BW4472 Exploded view, part numbers, cross reference.

[augidog]

EDIT: Is there not a 'Mechanical Connection' to the item that is in Park. Did Vans with AWD have a different park mechanism or was it in the TC ?

sixsix, if you haven't already, open the exploded view. I looked at that thing for hours alongside pictures of parts. It's an amazing contraption, so I guess "Smartdrive" is a fair claim.

There is no "hardfast" connection between the tranny and either driveshaft. The trans output drives the planetary gear which drives the the viscous coupler, and physics shares the torque between the chain to the front and the ring gear to the rear output shaft.

[MountainManJoe]

EDIT: did finally work, but this 508 thing has been going on for a few days now.[/color]

@sixsix
It seems we were getting a barrage of traffic from Singapore. Nothing good I'm certain. We've blocked all Singapore based IP addresses. Hopefully we're out of the woods for a while. Keep me posted on forum accessibility.

[MountainManJoe]

EDIT: Is there not a 'Mechanical Connection' to the item that is in Park.

The only thing park gear does is latch the transmission output so it can't move. Nothing else down the line changes.

Did Vans with AWD have a different park mechanism or was it in the TC ?

Nope. They are identical.
The difference is that RWD van axles are mechanically linked to the transmission output.
The Pre-99 AWD van axles have the transfer case between them and the transmission output.
And just like trucks with open diff do a "one-wheel-peel" when they lose traction (one wheel free spinning), then so can an AWD van free spin one axle. Exact same principle.

In the post-1999 vans, the rear axle is locked again to the transmission. This time there is no open differential. Speed differentiation for the axles is achieved by feathering an electric motor clamped clutch.

My Savana AWD has a Borg Warner 44-73 transfer case. It's the big brother to this guy, but the principle of operation is identical. I too have to make sure it's flat towed, and if I remove any driveshaft then the van won't go anywhere, and it will roll on it's own. However, it is a beast off-road. I was impressed.

[sixsix]

While I certainly had no intention to " Clog Up " this thread, I really do appreciate the layman's brown paper bag description and operating breakdown.
I drew it out, like stick figures to show me there is no direct connection between the transmission and the 2 driveshafts.
The 'clincher' statement was Joe's, "The BW4472 transfer case has an open differential inside".

And here's to hoping aug can bring a few skills and expertise & perhaps an search algorithm or 2. I remember a few skills learned in the late 90s for "eyeball draws".
Nice team work, Guys. I Love great photos.

[augidog]

While I certainly had no intention to " Clog Up " this thread, I really do appreciate the layman's brown paper bag description and operating breakdown.
I drew it out, like stick figures to show me there is no direct connection between the transmission and the 2 driveshafts.
The 'clincher' statement was Joe's, "The BW4472 transfer case has an open differential inside".

When I realized my T-case had pooped the bed, I HAD to learn this stuff. I wasn't really interested in just bolting in a 30 year old replacement.

I was taken aback at the lack of experienced content on the BW4472 after so many years...and trust me, I dove deep and still found nothing.

After diving deep, I got super lucky finding new and like-new parts. Who wouldn't take pictures of this stuff? This is good gear heading.

And here's to hoping aug can bring a few skills and expertise & perhaps an search algorithm or 2. I remember a few skills learned in the late 90s for "eyeball draws".
Nice team work, Guys. I Love great photos.

There's no magic...it's SEO (search engine optimization,) instead of the default lines of text, a webmaster can express the tone of the site, and attract like-minded folks.