Transfer case swap to a 2 speed - manual shift

[mdmead]

Great info!

Regarding raising the engine/trans/t-case 2", I think that is what I'll end up doing with my 5.3L swap. In my case it is because the oil pan interferes with the front diff, but I really like the idea of pulling the oil pan up farther from harm as I've scraped my stock one a few times off road. (With a 4-5" welded in subframe lift, I should have lots of clearance on top of the engine to play with.

[doyoulikeithere]

Oh Ya I remembered one more thing .
The T5 has a bunch of brace bars.
2 bars run from the engine mounts to the bottom sides of the bellhousing.
2 bars run from the bottom sides of the bellhousing to the bottom centre of the tailhousing, like a wishbone.
1 bar runs from the top left side of the tailhousing, by the shifter, up to the rear face of the left cylinder head.
I wanted to keep all that installed to hold everything in snug and secure
But when I changed it to a 4wd tailhousing, I had to make a new top-left brace bar cuz the mounting point changed.
I used that bar that came off of the stock AWD transfer case that was earlier quoted as 'should be hung on the wall'.
In a sense that still holds true cuz now its a transmission brace, not a transfer case brace.
I cut/bent/welded it now it makes a beefy brace bar for that spot on my T5.
There is pix of some of this stuff in here...
viewtopic.php?f=16&t=6380

[krsowles]

I'm loving the info flowing here! When I lift my 91 awd this summer, (4") I would like to install a 2-speed, manual shift TC with an auto trans. I want to start finding parts now, so here is my question; Most people in this world are smarter than I am, can someone state, somewhat simply, what I want for a transmission/transfer case combo? Would prefer to stay with stock, rebuilt v6. I cannot seem to follow anything right now, well enough to feel confident I'm getting right stuff. Just for fun, the tire size I will shoot for will be 30-31", what gear ratio do folks suggest? I live in Vermont, lots of hills! Would love to travel the interstate as well, so need a happy compromise. I understand the job is not "bolt-in" and will fight the battles, but it seems like many of you have done this and can save me some of the learning curve! Thanks so much! Kelly
:-k

[MountainManJoe]

You are in the right section. Did you check out the other threads? Lifted is working on one right now.

[krsowles]

I've checked out several, yes. Just can't seem to cipher all the numbers, thoughts and afterthoughts! Two kids home sick and I'm @ 101, with what feels kinda like a migraine but I can open my eyes and see light without scurrying like a vampire! I'm hoping for someone to say "this seems to be easiest route, look for an XXX donor vehicle and some blah blahs too". Seems to me I have multiple yj driveshafts and several xfer cases too. Two nps (231s?) from 6cyl yjs and a ba5? peugeot. A good example, I can't remember what I have right now! I would also like to thank you folks for the therapy. Back in the day when sick, I stayed in bed. With boys, I have to get up but my rest is a quiet room trying to read about Astros! thanks, Kelly

[MountainManJoe]

Yeah I have a hard time wrapping my mind around it too. It sounds like none of them are "drop-in" and always require rebuilding/modification/rewiring. The 231 requires crossmember notching.

[krsowles]

My wife is home helping now and I'm hiding. If I re-read this (over and over again) correctly, my best bet would be a s-10 or s-10 blazer donor. The 231c TC seems to fit relatively easy, has semi factory shifter, rear springs should work for 4" lift and if lucky enough perhaps 4.10 gears front and rear. So possible axle swaps both ends? Possible or desireable? Chime in with any input or stuff I've overlooked cause I do it often. Thanks Kelly

[photo_van]

The easiest tc to put in an Astro is a 231c from an S-10 Blazer or pickup. You will need a new front driveshaft and a shifter. You may not have to notch the cross member if you do a body lift and shim up the transmission mount a little.

Keep in mind, if you use a 231 you will no longer have AWD, just 4wd (hi and lo) and 2wd. Some have said to have issues with 4wd in our vans on slushy roads. I have a 242 in mine which has awd, 4 hi and low, 2wd, but it was definitely NOT a bolt up!

As far as gearing, many like 4:10 for 31" tires, I have them but yet to install. I can say that my 3:43's feel "tall" for mountain driving with 31's.

[photo_van]

Looks like we posted up at the same time!

I'll be putting an S10 frontend in mine when I change gearing. I'm hoping for a bit better mph with the disconnect. You can't use the s10 rearend, different offset.

As far as blazer springs, they must be from an older model (can't remember the years off hand, but it's on here somewhere.

[doyoulikeithere]

Wow, there's some great info here, and I find more every time I read it again!
Thing is you cant just make a list if you need to account for a bunch of variation between year/model/wants/needs/budgets/wives/... You get the picture.

I think it is best to stick with a Tcase that is of the sameish year so that your computer will play nice with it if its a newer van. But I could be wrong, Ive never had a newer van than 95.
Anyways, I got a few more tidbits to toss in the ring. I put an NP231C into my 87 Stro. I used a shifter on the floor from a late 70s to mid 80s chevy 4x4 pickup, like we saw in the red pic earlier up^. It fit right in the original hole for the 5 speed lever. I ditched the stock 5spd shifter offset thingy and cut a new hole in the floor just to the right of the Tcase lever.

The 3.73:1 S-10 Axle I put in front had an actual U joint flange, and so did the 88 sten NP231 I found for 150 bux, with a mechanical speedo. Then, I found a skinny front driveshaft from a Jeep CJ7, and bolted it straight into the front, with new UJs of course. It slips yoke just barely closed enough to let it fall into the flange cups, but opened up about a 5/8ths once its bolted up.. I realize it isnt super strong, but I'm not pushing it either. Its a part time S-10 front axle so it only gets used in 4wd occasionally if I get stuck, which really hasn't happened yet in 2wd.

I don't keep real gas records, I just fill it up and go. It seems to get pretty far on one 65 litre tank though. I can drive to & from work 75K, and then some all week and cruise around on the weekend too at least, before its gasping...

I did not need to notch my cross-member. I did need to lift my engine up 2" in order to get clearance enough to put the clutch slave, and the front drive-shaft in the same place. Not a worry if you drive an automatic. I have collected enough parts now to try something else though soon. I want to install an internal slave cylinder/throw bearing, so I can do away with the external cylinder for the clutch, and then set the engine back down on factory motor mounts. It will give better DS angles on the front mostly, but on the back as well. I have some 4 degree shims as well to install if it persists. Anyways, Thats the plan for the upcoming warm weather. Heres a link - Have any of y'all ever tried or heard about these? http://www.speedwaymotors.com/GM-T-5-St ... layId=1945 I may also put the AWD T-case back in someday. I liked it too, but want to drive the lo range part time for now.

The attachment image80.jpg is no longer available

A shot of the engine mount lifting it up 2".
I want to go back to factory mounts this spring...

You can see the big arm that sticks out so you can attach a slave cylinder. Of course, If you want to run headers, or a front drive shaft, It's just in the way! Grrr.

This is the S-10 Gearbox I bought for parts so I could convert the astro gears to 4wd.

this is the parts trans & an NP207 that came with it. They cost 50 bux, and the mainshaft was in perfect condition. I used that and the tail-housing. I put the gears from my spare Astro T5 on the shorter main-shaft, to get an Astro 4wd 5 speed for a 4.3.

[youtube]http://www.youtube.com/watch?v=Dcub66Yu ... AAAAAAAKAA[/youtube]

[krsowles]

WOW! You guys set it straight! PV: I'm not sure I fully understand the "slushy road problem" but I live in a snow-prone area and plow all winter for a living, so I'm not too nervous and want 2 wheel drive for interstate cruising. How do you like your 3.43s with 31" tires? Sounds like you are planning to switch. I don't live at 7000' but any road around here that goes a 1/4 mile somewhat staight and level is called a "flats'! 4.10s and 4.33s are preferred in pickups around here, that is why I was thinking it. DYLIT: I'm a jeep fan and not planning on serious off-roading(is that an oxymoron?). I want 4wd to travel up and down, back and forth to go skiing, biking and the hockey rink. I like the thought of a driveshaft from my first love! How do you like your 3.73s? I don't remember your tire size off hand but are they something I should be considering?
I'm on the prowl now for an early 90's S10 with what I need. Thanks all, very much, for helping out a poor lost newbie. Yes, there will be pics!

[photo_van]

The slush factor as I understand it, is serious pull from one side to another when going from slippery to firm surfaces at higher speeds. This is apparently a very noticeable condition to some.

I used my 98 with the AWD case for 8 years and it was the best snow car I ever owned, still is I think but we haven't had much of a winter to test the new case. I wouldn't go right out and put a 231 in until you find a need for it. The AWD in combination with the automatic trans is capable of a lot of off highway situations; you'd be surprised (or at least I was). The only reason I put low-range in mine is that I do some semi-serious off highway and there were times that I was worried about getting stuck; specifically steep rock crawling, deep sand and reverse (R is pretty weak).

As far as the 3:43 and 31's, again, I've been getting by with that for 8 years, but it doesn't take much of a grade for it to kick down into third. If I have a load at all (full tank and groceries) it kicks down into second on the four lane between town and home. I don't like the sound of my van in 2nd gear at 55mph

[doyoulikeithere]

DYLIT: How do you like your 3.73s? I don't remember your tire size off hand but are they something I should be considering? Yes, there will be pics!

I like my 3.73 just fine. I run 235/75-15LT. I have no probs doing up to 110KMH in 5th gear, up a long long fairly steep hill everyday. It will go a lot faster up that hill, if I shift down to 4th (1:1) BTW, I LOVE the sound my engine makes from 80 to 100KMH in 3rd gear if I wanna downshift to pass someone, then I hit 4th gear, which also sounds awesome after the 3rd gear windup. Then of course 5th gear barely ever gets wound up to those kinda RPMs cuz it would be just crazy fast!

[krsowles]

Nothing wrong with that! Only problem I have is converting that to MPH, I'm just not that smart! I'll go check my speedo later... Thanks for the info though! Honestly, I thought 2wd option would save some me some fuel. I want to swap subframe from my parts van with almost new v6 and reman trans and thought if it were all out and accessable, it would be a good time to do it. Still want to lift it so I'll need springs from s10 anyway. Guess I need to ponder, if PV says awd good for what I'm doing, is it worth another battle? If I forgot to mention it, I love the info here! The poeple are always willing to help, thanks again!

[LiftedAWDAstro]

You'll want 4.10's with 30" - 31" tires. I am not too far from you and the hills here killed my old 98 that ran 30" tires and 3.42's. When I swapped to 4.10 gears it was better than stock and would climb interstate hills in OD with no issues at all. Since we have hills here in central NY and in fact do quite a bit of traveling into the Adirondacks, I will be going to 4.10's in the spring and will keep the stock tires until I lift it. Even with the stock 215's, 4.10's are not too much gear for these 5,000# AWD beasts!

As for the transfer case, unless you need low range, don't swap it out. I think the reason these vans pull when in the slush and snow when swapping in a 2 speed case is the fact the front and rear diff ratios are exactly the same. Almost all 4x4 vehicles run different ratios in the front. The difference is minimal, for example, 4.10 in rear and 4.09 in front, 3.55 in rear and 3.54 in front etc. This makes the front end pull slightly harder when locked into 4x4 so the vehicle tracks straight. I bet the S-10's are setup this way stock.