Lotus Elan

Knock-off Spinner Tightening Rationale (Yet Again)

PostPost by: jimj » Sun Jan 11, 2015 11:08 am

Propounding further my excellent theory; as the car accelerates the inertia in the spinners makes them want to stay still, loosening, when braking the rotating momentum of the spinners makes them want to carry on rotating, clockwise viewed from the right, anti-clockwise viewed from the left, thereby tightening.
I rarely set off with wheels spinning, as an example, but do occasionally lock up a wheel or 2 under braking. Then the spinners go from spinning to stationary in an instant, the momentum of the rotation is much, much greater as you move out from the centre so the ears, especially, are just wanting to carry on rotating, tightening.
Jim
jimj
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 1135
Joined: 25 Feb 2008

PostPost by: rcraven » Sun Jan 11, 2015 11:56 am

If that theory were true, Rudge Whitworth wheels would soon come loose, but they don't.
Robert
rcraven
Third Gear
Third Gear
 
Posts: 254
Joined: 23 Oct 2007
Location: UK

PostPost by: stevebroad » Sun Jan 11, 2015 12:24 pm

abstamaria wrote:Now, I have to understand why RW spinners are threaded the opposite way, simply because they are female nuts.

Andy


But aren't Elan spinners also female? I'm sure mine were which makes them the same as RW spinners, or am I missing something (not unusual)?

I had an old Ford transit many years ago. Trying to undo the offside (right hand side), I ended up with a scaffold pole extension on my T-bar until I realised that the nuts were handed! Why?

Reading various threads (sorry :-) ) on other, non Lotus, forums, opinion seems evenly divided. Someone mentioned that Porsche don't bother and use RH threads on both sides, no idea if this is true.

It seems to me, judging from the quantity of discussions on the forums about this subject, that the direction of the thread makes little or no difference. Even if it did, it would be difficult to confrm loosening was caused by thread direction amongst all the other possible causes, mechanical as well as human.

We are enthusiasts, so our cars are kept in a good condition and we conduct regular checks, yes? No problem, then.

If you are worried, a little dab of torque seal will give you a quick visual check that everything is tight.
stevebroad
Fourth Gear
Fourth Gear
 
Posts: 930
Joined: 08 Mar 2004
Location: Essex, England

PostPost by: rcraven » Sun Jan 11, 2015 1:35 pm

stevebroad wrote:
But aren't Elan spinners also female? I'm sure mine were which makes them the same as RW spinners, or am I missing something (not unusual)?


Yes, the threads on both Elan and RW spinners are female, but the important difference is (or is said to be) the taper. On an Elan spinner the taper is male, on a RW spinner it's female.

There is a diagram here: http://www.motorsportmagazine.com/archive/article/may-2001/41/r-u-d-g-e-whit-worth-hub
The relevant bits are the tapers D (on the wheel) and G (on the spinner).
Robert
rcraven
Third Gear
Third Gear
 
Posts: 254
Joined: 23 Oct 2007
Location: UK

PostPost by: abstamaria » Sun Jan 11, 2015 1:57 pm

Thanks, Robert. What I meant to say is that RW spinners are left-handed (tightening counter-clockwise) on the right side of the car, as compared to the Lotus spinners, which are of course right-handed (tightening clockwise) on that side. The reverse is true on the left side of the car.

The difference is that RW spinners are female and Lotus male, as pointed out. The wheel taper on a RW wheel presses against the taper on the inside diameter of the spinner. The wheel taper of a Lotus wheel presses against the outside diameter of the spinner.

The only way I can make sense of this is that the spinners rotate differently, following Chapman's quasi-epicyclic example, and that mechanical precession acts opposite to that "rotation."
abstamaria
Third Gear
Third Gear
 
Posts: 324
Joined: 12 Nov 2010
Location: Manila, Philippines

PostPost by: abstamaria » Sun Jan 11, 2015 2:03 pm

Thanks, Steve. I'm actually not questioning Chapmans's theory, just trying to understand it.

I use 26R hubs and their aluminum spinners. When I was racing, I safety wired the spinners. But I don't think they ever loosened.

Andy
abstamaria
Third Gear
Third Gear
 
Posts: 324
Joined: 12 Nov 2010
Location: Manila, Philippines

PostPost by: abstamaria » Mon Jan 12, 2015 3:48 am

Here is the issue. The left spinner is for an MG, a Rudge Whitworth design. The one on the right is for the Elan. Both are for the right side of the car. Note that ?undo? for the MG is clockwise, while ?undo? for the Lotus is counter-clockwise. The question is why.

L1000952.JPG and
abstamaria
Third Gear
Third Gear
 
Posts: 324
Joined: 12 Nov 2010
Location: Manila, Philippines

PostPost by: abstamaria » Mon Jan 12, 2015 3:53 am

The reason for the different tightening direction for the designs is said to lie in the way the spinners contact the wheel. Here is the MG (Rudge-Whitworth) on the left and the Lotus spinner on the right. The reason for the descriptions female? and ?male? are apparent here.

L1000948.JPG and
abstamaria
Third Gear
Third Gear
 
Posts: 324
Joined: 12 Nov 2010
Location: Manila, Philippines

PostPost by: abstamaria » Mon Jan 12, 2015 3:56 am

We're familiar with the Lotus KO wheel. Here is a Rudge-Whitworth wheel for comparison, with the spinner removed. Note how differently the RW spinner contacts the wheel. The RW spinner presses down on the wheel at the outer diameter of the wheel's flange, "encapsulating" the contact area.

L1000962.JPG and
abstamaria
Third Gear
Third Gear
 
Posts: 324
Joined: 12 Nov 2010
Location: Manila, Philippines

PostPost by: abstamaria » Mon Jan 12, 2015 3:59 am

Another comparison between RW and Lotus knock-off spinners. The aluminum 26R spinner is at the top, also ?male.?

L1000946.JPG and
abstamaria
Third Gear
Third Gear
 
Posts: 324
Joined: 12 Nov 2010
Location: Manila, Philippines

PostPost by: Craven » Mon Jan 12, 2015 11:17 am

Epicyclic force.
Imagine a large gear wheel, a starter ring gear say, but with teeth on the inside as well as the outside.
A small gear (fixed axis), like the starter pinion, engaged on the outside of the large gear (ring gear) a point contact at 12 o?clock and a similar gear engaged at the same position on the inside of the large gear, point contact at 6 o?clock.
Now as the large gear rotates clockwise around its axis the motion of the small gears are, the inside gear will rotate clockwise as the large gear BUT the outside gear will rotate Anti-Clockwise.
If a Male cone on a spinner with a diameter less than on the hub is considered to be equivalent to the inside small gear and a Female cone spinner with a greater diameter greater than on the hub equivalent to the outside small gear, then forward motion of a Lotus Knock On road wheel will cause an appropriately handed spinner thread to tighten in the direction of wheel ration. If an RW spinner has a Female Cone then the same handed thread would tighten in the reverse direction of wheel ration.
Helps me to visualise process anyway!!
For what it?s worth Ron.
Craven
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 1092
Joined: 14 Sep 2013
Location: south coast uk

PostPost by: billwill » Mon Jan 12, 2015 11:56 am

The design needs to cope with both accelleration and deceleration (braking) factor which would lead to both LH thread or RH thread.

But as jimj said earlier Braking is more severe than Accelleration and is likely to occur in hairier situations, so it is better to design the wheel spinnersto be tightened during braking situations.
Bill Williams

36/6725 S3 Coupe OGU108E Yellow over Black.
billwill
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 4724
Joined: 19 Apr 2008
Location: London UK

PostPost by: Craven » Mon Jan 12, 2015 12:38 pm

It?s understood the forces that can loosen the spinner, but the whole point of using the epicyclic forces is to have, if you will, an ?automatic? arrangement that should keep the spinner tight.
Ron.
Craven
Coveted Fifth Gear
Coveted Fifth Gear
 
Posts: 1092
Joined: 14 Sep 2013
Location: south coast uk

PostPost by: abstamaria » Mon Jan 12, 2015 1:35 pm

Hi,mRon,

On the right side of the car, the whele spins clockwise going forward. Assuming an epicyclic effect on the spinner, the Lotus spinner will spin counterclockwise thereby loosening.

Wouldn't that be the effect?

Andy
abstamaria
Third Gear
Third Gear
 
Posts: 324
Joined: 12 Nov 2010
Location: Manila, Philippines

PostPost by: stevebroad » Mon Jan 12, 2015 2:20 pm

I can now see why they are called male and female, they refer to the relationship with the wheel rather than the thread. Not the usual reference method but at least I now know :-)

At the end of the day, does it actually matter? Manufacturers use both methods so who is right?

If tightened properly and reguarly checked they won't come undone, whichever way you have them. I would be more concerned with losing the drive lugs as I have experienced this. Car now converted to nuts so no worries :-)
stevebroad
Fourth Gear
Fourth Gear
 
Posts: 930
Joined: 08 Mar 2004
Location: Essex, England
PreviousNext

Total Online:

Users browsing this forum: No registered users and 9 guests