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RWD to AWD Q's

PostPosted: August 10th 2020, 6:14am
by Cantttype
I did some searching, but I dont know the terminology for what I am looking for.

I have a STOCK RWD 03 Astro. I needed a vehicle and settled for a RWD instead of waiting for a AWD. It runs well. No real issues.

I want/wanted an AWD for:
- a 3-4in lift
- some beefier(32s?) tires
- basic offroad capabilities nothing crazy
- to turn this into a fun van for camping.


I found an STOCK AWD with a bad transmission for $1k. He claims(I havent gone any further than the post) the engine works well.

What would be the most simplistic method of getting AWD capabilities? I am wondering if my tranny will fit in the other van or if getting another would be worth while and using my van for engine parts later or just selling it.

S/n: I think the AWD one has the better rear doors(dutch?) instead of the ones on my van which just open side to side.

Please help! :ty:

Re: RWD to AWD Q's

PostPosted: August 10th 2020, 1:07pm
by tungtide
2 WD and AWD have similar, but different transmissions. Buy the AWD sell the 2 WD you can get a used tranny or opt for a rebuild. The two doors that swing out side to side are often referred to as Barn doors.

Re: RWD to AWD Q's

PostPosted: August 10th 2020, 11:04pm
by Leeann_93
Can you put your RWD trans into your AWD van? Yes. After you take it completely apart to swap output shafts, which you would have to do to rebuild the AWD trans anyway.

Re: RWD to AWD Q's

PostPosted: August 10th 2020, 11:33pm
by AstroOafAdventurer
So, I'm curious, as I too desired the AWD but couldn't pass up the RWD deal I found.
Being this model uses a subframe, are you not able to just swap an AWD subframe into the RWD body?
I'm not sure about the T'case, but looks like engine, tranny, and front axle are all mounted to the subframe...

Re: RWD to AWD Q's

PostPosted: August 10th 2020, 11:41pm
by AstroWill
Cantttype wrote:I want/wanted an AWD for:
- a 3-4in lift
- some beefier(32s?) tires
- basic offroad capabilities nothing crazy
- to turn this into a fun van for camping.

AWD is not required for any of that, basic off-road capabilities can be had by using a traction adder, like a limited slip or a locker. I have a list of them for our vans here: https://sites.google.com/site/astrosafa ... ferentials

A whole lot easier and cheaper than converting to AWD.

If you are dead set on converting to AWD, then yes it can be done by swapping out the subframe and all needed accessories, but it's not going to be as cheap nor as simple as adding an LSD/Locker/etc.

Re: RWD to AWD Q's

PostPosted: August 11th 2020, 5:28am
by Cantttype
AstroWill wrote:AWD is not required for any of that, basic off-road capabilities can be had by using a traction adder, like a limited slip or a locker. I have a list of them for our vans here: https://sites.google.com/site/astrosafa ... ferentials

A whole lot easier and cheaper than converting to AWD.


Ok! good info. Huge help!
I watched some rwd stuff, and I was unaware of locker/LSD idea.

Found this vid referencing the G80 from your part list if anyone else is looking. https://www.youtube.com/watch?v=uVxLAoJZuOo
He said he prefers the LSD.

After doing some searching I couldnt find the G80.

Im leaning towards the Yukon Gear & Axle (YDGGM7.5-3-26-SM) 26-Spline Dura Grip Positraction for GM 7.5/7.625 Differential with 3.23 & Upward Axle Ratio. Easy buy on amazon.
This video talks about the LSD
https://www.youtube.com/watch?v=tesxT2AlArA

Re: RWD to AWD Q's

PostPosted: August 14th 2020, 4:56am
by Cantttype
tungtide wrote:2 WD and AWD have similar, but different transmissions. Buy the AWD sell the 2 WD you can get a used tranny or opt for a rebuild. The two doors that swing out side to side are often referred to as Barn doors.



Does $900 sound legit for a rebuilt transmission?
https://www.atransmissions.com/product/ ... 1996-2005/

Re: RWD to AWD Q's

PostPosted: August 14th 2020, 5:37am
by markmitch
as for the swap of the AWD front subframe , yes it can be done but certain years will also require the wiring harness and ecm so your computer knows when your in AWD or not or so I was told when I looked into doing this. I am still going to start buying the parts to do this but my van is an 89 so much easier to do but I have a V8 in it so I have to either buy a custom oil pan or make one myself. Then i will build a transmission too,

Re: RWD to AWD Q's

PostPosted: November 21st 2020, 12:22pm
by Cantttype
How difficult would adding a selectable(mechanical or electric) locker to a RWD van be? I dont think the AWD is going to happen and the RWD I have runs pretty well.

Re: RWD to AWD Q's

PostPosted: November 21st 2020, 2:42pm
by AstroOafAdventurer
Cantttype wrote:How difficult would adding a selectable(mechanical or electric) locker to a RWD van be? I dont think the AWD is going to happen and the RWD I have runs pretty well.


You would have to swap the axle out for a model that has those locker options as none are made for the stock rear. Someone on here did a Ford 8.8 swap for better locker options.
Here it is to give you an idea:
https://www.astrosafari.com/viewtopic.p ... 8&t=143268

Re: RWD to AWD Q's

PostPosted: November 21st 2020, 7:56pm
by markmitch
No offense but there are posi units for this van rear axle as many here have done it.

Re: RWD to AWD Q's

PostPosted: November 21st 2020, 8:09pm
by AstroWill
Cantttype wrote:How difficult would adding a selectable(mechanical or electric) locker to a RWD van be? I dont think the AWD is going to happen and the RWD I have runs pretty well.

Unfortunately, like AstroOafAdventurer said, there are none available for our rear differentials. The only option if you want a selectable locker is to go with a different rear end.

Re: RWD to AWD Q's

PostPosted: November 22nd 2020, 4:54am
by sixsix
markmitch wrote:No offense but there are posi units for this van rear axle as many here have done it.

Are not "Lockers" and "Posis" two TOTALLY different mechanical units with differing definitions.

I picture my dad getting out before a 5' deep puddle and turning the big fist sized knobs in the middle of his front axles on that big old IH Travelall back in the late sixties.

I should do some reading...

Re: RWD to AWD Q's

PostPosted: November 22nd 2020, 5:28am
by Rod's Trucks
Sixsix,
Your dad would have been engaging ('locking')the front hubs to connect the wheels to the axles ( engaging the 4x4 capability of that old IH Travel-all).
Nearly all of the 4-wheel drive rigs used that setup back in those days. WARN was the big-name manufacturer for hubs back then.
As I understand the subject ( and I may be incorrect): 'Lockers' and 'Posi's' are different in design. Please correct me if I am wrong, but true 'lockers' are more for the hard-core off-road guys, and mechanically 'lock'ing both axles to make them rotate at exactly the same speed. They can be noisy and hard on tires when used on any hard surfaces. 'Posi's are limited-slip designs using clutches or helical gears, and are more street friendly.
I believe the relatively common G80 diff setup that could be found in our vans, is sort of a 'locker' but not in the true sense. It requires a fair amount of difference in axle rotational speed to engage. I have never had the opportunity to drive an Astro with a G80 diff, so I have no first-hand experience.
I am not sure if the other 'lockers' are the same way. I am sure somebody will probably explain it with more detail.
Then there are the 'Limited-Slip' diffs (Posi's in the GM parlance) ....another style of rear end, and another discussion, but not as rigid as the 'lockers'.

Rod J
Issaquah, WA

Re: RWD to AWD Q's

PostPosted: November 22nd 2020, 6:06am
by Cantttype
The G80s are difficult to find. There are a few options for similar items, but you gain a lot more from the ability to turn on the locker as opposed to spinning the wheels to force it to lock.

Swapping the rear axel is what I was thinking about. How hard would that be?

Re: RWD to AWD Q's

PostPosted: November 22nd 2020, 6:51am
by Rod's Trucks
The hardest part will be to to find a setup (air-locker or electric) that fits the Astro axle assembly; even if money is not a concern.
Nobody seems to make one for our axle housings.

Rod J

Re: RWD to AWD Q's

PostPosted: November 22nd 2020, 1:50pm
by AstroOafAdventurer
Cantttype wrote:Swapping the rear axel is what I was thinking about. How hard would that be?


I provided a link in my previous post to give you an idea of what's involved.

AstroOafAdventurer wrote:Here it is to give you an idea:
https://www.astrosafari.com/viewtopic.p ... 8&t=143268


This.

Re: RWD to AWD Q's

PostPosted: November 22nd 2020, 2:39pm
by icebrrg3rd
sixsix wrote:
markmitch wrote:No offense but there are posi units for this van rear axle as many here have done it.

Are not "Lockers" and "Posis" two TOTALLY different mechanical units with differing definitions.

I picture my dad getting out before a 5' deep puddle and turning the big fist sized knobs in the middle of his front axles on that big old IH Travelall back in the late sixties.

I should do some reading...


Lockers and posis are different, but lockers are not what you're thinking about. Those were for locking the hub to the axle, which back then was always turning when driving. That has been replaced for the most part by the mechanical lever or electronic push button inside most 4x4s now-a-days. That does not lock the differential, just engages the front wheels to the driveline. A locker or other limited slip (inside the diffs) would be needed to make all the wheels have traction. Open diffs would allow one wheel to spin while the one on the other side doesn't.

Oh, and glad your dad did it BEFORE the 5' deep puddle, many would get stuck IN it before realizing their hubs weren't locked.

-Andrew

Re: RWD to AWD Q's

PostPosted: November 22nd 2020, 3:09pm
by sixsix
Thanks, makes sense now - I could use some internet surfing / Wiki time.
Yeah, the "Suburban-Like" truck was a beast - like the old school Broncos.
They had that 'bulldog low' gear - we NEVER got stuck or worried, a bit.

Hardest part of our trips was the hose off when we got back to the garage.
Then cleaned the truck...

It had an aftermarket, refrigerator style A/C unit back in the rt side behind the wheel.
Other side had the spare. It bristled with Radios, antennas, rescue and flying gear.
CAP, Ham, EMT, Scuba, climbing and ROTC was big back then.

Re: RWD to AWD Q's

PostPosted: December 10th 2020, 6:15am
by markmitch
I had a 1989 Chevy K5 Blazer with a Muncie 465 and a 203 and I think 3:73 gears and that truck was very hard to get it stuck. I even climbed hills I probably should have never done it but it was fun. I had a 3 inch body lift and 3: suspension lift with 33x10:50 R 15 tires. Had so much fun and never had a locker or posi. Till I broke the frame where the steering box is bolted.