Wyo, that's the thread, I don't know why it's not in my saved threads list, but it is now. Check some of the wheels at Discount Tire, they have several types that have RWD-friendly offsets available. I think you can see them online at tires.com
No, your post was informative, I'm learning as I go with how some auto parts work. I haven't gotten under my Fury to see these TB's and the way they are set up. I was curious if someone had a link to a schematic or 3D exploded view. <span class='smallblacktext'>[ Edited Mon Jun 25 2007, 10:49PM ]</span>
Joined: Tue Mar 13 2007, 12:47PM
Location: Oregon
Posts: 65
One piece of bad info in this thread that needs to be corrected is the statement about steel alloy and manufacturing process affecting the spring rate. That isn't true, all steel has the same basic spring rate regardless of the alloy. The spring rate of a torsion bar is determined by the length and the diameter.
The 30 degree preset is a requirement for the thinner (low spring rate bars). I don't know what size these new bars are but hopefully they are big enough that they'll be able to survive without the preset twist. Mopar left off the preset on their race bars since the stress level was low enough inside the bar that they didn't need the extra margin of safety.
Joined: Tue Mar 13 2007, 12:47PM
Location: Oregon
Posts: 65
Well the offset (preset) provides some extra safety margin when the bar is twisted against the preset. So yes, a little thicker bar would also do the same trick but at the cost of being heavier and stiffer. The OEM engineers were pretty clever which is why they did the presetting twist. That way they were able to use a thinner and lighter piece of steel to accomplish the same thing as a bigger bar.
Since a 1.16 bar has about double the spring rate of a 0.98 bar I'd say Scott should be safe. Double the spring rate means the stress level is probably dropped in half for the same load since the twist will be reduced.
Joined: Tue Oct 11 2005, 01:33AM
Location: Calgary, Alberta
Posts: 5893
Outstanding information. !thumb
I've often wondering during our T-bar threads why Mopar made their bars side dependant.
Scott, did you ever compare the weight of the new vs old bars? I'm wondering if the weight difference is significant. Would T-bar weight be classified as unsprung mass?
I never put them on the scales, but I did do the old one-in-the-left, one-in-the-right routine. The difference was noticable, but not dramatic.
The whole preset twist thing makes no sense to me. The only thing I see being different is the amount of threads in/out on the adjusting bolt and the angle of the adjusting arm in the lower arm. The amount of tension produced by the lower arm doesn't change. None of the distances change. The angle of the lower arm to the body or T bar doesn't change. How does this relate to safety?
