Question About 620 Stock Leaf Springs?

[650savag]

I've always noticed that my '78, 620 had a very stiff feeling rear suspension and I am wondering if the previous owner added a leaf to the rear? It has three long leafs that are clamped on both ends and then a short one that is only clamped by the middle clamp. These four look to be the same thickness (about 1/4" thick), In addition to these four leafs, there is another long leaf on each side that is a lot thicker (about 1/2-5/8" thick). These thick leafs look like they may have been added for stiffer suspension. Could someone that has a stock rear suspension look and see what their truck has? Also, would this extra leaf add to the towing and load capability or just raise the truck up. I don't do much heavy hauling or towing and I'm more interested in a better ride (commute 60 miles a day). How much trouble is it to remove the extra spring? I haven't had any experience with rear suspension. Thanks for all the advice. Dan

[flyerdan]

Just went out and had a look, on the 78 I drug home last weekend there are two leaves, think some were pulled on this one. On my 75 there are four leaves attached at the ends and a larger overload on the bottom. On my 73's (one is now a trailer), they both have three long leaves, plus an overload nearly a half inch thick on the bottom. I've had 1400 pounds in the 73 on several occasions.

[datsunaholic]

This is what a stock 73-74 spring pack looks like:

 

 

Later years went with more, smaller leaves. Usually 4 plus the overload, which was tapered and smaller on the later trucks. Longbeds usually had an additional spring.

 

Here's a modified '76 longbed set:

 

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That has an added upper overload. That's how I like it.

 

Removing leaves smooths out the ride, lowered the truck, and reduces the load capacity. On the 4-leaf springs, each leaf removed takes away about 400lbs load capacity, or just under the load. Leaving only 2 leaves gives you about 200lbs capacity and risks bending the upper leaf when cornering.

[650savag]

Datsunaholic, That pic of the '73-'74 pac is what mine looks like but it has a very short one on the very bottom (5 total leafs). My overload leaf is just like the one in your pic (thick and squared on the end) (no taper). Mine rides very rough when I hit a bump with the rear tires it feels pretty solid. I put 4 new, good quality, shocks all around and it helped the front but the rear is still very stiff. Is it a big deal to remove the overload leaf? Anybody ever done this? Any special precautions to take? Thanks for the pics and advice. Dan

[datsunaholic]

The overload leaf doesn't stiffen the ride, since most of the time it's clear of the spring pack. But if you DO remove it, and manage to get a large load on the springs (like hitting a speed bump with 700lbs in the bed) you can end up bending the springs permanently. Better to take out one of the regular leaves.

 

The huge overload I've never seen on a KC, someone might have changed the whole spring pack, like I plan to do in my '78 4X4. I picked up a set of stock '73 springs to go in it (someone removed leaves from my 4X4, makes no sense. Completely de-arched)

[650savag]

Thanks for the good advice. I've decided to leave it set up like it is. I swapped out all 4 tires and rims today and noticed a remarkable difference in the steering and the suspension. I've been running wide rims and 70 series tires on it ever since I had it and they were getting pretty worn. I had a chance to get 4 stock Datsun rims that had 4 brand new Goodyear 205/75R tires on them for $140 today and so I spent most of my saturday swapping them out and I can't believe the difference it made (especially in the steering). Thanks again Datsunaholic and Flyerdan for the good advice. Dan