Good day everyone! So a while ago I bought a 1999 Blazer that turned out to be a HUGE p.o.s. I gave up and bought a 1998 dirt cheap and have been using parts from the '99, such as the MAF sensor, fuel tank, PS hoses and pump, and select body parts. My question today is about the drive train:
The '99 had the auto 4x4 selector and the '98 has just the 3-button panel. The 4x4 works intermittently, so I was curious as to whether I could swap out the transfer cases and front diffs from the one that I know works-even though they are different-and if it would be easy enough to change the wiring harnesses. Obviously it would be easier to fix the tc, but having the option of auto 4x4 is kind of appealing. I'm not afraid to get a little dirty, so doing it myself is fun.

Just need some info as to whether the swap is worth my time or if I should just evaluate and repair the stuff I have in there.

Thanks!

 

I would fix the unit you have in it, the two systems are totally different so everything would need changed over. The harness from the switch to the computer and on down to the TFC, you would have to split it out or add/modify the existing wires.


The Auto system uses a clutch in the TFC versus the solid engagement in the 3 button one, the only problems I've seen in the 3 button unit (internally) were busted/worn parts from the owner doing stupid things or a low fluid level. More things to go wrong with the clutch system, and the encoder motor has a brake on it that goes out a lot. Not that the 3 button encoder motor is bulletproof, but it is simpler. Auto has 2 extra speed sensors to go bad...


The auto system also uses a special ($$$) GM fluid or the clutch can burn up or chatter, the 3 button uses plain ATF.


Personally, I find the Auto feature un-appealing. There is always a little bit of pressure on the clutch, even in 2 wheel. This turns the front driveshaft, putting wear on the U-joints, pinion bearings, etc. With the system set in auto the front axles are engaged too, adding even more drag and reducing your MPG even further. If your tire circumference front to back is off by even a little bit, the speed differential between the front and rear driveshafts is interpreted as loss of traction and the clutch engages, that is bad on dry pavement. So no replacing tires in less than a full set, and they have to be matched.


I miss the old lever style 4X4. Lube the pivots occasionally and engage it a few times a year, very few issues and the ones that did crop up were usually an obvious mechanical failure. With the buttons, you still have all the mechanical failures plus electronics!