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Building a 5 speed AWD Astro. Questions.

16K views 57 replies 12 participants last post by  4.3LUV 
#1 ·
Hi There.
I have a 1987 2WD Stro with a T5 speed Trans and a fresh 4.3.
Its fun!. But, I want to pull the subframe out and replace it with a subframe from an AWD Stro. Am I imited to subframes up too 1994 ? What do you you think an S-10 T5 Trans and T-Case will fit in like?
Is the offset going to line up with the Astro Front diff?
I am wondering if the S-10 part time 4wd will fit/work in the astro also. Will I need to put in an S10 Diff? Will the CV bolts be compatible? Seems like I might need a donor AWD Stro, and an S104x4 too if they will all fit together....
Any good GM guys out there help me out with this puzzle?
the end result should be an 87 Shortbox astro body, with Part time S10 Awd, a 5 speed S10 trans/case, a 5 inch lift and Mudders!
Will a 95 AWD subframe fit in my 87 shortbox! Arent the front two mounts in a difrent spot? I wish could find that old astrosafari article about grafting a 96 Nose onto an 87 shortbox.
 
#2 ·
Hi Mike,

I don't have many answers for you but I'd like to "vote" for this thread as I want to do basically the same thing. I'm interested in taking either a 2WD or 4WD astro and converting it to 4WD with a T5. Full time AWD would be OK but a traditional 4WD would be better. It sounds like it might be better to start with a 4WD if the subframe is different. I could then swap in a T5 and part time transfer case from an old s10 and I might be in business.

Is the shifter position on the transmission different between S10 and Astro/Safari T5s?

I might have to have a different front driveshaft made but that wouldn't be a big deal. Anybody have the picture of the bottom of an AWD astro/safari?

Thanks in advance,

Andy
 
#3 ·
The shifter is an Astro is offset with a special adapter that mounts to the normal T% Shifter mount spot, a small recangular box on top of the trans. The Astro uses a thing that mount to the top of the T5, but then it's purpose is to move the shifter handle about a foot or more to the left (Drivers Side) I imagine the "OFFSET ADAPTER" will fit all T5s but I could be wrong. My 87 jeep CJ7 had the same T5 in it and the box on top where the shifter hooks in was the same too.
The subframe swap between 2 and Awd is a snap. nothing hard about it as long as the vans are of a similar year. I think the newer nose style vans subframes wont fit the older style vans, but again, I'm open to correction from someone with "the facts".
My biggest question are if the S-10 front diff will bolt in place of the astro front diff, and hook right up to the axle bolts (CVjoints) and if the transfer case front driveshaft will line up to the astro front diff. full time AWD sucks down way too much fuel. Part time 4wd would be so much better eh?
I'm also interested in purchasing a world class T5 from A V8 Camaro, and using it place of the weakling Non WC T5 in my astro 2wd. I see one locally for 250 and im thinking about it.
 
#4 ·
Seems the S10 T5 has a 14 spline input, but my astro has an 11 tooth spline. So, Ok, I have to use the S10 Clutch disk. Now the 64 dollar question is, will the S10 Trany and Tcase line up to the front Diff of an Astro, and do we need an S10 Diff to complete the part time 4wd conversion? S10 dont have locking hubs do they?
 
#8 ·
"The All-Wheel-Drive Astro Van uses the same front differential as a 4x4 S-10 Truck."

According to the jags that run Astro swap page: http://www.jagsthatrun.com/Pages/AstroVan_V-8.html

So I think if you're starting with an AWD Astro, and you use an S10 transfer case, you won't need to change the front diff. The S10 front driveshaft should work with the S10 transfer and front diff since it's the same, Only question is if the front driveshaft length is any different between the two platforms. I seem to recall it isn't, but I can't remember. anyway just changing the length is not a big deal.
 
#9 ·
Ya, I think the Astro Transfer case swap will work just fine. Some of the guys in here have done it, I read it works. I think the S10 front Diff is a bit differrent though, and has a mechanism that releases the axle/drive. Instead of getting out of the vehicle and turning in the hubs like in the old days. ha ha. Isnt it a vacuum plunger or something like that. I heard that Astro doesnt have it but S10 does. One guy in here said that he put in an S10 T-Case and his Stro developed a big vibration, so he put in the S10 Diff with the releaser and it was Smoooth ever since. :D
The whole reason I wanna put in the T-case is to take it outta AWD eh!
Apparently, the S10 T-Case is thicker, and so the shafts wil need to be changed. I dont know if the S10 Shafts will be the same length, but a good Idea to grab them too if possible eh?
:feedback:
Cant wait till it SNOWS!!!
Last winter I got my 95 AWD spinning like a top in the snowy parking lot with the wheels cranked hardover at full boogie! Wish I had Video. Oh, PS theres a PDF attached (I hope) of all the T5 parts. Its a keeper. Compare the Astro T5 to the 88-92 WC Camaro Specs. Hmmm
 
#11 ·
I think it might bolt on to a 4wd S10 T5, but keep in mind that the S10 T5 shifter is about an inch or two forward of the Astro Shifter. Also, the thing that moves your astro shifter to the left has brackets that support it. (see pdf) I doubt the S10 4wd T5 has holes to bolt these supports onto. Look close at the PDF I attached. The shifter Adapter from the astro T5 needs to be supported. Maybe difficult on the 4wd T5. Also, notice the very bottom of the astro T5 has a big tab hanging down low... There are 2 steel brace bars that connect from this tab to the Motor mounts on both sides in my Astro, and also 2 more steel brace bars that extend down from the 2 top bellhousing to engine attaching bolts, to the trans tailshaft case.. All these steel brace bars hold the t5 in pretty solid. Not sure how it would like an S10 T5 without these braces. If it ever stops raining here I will try to get some pics posted. I also noticed on the pdf that the input shaft lengths are diffrent between S10 and Astro. Not sure how this will effect clutch action.
 
#12 ·
well, I dont get much free time so it always takes a long time but I'm back.
I've collected an NP231C, and I modified an Astro T5 to accept a transfer case.
I have finally pulled the sub-frame out of my 95AWD, and I'm prepping it to fit into an 87 van.
I now can clearly see I've hit obstacle #1.
The Astro bellhousing uses a hydraulic clutch, and the cylinder bracket sits directly in line with the front drive-shaft!!

That kinda puts a damper on things eh! Scratching my head I wonder if making custom engine mount brackets that would lift the entire engine up exactly 2 inches will fix the issue?
 
#14 ·
Thanks for the tip KobaltBlau. Thats a sweet unit there, I like it but cant afford it.

I've been thinking on lifting the engine up 2 inches.
If that clears successfully, and I think it might, it will also solve a couple of other things.
For instance, after a 2 inch body lift is added, my floor shift 5 speed will sink into the floor 2 inches.
Unless I raise the engine 2". Hmmm, I wont need to trim my fan shroud either, Nice!
Tonight I took some stock mount brackets, and some angle iron and a welder, and tried to fab up an ugly set of mounts that will shift the engine straight up 2".
I hope it gives me the space I need! The other Pro to lifting up, is that the oil pan will no longer be one of the lowest points underneath. It has a few good scars already!
I'll let ya know if it works.
I had another bit of bad luck and my cherry picker jack bit the dust, but I have another jack coming soon so I can lift stuff again...
 
#15 ·
KobaltBlau said:
Great PDF! So you think the astro shifter tower thing would bolt to a 4WD S10 T5?
Actually, after looking over the parts I decided against using the "astro shifter offset" device.
It doesn't fit the S10 box top very well, and the support brackets do not line up to anything.
It will interfere with the transfer case lever, and appears to be quite susceptible to collecting water that would drain into the transmission. SO, The stock S10 Shifter lever plate is WATERTIGHT.
I will need to bend or cut/n/weld THE LEVER to the correct angle after its in the van.
 
#19 ·
Well, those mounts I whipped up were not much more than a learning experience.
Upon closer inspection, on AWDs, the Bracket on the drivers side is completely different than the 2wd Brackets I started with.
So, now I will make some much better units out of 1/4 inch material.
 
#20 ·
The good thing about adding the transfer case is the ability to retain the VSS.

Reagrding the clutch slave cylinder, I'm wondering if you could use a newer pull-style clutch cable(?) setup from an F-body. I forget where I came across it, but since the cable enters from the rear of the BH, you might be able to gain enough clearance for the front driveshaft to pass by.
 
#21 ·
Ok, after much trial end error, I've fabbed up a set of mounts that hold the motor up 2 inches above stock, and should be plenty strong.
Looks like it will clear the front driveshaft nicely now. Just need to fab a mount for the transfer case to cross member.

:think: Not sure what was meant about retaining the VSS??
I picked an NP231 Tcase that has a mechanical speedo drive to be compatible with my 87 van where this will all be living.
I hope the cable will be long enough to reach it!!
Will post more pic as soon as the rain stops and I get back at it.
 
#22 ·
Casey said:
The good thing about adding the transfer case is the ability to retain the VSS.

Regarding the clutch slave cylinder, I'm wondering if you could use a newer pull-style clutch cable(?) setup from an F-body. I forget where I came across it, but since the cable enters from the rear of the BH, you might be able to gain enough clearance for the front drive-shaft to pass by.
Hi Casey.
I haven't seen the f style cable before, but I think I can imagine it.
Maybe someone can confirm this for me, but maybe some of the older 2.5 litre 4 cylinder Astro with a clutch might have had a cable clutch.
Mine has a 4.3 with a hydraulic clutch. I ended up taking the motor mount brackets off the engine block.
Cost me 2 bux for a 2 foot metal bar I bought and cut up into lengths and got my drill, grinder and welder and beefed them mounts up with a 2 inch lift to meet the body lift.

I'm told it wont rain tommorow. I still have so much to do.... I Will take some pix.
 
#23 ·
Rain rain go away...
I need to get the t-case mount figured out / made.
Then I need to remove the front axle and half shafts.
I have new shafts to put in, and a 3.73:1 S-10 front axle (with the locking/un-locking cable actuator) Then its ready for a rollunder...

Wow when its done it will have all brand new parts: tie rod ends, idler arms, centre link, wheel alignment, Tires, brakes, half shafts, and a clutch too.
The 95 VIN W engine on it has about 365000 KMs, (225000M) and runs great, so I want to use up whats left of it before I put in the rebuilt VIN Z one i have with only 30000K on so far.

I will post some picture when its daylight, not raining...
 
#25 ·
Thanks Jim.
I hope they work out ok, are strong enough and dont make a huge CG weight shift prob.
Anyways, I work kinda slow, when I get the chance. So after this weekend, I have the 2wd van fully ready to separate the frame/body.
Just waiting on weather and more free time.
Was ThanksGiving here today. Mmmmm
 
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