RE: [Chrysler300] Fw: Torsion bars

["Rich Barber" <c300@xxxxxxx>]

Good point on thermal expansion.  I don't know the length of a torsion bar,
but a 48" long steel bar may change its length by less than 1/8" over a
temperature range of 200 degrees.  Production tolerances, chassis flex and
other variables mandate provision for some end tolerance and motion.  My
parts book shows a "cushion" in front of the front end of the "BAR or
SPRING, Torsion" for the '57 models.  I think I read that something
different was done in subsequent years--perhaps a spring to absorb linear
variances and to keep the torsion bar somewhat stable in its sockets.

I'd like to see a dial micrometer on the unrestrained end of a torsion bar
under normal angular deflection.  Theory notwithstanding, I'd not be
surprised to see it shorten up a mil or two.

Rich Barber
Brentwood, CA

-----Original Message-----
From: Chrysler300@xxxxxxxxxxxxxxx [mailto:Chrysler300@xxxxxxxxxxxxxxx] On
Behalf Of Paul Holmgren
Sent: Saturday, August 12, 2006 10:50 PM
Cc: Chrysler300@xxxxxxxxxxxxxxx
Subject: Re: [Chrysler300] Fw: Torsion bars

mjraguse@xxxxxxx wrote:
> 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   

Interesting, as a given, the Tbar is of some lenght, heat/cold cycles 
suggest that with the lenghts we see for Tbars, they should have room 
for thermal expansion/contractions  ???

-- 
Paul Holmgren
2 57 300-C's in Indy
Hoosier Corps L#6


To send a message to this group, send an email to:
Chrysler300@xxxxxxxxxxxxxxx

For list server instructions, go to
http://www.chrysler300club.com/yahoolist/inst.htm

For archives go to http://www.forwardlook.net/300-archive/ 
Yahoo! Groups Links



 






To send a message to this group, send an email to:
Chrysler300@xxxxxxxxxxxxxxx

For list server instructions, go to http://www.chrysler300club.com/yahoolist/inst.htm

For archives go to http://www.forwardlook.net/300-archive/ 
Yahoo! Groups Links

<*> To visit your group on the web, go to:
    http://groups.yahoo.com/group/Chrysler300/

<*> To unsubscribe from this group, send an email to:
    Chrysler300-unsubscribe@xxxxxxxxxxxxxxx

<*> Your use of Yahoo! Groups is subject to:
    http://docs.yahoo.com/info/terms/