Tarett 25mm sway bars - how best to measure?

[175K911]

I have Tarett 22mm sway bars on my car, have always liked Ira's parts. But about 8 or 9 years ago I asked if he's ever made any bars that were heavier than the 22mm equivalent he sells. So he made me a pair that are 25mm equivalent. Since they're hollow bars and the exterior dimension is the same on them all, he'd made the 25's with thicker stock to get to the 25 number. I've never used the 25's, they're taking up space on the parts shelf in my basement so I want to sell them, but have to figure out a way to demonstrate that they're not the 22mm bars he sells with his sway bar kits. I suppose I could weigh the 22 vs 25, any other thoughts?

[gtc]

Somehow measure and compare the torsional stiffness?

[Cory M]

weighing the 22 and 25 together would be the easiest method

[Dr J]

Take the fourth root of (D_outer^4 - D_inner^4)

That should be close to 25 if it is a 25 mm equivalent.
Where D_outer is the outer diameter and D_inner is the inner diameter.

I am assuming the 25 mm equivalent means the 25 mm is a solid bar. If I'm wrong let me know to modify the formula.

[175K911]

Originally Posted by Dr J

Take the fourth root of (D_outer^4 - D_inner^4)

That should be close to 25 if it is a 25 mm equivalent.
Where D_outer is the outer diameter and D_inner is the inner diameter.

I am assuming the 25 mm equivalent means the 25 mm is a solid bar. If I'm wrong let me know to modify the formula.

The bars are actually hollow. These bars are constructed to be the torsional equivalent of a 25mm solid bar without the weight of a solid bar. And there’s no way for me to measure the wall thickness because the ends have welded in pieces that the sway bar arms bold to.

[Cory M]

I've got a couple loose 22mm bars in the garage. Want me to weigh them so you have a reference to compare to?

[Cory M]

Fyi, I weighed two new 22mm bars on my bathroom scale and they were both 3.9 pounds.

[Travis Neff]

A 22mm solid bar has the same stiffness as a hollow 25 as far as I can tell.

[175K911]

Originally Posted by Cory M

Fyi, I weighed two new 22mm bars on my bathroom scale and they were both 3.9 pounds.

Great, thanks! Saves me having to pull the rear off the car to weigh. I’ll check mine later this morning.

[175K911]

On my scale, the normal 22mm equivalent bar is 3.8 lbs.

The custom 25mm equivalent is significantly heavier at 6.9 lbs.

And I’d forgotten that I’d used one of the 25’s on the rear of my car for one summer. So one new, one used