A different way to lift our vans??

[Captn. Crunch]

[quote="photo_van"]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!

The way it was explained to me was like this. A t bar crank puts more downforce on the front wheel. The wheel can't go down so the van goes up. The trouble only really begins when you are off road in four wheel drive. Stock setting on t bars at full droop on the front suspension will only be 250lbs which can easily be overcome by motor torque and becomes wheel spin. Crank your t bars and now you have three or four times the amount of spring rate on that wheel at full drop, which is by the way where your cv angle is at its worst. Add motor torque now and you will blow a cv joint before the wheel will slip.
You've demonstrated that there is nothing to fear from a t bar crank if you stay on the pavement. Just be mindful of what's happening under your van when you start stuffing your tires into your wheel wells out in the woods

[photo_van]

The way it was explained to me was like this. A t bar crank puts more downforce on the front wheel. The wheel can't go down so the van goes up. The trouble only really begins when you are off road in four wheel drive. Stock setting on t bars at full droop on the front suspension will only be 250lbs which can easily be overcome by motor torque and becomes wheel spin. Crank your t bars and now you have three or four times the amount of spring rate on that wheel at full drop, which is by the way where your cv angle is at its worst. Add motor torque now and you will blow a cv joint before the wheel will slip.
You've demonstrated that there is nothing to fear from a t bar crank if you stay on the pavement. Just be mindful of what's happening under your van when you start stuffing your tires into your wheel wells out in the woods

I'm kind of following you. But again, under static vehicle weight, there is the same amount of force no matter where the t-bars are adjusted. The T-bars don't "force the wheels down" any more than they "force the body up" There is only so much given force per static weight of the vehicle and it only takes so much force to keep it's belly off the ground (statically). Now, if you are suggesting that there is more stress on the T-bar under full compression of the suspension, I can buy that as there is now more travel to the stop, so it will take more energy to fully compress the suspension.

What you really are doing is increasing the "pre-load" so the suspension doesn't have to travel as far before reaching static equilibrium (I'm making this up as I go, but it sounds good! ) I think that's what your talking about at at "full drop", there is a higher pre-load. If the suspension is at "full drop" then it is on the "stops", as vehicle weight is applied it comes off the stops. Your suggesting that it takes 3-4 times more weight (force) to get the suspension off the stops. It's hard for me to think my van really takes 1000# to come of the stops, but I don't know. It would be interesting to measure that force. I tend to think it's not that much (especially since my t-bars are more relaxed than they might otherwise be due to the extended suspension travel) But if it is 1000#, then think of all the additional traction I have!!! Perhaps that's why I can always "walk up" the checker boards when other vehicles spin? BTW, isn't a lot more force generated by a spinning tire that suddenly comes under tension? I've always heard traction is good, spinning is bad, it breaks things?

Again, I don't know the answers, just stating my experience. That said, I've had my rig on a lot technical jeep roads (that's what I built it for, that and camping at the end of those roads!) So far, no blown CV joints (knock on wood), but I'm more of a crawler then a tire "stuffer". But this is why I've seriously thought about dropping the diff; to lessen the CV angle. Out of curiosity, do people on Chevy truck forums break a lot of CV joints??

Thanks for the conversation

[Captn. Crunch]

The way it was explained to me was like this. A t bar crank puts more downforce on the front wheel. The wheel can't go down so the van goes up. The trouble only really begins when you are off road in four wheel drive. Stock setting on t bars at full droop on the front suspension will only be 250lbs which can easily be overcome by motor torque and becomes wheel spin. Crank your t bars and now you have three or four times the amount of spring rate on that wheel at full drop, which is by the way where your cv angle is at its worst. Add motor torque now and you will blow a cv joint before the wheel will slip.
You've demonstrated that there is nothing to fear from a t bar crank if you stay on the pavement. Just be mindful of what's happening under your van when you start stuffing your tires into your wheel wells out in the woods

I'm kind of following you. But again, under static vehicle weight, there is the same amount of force no matter where the t-bars are adjusted. The T-bars don't "force the wheels down" any more than they "force the body up" There is only so much given force per static weight of the vehicle and it only takes so much force to keep it's belly off the ground (statically). Now, if you are suggesting that there is more stress on the T-bar under full compression of the suspension, I can buy that as there is now more travel to the stop, so it will take more energy to fully compress the suspension.

What you really are doing is increasing the "pre-load" so the suspension doesn't have to travel as far before reaching static equilibrium (I'm making this up as I go, but it sounds good! ) I think that's what your talking about at at "full drop", there is a higher pre-load. If the suspension is at "full drop" then it is on the "stops", as vehicle weight is applied it comes off the stops. Your suggesting that it takes 3-4 times more weight (force) to get the suspension off the stops. It's hard for me to think my van really takes 1000# to come of the stops, but I don't know. It would be interesting to measure that force. I tend to think it's not that much (especially since my t-bars are more relaxed than they might otherwise be due to the extended suspension travel) But if it is 1000#, then think of all the additional traction I have!!! Perhaps that's why I can always "walk up" the checker boards when other vehicles spin? BTW, isn't a lot more force generated by a spinning tire that suddenly comes under tension? I've always heard traction is good, spinning is bad, it breaks things?

Again, I don't know the answers, just stating my experience. That said, I've had my rig on a lot technical jeep roads (that's what I built it for, that and camping at the end of those roads!) So far, no blown CV joints (knock on wood), but I'm more of a crawler then a tire "stuffer". But this is why I've seriously thought about dropping the diff; to lessen the CV angle. Out of curiosity, do people on Chevy truck forums break a lot of CV joints??

Thanks for the conversation

[Captn. Crunch]

Again, I don't know the answers, just stating my experience. That said, I've had my rig on a lot technical jeep roads (that's what I built it for, that and camping at the end of those roads!) So far, no blown CV joints (knock on wood), but I'm more of a crawler then a tire "stuffer". But this is why I've seriously thought about dropping the diff; to lessen the CV angle. Out of curiosity, do people on Chevy truck forums break a lot of CV joints??

Thanks for the conversation [/quote]

There is enough breakage to warrant a couple of mods that are very common with the S-10 IFS offroad crowd. #1 is the bravada shaft swap where they get rid of the problematic and inherantly weak two piece pass. side axle with the one piece unit from the Bravada or astro/safari awd. Spare axles are a common piece in their tool bags. The flanged axles vs. the slip in are preferred for ease of replacement.
Those who truly push their rigs often opt for a solid front axle swap. You must remember these guys are REALLY wheel. Body lifts on top of suspention lifts-35" tires. As you mentioned wheel spin, this is a real killer with a tire as heavy as a 35" is spun up and suddenly grabs.
Our vans weren't built in a way that promotes our placing them in situations that will cause this kind of damage. The long wheelbase and unibody construction procludes us trying extreme wheeling. The small wheel wells prohibit the use of excessively large wheels so we and our vans will probably get away with cranked and 31" tires.

[photo_van]

Good info, thanks!!