC mounting.