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MY QUESTION: How much is the expected difference in the diameter of the control arm pivot bearing, front to rear? Less than .5 mm?

Here's why I'm asking. My problem: I've managed to lose track of which of my completely disassembled '72 240Z's front control arms is the left one and which is the right one. So, I know the pivot bearing of a control arm is necked down in size slightly front to rear. I also know the following about installing a bushing, per Wick Humble's book: "With the left control arm positioned right-side up and the ball joint end to the left, the bushing's small end goes in the back side of the control arm." This fact should help me determine left control arm from right--if I can tell which is the small end of a control arm's bearing. However, my measuring the diameter of one of the control arm pivot bearings doesn't produce (for me) a discernible difference in diameter from front to rear of the bearing surface. Measuring a new bushing doesn't produce a discernable difference either, front to rear. I'll replace my cheap plastic caliper gauge with a better one right away. Meanwhile, have any of you got any ideas about telling the difference between left and right front control arms, please?
 

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Who knows what bushings Wick had available in 1990 when he was writing that book (I have it too).

There isn't a right or left front control arm until the steering knuckle is installed, and then the strut assembly. The control arm by itself is interchangeable, same with the rear.

I'm getting ready to install a set of Prothane polyurethane bushings in the next few days. The diameter of the bushing that goes inside the control arm is the same on the front and rear side of the bushing. The part of the bushing that is outside of the control arm but still within the mounting flanges on the engine cradle/cross member does vary. The half of the bushing that goes in the rear of the control arm is longer than the half that goes in the front. This is pictured in the instructions and the bushing halves even have different part numbers printed on them.

Not sure what bushings you have but I'm going by the instructions in the Prothane kit.
 

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Who knows what bushings Wick had available in 1990 when he was writing that book (I have it too).

There isn't a right or left front control arm until the steering knuckle is installed, and then the strut assembly. The control arm by itself is interchangeable, same with the rear.

I'm getting ready to install a set of Prothane polyurethane bushings in the next few days. The diameter of the bushing that goes inside the control arm is the same on the front and rear side of the bushing. The part of the bushing that is outside of the control arm but still within the mounting flanges on the engine cradle/cross member does vary. The half of the bushing that goes in the rear of the control arm is longer than the half that goes in the front. This is pictured in the instructions and the bushing halves even have different part numbers printed on them.

Not sure what bushings you have but I'm going by the instructions in the Prothane kit.
Thanks, OREGONIPA. I appreciate the response you sent. I agree Wick must have been talking about something else. The zcarsource.com catalogue has it wrong too. At any rate I got my bushings in!
 
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