Chevy & GMC Vans

I admit I'm on the fence on final ratio. If I had a G80 and 3.73s, I'd probably just leave it alone, especially since I'm currently only running 245/70-16 (29.5") tires.

However, I have open diffs and 3.42s, so I really need to make some change. Seems silly to spend the cash on gears and a locker just to go to 3.73s, if I might want more tire later (although I doubt it, as I prefer not to raise the front any farther).

At any rate, you've convinced me the G80 isn't the right path, so I guess I get the Detroit locker and just be extra careful on the snow...

Decisions, decisions...

Herbie,

I wouldn't fear the gear! Go with 4.10's. You won't notice any worse fuel economy, you'll have more towing, pulling and climbing power and the van won't bog on hills. I went with 4.10's in my 05 that ran no lift and only slightly larger diameter tires. My mileage went from around a 15.3 average to a 14.7 average. Also since you rarely drive in snow, look at the Powertrax No-Slip locker. It is a much cheaper (to buy and install) option than a Detroit locker. You can install one with basic hand tools and no setup needed!

The 3.73 and 30.7" tires I'm running now is a little sluggish in OD and hunts a bit though I've gotten used to it somewhat.

Looking at the gearing/rpm calculator on Randy's Ring & Pinion, 4.10 gears and my 30.7" tires would put me near identical rpm cruising at 70 mph compared to my current stock 3.73 gears and original 27.8" tires and I think I'd be happy enough with that unless I ever went to a larger diameter tire.

With your 29.5" tire diameter, you'd be turning a couple hundred more rpm at that speed which I don't think is a big deal. The low end grunt, heavy load and towing benefits that Lifted mention would certainly make it worthwhile.

I have 3.73's here driving around at 6000-10000 and it is brutal. With the next astro, I will be going to at least 4.10's and even up to 4.56's with 31's. It's just nuts to put 3.73's into anything but cars...but that's just me. I do however appreciate the semi lockable nature of my current axle. A true open diff would sink me with the current non functioning transfer case.

beware of 4.56's with these rigs. The ring and pinion are quite small in the 7.2" front carrier. They become embarrassingly small at 4.56 and are avoided like the plague by S10 offroaders due to catastrophic failures

Ok, based on what you are saying...4.10 is the limit?

i have no personal involvement with these and the info I am imparting is what I have read on offroading s10 and zr2 sites. I like my 3.73's and they are beloved with the S-10 offroaders for their durability. There is much talk of 4.56 sets grenading off road, not much with the 4.10

http://www.zr2usa.com/mboard/index.php? ... omsearch=1
Here is a link to the discussion on 4.56 gearing in our 7.2" ifs