Chevy & GMC Vans

This is bit long, sorry. Trying to make a decision on what direction to go.


I just found a guy selling a complete 1998 Safari with 187k miles on it for $600.

Considering buying it for the Borgwarrner TC, engine/tranny and assorted bits and pieces.

Being new to this area of AWD/4WD and the Borg Warrner TC, should I expect to be doing a complete rebuild before installing it or can I plug and play? The obvious consideration of it's condition aside.

Can't thank all of you who have contributed to the wealth of knowledge to this site. I have found it invaluable.

I also found a 2000 Blazer for $300 and have been considering swapping all that has been recommended from the Blazer to the Astro/Safari, etc, front end, TC, rear springs etc.

I won't be doing any real heavy wheeling but would like to have a capable trail truck. If the front diff has an open carrier what is the issue with these vans being run the Blazer TC in 4hi all the time?
I ask because over on another thread someone mentioned this was a bad idea.
I don't understand what the difference in 4Hi and the Borg Warnner TC is, or it is because of the limited amount of slip in the Borgwarrner TC?

Thanks for many info.

The bw case uses a viscous coupling. When there is wheel spin the difference in front/rear wheel speeds is noticed in the coupling. When the fluid shears it semi-solidifies transferring power to the front shaft. It works great right up until it doesn't. Running tires at different pressures is enough to cause shearing. Extended shearing will heat the fluid until it looses its ability to return to a liquid. A new coupling must then be installed and they are somewhat pricey. Over $300 iirc. You can throw in the used one and rebuild yours for a spare and just for the fun of seeing what's inside.
If you go the way of the blazer, it will be three or four button. Np233 or 236. Both have 2hi selection so there's no need to run 4hi. 4hi is not recommended on pavement even with the open front diff unless you also transplant the two piece front axle. I would still use 2hi regardless. It's just less wear and tear on all the spinny things.
I am in the process of doing the np236 four button swap into my 99. I just twent minutes ago downloaded all the wiring and plug/pin diagrams. The tc is installed and I just need to run some wiring to see if this will even work. So you can do the bw case or join me in the electronic jungle!

Thanks for the response Cap'in.

I have had jeeps before that I ran in 4hi all the time. Even did a 3month stint with 4hi engaged with a Power Locker in the front diff.

I blew the rear pinion out of it wheeling and was too broke to have a new gear set installed.
It had 40" Mickeys and Dana 44's front and rear. I had no choice but to drive it in FWD, man did the locker chunck like mad on tight corners. I thought about running with one hub unlocked but didn't want to stress the Locker.
In the end one of the hubs blew up on a corner leaving me strained, guess I blew the locker up in the end with all the cornering, meh, live and learn.

Anyway,back on track. I was asking about 4hi thinking these vans or the Blazer TC might have issues that are prone to failure running 4hi all the time. As in havering it in 4hi for bad winter conditions and forgetting it is engaged.



I really dig the 98 TC, a '98 was my first experiance with these AWD vans and fell in love with them and how it worked.

I would really like to run an electronic shift set up but have no luck with electronics, besides, a TC shifter looks cool sticking out of the floor in a van. I like to be different.

I will be following your install with much interest. Good luck man.

That ain't no Dana 44 under your van! The spindly little crap GM used looks like it should be in a respectable lawn tractor. You drive in four high on pacement and it won't take long before things start groaning and popping. 4 AUTO in the NP236 is a great feature. It's why I chose the 236 for my swap. 4AUTO is exactly what our 99+ vans have now. On demand awd. Other members have put in manual tc's and noted a " darty" front end in the snow. My van is routinely full of Boy Scout while pulling a trailer-I don't need any surprises

truC wrote: I really dig the 98 TC, a '98 was my first experiance with these AWD vans and fell in love with them and how it worked.

I would really like to run an electronic shift set up but have no luck with electronics, besides, a TC shifter looks cool sticking out of the floor in a van. I like to be different.

I will be following your install with much interest. Good luck man.

If you want the Viscous Coupler and lowrange in a manual shift, go with an NP 249. I wouldn't do that without putting in a new VC though. I too prefer a manual shift and the lack of lag that can be an issue with the autos. Having a pre-'99 didn't allow for electronics anyway. I opted for an NP 242 as I wanted 2wd (not available in 249) and didn't want to drop the 2 bucks for a new VC. It's a bit of work to install, but I use the AWD much of the winter here so it was well worth the energy.

And, like CC said, you'll blow up the frontend in no time running "part time" 4wd on pavement.