Torque Twist with Full Droop?

[Mad Scientist]

When running a full-droop setup (with a shafty, of course), is torque twist an issue? I am not talking about the suspension unloading when sidehilling and whatnot, I mean that all-too-familiar chassis lean you get under heavy throttle.

It would seem that most torque twist is a result of shock compression on one side when running a "standard" shock setup (i.e. - coil-over compression shocks). So, with the shocks already at full compression on a full droop rig, there is no more compression to make the truck lean. However, does the other side lift at all under throttle?

This would be without any springs on/in the shocks, just oil.

 

[Defender]

ya you can still get tt, but instead of the shock compressing the opposite side will extend.

 

[BENDER]

Without internal springs, I'd think the chassis would unload.

 

[Badd]

droop is very hard to get right on a shafty . I did have T T on my tuber but after playing with the springs & finding some to drop fully on TLT axle. T T was so bad I about said to heck with it all , but then I started playing with the oil . that is where I got the T T out . the only time you see any at all is on a hard climb and the right front will unload just abit . I started out with revo shocks but soon changed over to Maxx type . I also tried running the batteries on the axles but change that also . all I can say to help you is be ready to try many setups . here is the build thread on my tuber ........ http://www.rccrawler.com/forum/showthread.php?t=62790&highlight=team+nrc "thumbsup"

 

[TimR]

I have noticed that on my TXT with a droop setup the right rear tire will compress a bit when climbing. That is about all that can compress now. So a droop setup won't eliminate torque twist completely.

 

[Big Mike]

So, with the shocks already at full compression on a full droop rig, there is no more compression to make the truck lean. However, does the other side lift at all under throttle?

It definitely will under the right conditions, and how much or little it does depends heavily on your link geometry, but springs and oil play a definite factor as well. It will be far worse with no negative spring and only oil, at least it was on my TLT based rig.

On the rocks it's very hard to tell, and on flat ground I get no twist at all (falsely leading me to believe I'd eliminated it entirely - impossible on a shafty) but if I do the accelerate up an incline test (spinning your wheels up an incline the truck can't make due to low traction, I use a piece of smooth particle board) I can watch the right side of my rig lift approx. 3/16" - 1/4" off the shocks.

Right now my set up has about a 1/4" of "free travel" unaffected by the springs. In the "bottom" of the travel range the springs come into play and keep the chassis from tipping around in an uncontrolled manner. I'm running 100 wt. silicone also, droop setups definitely need a heavier oil for slower damping of the shock movement.

These threads are both pretty long, but they have a lot of info on torque twist, link geometry, squat/anti-squat and instant center, etc. Check 'em out:

http://www.rccrawler.com/forum/showthread.php?t=54791

http://www.rccrawler.com/forum/showthread.php?t=65382