Mystery: Find the difference between these control arms.

[HRH]

I don't know if this is going to be as good as Fisch's thread, but it sure fooled me for a little bit.

 

Before we start, here's a snow picture of the 720 right before I killed the left front axleshaft. Actually, the bolts worked loose, the shaft is still hanging on by one bolt, but the boot is phuckered. Red locktite this time after I fix it.

 

Now, on to the mystery: What is the difference between these two control arms? Winner gets 1 million state credits as we used to say for any contest at Northern Arizona University. (Yeah, basically worthless.) :)

 

It might be easy, but I'll give a hint if you guys get stuck. EDIT: It's not that the one marked bad is bent.

 

[Mark_Z28]

The tab on the right rear corner is different? Looks like a brake line holder or similar.

[datzenmike]

Those are not off that truck.

 

Ah ha ha 510 right? :o Saw the brake line, maybe for E brake?

 

The bottom one is marked L but is a right?

Edited February 8, 2009 by datzenmike

[HRH]

Nope. Follow-up: They are rear lower control arms for a Datsun car, but which is which? One IS a 510.

[datzenmike]

610

[HRH]

What about the 610? Oh, yeah, and ignore the L, not sure why that's there.

[datzenmike]

Bent is 510 the one marked L is from a 610.

[HRH]

Very good jedi Mike! :D But, why are they different considering hollander interchanges both 68-73 510 and 73-76 610 lower control arms? Look closely. There is a MAJOR difference.

[LAYEDOUTB2K]

the depth of the part that the axle bolt to?

[HRH]

@*#$*@#$@#$!!!!!! Well, I thought it was an optical illusion, but decided to go out and measure it. It's about .5" difference, and I can't believe neither I, nor my Datsun guru saw it. We were still pondering on the other difference. Good thing I can swap out the stub no problem.

 

So the physical mounting points and spring perch of the 610 and 510 control arms are the same. The difference is strength and flange depth as LAYEDOUTB2K pointed out. Thanks for that seeing as I missed it!

 

The main difference is plating has been added throughout the 610 arm, as opposed to the naked one-wall control arm of 510 design. I had my fabricator/Datsun guru replicate the 610 arm, which is a bit hard to see due to the rust. This pic will help:

 

 

 

Look at the ring around the spring hole. Bare for the O.E. 510, strengthened into the bearing tube for the 610. I didn't think the 610 was that much heavier, but apparently they decided it needed strengthening. Good thing for rally.

Edited February 8, 2009 by HRH