REAL WORLD differences between 98 and 99 AWD ??

[LAZ 1]

I have BOTH 1998 AND 1999 AWD Safaris.

I suppose there is more to the differences in the transfer cases and AWD systems than just GM marketing and hype, but honestly, with my limited experience with each, they don't feel all that different to me.

I plan on investing some time and effort and $$$ into the 1999 as a genuine rough road LONG TERM CAMPING vehicle. aka Going to the BAJA FOR THIS COMING WINTER.

Can some one give me a run down on the pros and cons and relative merits and weak spots of each version of the AWD??

Longevity and durability in rough conditions with heavy loads??
Recommended MODS and tweaks to toughen up the drive train??

And as a side issue,

The 1999 came with 3.42 gears. I will be running LT 235/75/R15 MUD TERRAIN type tires and LOTS OF WEIGHT!! Probably will be running close to max GVW all the time.

Would I be better off modding the 1998, which came with the older style AWD but has 3.74 gearing??

Should I really be looking at 4.10 gears and some type of locking rear diff whichever rig I build??

thanks in advance,
LAZ 1
[;{)

[Stroverlander]

I had a '97 AWD 3.42 with Borg Warner and my '04 AWD 3.73 with NP136 and G80 rear locker. The '97 was unstoppable in heavy snow, especially with snow tires. I haven't had much opportunity to drive the '04 in heavy snow but it works well in light snow, slush and ice, the locker really helps as well.

The '97 was lighter and I didn't run larger tires on it but I wouldn't want the 3.42 gears on my '04 with 31" tires as I feel 3.73 is marginal at best especially with the van being heavier and loaded frequently.

I'd say both have been about equal in terms of reliability, the NP136 can be susceptible to encoder shift motor failure.

I guess you just have to consider what type of terrain and conditions you're going to be dealing with and determine if you require a gearing change and/or locker.

[LAZ 1]

I have a chance to get a supposedly good 1997 Transmission and transfer case which is already pulled out at a decent price. I was thinking of getting it as a spare and slowly building up the trans with some HD parts as budget allows.

Would the trans and transfer case from a 97 be an easy swap into my 1999??

Any recommendations as to what to look for and what to beef up??

I already had the P1870 error fixed on my 98 trans so I know about the valve rebore job.

Thanks.

[Herbie]

I have a chance to get a supposedly good 1997 Transmission and transfer case which is already pulled out at a decent price. I was thinking of getting it as a spare and slowly building up the trans with some HD parts as budget allows.

Would the trans and transfer case from a 97 be an easy swap into my 1999??

Any recommendations as to what to look for and what to beef up??

I already had the P1870 error fixed on my 98 trans so I know about the valve rebore job.

Thanks.

I wouldn't worry about trying to "build up" the tranny and t-case, either of the ones you have will be plenty stout for what you're describing. More importantly, I do not think there is a whole lot you can do to make the stock parts more heavy duty. Upgrading to a stouter tranny or t-case would be beyond the scope of this discussion - you'd need to try to fit 4L80e/np24x type parts or better, so now you're getting way into custom-land.

The real issue will be the gearing. Based on my experience with a lifted/30"-tired/loaded van, I'd say the 4.10 gearing should be high on your list if you really will be doing lots of weight and bigger tires. I have the 3.42 gears currently, and it's tolerable but not awesome. Only thing that keeps me from doing the re-gear is the cost of having the setup done, and when I start that project, I'll be doing 4.11 and a locker in the rear. *IF* I had the 3.73 gears, I'd probably be tempted to try to stick it out a while longer, but conventional wisdom around here indicates the 4.11 is the way to go.

I don't think there's a problem with the design of either t-case system. Build up whichever van will suit your needs otherwise.

If you're wanting to "harden" the van for a long Baja expedition, there's really only one item: Add the mandatory transmission cooler. After that, you're better off thinking in terms of preventative maintenance, rather than "mods". Replace the upper and lower balljoints and ilder arms, etc. up front - those are the things that will go, and any lift you add will exacerbate the wear there. Basically all the things that are covered here and in the Off-Road section.

[LAZ 1]

"If you're wanting to "harden" the van for a long Baja expedition, there's really only one item: Add the mandatory transmission cooler. After that, you're better off thinking in terms of preventative maintenance, rather than "mods". Replace the upper and lower balljoints and ilder arms, etc. up front - those are the things that will go, and any lift you add will exacerbate the wear there. Basically all the things that are covered here and in the Off-Road section."

Good advice.
thanks
LAZ 1

[LiftedAWDAstro]

First thing is a large transmission cooler. After that, I would build the 98 for what you want. The BW4472 transfer case is way more reliable with only a few failures noted on here where the NP136 is well documented with issues. You already have built the tranny up enough to make it reliable (when adding the cooler). The 98 has the 3.73 gears...all you need to do is add a Power Trax No-slip locker to the rear open diff and you have true 3 wheel drive. The G80 posi in the 99 can break easily when stuck and it suddenly locks in.

As for suspension mods...do an add-a-leaf in the rear, maybe even a second added leaf if really heavily loaded. Do the body lift up front and add lift with torsions as needed for tire clearance. Keep it to the lowest amount needed for idler arm longevity. Any parts replaced up front should be Moog parts.

[LAZ 1]

First thing is a large transmission cooler. After that, I would build the 98 for what you want. The BW4472 transfer case is way more reliable with only a few failures noted on here where the NP136 is well documented with issues. The 98 has the 3.73 gears...all you need to do is add a Power Trax No-slip locker to the rear open diff and you have true 3 wheel drive. The G80 posi in the 99 can break easily when stuck and it suddenly locks in.

As for suspension mods...do an add-a-leaf in the rear, maybe even a second added leaf if really heavily loaded. Do the body lift up front and add lift with torsions as needed for tire clearance. Keep it to the lowest amount needed for idler arm longevity. Any parts replaced up front should be Moog parts.

Great advice.
I will definitely look into the trans cooler as first priority.
thanks
LAZ 1