Re: [Chrysler300] Fw: Torsion bars

[mjraguse@xxxxxxx]

In a message dated 8/10/2006 10:28:49 AM Eastern Daylight Time, 
wgraefen@xxxxxxx writes:
So long as they are in far enough to allow installation of the clip, I think 
they are permitted to float anywhere within the forward / rear distance the 
engineers gave them.  

Wayne

I agree with Wayne on this discussion. Think for a moment of the build 
variation, car to car,  of a point on the front lower control arm and the rear 
anchor. Probably few cars are ever precisely the same but vary by some amount.So 
installation float must be accommodated.   But after the bar is installed and 
the load is applied I doubt the bar moves on either end. The struts provide 
dampening for road shocks of the lower control arm of course, but allow little if 
any compliance of the arm.  So the bar stays put...   
Now if we can discuss the theory of the bars contracting and elongating..I 
propose that it doesn't happen. I had to review Hook's Law from my engineering 
library and I will explain.... All deflection of a torsion bar is in shear and 
the engineering formulas and experiments demonstrate that for a torsional bar 
of uniform cross section there are three constants when the bar is under a 
torsional load. Namely the angular deflection, the particular modulus of 
elasticity for the bar..this depends on the microstructure.. and the length.  The 
twist is contained in the shear stress of the bar.  As with any structure, don't 
exceed the elastic range and it will return. Such is the case of a torsion bar. 
 
Now lets think about if the bar did continually contract and elongate on load 
deflections...there would be so much wear in the sockets that you would have 
big wear ridges to over come when you remove a bar...Anyone ever see such 
wear?  I haven't. Therefore no stretching and shrinking..Only what Wayne has 
indicated..installation tolerance due to car variation.  Put them in, snap in the 
ring and lube the front end of the rear anchor, place the rubber seals on and 
adjust.  

On failure I have never had one fail either. And I am speaking from a pretty 
large sample space of cars all through the late 50's right up the three 
transverse torsion bar Cordobas and Imperials currently in my barn.  .Even our new 
58 Chrysler never failed one because the corrosion problem experienced in 1957 
was identified and the lube was installed with the seals by the 58 model 
year...But if a bar is removed carelessly without the proper puller then you could 
be setting yourself up for an eventual failure...If the outer surface is 
gouged for example by using a vise grips to hold the bar, significant stress risers 
in the outer surface are introduced..I must add that the maximum stress in 
any spring is at the outer surface so significant corrosion as well as the nicks 
I am speaking of can initiate early failure.  Perhaps that is what caused 
Gil's failure on his 64 model...otherwise failures are very rare.   
Marv   


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