Looking for info on a lift

[nely]

according to your 05 1500 express it shares the lower control arm with avalanche suburbans tahoes and pickups. i can only assume these lifts will work on the awd vans aswell.

im looking up the parts numbers on those torsion bars without luck. ill keep trying

 

[zuren]

frame dimensions are probably the best. next time i have an express van and suburban in the shop i work at, i can take some measurments

What dimensions do you need? I'm sure those of us with Express vans could help out.

I "heard" somewhere that the Express may share some design features with the Avalanche and Suburban. I didn't record where I found that info but it was speculation anyway.

 

[nely]

How about the width between the lower control arm mounting points?
Measure from center of bolt to center of bolt.

Im gonna speculate that the 99-06 chevy truck kit will be the one to use. Its the only one that doesnt say it will not work on awd models. It doesnt have the coil springs like on the suv/sut kit. Im just not sure if the lift knuckle will work on the vans.
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[chasespeed]

It was helpful and not helpful at the same time. None of the numbers on my bars appear on that list of GM pickup torsion bars. I take this to mean that the AWD vans have bars that are specific to them. The thought is that installing a torsion bar with a higher rating will lift the front easier but may make the ride harsher. Adjusting the torsion keys on mine yielded zero lift. I'm considering 2 different reasons:

A. The torsion bars could be tired at 120,000 miles and won't lift the van.
B. According to Photog (member here), GM independent front suspensions have limited travel so the shocks may already be sitting at maximum travel. Turning up the torsions bars won't yield any lift because the susp. has no where to go.

To test B, I need to unbolt the top of the shock and see if the suspension travels down further than what the shock allows. If it does, keeping the current bars and installing longer or adjustable shocks may be the answer. I haven't had time to do this.

Okay, we all know t-bars are just springs that work on torsion...

Even if you remove the shock mount... LOOK HARD. There is probably a droop stop somewhere. They usually use something HARD to limit travel in suspension and steering components. It may be a hard metal stop, or have a rubber/plastic snubber..

Once all is clear, even then, you are only able to adjust your static ride height, BUT, problem areas are CVs, and ball joints being near the edge of their tolerances.

All things being equal, if nothing is preventing further droop, adjusting the bars, should yield higher ride height.

Chase

 

[TroySmith80]

As for the Roadtrek picture, Roadtrek offers a Quigley converted van. I'm not sure if Quigley uses Fabtech suspension parts or if the owner of that van added hardware.

I thought quigley put solid axles under the chev's, just like they do on Ford.

Adjusting the torsion keys on mine yielded zero lift. I'm considering 2 different reasons:

A. The torsion bars could be tired at 120,000 miles and won't lift the van.
B. According to Photog (member here), GM independent front suspensions have limited travel so the shocks may already be sitting at maximum travel. Turning up the torsions bars won't yield any lift because the susp. has no where to go.

Don't mean to sound negative here, just trying to help figure this issue out... Neither of those options makes sense to me because:

A. Unless your van is resting on it's bump stops, the torsion bars are still lifting it up. If the torsion bars are tired, your ride height may come down a little from what it once was. Even if that is so, turning the bars should result in a lift because you're increasing the pre-load on the spring. Tired or not, they're still holding the van off the ground.

B. This would be true if the van was sitting static at full suspension extension. In that case, adding preload would not increase ride height. However, the van does not sit at full extension. It sits somewhere in the middle of its travel, so that if you drive over a hole, the suspension can extend into the hole. So your shock is not a limiting factor when your van is just sitting there, and rotating the bar should yield an increase in ride height.

If you adjust the rotation (pre-load) of the torsion bars, due to friction in the linkages, the front may not instantly rise. You may have to go jump on the bumper once and bounce the suspension, and then when it comes to rest, it will do so at a slightly higher point than before. Conceivably you may even have to do this while rolling, because the tires will have to be ever so slightly closer to each other due to the suspension arms being at a steeper angle. I doubt it would be that sensitive though.

I hope that all makes sense. Seems logical to me. Let me know if i'm not thinking correctly.

 

[TroySmith80]

By the way, thanks Nely for taking the time to look all this stuff up! And Zuren!

 

[nely]

No problem. Just figure i can help you chevy guys out. Since chris has me covered on my e350s

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[chasespeed]

If you adjust the rotation (pre-load) of the torsion bars, due to friction in the linkages, the front may not instantly rise. You may have to go jump on the bumper once and bounce the suspension, and then when it comes to rest, it will do so at a slightly higher point than before. Conceivably you may even have to do this while rolling, because the tires will have to be ever so slightly closer to each other due to the suspension arms being at a steeper angle. I doubt it would be that sensitive though.

Basically, yes. You can do it on the ground.... I have found, that sometimes, its easier to jack on the frame, until you are at, or above your intended ride height, and crank, until you reach that point. KEEPING COUNT of the turns. Could be quite a few turns to make a difference, depending on the threads, the key, length of control arm, etc etc...

Chase

 

[zuren]

I thought quigley put solid axles under the chev's, just like they do on Ford.




Don't mean to sound negative here, just trying to help figure this issue out... Neither of those options makes sense to me because:

A. Unless your van is resting on it's bump stops, the torsion bars are still lifting it up. If the torsion bars are tired, your ride height may come down a little from what it once was. Even if that is so, turning the bars should result in a lift because you're increasing the pre-load on the spring. Tired or not, they're still holding the van off the ground.

B. This would be true if the van was sitting static at full suspension extension. In that case, adding preload would not increase ride height. However, the van does not sit at full extension. It sits somewhere in the middle of its travel, so that if you drive over a hole, the suspension can extend into the hole. So your shock is not a limiting factor when your van is just sitting there, and rotating the bar should yield an increase in ride height.

If you adjust the rotation (pre-load) of the torsion bars, due to friction in the linkages, the front may not instantly rise. You may have to go jump on the bumper once and bounce the suspension, and then when it comes to rest, it will do so at a slightly higher point than before. Conceivably you may even have to do this while rolling, because the tires will have to be ever so slightly closer to each other due to the suspension arms being at a steeper angle. I doubt it would be that sensitive though.

I hope that all makes sense. Seems logical to me. Let me know if i'm not thinking correctly.

I'm trying to understand how GM suspensions work as well. One thing that the tech article talks about is preload on the bars and the misconceptions around it.

Exerpt from paragraph 3:

Another con is as you increase the ride height by adjusting your keys, the ride gets worse. Now it's a common misconception that there is more of a load on the bar and this is the cause. That is impossible since the LCA moves as well, so there is no more torsion on the bar than before, the spring rate does not actually change like many belive. The twisting action does not change the pre-load on the bar directly, so cranking your bars is just like adding a block in the rear or a coil spacer. It is simply changing the position of the spring. Just to clear things up, pre-load is the amount by which the torsion bar can't return to its original (unloaded) position due to be installed in the truck. The reason for the bad ride quality is instead a combination of things. First of all, when you adjust the height up, the angle between your LCA and the ground is increased which effectively does reduce your pre-load by reducing the leverage your LCAs have on your torsion bars. This negativly effects the ride by taking the torsion bars out of the preload range they were designed to work in. In combination with that, if you crank too far your UCAs have very little room left between them and the lower bump stops, reducing downward travel.

According to the article any adjustment does not change preload, it changes position. The spring is still tired no matter what position it is in. It may be holding the front up but it also may be sagging from new with nothing left to lift the van. I don't know what a factory set ride height is for the front of one of these vans so it's hard to compare. An option may be to install new 1/2 ton or even 3/4 ton torsion bars but if you looked at the chart in my link, I'm not sure what I have to start with.

If you look at the kits used for lifting and leveling Chevy trucks, they almost always include new keys and either a shock extension or a new longer shock. I've read elsewhere that GM shocks are notoriously short, thus the reason for needing the extension or new shock.

Another thing I've noticed is that companies like RevTek Suspension make statements such as this:

http://www.revtek.com/gmcsusp.asp

•On GM HD Vehicles - these keys will only fit Vehicles with color codes Blue, Brown, Purple and Yellow on the stock key. If your vehicle has Green, White or Orange colors then you may not achieve any lift at all.

My keys are so rusted that I don't know what I have. My bars have an orange and blue colored stripe but that may not necessarily correlate to key color. It doesn't make sense to me why a vehicle with one key color would achieve lift but another key color yields nothing (assuming same vehicle, same setup and you are replacing the keys with an aftermarket key).

A lot of this doesn't make sense to me either but this is the best assessment I've been able to make. I've tried calling these suspension companies but as soon as they learn I'm working with a van, they are less inclined to help. If we can confirm the vans are "most like" something else, I'll call back and act like I have a (insert GM truck here) and see if I can get some explanations.

And components having a shorter lifespan after "cranking" the torsion bars should be considered a given. The angles change and it's harder on everything.

 

[nely]

The tightening of the torsion keys will change the position of the lower control arm and lift the van. But now that the lca is positioned lower in the travel of the suspension, its only rational to think that the extra up travel the lca sees will actually increase the spring rate in the upper portion of travel now that it travels farther in its range of motion b4 it hits the suspension stops.

Sorry thats incorrect. The spring rate wont change. But the force needed to make the lca travel to the stops will increase.

For example 250lbs spring rate.
250lbs compress 1"
500lbs compress 2"
& so on
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[TroySmith80]

Hmm, good point. I guess turning the torsion bar to adjust ride height really isn't "pre-load". Poor term to use. I guess i use it out of habit, thinking of motorcycles and mountain bikes, where turning the collar on the shock body pushes the spring down and increases ride height. I guess in that situation also it may be technically wrong to call it pre-load since the amount of compression the spring is experiencing hasn't actually changed.

In any case, I think we are on the same page now, that turning the torsion rod must result in a change in ride height.

Installing "new 1/2 ton or even 3/4 ton torsion bars" would increase the spring rate, which would likely give you an increase in ride height, but would also give you a stiffer ride (which may or may not be a bad thing). But, you don't have to have a stiffer spring rate to get increased ride height.

I can kind of understand the company's reluctance to help on the van. It's a pain in the *** for them, and probably a super tiny portion of their business. As a business owner, i've been on that side of things and been frustrated at having to spend an inordinate amount of time and effort on projects that are going to bring back very little to the bottom line. Sometimes it's worth it though for the reputation of customer service, and maybe having a niche market to yourself. Other times it's just a waste of time and effort! lol

 

[TroySmith80]

Hmm, check this out Quigley IFS (so i was wrong about them always using straight-axle) lifted 4x4 3500 van:

http://www.sportsmobileforum.com/viewtopic.php?f=3&t=1726&hilit=Chev*

And the post is from 2008! Long time ago!

I just emailed quigley asking for any info on adding ground clearance to factory AWD GM vans.

 

[dhally]

I talked to Quigley a few weeks ago (before I bought a Ford) and they now offer a Chevy IFS conversion with 2" lift for a big upcharge. It isn't on their web site. They told me it is done with lift blocks in the back and their own custom spindle in the front.

They do not offer a lift on a 2wd van.

I didn't ask if they could lift an AWD van.

 

[zuren]

I wanted to update this thread with information related to potential body lifts on Chevy Express vans.

If anyone has been tracking my build thread, I have run into an issue mounting components in the rear cargo area where the mounting bolts would be blocked by the frame rails under the van. I'm weighing my options to resolve this, one option being a body lift.

I spent some time under my van this weekend looking at how the body is mounted to the frame. I would only be lifting 1 inch to gain the clearance I need for the bolts to drop through and give me some space to work. It appears that a mild body lift is possible without major modifications. There are 12 mounts (6 on each side) that are fairly straight-forward but there are 2 other areas that need some consideration.

One area that needs attention is the fan shroud in the engine bay. The entire shroud (upper and lower halves) and radiator are supported by a portion of the body so everything would go up. The issue becomes the fan within the shroud since it is attached to the engine. I will need to research this more but it looks like you could just trim the lower section of the shroud to get you the clearance you need.

The next issue is the gap between the bumpers and body that would form. I'm only looking at a gap increase of 1 inch that I'll probably just live with.

Anything more than 1 inch will start getting into modifications with linkages and gaps that would look pretty ugly. I'm not sure if this is the route I'll be taking but I wanted to post my findings in hopes that it may help someone else.

 

[RustyBadger]

If anyone is interested, this van was for sale a couple years ago. Here is the link to the ad (has pics), and it confirms that it is a Quigley conversion for Roadtrek.

http://www.rvloco.com/forum/showthread.php?t=56778

Nice van.