Stopping The Hop
How Rear Telescopics Control Axle Movement
The original lever arm dampers on the Minor were quite an innovation in their day; certainly a great improvement over the friction dampers commonly used on the ‘popular cars’ of the time. More expensive cars already used forms of hydraulic dampers for a refined ride. Times moved on and suspension improved. Roads get better and we all drive faster.
The cause of axle tramp on leaf sprung cars, correctly known as “spring wind up”, is lack of sufficient axle location and inadequate damping of the unsprung forces in the suspension; i.e. the axle and wheels. As the car accelerates from rest the natural tendency of the applied torque is to try to rotate the axle casing. This is obviously difficult to do, as it is attached to the spring, and hence the car. Most of the effort goes to turn the wheels, but some will also manage to rotate the axle against the spring resistance. This causes the spring to take on the shape of a shallow letter S, which in turn will snap back ‘straight’ again, but slightly in the other direction. The torque will again try to wind up the spring and the whole sequence starts over again until eventually friction and reduced transmission forces cancel it out.
The lever arm damper is not capable, because of its design and location, of controlling these forces adequately, hence the most common fault on the Minor- axle hop. The same theory applies on enthusiastic cornering. Only this time one side of the car is now lighter because of weight transfer, and as a result, offers less resistance to being ‘wound up’, and wheel patter occurs.
By off-setting the lower attachment pin away from the axle centre line, causing the dampers to angle in towards the middle of the car, a rear telescopic damper conversion kit will offer the following:-
Superior control of unsprung weight, hence better tyre adhesion.
Efficient damping of wheel patter caused by axle tramp.
Smoother acceleration and smoother cornering.
Greater resistance to spring wind up (because of the off-set pin).
Cooler running (thinner tube walls), hence less fade out due to heat.
Cheaper replacement costs.
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