Stock spring thickness/height difference?

In 1968 spring packs were offered in the front from 7 leafs to 12, and the rear from 5 to 13 depending on the order. That being said how would the factory make up the height difference from say a 12 pack front at 2 5/16” and a rear 5 pack at 1 9/16”? I'm thinking factory shims on the rear to make up the 3/4” difference. Thoughts?

 

odds are if it had 12 in front it woulda had around the same in the rear. if not who knows...

 

I was not around Jeeps in '68, but I would guess that Jeep did not mismatch the ride height front to rear. The springs were matched to give a level stance, regardless of the leaf count. These are the factory springs from my '75 -



These are the factory 9-leaf front / 5-leaf rear spring packs. The thickness of the pack is a little different front to rear, but not by more than an inch or so. I saw quite a few new Jeeps equipped with these springs back in the day, and they sat level. Same for the HD spring option.

I recall Ken (oldtime) posted a list of the springs available in the '60s. Jeep must have used two or more suppliers for springs, because you could have different leaf counts that were defined by Jeep as functionally equivalent. So one Jeep could have 13 leaf rears, and the next could have 10, and the ride height and stiffness nominally would be the same.

In the '70s, Jeep offered a standard spring, and an optional HD suspension (springs and shocks). I would expect no more variation than that in the '60s. The book might show 10 and 13, but they were the same option, depending on where Jeep was sourcing springs at that time. ... I presume.

 

Weren't the number of leafs used to determine spring rate, and not height?. which is why you could have different number of leafs in a given spring pack but get the same ride and height.

 

How I imagine the process is that Jeep sends out a request for bids on the contract for springs, and they have a spec - the physical dimensions, a ride height with a certain load, and a rate spec of some kind. Then the suppliers come back with bids. The suppliers would have some leeway in the design, ie the number of leaves.

I recall that the packs with lots of thin leaves tend to go flat and rock hard, due to friction between the leaves I presume. There's also the groove down the enter of each leaf, which would change the inter-leaf friction some.

So my feeling is that Jeep wanted two suspensions to offer to customers at any one time (standard and heavy duty) and that the variation in leaf count just comes from manufacturing differences between suppliers, or evolution of the spec.

 

I have a 12 pack front and a 5 pack rear with shims on my 68. I believe the PO swapped out the rear springs and added the shims to make up the difference. I have one broken leaf in the rear, if I can't find a used leaf I may remove 4 leafs from the front and add 3 of them to the rear (add 2 replace replace 1) with new u-bolts. All the bone yards in my area are running dry of early 5's

 

Those springs are still sitting on my parking pad ...

 

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