Chevy & GMC Vans

I wanted to chime in on the idea of a front suspension lift, differential drop set up as used in the 4x4 trucks. Seems this would alleviate a lot of the side effects of "cranked" or re indexed torsion bar keys, if it could be utilized in our vans. I've studied the major players that make these kits for the GM trucks and have compared our vans suspension setup to the full size trucks. I've visited my junkyard to look at various model year GM products and was surprised to see that the upper control arms on a 99'-95' Suburban and K1500 trucks looked to be identical to what's used on my '03 van. The measurements are the same. And our front diffs are just scaled down versions of the K series trucks with the same mounting configuration. Fabricating the lower sub frame to bolt to the existing lower control arm pickup points looks to be doable without too much design change that the aftermarket companies are using. By using this setup, the lower control arms are lowered and the front differential/axle assembly is lowered, (oil pans would be happy for some breathing room, CV joints would celebrate the decrease in angle). Here's the difficult part of this concept. Our sub frames have an unusual shape at the section that our upper control arm mounts are welded to. You cant just drop the mounts down by either fabricating an adapter plate or cutting and re welding those mounts on the lower section of the frame, WITHOUT, sectioning out the odd part of the frame out and re enforcing it elsewhere. It's doable, but not easily. NOW, some lift kit manufacturers leave the upper control arms intact in their original mounting location. They compensate the lower control arm drop by including a taller steering knuckle that makes up the difference. But what if WE just used a spacer between the upper control arm and already "flipped" upper ball joint to make up the difference of the dropped lower control arms? In essence, the steering knuckle would theoretically be lengthened.

Thoughts? Comments? Prescription for such lunacy?

Hi Racrx7,

Very interesting concept. It sure would be nice if Pro Comp or Das Mule Expedition could get excited to make proper lift for Astro vans.

But meanwhile, a more doable idea might be to get Fox or Pro Comp or Bilstein coil over front shocks that could fit on Astro AWD. Then torsion bars could be loosened and a bit or extra spring lift could be done at the coil over shocks.

Astrophysics.

A spacer between the upper control arm and ball joint?
Lumpy and Cargocrawler both did that to lift their 2WD. No reason it wouldn't work on AWD.

A spacer between the upper control arm and ball joint?
Lumpy and Cargocrawler both did that to lift their 2WD. No reason it wouldn't work on AWD.

That's what I was thinking lol. I'm looking at one lift kit in particular that looks to share a lot of the same features of my Astro

I haven't done a lift nor do I have an AWD but I remember seeing that in their lift threads.
Thing is the torsion bars run into the lower control arm anyway right? If that is the case the key would be lowering the pivot point of the lower control arm to ease up the twist on the torsion bar.

If that is the case the key would be lowering the pivot point of the lower control arm to ease up the twist on the torsion bar.

That is correct. You either lower BOTH upper and lower control arm mounting points to achieve the lift, or lower the lower control arm mounting points AND extend the length of the steering knuckle by an equal amount to maintain correct geometry of the suspension. My next visit to the junk yard will be to take more measurements and photos of a mid 90's 1500 truck. I know the upper control arms appear to be the same, I'm wondering if the steering knuckles are. If that is the case, longer steering knuckles can be obtained from various lift kit makers.

Upper control arms are the same, steering knuckles are Astro specific with '03-'05 being different than earlier years if that helps.

Upper control arms are the same, steering knuckles are Astro specific with '03-'05 being different than earlier years if that helps.

I thought I remembered reading somewhere that in '03, the Astro switched over to 6 lug components used in the 1500 series trucks.

They are the same 6-bolt lug pattern but knuckles (and hub bearing assemblies) are still Astro specific with different spacing/location for ball joints and tie-rods. I'd still like to see a comparison with 1500 knuckles to see just how different (or similar) they are.

Hey guys.

I've been thinking along these lines too, wondering about the 1500 Series running gear and what fits our vans. I want a lifted van with 31's but no way am I going to lift it and run those tires with the stock diffs. and transfer case.

We're in Sedona right now, seeing so many lifted vans down here has given me the itch to lift my '04 AWD.

Of course the "easy" route is to just swap in a solid axle.

This is a '93 Z71 suspension. Looks very familiar to me

Looks good, you getting busy pulling the knuckle off?

Ya, I used my parts lookup from work and the astrosafari shares the upper ctrl arm & BJ assembly with a ton of chevy and GMC pickups and the escalade and tahoes etc...
And that assembly doesn't seem to change with the years, so a knuckle from a 95 with 5 studs will attach to the same p/n of arm/bj assy as the 6 stud 05 astro knuckle...

Instead of makeing all that stuff but a donner truck with full frame and do what jeep guys do. My neighbor droped an el cameano body on a truck frame when i was in high school it worked

I've given this some thought over the years as well, but I always seem to come back to the same answer; why? I can see the idea tempting if one is looking for more than 2-3" of suspension lift. But I've been running my torsion bars cranked 2-3" over stock for ~100,000 miles now and have yet to see any "side effects". I know some claim that there is more stress placed on the T-bars. Until a physicist shows me the equation to back up that claim, I'm not convinced that there is significantly more energy spent to hold 1000# 6" above the surface of the earth then that spent to hold it 4". In other words, only the index is being changed, they're still holding the same weight. If I'm missing something here, I'm all ears!

It does put a steeper angle on the ball joints but I haven't been going through those inordinately; I replaced them all years ago when I rebuilt the frontend. Also, I've yet to wear out a CV joint.

That said, it would still be a cool project!

Since flipping my upper ball joints last year and installing longer shocks up front, I now have 1" more extension travel then stock. This puts a little bind in the CV when the suspension is topped out, so I'm still considering dropping the front diff an inch or two. I'm not sure it can be dropped much more then that before it hits the lower control arm mount, but that should get the axle angles close to stock.

Good luck with it!