Re: torsion level

Posted by Ross On 2017/7/19 6:17:16

Mr Allison, developer of the Torsion Level system, was aware from the get go that the cars would need a leveler. On an interconnected system such as TL, the car is essentially balanced at its center of gravity to take advantage of the car's higher translational rather than polar moment of inertia. Thus the "level" part. However, being balanced at its center of gravity, even slight variations of load will cause it to settle to one end or the other. This is countered by the hysteresis of the rubber bushings to some degree; they were designed to be sufficient to keep the car from settling one way or the other after passing bumps or dips. Load changes were to be handled by the leveler.

I don't think Mr. Allison was taken by surprise by characteristics of his own design and needed to add a leveling device after the fact. The cycle-car prototype is fitted with a leveling sytem; he made them from two Hudson window regulators, complete with cranks.

If TL cars are in need of constant re-leveling now it is due to deterioration of the rubber bushings that have lost their self centering effect. The upper inner bushing have a major influence. I treated my 56 to all new bushings 40,000 miles ago and it still levels rarely while underway.

Another cause of excessive need for leveling is shocks with excessive rebound action. I installed some really stiff Gabriels (I think) on a TL car years ago and had to take them off. The self centering action of the suspension was no match for their rebound setting and the car would nose down after every bump causing the leveler to come on. Generally speaking TL cars can get by with fairly soft shocks because the natural frequency of the suspension is much lower than conventional. They should be stiff enough to prevent wheel bounce and not a whole heck of a lot more for best ride.

There is probably a copy of the SAE paper on TL on site somewhere. That is an interesting read.