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Knock-off experiment

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gjesion Avatar
gjesion Jerry Jesion
Woodhaven, MI, USA   USA
I have read and heard that wire wheels are self-tightening. Being an experimentalist I decided to see if it is true. I loosened the nut, then gave it 2 hits with my 4lb HF dead blow hammer. Next, I placed a piece of green pin stripe tape across the nut and hub and then cut it. The following picture was taken after about a 2 mile trip with a max speed of 50 mph. Looks like they do self tighten!

Regards,
Jerry

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Attachments:
IMG_0296.JPG    36.4 KB
IMG_0296.JPG

copernicus Avatar
copernicus Nick Kopernik
Snowless Winter, CT, USA   USA
Jerry, good to know your hubs were in their proper places!


Aridgerunner Avatar
Aridgerunner Silver Member Bill Bussler
Montoursville, PA, USA   USA
1956 MG MGA 1500 "The A"
1959 Triumph TR3A "The Mistress"
Jerry, thanks for posting that picture. I'm going to try that on my A. After the snow and road salt is gone, in a couple months.

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PeterC Avatar
PeterC Platinum Member Peter Caldwell
Madison Wisconsin, USA   USA
Jerry, I'm curious if the accelerating or braking is more responsible.

Peter C


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Billm Avatar
Billm Bill Masquelier
Santee, CA, USA   USA
I do know that if you assemble the car incorrectly (backwards) that the knockoffs will not only loosen but will make an interesting sound as they bounce off of the pavement at 65 mph!
BTDT!
Billm

Mitchman2 Avatar
Mitchman2 Mitchell Andrus
Mills River, NC, USA   USA
I would not have guessed that this would be the result.

What mechanism moved the spinners? How wobbly are your splines? Seriously, assuming the wheel and hubs are locked together the spinners should have zero torque applied to them.



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ghnl Avatar
ghnl Silver Member Eric Russell
Mebane, NC, USA   USA
1961 MG MGA "Calvin"
http://www.mgaguru.com/mgtech/wheels/wl102.htm

My guess is you wouldn't have needed the 2 miles. I put the wire wheels on my MGA with the knock-offs hand tight. I only needed to move the car out of the garage and into the driveway so I could bring a different car in. When I was done with car #2, I rolled the MGA back in. I probably moved it 100' or less. I didn't even drive it - just pushed it. I then needed a hammer to loosen the knock-offs to take the wheels off again.



Eric Russell ~ Mebane, NC
1961 MGA #61, 1981 Alfa Romeo GTV6, 1984 Alfa Romeo Spider, 1991 Honda ST1100

Steve S Avatar
Abingdon West, Southern California, USA   USA
You have to remember that the spinners not only grip the threads of the splined hub, but also the outside surface of the wheel hub. So any movement between wheel and hub will result in the spinner moving. This is one aspect of how the self-tightening process works, and also why greasing the flat inner lip of the spinner is so important. There is always some movement between wheel and hub, however minuscule. You may also find that the front and rear spinners tighten at different rates (and different amounts) because the fronts are only influenced by braking, not acceleration.

A on a shoe string Avatar
A on a shoe string Peter Stevenson
Aubusson d'Auvergne, Auvergne, France   FRA
1960 MG MGA 1600 "A"
1972 MG Midget MkIII "Midget"
Clever init?

Imagine the wheel spinner is not totally tight such that there is a gap between spinner and wheel effective diameters on their cones, as per the diagram (not to scale as Doc would say, and, drawn for simplicity not accuracy).

Assuming the spinner does not slip on the wheel, both will cover the same linear distance of; Angular rotation x Pi x diameter. If we say the angular rotation of the spinner is 'A' and of the wheel 'B' (turns, degrees, doesn't matter)

So; A x Pi x D = B x Pi x d

rearranging, A/B = D/d. i.e. the spinner and wheel travel a different rotational distance in the ratio of D/d. So long as the RH and LH threads are on the correct sides, the spinner will tighten up until the cones on spinner and wheel perfectly match, at which point D = d.

It only works if there is a side load on the wheel (e.g. the weight of the car); jack up a wheel and try it - nothing will happen. Repeat the experiment and drive in reverse and the spinners will loosen. Which is good reason to make sure they are good and tight to begin with.

None of which is getting my children's book Poppa Buys an Old Car finished or getting the wings (fenders) fettled to fit. The wheel arches on the rear wings have a 2" differrence from one side to the other and I'm not sure how to fix it so this has been a helpful distraction.


Drive safe, keep your wheels tight, Pete


Attachments:
wheel nuts.pdf    28.1 KB

A on a shoe string Avatar
A on a shoe string Peter Stevenson
Aubusson d'Auvergne, Auvergne, France   FRA
1960 MG MGA 1600 "A"
1972 MG Midget MkIII "Midget"
Correction, A/B = D/d

Just thought I'd point out my error before someone did it for me.

gjesion Avatar
gjesion Jerry Jesion
Woodhaven, MI, USA   USA
Mitch,
Hubs and rims replaced 2 years ago. Hopefully not much wear.

Regards,
Jerry

Mitchman2 Avatar
Mitchman2 Mitchell Andrus
Mills River, NC, USA   USA
As the wheel moves forward, a new set of spokes at the top of the rim is put under tension. As this tension pulls up on the inner hub, the inner hub moves upward and if in contact with the spinner drags the spinner along with it. The spinner turns til tight.

The real-world model is the hoola-hoop. As it orbits it ALSO ROTATES, but always in solid contact with the body.



The Flat Earth Society has members from all corners of the globe.

'30 Model A Ford Town Sedan
'48 MGTC Q Special
'58 MGA roadster
'66 Series 1, 4.2 Jag E-Type OTS

Grey Fox Charlie Blow
Lincoln, Lincolnshire, UK   GBR
This is an interesting topic.

Many years ago I had an MGB GT with wire wheels and a friend had a Lotus Elan with steel wheels with knock on hubs.

He arrived at my house one day and jumped out of his Lotus with the wheel spanner in his hand and started to tighten up all four wheel nuts.

I asked why and he said that the car's handbook advised this every 500 miles as the wheel nuts came lose and there was a possibility of losing a wheel. (I have subsequently met someone with a Lotus Elan with steel knock on wheels who has had a wheel come off while driving)

We compared the wheels on the Elan and the MGB and the B has left hand thread on the near (left) side and right hand thread on the off (right) side.

The Elan has the threads on the 'wrong' way - left hand thread on the off side and right hand thread on the near side. We were concerned that the car had been assembled incorrectly but the handbook indicates that is the correct way.

A few weeks ago we were treated to a visit to a well known Jaguar specialist who prepares cars for racing (with a great deal of success) and i noticed an E Type, with wire wheels - left hand thread on the near side and right hand thread on the off side. I asked if that was normal and was told that that is the correct way. This sugests that MG have got it wrong!!

My MGB GT never had wheels come lose, in fact they always seemed tighter than when I put the wheels on.

Just to add further confusion - my wife owns a 1966 Alfa Romeo Giulia with steel wheels with the normal four studs and guess what - the threads on the nuts on the near side of the car are left hand thread and on the off side, right hand thread. This always confuses tyre fitters.

Coonfused?

Charlie

A on a shoe string Avatar
A on a shoe string Peter Stevenson
Aubusson d'Auvergne, Auvergne, France   FRA
1960 MG MGA 1600 "A"
1972 MG Midget MkIII "Midget"
Which side has the LH threads will depend on whether the spinner has a male or female cone. I believe MGAs have a female cone that tightens against the wheel. Are Jaguars the other way round?

A on a shoe string Avatar
A on a shoe string Peter Stevenson
Aubusson d'Auvergne, Auvergne, France   FRA
1960 MG MGA 1600 "A"
1972 MG Midget MkIII "Midget"
In reply to # 3890851 by Mitchman2
The real-world model is the hoola-hoop. As it orbits it ALSO ROTATES, but always in solid contact with the body.

A good analogy.

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