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Ondonti said:
Im also guessing there are no actual facts to support strength comments about the 3.8 awd setup. Just hearsay.
I came across an AWD Caravan in the junkyard that had the trans removed but the PTU was still there so I got a good look at it. It has a rather weak looking hollow splined shaft, similar to the stator shaft on an auto trans, to drive the rear wheels. This shaft is directly driven by the diff housing, while the right side front axle goes through the shaft and into the diff side gear. The PTU doesn't have the same bolt pattern as the output housing we're using but it could be made to fit. I don't think I would trust that shaft, though, unless it could be beefed up.
 

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Here is the page on my site with the technical drawings from the 92 FSM.
AWDFWDTECH

Just remember, 3 wheels are driven off one side of the transaxle diff, the drivers side front is driven off the other side. I agree, the rear can be replaced with a regular axle. A yoke or flange will need to be fabbed to come off the PTU...

I drove one of these vans in the dirt with the AWD always engaged (vacuum motor activated or locked). A lot more fun than just FWD. BUT! I you want to get it to launch, this is NOT an ideal setup. The rear driveline has an overruning clutch for a reason. If you don't have gears perfectly matched front to rear, SOMETHING is going to break. An open rear diff will help, but not for long. Eventually, the difference in speeds front to rear WILL cause carnage. Don't make the mistake of thinking of the PTU as a center diff. Maybe if it was driven off the ring gear like in the 3000GT...

Brent, there was a 3000GT trans/transfer case on KSL a few months ago... I did give it some thought.
 

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I can't say, other than the 3000GTs have a better design. Unless I'm mistaken, the 3si transfer case is driven off the ring gear, not one side of the differential.

All I am saying is that if you want to stress the Caravan AWD system, lock everything up. If every wheel has equal traction, then no problem. But as soon as one of the three wheels driven off the one side of the diff loses traction, or one has more traction, bang... Remember, the PTU replaces the right extension housing on the trans, takes the same space as the intermediate shaft on the turbo 4s. Remember a couple years back when Gary Donovan broke a diff housing clean off a trans? I can see this happening with a PTU in the right circumstances.

If you watch rock crawling, you see all wheels locked a lot. OK, when you use known weak components with big tires, parts break. I wouldn't use 35" tires on my Grand Cherokee and go rock crawling. Granted with the AWD system, you aren't using big tires, but you will be giving ridiculous stresses in a dragrace launch. With three wheels locked, there will be a problem. Kind of why you don't drive a part time 4x4 system engaged on the street. There has to be some give in the system somewhere. If driven on the street. This whole discussion is completely irrelavent if you are talking about a track only system.

I AM NOT, trying to discourage. Just trying to explain.

And even the DSM crowd sees their transfer case as a weak link...
 

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I just find the actual information very interesting rather then "i think that blah blah"

The 3s guys say they have to weld the center diff when power gets high or they break.

Seems that billet and cast steel transfer cases are available for at least the 3/s platform and Im sure dsm guys can get that stuff if they want.

How does that rear clutch thing work?
 

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TO the best of my limited knowledge... And going off my ever failing memory, remember, I haven't been working with this stuff in a while.

The overrunning clutch attached to the rear driveline allows the rear wheels to freewheel when you let off the gas. The driveline still turns, but if the rear wheels and rear diff turn faster than the driveshaft turns, the clutch allows some slip. This keeps driveline breakage down. In a nutshell, remember when you ride a bike and you can stop pedaling? The freewheel action in the rear cogs keeps you from having to pedal. Sort of the same thing.

I agree, blah blah blah only goes so far, remember the days of not doing a cold air kit because the computer will fry if you don't use the factory setup? That is STILL on GD's site... And I put that crap to rest years ago!

Look, I've held all the AWD parts in my hand at one time or another. I don't think the PTU is up to large doses of torque. And I am SURE the rear diff section isn't either. But since the rear axle has hubs that accept shafts, it would stand to reason you could substitute say a Ford 8.8 IRS rear diff in its place and use that same axle assembly to make a minivan RWD. All but bolt in, not much fab other than how to hang the diff and axle shafts. With the PTU driven off one side of the trans diff you are going to put tremendous stress into a relatively weak structure.

I have only seen pics of the 3si setups, but they look substantially more stout. And appear to be driven off the ring gear, or maybe even a shaft elsewhere in the transaxle. I just don't know, and haven't looked yet.
 

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Brent, I found some pics of the 3000GT AWD transaxle I will try to post them this evening. But it looks like the rwd is driven off the same transfer shaft that drives the fwd ring.

Funny thing, this trans was for sale on KSL some months ago, and I skimmed the pics for my own archives, even though I wasn't looking at 3 liter stuff at that time.
 

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Brent, I found some pics of the 3000GT AWD transaxle I will try to post them this evening. But it looks like the rwd is driven off the same transfer shaft that drives the fwd ring.

Funny thing, this trans was for sale on KSL some months ago, and I skimmed the pics for my own archives, even though I wasn't looking at 3 liter stuff at that time.
 

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can i have the getrag? it will fit in my P-body 24v 3.0 duster.... :D *drool*
 

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What I like is that all wheels get attention of their own, not three wheels sharing one side of a diff. And darnit, if I could get the CD to burn right I downloaded a 3000GT/Stealth FSM. I would pull the internals of the transaxle to see what makes this tick.

I guess what I would like to see would something that bolts on in place of a Chrysler diff cover, and runs directly off the ring gear. I know *I* cannot fab anything like that... But yes, I wouldn't want to turn the motor around just to get what I want, but then again, why not. Uniqueness seems to be in style around here...

As a side note, I also have the 2K6 Evo FSM...
 

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I was just digging through a Honda CRV FSM (I love torrents), and the mechanism they use for the rear drive transfers power off a smaller ring gear on the main diff! This smaller ring drives the transfer module and power is delivered to the rear. I haven't gone any further here, but this DOES sound interesting. Though, RWD is added as needed, there isn't any method to turn off the RWD. I just haven't read how they do this, electronically, hydraulically, vacuum?

I'm not advocating grabbing Honda parts, as I just don't think the CRV parts will hold up. Just something more to think about.
 

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ok i know how hard it is to put a fwd stealth rans in i would hate to put that in!!... but that does esplain the bolts on the side of the stealth trans :p thanks
 

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I have those 700mb torrent files and also the small 5 meg 6g72 manual
um actually

The .rar file unpacks to a .iso file and my computer doesnt know what to do with that.


BTW

SOmeone on the 3000gt boards translated a japanese getrag service manual. From what I know, there is no such thing as an english service manual because getrag made a contract with mitsubishi to pretend the transmissions were not servicable. Thats why real getrag transmissions suck.
 

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You need an ISO burning program. THere are good and bad ones. You will need a couple. I'd tell you what I use, but I can't get on my other PC right now, monitor died overnight. Damnit....
 
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