Lower Backspacing=Weaker Axles???
I have been debating Cragar Soft 8's or maybe just a nice Wheel Spacer Kit, and they got me thinking physics (never a good thing
Lets say you have a 93-95 ZJ (Dana 35 rear, stock)
Lets also say you keep the same tire size.
You still have the same force distribution from the road on your tires (since your ZJ still weighs the same). But now that force is applied 1.25" to 2" further out than it was before. Doesn't sound like much, but when you consider that the nearest downward (vertical) force on the axle (wheel bearing) is only 8" or so away....
What is it? Torque=Force*Radius? (90deg angle, so the cross product is just multiplied)
... so an increase in the radius of 25% (8" to 10") increases the torque by 25%.
This means that the axle is about 25% more likely to snap when experiencing a high load.
Should I be worried about a higher propensity for my 15 yr old Dana 35 axles to snap? What about shearing (torsion)? I think the equation for torsion is similar, yeilding a similar increase, but that gets into other (more complicated) stuff...
let the debate begin!
or maybe just polite conversation... either is fine with me.....
'93 5.2L V8, Laredo, 242 TC swapped from a 249, 3" Coils up front and Front coils in the Rear, JKS Adjustable Track bar, K&N Cold Air Intake with Amsoil filter, Rear cargo area shelving, and KOR's Steering Gear Brace, IRO's Over-The-Knuckle Steering, Top Light Rail, Top Tire Carrier... for now...
OR If you prefer acronyms: 93 5.2 V8, 249>242, 3" FC, ~2" RC, JKS Adj. TB w/ KOR TB Bracket, K&N CIA w/ Amsoil filter, Shelves, KOR SB, IRO OTK HD steering