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! 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