Re: IML: Torsion Bar Front Suspension

[Mark McDonald <tomswift@xxxxxxxxxxxxx>]

Dear Rolland,

Thank you for your insightful comments.  I wish we had more people on this list with actual "hands on" experience from Chrysler.  This is just one more reason why this list is great!  (Not to take anything away from anyone else's comments-- I just love to hear stories from inside Chrysler.)

I hope this doesn't offend anyone or lead us too far astray, but I find it fascinating that the torsion bar-- or torsion "beam," as they are calling it-- is being used on today's 2007 Honda Fit.  The reason is, as Rolland explains, that torsion bars, or beams, take up very little vertical space, making them very useful in a car that sits low to the ground.  So an "old" technology is new again.  :)

As I recall from my childhood, Caddys tended to make you feel a bit like you were on the high seas, due to the coil springs rebounding several times when going over a bump.  The Imperials, though, don't have this "up and down, up and down" motion, due to the torsion bars. 

I personally prefer a little better handling, whether it's due to torsion bars or whatever, and Imperials have that.  With the Caddys and the Lincolns you are fine if you are going in a straight line.  But try an emergency lane change at 65 mph and it's a different story.  In my Imperial, I always feel in control.

Mark M


On Friday, July 21, 2006, at 07:16 PM, RWestra@xxxxxxx wrote:

> I worked at Chrysler Central Engineering from 1959 to 1961 when the "Torsion-Aire" suspension was just two years on the market.  The stated reasons for going to a torsion bar spring were two-fold as I recall:
> 1.  Packaging - lower front profile for the 1957 cars.  It was easier to package a long bar parallel to the frame than try to tuck a coil spring between the upper and lower control arms.
> 2. Adjustable suspension height to avoid matching front coil springs at the plant. 
>  
> Along with the torsion bar spring a new suspension geometry was introduced to improve handling and control front end "dive" when braking.  This had nothing to do with the choice of spring configuration but it may have been easier to design in the desired geometry without a coil spring to restrict packaging.  
>  
> As I recall the torsion bar spring rate was higher than the coil spring.   This stiffer ride improved handling.  To compensate for the stiffer ride a new 14" tire was introduced.  This provided the "Aire" component of the "Torsion-Aire" ride.   (more than likely invented in the marketing department).  The new suspension was a good one and probably the most advanced of its time.  It represented probably the best ride/handling compromise of its time but this was due mostly to the geometry and tire selection and probably had little to do with the spring configuration.
>  
> I'm not sure but as I recall the suspension design looked a lot like the Citrone at the time.  As for the torsion bars influence on ride and handling it really didn't.  The conventional wisdom at Chrysler was:  whether you take a piece of spring steel and stretch it into a rod or coil it into a spring it is still a spring and like all springs must obey  Hookes law. 
>  
> This is my 2 cents worth on the Torsion-Air ride of the 50's at Chrysler.  My memory of events nearly 50 years ago is not perfect but this is my recollection. 
>  
> When I worked in Chassis research a rear torsion bar car was prototyped (a 1959 Plylmouth) and development work continued for 2 to three years but it never made it to production.  The comments were: "the leaf spring, with its multi functions, is just darn hard to replace. 
>  
>                                                                                             Rolland Westra