Thanks John that explains a lot. In the last few years, I’ve been an SF giant baseball follower. The terms used to describe the different pitches drew a lot of my attention. A slider, a cutter, and then the infamous curve!!
The pitch that separated minor league hitters from the major league guy…
At first, I thought of the ball moving in a horizontal arc!! No, all pitches do that. A straight l8ne path does not exist. Variable, for sure.
But, then how the pitcher uses his fingers on the ball and the relation tot he seam !! That has to be it, As in your example, top spin and it just drops a way!!!
And a bit like pool. The stroke of the stick and where it hits the ball.
All: Inertia. The hub turns. the spinner remains in place for just a second. The hub gets screwed in to the spinner.
In response to someone calling the curve ball an optical illusion, Dizzy Dean said ‘You go stand behind a tree and I’ll hit you with an optical illusion’.
“Certainly a loose wheel is not going to tighten itself but one that is tight will get tighter .”
Bit of an oxymoron there! If the wheel is loose then RW theorise it will tighten. If a wheel is tight how can it get tighter as there is no opportunity for movement? The spinner’s 31oz mass is centred on the hub so little centrifugal force available to overcome 220ft/lb of friction.
“Perhaps the only way you will know for sure is to try it.”
I did unwittingly in my Lotus and the spinner did not move with 80mph forward momentum. When we used the mallet on it it was more than hand tight and only a couple of whacks were required to tighten but the automagic feature clearly was not with me that day…
Although not a scientific test I have to add that I also did the sharpy test and indeed my wheel nut tightened maybe 1/4". I had red all the literature but there were still many questions here on JL. I questioned it because even though I tightened the nuts to a point with a hammer that there was no movement when forcefully shaking the wheel I didn’t beat them to death. When removing they required some sweat, bad words and always a little more damage to the spinners.
Rather than idle speculation, if anyone doubts the self-tightening action, it does not require high-speed, or a long drive to test it. Simply loosen a knock-off slightly, then drive a few hundred feet at low speed (actual speed is totally irrelevant - feel free to crawl at a snails pace if it makes you feel safer). A VERY loose knock-off may well NOT tighten, as it will not make the requisite contact with the hub, so just loosen it a bit - perhaps 1/8-1/4 turn? Absolutely NO danger involved in doing this, and NO chance of any damage whatsoever to the car…
Great idea Ray. I wonder whether original Jaguar spinners will perform differently to the poorly made and out of spec Orson Engineering ones. The latter may well move when on the car because the threads and contact areas are wrong.
Would not surprise me a bit if some of the repro ones do NOT work properly. I seem to recall at least one batch of SS knock-offs years ago that did not even make contact on the taper!
I do think one over-looked factor is just HOW loose they start out. They will self-tighten if slightly loose, but if REALLY loose, they will not, because the hub taper will not contact the spinner taper. Hence the recommendation to give a couple of good whacks with a mallet, then go for a drive. Loosen the KO by 1/2 turn to a full turn before driving, and I would not be surprised if they don’t self-tighten at all, and the KOs inertia alone will be able to make them unscrew on rapid deceleration.
I’m not convinced spline drive and peg drive wheels can be considered equivalent.
On a episode of Jay Leno’s Garage, Jason Len mentioned that peg drive wheels have a tendency to come loose, whereas you never hear that about spline-drive wheels. You also tend to see peg-driven spinners safety-wired a LOT more often than spline driven spinners.
I don’t know enough about the anatomy of peg driven wheels/hubs, but I think we should be carful mixing them into this discussion.
My limited understanding is that an Elan hub doesn’t use an inner taper, and that the the spinner uses an internal taper, rather than an external taper as a spline-drive wheel does.
IIRC they are similar but have the wheel supported by external cones rather than internal ones. That reverses the direction of the epiclycoidal self-tightening compared to R-W. Not positive about this.
Replace tension in the spokes for tension in the wheel disc instead. Deflection, however slight, will exert force on the parts which if loose, will move. In this case tighten.
Robert is correct about the Lotus system which reverses the way the RW hubs/cones work. This was because Colin Chapman did not want to pay royalties to Dunlop/Jaguar for use of the RW patent. So he engineered the spinners the other way around however Dunlop took them to court and Lotus lost as the Judge said it was a clear violation of the patent.
Ok, so the perceived wisdom is that the nuts are or are not self tightening, but they do seem to tighten when the car is driven. And to do this the right side spinner has a left handed thread, anti clockwise (counter clock wise for our former colonial cousins), and the left side spinner has a right handed, or conventional, clockwise thread.
So why do Bentleys have left hand threaded nuts on the left side wheels, and right handed threads on the right side?
Had a tow company drop off a xk140 that was towed backwards with a rear end suspended tow. Both front wheels came loose, with 1 spinner missing and wheel almost off the hub.
I have seen the same with an mg as well.
As a Mechanical Engineer, I would say that proposing this as a more viable explanation to what has been laid out above is grasping at straws.
A spline-driven alloy wheel doesn’t “hang” from a small number of upper spokes like a wire-wheeled car does. For this reason, the stress distribution in the alloy wheel would be shared much more equally in the upper and lower portions of the wheel, and any hub deformation would take on a entirely different profile.
Also, the hub on a center-lock alloy wheel is usually a massively stiff forging, whereas the hubs on original Dunlop wire wheels were effectively pressed sheetmetal. A lot of modern wire wheels (Daytons for example) also use a much more substantial hub than original Dunlops.
Any deformation in the center hub would therefore be orders of magnitude lower in either the alloy wheel or the Dayton. So, if your deformation theory were to hold any water, you would expect the self-tightening behavior of these wheels to be all but zero…but that’s not what we’re hearing.
