Chevy & GMC Vans

Captn. Crunch wrote: 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 wrote:

Captn. Crunch wrote: 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