Why do wheel spinners tighten clockwise on the left?

Incorrect. Try the demo with the drill and nut. Acceleration and deceleration will most certainly spin the nut on or off.

 

The amount of inertia caused by the weight of the nut under acceleration and braking will have such a little effect it is negligible and does not apply here at all.

Just for fun I will explain it again as my original explanation above is not 100% accurate having read it again:

The weight of the car is bearing down on the wheel via the bottom of the nut (in the case of the Elan) on the taper. This means the nut is not absolutely concentric with the wheel. Its a tiny amount off owing to the vertical load.
Owing to the taper, the fact they are not 100% concentric means the diameter of the wheel taper is slightly larger than the diameter of the nut taper at the point of contact.
At the bottom of the nut, friction is high owing to the load, so the surface of the nut will move exactly with the surface of the wheel hole in a tangential direction.

So, we have one smaller ring attempting to drive a larger ring at its circumference. They move at the same linear speed at the circumference but because the larger ring has a larger circumference this will result in it trying to rotate at a slower rotational speed hence will try to unwind if threaded wrongly.

 

Try the demo. One way the nut will tighten. The other way the nut will come off. Just like our buddy the spinner. Have you ever spun a rim on a tire?

 

It will indeed, but thats not the cause of the spinner issue we are discussing. When you fit the spinner you wack it with a hammer to tighten it. The amount of force needed to loosen it is high. To replicate this in your demo, you would need to tighten the nut on the shaft. Now it doesnt move when you rotate the shaft. The amount of inertia is nowhere near enough.

 

This thread is going down the airplane physics road.

I do know from personal experience that KO spinners tightly installed, (granted sans saftey pin that should have been there) on the incorrect sides of a mid 60's corvette will loosen and fall off... took me the better part of the day to find the spinner in the ditch

 

Yes, it is, and for the same reason....... No one tends to listen to the opinions of the actual Physicists / Engineers.

Looking up "information" on the internet without having the required background of understanding behind the basic subject material is a loss leader.

 

Since we now agree that a loose spinner will fall off when the hub spins in the same direction then that's a good enough reason to tighten in the opposite direction. I don't think they are all that tight to begin with. If the rim is not perfectly flush to the hub during tightening then it doesn't matter how tight you get it. It will be loose when you pull out and that's where the demo comes in. I don't think it needs to be any harder than that.

 

Its not complex physics, just basic mechanics. Same as in a gearbox, a smaller wheel (spinner) driving a larger wheel (inside of the wheel hole) on its circumference, (as gears in a gearbox) the larger wheel will turn more slowly. In this case the driving wheel is inside the driven wheel but the principle is the same.

The only aspect which is difficult in this situation is the acceptance that the spinner and wheel tapers, at the point of contact, are different diameters. The diameters are only a few thou different, owing to the weight of the car applied vertically on the wheel but thats enough to give a cumulative effect.

 

Speaking as someone who has had a Ferrari wheel fall off while driving (although mine was a standard bolt-on wheel), I highly recommend properly knocking on your knock offs! ;D

 

Andy,


It's an old post but I want to point out that using Precession process to explain the spinner thread should work, just like it works for the bicycle pedals.


Consider the right side wheel with male taper spinner, with the wheel turning CW, the radial force (contact point between hub and spinner) turning CCW as wheel moving forward. Precession process says the inside tapered spinner tends to turn CW relative to the hub, hence RH spinner is used here and LH spinners for left wheels.


Now for female taper spinner on same right wheel. Radial force turning CCW as above with wheel moving forward. Precession says inside male taper hub tends to turn CW relative to the spinner, or spinner wants to turn CCW relative to the hub. So it needs LH spinner for right side wheels.


Brian

 

Not to change subject. What were the Dunlop wheels on the D type made of? Aluminum? were they stamped and riveted or Forgings?

 

Andy,
I didn’t read this entire thread in detail but I have a Dino with knock offs and a friend with an early lotus referred me to this article when I was trying make sure I assembled the hubs on the correct side, Forgive me if already posted.
I confirmed they self tighten when i forgot once ...

And, from an archived entry in the Lotus Elan forum: http://www.lotuselan.net/forums/elan-archive-f16/knock-off-direction-t9539.html

---------
Rudge-type knock-ons use spline-drive and Lotus-type knock-ons used
pin-drive... but that's incidental to the knock-on direction issue. Use
"spline-drive" and "pin-drive" as identifiers, but don't confuse the
drive methods as having anything to do with the knock-on direction. Rudge
could just as well have used pin drive, and the knock-on direction would
have still been the same.

The key issue is how the knock-on nut meets the wheel... regardless of the
drive method. Whether the nut's mating face has a male taper and fits into
the wheel or has a female taper and fits over the wheel. Pins and splines
have nothing to do with it. It's whether the rotating motion is imparted
internally or externally.

Chapman demonstrated the principle to his designers by placing two
concentric rings on the table. He grabbed the inner ring and moved it in a
circle (oscillating/ orbiting rather than spinning/ rotating) large enough
to carry the outer ring with it. The outer ring turned/ rotated in the
same direction. Then he grasp the outer ring and repeated the movement.
The inner ring turned/ rotated in the opposite direction.

Another way to demonstrate Chapman's second trial (grasping the outer ring)
is to put a washer or large coin in the bottom of a shallow can and swirl it
around. The washer will orbit with the can... in the direction the can is
swirled... but as it rolls around the inside of the can it's rolling
"rotation" will be in the opposite direction. Swirl clockwise and the
washer will orbit/swirl clockwise but roll/rotate counter-clockwise.

The coin-in-a-can demo happens at higher speed and is harder to follow than
Chapman's rings-on-the-table demo. If you can't see it, paint a hash mark
on the washer so your eye can pick up it's rotation more easily. Or just
use Chapman's demo in the first place. It's better. He used it because
it was easier for non-believers to see... and it illustrated both effects,
driven by either the inner or outer ring.

 

Read the article by Pat Symonds starting page 34:

https://issuu.com/thisisnotadrill/docs/rceteh115webpub

 

Love threads like this that address basic questions and are met with such a clear response. Thank you, both to the original question poser and to Andy WW for his response. Some people really can look at an age old problem and find a new way to solve it. Chapman was a maestro with this.

At the risk of going down an unrelated path, a friend of mine had a "similar" quest: looking for a fastening ("nut and bolt") system that maintains its torque when subjected to vibration and heat. Thread locker, lock washers, nylocs all fail. The clever (to me anyway) solution is a traditionally threaded nut coupled with a special washer system that expands when subjected to reverse (unwinding) torque. If I can find a link I'll post it.

 

Nordlock washer? They are clever. I used these on my Lotus Esprit exhaust manifold as the studs kept unscrewing. A nut which locked onto the stud was no use but these lock the nut/stud onto the flange of the manifold.

 

Yes, that's it. For those that don't know the method, here's a link:

 

As a memory aide think of a stripper: " Down in front take it off !" In other words strike the knock off down towards the front of the car to remove. If they were not installed this way they WILL come off on their own. I once owned a Jaguar XKE and rebuilt the front suspension. I inadvertently installed the hubs on the wrong sides. Within 200 miles the right front wheel came off. Not a good day !

 

Because the British just like to invent words like "Undo".

 

Meh..it is what it is. Just tighten the wheel as instructed and you won't have issues. If i over thought every engineering decision i deal with i would be in the looney bin.