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Old 01-14-2024, 10:44 PM   #21
itsnotbroken
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Join Date: Jul 2021
Location: Hesperia, CA
Posts: 6
Question Re: Caster Mod for pre 73

I'm attempting this mod on a 1965 GMC Suburban 1500.
Last year I swapped power steering from a 73-87. (gearbox, pitman, idler, drag link, inner tie rods) It is extremely twitchy now that it has power. (and probably that I'm not used to a new gerar box compared to the old worn out manual box)

I had the LCA shafts milled 3/4" back from the original location.
While I have it apart, I'm swapping spindles to add disc brakes.
I'm using OEM contral arms, 2" drop coils (have been on the truck since 1987) new CPP drop spindles. I'm not planning on moving the suspension travel. RIde height should end up with the top of a 29" tire sitting exactly at the top of the wheel well opening. The leaves me about 4" travel until it rubs on the inner fender.

I am mocking it up now without the coil springs, and my lower ball joint is binding before I hit the upward travel limit beacause it's still pointing 90 degrees straight up relative to the control arm. It needs to be pointing backwards towards the upper ball joint.

The upper ball joint is aimed generally at the lower ball joint location in the caster plane, so this mod doesnt affect the upper ball joint. It is also binding close to the upward travel limit in the camber plane (it's almost 45 degress from level), but this would be doing this whether or not I moved the LCA forward. I have to solve this separately.

I can fit a digital level between my ball joints & the king pin angle (caster) is showing around 22 degrees at ride height. I have no shims on the upper arm shaft.

Even thought I'm changing spindles, I'm not convinced that this is causing the issue. The ball joints run in a straight line throught the spindle holes.

Anyone else get weird readings like this?

Mark V

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