turning torion bars down?

[Stormer]

There's only one stance suitable for Imperials.

You damn straight.

 

[commando1]

You damn straight.

You've become a stranger around here. Too boring for ya?

 

[Stormer]

You've become a stranger around here. Too boring for ya?

Na, just been very busy & very disconnected.

 

[kmccabe56]

Alan, this one of the rare times here I have to disagree.
I won't try to research the mountain of data on torsion bar out there and then attempt to boil it down to a few lines here.
Basically, a car's ride height is a function of applied load vs. spring resistance.
That's why when you go to a larger diam. bar, the ride ht. increases.

Whoa, for somebody who likes to preach stock (and I'm a believer too), suggesting that the ride height increases if the bar diameter increases is pure hogwash.

The ride will be firmer with a larger bar, but when you go back to your favourite FSM, it tells you how to set ride height and ride height has nothing to do with bar diameter.

 

[kmccabe56]

Not being a mechanical engineer I do not see how changing the relative position of the wheel will change the spring dynamics, having the wheel already 2" into its travel will. Changing to a heavier bar and running the bolt to the same setting will cause the car to sit higher but the ride height will not change the bar position (amount of static twist) that is purely a factor of static weight. That is assuming the same bar just a different ride height, now switch to a heavier bar and you will see less twist just from the static load, so you will need to run the adjuster in less.

So without changing the bar but just the ride height the degree of twist on the bar will not change.

Now if you change to a heavier bar it can resist the weight easier and will not twist as much. Because of this you will not need to run the bolt in as much, adjusting it the same the car will sit higher.

The adjuster bolt was designed to even out differences in springs, was not designed to alter ride height. The factory service manual does not give a range just the difference (measured from the bottom of the ball joint and the bottom of the torsion bar socket) on the 69 C-Body it is 1-1/8" (+/- 1/8"), doesn't matter what bar, tires etc. Same measurement, all bodies, all engines all bars... (within the c-bodies).

I wouldn't lower the front with the torsion bar more than 1", any more you risk having handling issues.


Alan

Damn good answer Alan.

 

[kmccabe56]

Here is an illustration to better show what is happening.

The fuchsia is the control arm.
The light blue the torsion bar and the socket with the finger all fixed together, the dark blue arrow representing the fixed orientation of the bar.

The Control arm moves independently of the bar and its socket with finger.

The top drawing represents a LOWER stance with the adjuster only partially in.
The middle drawing represents an AVERAGE stance with the adjuster in a little more.
The bottom drawing represents a HIGHER stance with the adjuster in much more.

The drawings are symbolic and represent a loaded car on its wheels and under static load, so there is pre-twist in them that is a constant in all three as the weight is a constant.

In all these the block that the bolt threads through is fixed (floating in its pocket but fixed in reference to the arm) to the control arm.

In all three illustrations the bar is in the same position.

The weight of the car is sitting on the control arm pivot which in turn is sitting on the bolt which in turn is .sitting on the block in the arm and ultimately out to the wheel. The control arm acts as the lever with the fixed point being the wheel and the weight of the car being at the extended point. The weight on the lever is trying to push down and the torsion bar resist and twist in doing so. The bar needs to be fixed at the other end to do this. The ONLY thing that is going to cause that bar to twist is a change in weight/force.
View attachment 128574


Alan

Can't make it any easier to understand than this. Can you include this in the book you're gonna do on the restoration of your car??