Rear torsion bars - what is inboard what is outboard?

[Vereeken]

When pulling my rear torsion bar I came to the conclusion that the bar is different on both ends.

I am talking about the single torsion bar. I understand that left or right bar are different based on color code but that is not my question.

I notice that a single bar has 2 different ends. One end has slighlty longer splines, I would say plus 0,5 cm. difference between the 2.

I noticed when pulling it that the longer splines where inboard and the shorter outboard. I would have assumed the other way around....

Is it relevant?

Michel

[pete3799]

The spline count is different inside/outside.

[Vereeken]

So what you are saying is that you can not install backwards?

[MBAtarga]

Originally Posted by Vereeken

So what you are saying is that you can not install backwards?

correct

[boyt911sc]

Michel,

The 915 type rear torsion bars have 44/40 (outside/inside) splines and stamped markings (L/R). The TB could not be installed backward. They only fit one way orientation if you follow the L/R setting.

Tony

[Vereeken]

I did not count the splines but I trust your mathematics. There is no L/R marking on an otherwise pristine torsion bar.

What got me worried was that the blue paint (for the righthand side) on the torsion bar was inboard . i would have expected that outboard.

[smadsen]

I'm told the load twists the T-Bar a certain direction...every time the suspension bounces. After 30-40 years, they don't enjoy being twisted the opposite direction. Put them back where they came from.

[Flojo]

Originally Posted by boyt911sc

The 915 type rear torsion bars have 44/40 (outside/inside) splines and stamped markings (L/R). The TB could not be installed backward. They only fit one way orientation if you follow the L/R setting.

exactly

[Kraftwerk]

Also, what I understand is, the two sets of splines on each bar are not exactly lined up, rather, the splines are slightly 'staggered'... meaning you can turn the bar and only move it 1/2 a "notch" . Right? Maybe I didn't express it correctly.

[icarp]

The rear T bars have 40 splines on the inside and 44 splines on the outside .
Each notch for the inside spline is equal to 9 degrees .
So 40 splines @ 9* per notch you get 360* total. 9x40= 360
44 splines on the outside allows for the 9* to be split into 4 parts each at 2.25*
To set the T bar 4.50* one way or the other, move the inner splines 1 notch in the direction you desire , more ride height or less, then move the outer splines in the opposite direction 2 notches with the spring plate .
1 notch = 9* on the inner, then 2 notches on the outer in the
Opposite direction =2.25* per notch x 2 = total 4.50*
As a result of the length of the rear banana arm length , (the math allows ) the ride height of
the fender lip to change about .250" to .300" per notch on the outer spline , depending on the stiffness of the T bar .
I hope this helps
Ian

[Kraftwerk]

Thanks Ian, excellent explanation.
When I did my suspension, I took notes of the "before' spring-plate with angle finder etc. when I finally brought it in for corner balance and alignment, the mechanic said i was off by one spline, but I didn't ask him if it was the inner or outer spline..