on the way to option NP8 .....transfer case swap 1997 Tahoe 2dr

[harascho]

Hi there,

it was a lazy sunday over here in the middle of Germany. I removed the gas tank to service the fuel level sensor and changed my NP243 for the new NP246.

With the NP246 the proper TCCM and all related sensors I hope to have auto 4x4 soon and all the stuff of option NP8.
The transfercase I used in my swap was still the 1997 electric shift NP243. To get the drivetrain running correct I opted for a 2007 NP246 and I will built a harness to have a NP8 system running in my 1997 Tahoe.
Then finally AFM and 4wd should work correct with the proper 4wd tunes in E38 and T42.

Here are some pics:

first the fuelpump module after one German winter:



even on the fuelline connections the salt did leave traces:



here is the new NP246 from Spaldings:





the old NP243 just removed





my old driveshafts and some of a NP8 option SUV



4L60E waiting for transfercase


only a little mess with the tranny fluid in the extension housing. Why is oil in the extension housing in 4wd applications at all? I understand the need in 2wd applications to lubricate the oil seal but in a 4wd??



and a 1997 front axle actuator (black) beside a 2007 one (white)... no difference at all..

[harascho]

I had time the last week so I completed the swap. The new NVG246 is in place, I had to re-route parts of the y-pipe, the rear shaft fits without modification, the front shaft is a little short and also too big in diameter, it hits the gear selector of the tranny.





I modified my old 1997 front shaft which is solid and smaller in diameter where it is close to the tranny ( cut a piece of the splined section at the transfer case end and changed the rear yoke to the slip yoke the front output of the NVG246 needs). I have two slip sections in that shaft now, one in the transfer case, the other in the shaft itsself.




I will do some tests with this setup, then I have to decide if it's ok to have a shop weld the shafts slip section or if I need further mods as a double cardan. So far it looks straight, there is not much of an angle to the front diff. We will see.

Wiring is done, I built a harness and stuffed the 2007 TCCM under the dash. I 've choosen the tranny cable entrance to route all inside the Tahoe.



I did some checks with the IGN on. 2H and auto 4wd seem to work ( at least the switch positions say this..) also neutral is ok. 4H and 4L don't work, the TCCM switches back to 2H or auto 4wd. Could be 'cause the shafts didn't turn so far and there were no signals from the shaft speed sensors.


I changed the tunes in TCM and ECM for the 4wd ones.

The gas tank is still outside of the Tahoe. I changed the fuel level sensor ( had a bad connection where the two wires enter the circuit board..) and built a longer rod for the sensors level arm) I now have 250 R when the arm is level with the bottom and about 50R when it touches the top. (I couldn't get the 40R.. I guess I can arrange that in EFIlive.)



Ok, this evening I mounted the tank, put some gas in and started ..... hmm.. at first the gas gauge still didn't move, eben after another 15gal in the tank. The gas gauge needle began to move after I modified the tune and enabled all fuel level sensor 1 faults. Now I have 140R across the sensor and the gauge reads half... ok. Next I realized at the gas station that filling up was possible without spilling the gas all over. I mounted a bigger dia vent hose to the moddle of the fuel pump module, now filling up is quick and easy.... ok

I payed close attention to do last minute checks before I mount the tank. I removed one of the rollover valves and actuated the rod of the level sensor with a wire. I had 250 - 50R through the full movement of the rod....
I removed the baffles ( the complete plastic kind of a bucket inside the tank...had to cut it in pieces when it still was in the tank to remove it...) and now I have the 2007 fuel pump unit in the middle of my gas tank. I hope it will stay that way...




Here are sime pics of the modified dash (2007 cluster, 2997 headlight switch and TC switch.) I have to work on this a bit more as soon as I have time..






Next the TC modes. I have 2wd and neutral for sure. In auto 4wd I guess I have 4wd cause its very hard to make a turn, it's like 4wd in the old NP243. I don't have 4lo and if auto 4wd is 4wd the the auto mode is missing. I did a quick check with a second TC encoder / motor unit.. still the same.

So now the fun part begins..... where are the missing TC modes ???

Harald

[tanz45]

Looks good man!

Lots of hard work. How lifted are you? Any pics?

[harascho]

Hi there,

here's a link to an online album which shows my drive train swap.

Pictures by harascho_album - Photobucket

I bought the Tahoe 2005 in CA got it lifted with a 6" fabtech knuckle lift and had wheels and tires.

I don't like the front ifs and the knuckle lift at all cause it's a weak point, no articulation and the 4" wider front track bothers me also . Sooner or later I will do a SFA swap. I like a multi link suspension with coils but as I am in Germany parts and knowledge will be a problem.

I buy an SUV in CA from time to time so I could use one for shipping all the stuff to Germany, that's no problem. But with such a project you need parts sources through out the work...

Harald

what setup do you have? pics?

[tanz45]

In the process of SFA on my 99 Silvy. There is a thread in the 4x4 section. Hoping to work some bugs out this weekend and get it on the road for some test drives. Only 2wd for now, need to get a front yoke and drive shaft made. but I'm sure I can throw some mud for now with the locked rear.