New Front Spring Travel

[duke36]

I have a new A- spring, front. What should be the expected travel distance?
It is well lubed with new shackles and stock shocks but is very firm.

[Joe K]

So where did you get this? At least three different spring manufacturers available now. Only one of these I would consider purchase.

Ford springs are quite the engineered product: different thickness leaves, different contour of leaves. The two manufacturers not considered do Model A springs as a side-line to their trailer spring volume business.

This would be the spring of choice: http://a-springs.com/ Many parts houses carry this brand - but not all.

Also, don't forget that comparison with your old spring is not advised since springs lose their contour and develop a "set." The front more especially.

Joe K

[duke36]

Have the A-spring. The ? is how much expected travel? Calc's would indicate that if the spring rate is 315#/ inch. (from Detroit Spring), then assuming model A sedan front weight distrib. is approx. 40% of 2400#= 960#, the travel would be 960/315= 3.04 in. Am I missing something here in calculating for a leaf spring ? Would it be 1/2 of that for each wheel ?.

[Joe K]

315#/inch would be the deflection rate AT its normal (full load) zero position.

For a cantilever spring, the actual K (spring rate) changes depending on the degree of deflection. (i.e. the spring "stiffens up" the more it is deflected.)

A spring deflection diagram would be what you need to fully examine interaction.

Interesting aside, Volkswagen used "variable rate" coil springs (action similar to a cantilever) and then added rubber "cushions" around each strut rod, the object being that as the car was more heavily loaded the spring rate increased FASTER than the variable rate springs alone would. This apparently was Porshe's idea, had a patent on it, and IMHO resulted in a very finely tuned suspension.

That was until the rubber cone got broken and fell out - then the car handling got "mushy" on the road - although the ride was still pretty good.

Ford "pre-anticipated" Porche in the use of variable rate springs and 60/40 shocks. I'm not sure this feature was ever patented. And when right made a very nicely riding and handling car.

Joe K

[37 Coupe]

Does the front spring require a web pad between it and crossmember like later Fords,or metal to metal?

[duke36]

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Originally Posted by 37 Coupe

Does the front spring require a web pad between it and crossmember like later Fords,or metal to metal?

I made one about 8" long out of denim with a hole for the center bolt, glued it to the spring and then greased it before installing in the crossmember. I thought webbing was too thick. The removed spring had no pad. Re - tighten the u bolt nuts after spring settles in.