Checking a front axle spindle for run out

[RMP&O]

A video of checking the front axle spindles for run out.

https://www.youtube.com/watch?v=odtvdREDSnE

A bent spindle will give wheel wobble! If doing a front axle rebuild check your old spindles for run out.

Cheers

[moore_rb]

Excellent video !

Technically, I've been noodling a lot about this topic, and while I agree completely that a perfectly round spindle is ideal, I also think that some very small degree of runout (like .015 or less) is probably still acceptable. (it would have been better if Nissan had chosen to publish a specification on this... )

The reason I think this is that the spindle doesn't turn when installed on the truck- only the outer hub and the wheel bearings turn, and the bearings do not make "zero lash" contact with either the spindle, nor with the bearing races - The bearings are designed to "float" on a very thin layer of grease, and this thin "grease cushion" (called endplay) is typically in the neighborhood of .010 when the wheel bearings are adjusted properly.

So, a spindle with .015 (15 thousandths) of total runout on the wheel bearing contact surfaces, can only yield (and translate) a maximum of .0075 of radial runout to the wheel bearings when they are turning (since the spindle maintains a fixed position on the truck, it can never translate more than half of it's total runout to the wheel bearings, the same way that moving to a 2-inch taller tire can only provide a maximum of only 1 additional inch of lift to your truck

and this .0075 figure would still easily fall within the .010 of acceptable endplay designed into the wheel bearings themselves; and so I would expect that the grease layer between the wheel bearings and the races should still be able to provide adequate "cushion" to absorb this .0025 difference in overall "roundness" between the spindle and the wheel bearings...

Now, if your spindle is more than .015 out of round, or is your wheel bearings are designed for less than .010 of endplay, then yeah- you are probably increasing your chances of increased heat and increased wear to the wheel bearings and races; and possibly even a wheel wobble that might be too severe to be cushioned out by the tires and suspension.

All of this is, of course, purely theoretical, chalk board hypothesizing. And since I have no inkling (nor desire) to go out and find a spindle that is exactly .015 out of whack to experiment with, I will probably just continue to rely on the math...

[RMP&O]

I will leave the math to you Rob, I don't disagree though that a certain amount of run out is acceptable. Considering that checking for run out didn't cost me anything, it is a worthy thing to check in my book. A bent spindle is also going to mess up camber.

Cheers