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aslanefe

Modified stock UCA for more caster

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In a post I had mentioned that I modified my UCAs for more caster and a few members asked me how I did that. I was doing it on my 69 Grande recently and below are some pictures showing the modification. Moved the ball joint mounting holes 20 mm aft. If my memory serves me right, when I had done the math to get +4 caster and ended up with 20 mm. May be someone can do the math using stock spindle geometry and verify that moving upper ball joint 20 mm increases the caster +4.

So, moving the ball joint holes 20 mm aft. Used a card board to trace the original holes and big hole for ball joint, then moved them 20 mm on the card board. Then made a template from the card board and made the steel doubler that is welded to the surface the ball joint is attached. The doubler was a piece of scrap sheet I had that was the same thickness as the UCA metal. Drilled the original and new (moved) ball joint mounting holes on the doubler. Used the original holes to attach the doubler to the UCA using bolts and nuts. had to slice the aft side of the UCA so the doubler will slide in. Welded the doubler and drilled the moved holes to UCA using the holes on the doubler. Had to cut the egg shaped top part and move that to rear so ball joint will fit. Need to trim some areas so ball joint grease fitting fits and is accessible.Then welded and braced everything.

Had done this mod on my 70 Grande a few years ago on a 3 bolt ball joint UCA. 3 bolt UCA is a little less work to modify. As far as I remember, I have +6 or +7 caster on my 70 Grande with stock strud rods and stock LCA.

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Smart mod, and not too terribly difficult.  Real nice fab work. On my tube arms I moved upper bj back 1/2 inch, and the lower bj forward 1/2 inch.

Did you ever give it a thought to install screw in ball joint sleeves? With them you're able to run the wheel closer to the ball joint. 

On a related note, the closer you get the caster angle to the SAI (steering axis inclination) the flatter your tire patch is during turning. Our Mustangs have 8° SAI.

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1 hour ago, RPM said:

Did you ever give it a thought to install screw in ball joint sleeves? With them you're able to run the wheel closer to the ball joint. 

On a related note, the closer you get the caster angle to the SAI (steering axis inclination) the flatter your tire patch is during turning. Our Mustangs have 8° SAI.

Did not need screw in ball joints. I am running 14 inch original steel wheels on the 69 and 15 inch steel Magnums on the 70, so I have plenty of clearance between wheel and ball joint. Also, after the mod, I trimmed the outboard edge of the UCA which gave me 1/4 to 1/2 inches more clearance. 

When I installed the modified UCAs on the 70, first set the caster to 9-10 degrees; then after a few weeks reduced it a little. It corners nice. Straight driving is also improved, wanders a lot less. If/when I get rid of the factory PS, it should not wander at all.

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