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Thread: All wheel drive
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post #9 of (permalink) Old Dec 22nd, 17, 8:35 AM
wannalaunch
 
Join Date: Dec 2017
Posts: 2
Re: All wheel drive

Hi,
I have an '03 Astro AWD, and I've been researching the idea of using it to convert my Camaro. Not a Chevelle, but at least a RWD chevy car.
That's how / why I found this thread.
The topic comes up once or twice per year on thirdgen dot org, but noone ever follows through.
I think bad66427 is mistaken, as a '66 Chevelle is at least as wide as my '86 Camaro. My rear axle width, including drums, is right around 62", while my Astro front end is right around 62.5" between the front wheels.
There are different ways of measuring track width, and who is to say which is correct?
But because of the brakes on my '03, a 15" front wheel is not an option. You'd need an earlier Astro AWD. Only the '03-'05 got the big brake upgrade, so I call it a lucky score.
The 7.25" front ring gear came in 3.08:1, 3.42:1, 3.73:1 and 4.10:1, plus the aftermarket offers 4.56:1, but there are no traction differentials. Powertrax used to offer a LockRight, but it broke the aluminum housing when off-roaded and bound up. 5-speed ZR2s had an iron housing, but this discovery hasn't inspired Powertrax to re-issue the LockRight.
Some Astro AWDs have been converted by their owners to the 9.25" front from K1500 pickups, there are traction diffs for those. There might be 3.42:1 gears for those, but most are 3.73 or 4.10, some are 4.56. The 8.25 from K1500s has no traction diffs and I can't find any 3.08s for those either.
In case it inspires any of you, my own plan is as follows;
As both my Astro and my Camaro use the GM 7.625" rear axle, that lets me put the Astro rear gears in my rear axle. One problem solved. I plan to remove the Camaro steering except for the column/wheel, remove the Camaro IFS/front brakes, remove the Camaro crossmember under the engine. Next is removing the Astro body off the Astro front subframe which holds the engine, transmission, transfer case, front differential, IFS/brakes/steering. I call it a module.
Then I can remove the engine/trans/case off the module to make it easier to move around.
I plan to cut away only as much of the Camaro as is necessary to position the Astro front wheels in the Camaro location. I suspect this will put the transmission farther forward than the Camaro had it. I suspect I will have to cut the transmission tunnel to clear the transfer case. Keeping the Astro subframe prevents problems with suspension geometry, drivetrain angle, and lets me keep the Astro front driveshaft. Nevermind that mine came without the front driveshaft...Anyway, as long as the rear half of the subframe rails stay parallel to the road, no caster problem.
My Astro came on a set of aluminum 16x7s shared with K1500 pickups. I have a new pair of 225/55R16s to put on them. For the rear I have a pair of '92 Z28 aluminum 16x8s that can fit a pair of Nitto 555R drag radials in a 245/50R16 size. This keeps the tire diameter at 25.7" front and rear.
If I wanted 6 lug rear to match the front, I could raid a '92-ish Isuzu pup, which used a 6-lug 7.625" Gm axle. You guys can raid K1500s, in the '80s they were 28-spline, in the '90s they were 30-spline.
I don't care about mismatched wheels, I'll probably end up with a mixed set of Cragar 17x9s anyway.
The last concern is the transfer case. Most of the good choices are New Process / New Venture Gear. Their ID is simple. The first digit is how many forward speeds, 1 or 2. The second digit is strength, a bigger number is stronger. The third digit is what type of shifting. 1 is a manual lever, 3 is electric for pushbutton, 6 is electronic for computer control, and 9 is full-time. AFAIK.
The preferred unit for behavior and for holding 1000 HP is the 149. It often gets adapted to the 4L80E. That's my own plan.
Adapting the Astro module seems to be a case of cut what you must, but nothing more, to fit it, then weld it in as much as possible. As far as then fitting the 4.3 or a V8 under a hood, that remains to be seen. I'm hoping I can move the powertrain back on the subframe since mine needs a front driveshaft anyway.
I'm hunting an aluminum-block-5.3L version of the LS for my own build, I'll be faking the discontinued E-ROD 5.3 since I can't afford the E-ROD LS3.
I won't be starting the work until spring, so no pics until then, but if you're curious, put it on your calendar to check the third gen forum .

Last edited by wannalaunch; Dec 22nd, 17 at 9:12 AM.
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