Ball joint mounting on top or bottom of LCA?

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S15DET
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Ball joint mounting on top or bottom of LCA?

Postby S15DET » 06 Feb 2009 12:10

Shown both ways below, which is correct?
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front suspension.JPG
Ball joint on BOTTOM (inside) LCA
front suspension2.jpg
Ball joint on TOP of LCA

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okayfine
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Re: Ball joint mounting on top or bottom of LCA?

Postby okayfine » 06 Feb 2009 12:57

Factory is top. Wouldn't mounting them below raise the control arm (if only slightly)?
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Re: Ball joint mounting on top or bottom of LCA?

Postby djlotus » 06 Feb 2009 12:57

When I tore my car apart the ball joints were underneath the lca. Not helping your case much, but that's the way it was and that's the way its going back together, at least unless I find that it's supposed to be on top.

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Re: Ball joint mounting on top or bottom of LCA?

Postby rnorrish » 06 Feb 2009 13:10

okayfine wrote:Factory is top. Wouldn't mounting them below raise the control arm (if only slightly)?


oooh, less bump steer!
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okayfine
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Re: Ball joint mounting on top or bottom of LCA?

Postby okayfine » 06 Feb 2009 13:29

djlotus wrote:When I tore my car apart the ball joints were underneath the lca. Not helping your case much, but that's the way it was and that's the way its going back together, at least unless I find that it's supposed to be on top.


All I have to offer at the moment is the exploded view from the front of the axle section of the Parts Catalog. The Chassis manual isn't helpful one way or the other.
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Pages from Axle.jpg
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S15DET
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Re: Ball joint mounting on top or bottom of LCA?

Postby S15DET » 06 Feb 2009 15:08

Like djlotus, mine were on the bottom when I took them apart, as were the ones on the '71 parts car that I had. The hole in the LCA seems to be a perfect fit over the boss on the ball joint, so I figured this was correct.

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Re: Ball joint mounting on top or bottom of LCA?

Postby ktberube » 07 Feb 2009 14:42

Mounting it top or bottom does not alter your geometry since the arm is what is actually changing position, not either of the endpoints. So you are free to mount it either way in that regard, but you may find that you prefer the top or bottom depending on your wheels and the clearance you get by mounting the arm on top. I have seen a variety of ball joints that can extend lower than others (especially if the zerk fitting is on the bottom). When using the "bump-steer spacers" (which have no effect on bumpsteer), the balljoint or lower arm can get too close to your wheel.

With that said, lets look at failure modes. In the almost unlikely case that all four bolts became loose or broke, with the arm mounted on top, the strut would be retained by the opening in the arm resulting in less damage than if you mounted it on the bottom.

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Re: Ball joint mounting on top or bottom of LCA?

Postby qwik510 » 07 Feb 2009 15:12

okayfine wrote:
djlotus wrote:When I tore my car apart the ball joints were underneath the lca. Not helping your case much, but that's the way it was and that's the way its going back together, at least unless I find that it's supposed to be on top.


All I have to offer at the moment is the exploded view from the front of the axle section of the Parts Catalog. The Chassis manual isn't helpful one way or the other.


I just went out and looked at my stock 1970 2 door and the ball joints are mounted below the LCA's.
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Re: Ball joint mounting on top or bottom of LCA?

Postby 510Martinez » 07 Feb 2009 15:57

OkayFine's pic shows the balljoint above the arm.

I also have a Haynes manual with the same pic, plus another side-view diagram and 2 photos also showing it goes above the arm. My arms had the joints on top and had small indentations only along the top of the arm.

I have a factory manual but it's in the shop buried. When I find it, I'll see what it shows too. However, it seems to me the pics would be correct.

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Re: Ball joint mounting on top or bottom of LCA?

Postby SeanT-wagon » 07 Feb 2009 20:28

Lol, that's my control arm in pic #2! Score for drunken scores!

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Re: Ball joint mounting on top or bottom of LCA?

Postby brknrekord » 21 Nov 2010 09:55

Yay for search! Mine were mounted to the bottom, but I suppose I will mount them above since that is the arrangement in the exploded view. Knowing the exploded view could be wrong, any more relevant or informed opinions out there?

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Re: Ball joint mounting on top or bottom of LCA?

Postby okayfine » 21 Nov 2010 11:38

Given the results in this thread, any further opinions would probably be split just the same. I didn't switch mine to bottom-mount, and I doubt anyone with bottom-mount switched to top-mount.
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Re: Ball joint mounting on top or bottom of LCA?

Postby S15DET » 21 Nov 2010 16:21

I vote for bottom mount for the "failure mode" consideration.

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Re: Ball joint mounting on top or bottom of LCA?

Postby andrew.lori » 15 Jan 2011 09:58

I remembered this thread this moring when I finished installing my front end's.
After everything was installed (Ball Joint on Bottom ) I was going to stick some struts in the cars to make them rollers again and ran into a PROBLEM . The 2 8mm bolts that hold the ball joint in place were now on top of the controll arm becaust the Ball joint was on the bottom. When I installed the struts the two Large 10mm Bolts that hold the Strut to the Steering arm would touch the two Ball joint bolts Not Letting The Steering Turn more than 1/3 of its full motion.
Moved the Ball Joints up top and the Bolts were now on the underside if the Controll Arm and out of the way of the strut Bolts. All this said I should have looked at my spare 510 becaust they are on top :)
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1972 Datsun 510 SR Monster Sold it
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Re: Ball joint mounting on top or bottom of LCA?

Postby Byron510 » 23 Mar 2016 11:00

Because this thread got tagged today, I thought I'd scan in the relevant pages from the FSM, showing the ball joints clearly on top of the LCA.

Just FYI. Not saying this is the only way, and certainly Brad puts in a good argument for reversal. However keeping the LCA in as much of a downward angle as possible, I have always mounted mine on top as shown here.

Byron
Attachments
FA 13 Lower Ball Joint (Medium).jpg
FA 13 Lower Ball Joint (Medium).jpg (104.96 KiB) Viewed 984 times
FA 14 Lower Ball Joint (Medium).jpg
FA 14 Lower Ball Joint (Medium).jpg (101.92 KiB) Viewed 984 times
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