Spindle pin lock bolt depth?

[gundee]

12 hours ago, Zed Head said:

 Hard to tell what the engineers intended when they put that package together.  Maybe the lock pin is mainly for manufacturing ease, or maybe it has am automotive purpose.  Who knows.

 

I am not sure why that lock pin is installed as well. I always thought it was to prevent the spindle from rotating in the strut housing.

[Zed Head]

In principle, yes, the pin end threads are meant to lock the inner sleeve solidly to the casting.  So, extending the concept, the casting, pin, inner sleeves, washers and nuts all become like one solid piece of metal, capturing the control arm ears.  But I think that the ends of the pin do see a strong tensile force at times through the washer, nut and threads.  One ear of the control arm presses on the washer, the other ear presses on the casting.  The ear of the control arm pressing on the washer stretches the pin, and the lock pin sees the load.  Everything has some degree of elasticity.  I didn't really spell that out up there, not sure I was even thinking of it clearly.  But it is there!  I pondered this long ago when I was looking down that casting hole with a rat tail file knocking down the lock pin hole deformation so I could get the pin back in.

And there's the leverage to factor in when the control arm gets twisted, which it does under acceleration and braking.  Constant twisting and levering, opening up that sleeve/casting interface, stretching and releasing the pin.  It looks like a great idea on paper, not knowing how loose everything will really end up when all of that rubber is inserted between the metal pieces.  Best laid plans.

Anyway, that's my theory.  Morning coffee.

[gundee]

I never considered brake and acceleration. I was thinking the up and down movement of the strut.

The spindle cannot be solid as I see it. Some rotation is necessary as the arc  of motion would

require that. Is the lock pin required to only rotate inside the rubber bushing inner sleeves?

[Captain Obvious]

Once everything is tightened down properly, there is no rotation of the spindle pin desired or needed. All of the rotation needs to be confined to the bushing. And that goes for either stock rubber, or poly. 

[240260280z]

The spindle pin has a front and back.

[Careless]

6 hours ago, Blue said:

The spindle pin has a front and back.

which, if anyone is wondering, is easily identifiable by holding the pin up to the upright casting to gauge the distance of the pin slot on the pin itself in relation to the pins position on the casting.

though the pin wouldn't even be in as far as it is in the first photo if it wasn't installed in the correct fore-aft orientation.

[gundee]

19 hours ago, Captain Obvious said:

Once everything is tightened down properly, there is no rotation of the spindle pin desired or needed. All of the rotation needs to be confined to the bushing. And that goes for either stock rubber, or poly. 

 

So once tightened are you saying the lock pin is still necessary or not necessary?

[Zed Head]

People have replaced the spindle pin with a 5/8" bolt and not had obvious problems.  So the lock pin is apparently not necessary.

It would be interesting to assemble all of the metal parts but leave the rubber out (you'd have to remove it from a factory bushing or replicate the inner and outer sleeves from metal tube) and see how it all fits together.  Under driving conditions the rubber certainly flexes allowing the metal parts to move.  The question is how far they move and how the loads are distributed.  I'm guessing that there are three areas of load transfer - the ends of the spindle pin and the lock pin.  The metal of the casting is probably much more rigid than the stamped sheet metal of the control arms.  The spindle pin is drawn and worked steel.  It's a puzzle.

 

[Captain Obvious]

Lumens, My claim is that once everything is tightened down properly, everything down there (on the strut side of the bushing elastics) all behaves as one solid member with no relative movement. In other words, there should be no relative motion between the strut housing, spindle pin, inner sleeves of the bushings, washers, or nuts.

If your question is "Do I claim that to be true regardless if the lock pin is installed or not?", then I'll hedge my bets and say "I think it should be, but I'm not a mechanical engineer and have not done the detailed analysis."

If your question is "Should I install the lock pin?", then my answer is "Absolutely. Why wouldn't you?" 

[Zed Head]

Maybe the lock bolt is just there to keep the spindle pin from falling out if a nut comes loose.  Maybe the spindle pin nuts aren't even really necessary.  Hmmm....