front upper ball joint question

[bmodracer]

I've seen this on a few cars now where they mounted the upper ball joint on the bottom side of the a frame. I'm guessing this would be the same as using a longer ball joint. What would be the benefit of doing this on a chevelle stub car? I am currently using the K6024 and pinto spindles.

[bmodracer]

True....but wouldn't that increase the angle of the upper a arm in relationship to the lower? Would that be a good or bad thing?

[Dirtracer50]

It would increase camber gain versus the ball joint mounted to the top of the a frame. Also roll center would most likely change as well. Any change in upper control arm angle at ride height has an effect on the frontend geometry.

[DaveBauerSS6]

I mount the left upper ball joint under the a arm to get more drop before the arm hits the frame.

The pivot points are what dictates the roll center, not the arm.

[Dirtracer50]

The upper A arm angle has to change if the ball joint is mounted to the bottom of the A frame versus the top and ride heights remain the same. Unless I'm missing something here anytime the upper A frame gains angle at a static setting the camber gain will increase. Please explain how this is incorrect if I'm wrong because I don't see any way that this is incorrect information.

[DaveBauerSS6]

The upper A arm angle has to change if the ball joint is mounted to the bottom of the A frame versus the top and ride heights remain the same. Unless I'm missing something here anytime the upper A frame gains angle at a static setting the camber gain will increase. Please explain how this is incorrect if I'm wrong because I don't see any way that this is incorrect information.

I think the key word is static. The arm is the same length. The inner pivot is static. The ball joint follows the arms arc. The a arm could be mounted 12 oclock vertical to the static position of the ball joint and your camber gain would be the same as 2 oclock. If the static position of the ball joint changes, then yes the camber gain can change.
Hope this helps, best I got.

[29 avenger]

anyone have a pic of this

[RaceMentally]

Finally Stocker didn't understand a simple geometry equation.

[dirt88]

the a arm tubing can be any shape, it could be shaped like this ^ and the measurement from the bj center and pivot would still be the exact same as -. You don't measure the tubing when you measure the angle.- IF you put them on the bottom you can change the a arm and leave the bj bolted to the spindle.I dont kno what all it does or what it changes but I do kno it u draw a line from the pivot of the bj on top of the a-arm then move the bj to the bottom of the a-arm those line WILL not line up mite not b much cause the a-arm is not very thick but it will change

[speedbuggy]

I dont kno what all it does or what it changes but I do kno it u draw a line from the pivot of the bj on top of the a-arm then move the bj to the bottom of the a-arm those line WILL not line up mite not b much cause the a-arm is not very thick but it will change

"It ain't what you don't know that gets you into trouble. It's what you know for sure that just ain't so."
~Mark Twain

The only reason it can possibly change is if, to make it physically go together, you are also changing the UCA length. If the ball joint is fully seated in the spindle and the LCA has not moved, it is not possible to change the UCA angle without lengthening/shortening the UCA.

[DaveBauerSS6]

I dont kno what all it does or what it changes but I do kno it u draw a line from the pivot of the bj on top of the a-arm then move the bj to the bottom of the a-arm those line WILL not line up mite not b much cause the a-arm is not very thick but it will change

The arc will line up , the ball joint will be the thickness of the a arm further down the arc.

Had the same argument about a j bar.