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Leaf springs to 4-link

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Gordo View Drop Down
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    Posted: 02 Apr 2017 at 9:34pm
My Datsun 620 work truck decided to snap another main leaf spring on the rear.

Partly because it's a 44 years old, partly because of the 2" lowering blocks, without traction bars, that allows a lot of spring wind up.

Probably has nothing to do with the fact that I have no concerns about side stepping the OS Giken clutch at about 5k....

Na....

Anyway, leaf springs for the old dog are about impossible to find, and when a set pops up, they are rust pitted to hell.

So I decided to go 4-link :)

Now there are tons of kits to do this with good ol 'merican cars, but only one guy makes one for the 620, and the design wasn't something I wanted to go with.

So I bought some parts (meant for 'merican iron), and some steel, and made some measurements.

Came up with this:







Note the bottom mount Watts link, which give the lowest possible roll center.
The Watts link bell crank is form a PT Cruiser.
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alleycat View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote alleycat Quote  Post ReplyReply Direct Link To This Post Posted: 04 Apr 2017 at 3:59pm
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Braden620 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Braden620 Quote  Post ReplyReply Direct Link To This Post Posted: 12 May 2017 at 3:55pm
Hows she handle?
If we ever forget that we are One Nation Under God, then we will be a nation gone under.
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Gordo View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Gordo Quote  Post ReplyReply Direct Link To This Post Posted: 15 May 2017 at 5:53pm
A lot tighter on off ramps, and faster.
On a 400 foot diameter cloverleaf off ramp, it's at least 10 mph faster than with the leaf springs.
When I can get the back end to swing out, it corrects instantly.

Total suspension set-up so far is an ADDCO front sway bar, no rear bar.
Front torsion bars dialed lower, and rear axle sits about 3 inches off the bump stops.
Tires are 225-60-15 TA Radials.

I think the 7k (390lb) HKS springs are too stiff, so I just picked up some 250lb QA1 springs that I'm going to try.

Typically, softer springs will make the back end stick more, so I may end up installing my ADDCO rear bar to reduce body roll even more.
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