Lotus Elan

Knock-on wheels and hub threads

PostPost by: Vanden Perre » Tue May 05, 2009 5:40 pm

Today I had a discussion with someone telling me that the hubs on my Elan are not correctly mounted. He says right hand side hubs are on the left and side of the car and the opposite.
I had a look in the archive of the forum and found a topic on this subject but I would like a confirmation.
My S3 has normal thread on the right side (normal thread is for me the one you turn the spinner clockwise to tighten it) and reverse thread on the left hand side.
In the old topic I found I read that this is OK but I also read that it is the opposite on MG and Triumph for example.
Can someone tell me how it has to be on an Elan and explain me if it is indeed different on other cars and if yes why?
Thanks.
Olivier.
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PostPost by: Frank Howard » Tue May 05, 2009 5:47 pm

Oliver,

Your car is correct. As far as other cars being the opposite, that is news to me.
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PostPost by: GrUmPyBoDgEr » Tue May 05, 2009 7:26 pm

Yes the Elan knock ons are the opposite way around to all other knock ons.
It's all abit complicated to explain the physics of it all.
Basically it's dependent on whether the cone on the spinner fits into or onto the cone on the wheel.
Splined wire wheel hubs have an external cone.
The Elan steel wheels have an internal cone.
These combinations effectively have an influence over the "self tightening effect" & are dependent on which side of the car they are fitted to.
There is a story about Chapman explaining the theory of this by placing and spinning an egg cup inside a napkin ring to show the influece of counter rotation to his "lesser engineers" :?

It 'aint easy :roll:
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PostPost by: Vanden Perre » Fri May 08, 2009 10:35 am

Frank and John,
Thanks for your answers. It confirmed what I thought about the Elan. However I do not understand why on other cars hubs are threaded the other way. If someone can explain me in details would be very pleased!
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PostPost by: garyeanderson » Fri May 08, 2009 10:52 am

elan-archive-f16/knock-off-direction-left-t7543.html

or search for "spinner direction" may help too.
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PostPost by: andyelan » Fri May 08, 2009 1:02 pm

Hi there

In actual fact there are really only 2 types of knock on wheel that you're likley to find on road cars. One is obviously the Lotus peg drive type but almost all the others are Rudge-Whitworth spline dive type. Even the Italian Borrani wheels were actually Rudge wheels but they changed their name in the mid '30s. So it's not really "Lotus vs Rest of the World" but rather "Lotus vs Rudge". The reason they tighten in different directions is down to their different design, Rudge use an external cone on the wheel while Lotus use an internal cone. One thought I had, however, and perhaps someone here can answer is, don't modern racing cars wheels have internal cones? I wonder which way they tighten.

One final tip some one here made is that Lotus wheels always tighten by turning/knocking towards the front of the car, ie in the direction of traval.

Andy
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PostPost by: GrUmPyBoDgEr » Fri May 08, 2009 5:08 pm

Vanden Perre wrote:Frank and John,
Thanks for your answers. It confirmed what I thought about the Elan. However I do not understand why on other cars hubs are threaded the other way. If someone can explain me in details would be very pleased!
Olivier



Hmmpf, I thought I'd done fairly well with the internal / external cone & the egg cup in a serviet ring explanation.
Try it yourself with a large piece & a smaller piece of tubing (or something similar) by first spinning the outer against the inner and the the inner against the outer to see what happens.
Regardless of what you call it (Rudge or Borani et al) the "Internal Cone" will demand a different tightening direction to the "External Cone", dependant upon which side of the car the wheel is fitted to.

To be honest, I don't fully follow the LH & RH thread thingy fully because the loads do reverse themselves depending upon if the car is accelerating or braking. I assume that the accelerating loads take up a higher proportion of the driving cycle :?

Cheers
John
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PostPost by: reb53 » Sat May 09, 2009 6:19 am

Actually John, I thought you'd done pretty well also.

Now have a go at "epicyclic effect". :)

Cheers
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PostPost by: GrUmPyBoDgEr » Sat May 09, 2009 7:36 am

reb53 wrote:Actually John, I thought you'd done pretty well also.

Now have a go at "epicyclic effect". :)

Cheers
Ralph.


Wikepeadia it, I'm too tired :D :D :D
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