GM fullsize AWD Van Info thread
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Scotty D
Active member
Oil pressure is great, runs great, just seems to have developed a leak.
I just degreased the bottom and the front of the engine and will try to find some of that dye stuff.
Is there a front main seal that could have gone out?
Anybody put P-Metric tires on their vans? I’m interested in weight/mpg savings of p-metric and Cooper AT3 has 115 sidewalls which are well above weight capacity of the van. I’d go C or D LT tires but they all have way lower weight ratings than the P metrics and E range is more expensive and rides rough/doesn’t carry tread wear and often snow ratings on AT tires.
chiliVANilli
Adventurer
The tranny in 04 savana AWD is slipping in 2nd gear. I'm going to do a fluid change and see if that helps. The 4 spd in this thing is horrible in the mountains and is too wide of a range, especially when loaded down. Is there a swap to something with an overdrive that can be swapped in? Sure would make it a better driver.
Scotty D
Active member
As far as I know, there is no easy swap for the 4L60E and certainly not one that is not also a 4 speed.
Get a good rebuild done, mine cost about 1800 bucks and just live with it. Its the only weak link in our rigs.
I suppose you might be able to lower the gearing in the rear end?
I'm going to need a rebuild of my 4l60 in the near future and have been doing a fair amount of research on swapping in a 6l80. In theory it might be possible to do without losing any oem functionality, but definitely not cheap or easy. I've got it about 90% figured out. If even possible, it is going to involve parts and BCM modules from a newer 3/4 or 1 ton, some fabrication, a transfer case swap, and some custom driveshafts at the least. No way to know if it it will work for sure until I get all the parts together and try it.
First I need to rebuild both diffs and and re-gear to 4.11's to solve some other problems, then I start searching in earnest for parts so I can test my theory.
Herbie
Rendezvous Conspirator
I'm running P-metric tires on my Astro at the moment. I'm due to get new tires shortly, and I've been again asking myself whether I can safely stick with P-metric or if I should switch to LTs. I even started a whole thread on the subject: https://expeditionportal.com/forum/...nsidering-sticking-with-p-metric-tire.218966/
My P-Metric Geolandar G012s worked great for their life. The question is always how much abuse do I expect to subject the next set of tires to. However many people want to weigh in with anecdotes, I find that most of them are on much bigger/heavier rigs than mine, so it's hard to sort out what I really need. Depending on how close to the GVRW you're running, a Savanna/Express is at least closer.
Scotty D
Active member
That would be amazing.
I am guessing that first gear in the six speed tranny is much lower than our stock first gear. That alone would make it worth it.
The too tall gearing of first and reverse are a constant source of frustration off road for me
Searched the thread, and didn't see anyone mention the LT255/80/17. This seems like a pretty great upgrade. It's a perfect 33" tire, narrower tread for better traction offroad and in snow, LT sidewall for plenty of support. Anybody running this size on a normal lift? (2-3"?) I'm guessing it would fit since the 31.6" size fits with no lift on a standard van.
chiliVANilli
Adventurer
Fluid change didn't help much, a little better, but still slipping at shift point. The fluid was black. Doesn't make since at 78,000 miles, but poor maintenance is obviously the problem.
Probably going to buy a rebuilt online, and install myself or have a mechanic install, since there isn't anyone up in our mountain town that does transmission work. Has anyone gotten a transmission from somewhere that they would recommend?This just reminded me of a post I bookmarked on another forum... I have NO idea if it's pertinent to your issue but thought I'd share just in case it's an amazing quick fix.
www.cheaprvliving.com
"A note here about a common GM transmission issue. Keep Q-tips handy. These transmissions (depending on year) have sensors which are prone to losing contact because of fluid seepage. Common issue is that the van starts in 2nd gear and doesn't want to shift higher. Disconnect the sensor connector and clean both ends with the Q-tip. It takes 2 minutes and you're good to go for a while again."
Info On Common Vans
This thread is intended as a write-up on the typical issues, fixes, and plus sides for the most common van platforms. Know that it is not all encompassing and your individual experiences may very. This is simply some general information for you to have should you be looking for a van, have a van...
www.cheaprvliving.com
"A note here about a common GM transmission issue. Keep Q-tips handy. These transmissions (depending on year) have sensors which are prone to losing contact because of fluid seepage. Common issue is that the van starts in 2nd gear and doesn't want to shift higher. Disconnect the sensor connector and clean both ends with the Q-tip. It takes 2 minutes and you're good to go for a while again."
That is a big part of my motivation. I've got 3.42s in the diff, live in the mountains, and drive my van with a light offroad trailers to way out there camping spots. I have had whole offroad clubs an a ride stop to ask me "******?" deep in the canyons of Utah.
I was originally looking at a transfer case swap to get 4lo, but didn't want to lose AWD as my wife regularly drives the van on snowy and icy roads half the year. Given how capable and reliable our AWD is compared to anything that would swap in, losing the seamless OEM function, the increased risk to the pretty weak 7.2" front diff, and the fact that I need a transmission got me thinking.
Re-gearing the diffs to 4.11 on 265/75r16 tires will bring the final ratio just a smidge lower than factory 3.73s and 245/75r16's. (1st and OD, 12.58 and 2.88, 11.41 and 2.61 respectively) With the 4l60 this should help to compensate for the load and location of my van without compromising too much on economy (and might even help).
In my current setup (stock with 3.42s) final drive in first, OD and reverse are 10.47, 2.39 and 7.83 respectively. The problems I have with this setup is it is slow off the line, hunts gears constantly, has to downshift to third and scream to get up any incline at speed, sometimes requires a questionable amount of momentum offroad to avoid stalling out the converter and the brakes get a workout when descending anything at low speed.
With a NP242 and current gearing 4lo in 1st and reverse would be 28.36 and 21.22 respectively. Advantages here besides the obvious lower gearing offroad is the ability to use 2lo and keep moving if you break something in the front drivetrain. I am using the NP242 because it is the best option for a manual shift TC that still has a decent Fulltime 4wd mode. Down side is there is no great place in my van for the shifter that wouldn't be in the way and get constantly bumped by dogs, kids, or feet, it requires more thought from the driver, and I'm not sure how the FT4WD would perform and hold up under constant winter use under such a heavy load. Realistically these vans will never be rock crawlers and 4lo is likely overkill, at least for me.
With a 6l80 and 4.11s 1st, OD and reverse would be 16.56, 2.75 and 12.58 respectively with a lot more choices in between. For what I do with my van this combo would get me pretty close to 4lo type of performance with out the complexity for use as a daily, and will likely result in better fuel economy as well. A key function to this working well offroad is the ability to use the 6l80's manual mode to lock into the gear you need, and is one of the more interesting part of the conversion to figure out and keep everything looking OEM.
Right now I am stuck trying to figure out if there is an off the shelf adapter out there that will work to get the BW4473 on to the 6l80 without having to get a custom input shaft built for the TC. Most of the 4wd 6l80 swap stuff available is for Jeep L(X) swaps and involve replacing the input shaft on a Jeep TC for a 32 spline input.
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