Re: IML: Torsion Bar Front Suspension

[Brad Hogg <luxoliner@xxxxxxx>]

The first torsion bar that broke on my 78 was after I'd driven the car 
across town and back over our very rough streets.  I parked the car in the 
driveway and walked into the house before I head the clatter as the right 
side torsion bar broke abdout 6 or 8 inches from the back end.

The second one broke either 6 or 18 months later...I remember it was in the 
spring, just not which one.  I'd just drove away about a block or less from 
home on my way to work one  morning when the left side bar broke in a very 
similar location as the other one had previously broken.  I replaced that 
bar when I returned home from work that evening with a bar from my 1976 T&C 
parts car.

Fortunately, a broken torsion bar does not render a 74-78 C body undrivable, 
just a bit bumpy.  You can still steer left and right through the full 
travel of the steering.  I was pretty impressed with this.  (this was with 
P235-75R15 tires)

----- Original Message ----- 
From: "Burton Bouwkamp" <northburt@xxxxxxxxxxx>
To: <mailing-list@xxxxxxxxxxxxxxxx>
Sent: Saturday, July 22, 2006 5:35 PM
Subject: IML: Torsion Bar Front Suspension


I was a motor and chassis engineer at Chrysler from 1951 to 1962. We
(Chrysler) had a problem in northern climates with broken torsion bars on
1957 models after one to two years of service. It was caused by corrosion of
the surface of the torsion bar from dirt/salt/moisture accumulating around
the bar at the socket cavities (either end). In 1957 we had not adequately
sealed the bar ends from exposure and accumulation of this corrosive mud.
The problem was the most serious in communities that used salt for snow and
ice removal. (We sealed these cavities in 1958, 1959, etc.)  Until the seals
were available we told our service people to pack these cavities with
grease.

The corrosive action of the mud attacked the highest stressed part of the
bar - the outside surface - causing stress risers which lead to fracture of
the bar. A mystery to many of us was why almost all failures happened while
the car was parked overnight - and not while the car was in motion. (It must
have had something to do with the ambient temperature change overnight.)

Burt Bouwkamp




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