Knock-off wheel removal

[Spinneyhill]

I wonder if the main force attempting to undo the wheel nuts results from elastic deformation of the wheel under hard braking (front and back) and acceleration at the back. The rim will move relative to the web of the wheel and the wheel nuts or bolts. The wheel must deform to mobilise the strength of the wheel. So there will be a torque in the middle part of the wheel (steel disk, spokes and hub, whatever).

[hchris]

Coming in a little late here but - I recently had the same dilemna with fitting spoke wheels on my Sunbeam Alpine (LBC to you guys , I believe) 

 

Having owned Chryslers for many years I am more than familiar with their practice of lh thread lug nuts on the left side wheels, so my research into fitting left and right hand thread axle hubs, with appropriately threaded centre spinners caused me no end of confusion. Eventually I decided to follow the Chrysler practice and installed left threads left side and rights the other; having buttoned it all up I went for a test drive, did some left turns right turns etc and within 3 blocks felt the wheels going clonk, clonk, clonk at the next turn; got home all right and sat down for more research.  

 

Eventually I found a very good article by a spoke rim manufacturer (no, kicking myself for not keeping it as a reference) who described the interaction of braking forces between axle and rim, this is the definitive reasoning behind correct threading - as someone mentioned earlier the easiest way to remember is the centre spinners must tighten towards the rear of the car on all wheels, quite the opposite to lug nut practice.

 

And just to make myself crystal clear - I am talking about male thread axle, female thread spinner variety of spoked rim. I have now completed 2 - 300 kms without drama so feel comfortable in letting the seatbelt off a notch or two. 

 

 

[SC38dls]

Damn, I just had a flash back to being in physics class and I’m 72 years old! 

 

Another fine mess you've gotten me into, Olie. 

 

Dave S 

[Gary_Ash]

Here is an article written by Alec Ulmann for the "Bulb Horn" magazine of the VMCCA in 1974 about Rudge-Whitworth center lock wheels.  The early patents for Rudge wheels go back to 1910 or earlier, so the left-thread-on-right-side concept has worked well for over 100 years.  Perhaps we need not sweat the details of exactly how and why it works, but it does.  The equipment for making the wheel centers and rims was owned by Dunlop in England, but was sold some years ago to Wheels India who continues to make wheel centers, rims, complete wheels, and some splined hubs, as well as a wide range of modern wheels.  An excellent dealer in these wheels is MWS Wire Wheel in England. 

 

[ejboyd5]

Some more interesting reading:

http://www.mgaguru.com/mgtech/wheels/wl102.htm

https://www.roadandtrack.com/car-culture/a28133/lost-art-the-smiting-of-the-knockoffs/

[Matt Harwood]

This was all very confusing for me. Thanks for all the additional information, I think I have a better understanding now. I don't think I'm going to worry about disassembling the Cobra to switch the hubs, especially since it's safety wired, but at least I understand the reasoning now. Thanks for all the feedback!

[emjay]

15 hours ago, 1937hd45 said:

This is why knowing if the taper is an inner or outer is so important. Bob

 

Why is everyone ignoring this very important difference in the knock off style?  British cars have an internal taper on the knock off while these wheels have an external taper on the knock off.  Under normal conditions there is no movement.  However, if the wheel loosens a bit, the wheel taper will on the knock off taper now there are two different diameters involved.  In one case the contact point is on the outside of the wheel hub and in one case it's on the inside.  This difference will generate rotation in different directions for each case.  The splines stop most of the movement but there will still be a tendency to revolve, but the weight of the car is to be transmitted through the tapers. 

 

The confusing bit on the British hub is the inboard taper is external on the hub, but the loosening effect is on the knock off.

[Gerse1982]

On 6/21/2018 at 6:18 PM, emjay said:

 

Why is everyone ignoring this very important difference in the knock off style?  British cars have an internal taper on the knock off while these wheels have an external taper on the knock off.  Under normal conditions there is no movement.  However, if the wheel loosens a bit, the wheel taper will on the knock off taper now there are two different diameters involved.  In one case the contact point is on the outside of the wheel hub and in one case it's on the inside.  This difference will generate rotation in different directions for each case.  The splines stop most of the movement but there will still be a tendency to revolve, but the weight of the car is to be transmitted through the tapers. 

Crunchy & Healthy Broccoli Cauliflower Salad

The confusing bit on the British hub is the inboard taper is external on the hub, but the loosening effect is on the knock off.

thanks for the clearance. this does sounds right.  Do you work, by accident, with wheels? i mean, you seem to know many details and terminologies. just interested if i could ask other questions if you don't mind? Roland

Edited May 21, 2020 by Gerse1982
grammar (see edit history)

[emjay]

No professional connection, just a mechanical engineer by birth and several trips around the Sun.  I just try to apply simple physics and a lot of observations to concepts.  I may not always get the complete set of details correct but do tend to look where others are not.   Still don't understand the logic behind left handed lugs nuts on the left side.  (Never tried to either)  As I recall the one time I had lug nuts tumbling in the hub cap it was on the right side with right hand threads.

[ejboyd5]

4 hours ago, Matt Harwood said:

 I don't think I'm going to worry about disassembling the Cobra to switch the hubs, especially since it's safety wired, but at least I understand the reasoning now. !

Practically, it probably won't make any difference with the use of your car, but personally it would bother me every time I looked at it and realized that somewhere in its past a mistake was made and that I had done nothing to correct it.  Thankfully the Rudge wheels were installed correctly by the factory on my 300 SL and have worked perfectly for the 54 years I've had it.  They do take some "thumping" to loosen however.  M-B (Rudge) uses the more common variation where one strikes toward the front of the car to loosen and toward the rear to tighten.  Why Lotus pursued "a better idea" and reversed directions we'll leave to the devotees of that marque to argue. 

[emjay]

13 minutes ago, ejboyd5 said:

Practically, it probably won't make any difference with the use of your car, but personally it would bother me every time I looked at it and realized that somewhere in its past a mistake was made and that I had done nothing to correct it.  Thankfully the Rudge wheels were installed correctly by the factory on my 300 SL and have worked perfectly for the 54 years I've had it.  They do take some "thumping" to loosen however.  M-B (Rudge) uses the more common variation where one strikes toward the front of the car to loosen and toward the rear to tighten.  Why Lotus pursued "a better idea" and reversed directions we'll leave to the devotees of that marque to argue. 

Thanks ejboyd5 for those articles you posted earlier.  I just had a chance to scan through them and they confirm that the principle of the Hula Hoop is at play.  I didn't see mention of internal tapers on the knock offs.  Perhaps I missed it.  I was thinking that the same principle applies to the lug nuts as well as the wheel starts to squirm if the lugs are loose.

[ejboyd5]

2 hours ago, emjay said:

 Still don't understand the logic behind left handed lugs nuts on the left side.  (Never tried to either)  As I recall the one time I had lug nuts tumbling in the hub cap it was on the right side with right hand threads.

 

Here's a link to a Wikipedia article on fretting precession that may help:

.https://en.wikipedia.org/wiki/Precession_(mechanical)

 

And here is a link to a website that has lots of information concerning threaded fasteners presented in understandable terms:

http://www.boltscience.com/pages/vibloose.htm

 

The horse is now well and truly dead.  Further flogging will be counterproductive.

[1937hd45]

8 hours ago, emjay said:

 

Why is everyone ignoring this very important difference in the knock off style?  British cars have an internal taper on the knock off while these wheels have an external taper on the knock off.  Under normal conditions there is no movement.  However, if the wheel loosens a bit, the wheel taper will on the knock off taper now there are two different diameters involved.  In one case the contact point is on the outside of the wheel hub and in one case it's on the inside.  This difference will generate rotation in different directions for each case.  The splines stop most of the movement but there will still be a tendency to revolve, but the weight of the car is to be transmitted through the tapers. 

 

The confusing bit on the British hub is the inboard taper is external on the hub, but the loosening effect is on the knock off.

Thank you, Glad you are able to explain this better than I could. 40+ years ago I did see FOUR wheels come off a "restored'"dirt track race car with 1930's vintage Dayton wire wheels that had the hubs installed  bass ackwards. Stuff like that makes for a memorable learning experience. Bob 

[mike6024]

That "fretting precession" sounds like the real reason lug nuts on the left had left-hand threads, not the Coriolis nonsense I mentioned earlier, haha.

[emjay]

"Precession" I knew there was a word for it, but Hula Hoop works.  I've thought about trying the Hula Hoop again since I know what I was doing wrong when I was six.

[Frank DuVal]

On 6/20/2018 at 11:23 PM, Matt Harwood said:

Why did engineers at GM and Chrysler fear for decades

 

Hmm, I 've never seen a GM car with left hand lug nuts or bolts. Not saying somewhere in the past they did not, just I have never seen them. Studebaker, Chrysler.... YES!

[Matt Harwood]

1 hour ago, Frank DuVal said:

 

Hmm, I 've never seen a GM car with left hand lug nuts or bolts. Not saying somewhere in the past they did not, just I have never seen them. Studebaker, Chrysler.... YES!

 

My '29 Cadillac has left-hand threads on the left side of the vehicle.

[Bloo]

So does my '36 Pontiac.

[SC38dls]

Frank at least you are correct about Studebaker’s. My 38 has them. 

Dave S 

[Frank DuVal]

You just increased my old car knowledge!

[mcdarrunt]

Built this 30 Plymouth about a dozen years ago with a Heidt's IRS and knock off hubs. Have slept since then but almost sure the left side was left hand and right side right hand. A call to Heidt's would positively answer the question on THEIR'S. As far as GM goes my 37 Buick has left hand lug BOLTS on the driver side.

[ejboyd5]

For those who may be interested, here's an article I did for the Gull Wing Group's 300 StarLetter:

 

Rudge Knock-Offs and Self-Tightening Spinners

Many 300SL automobiles are equipped with knock-off wheels that follow the Rudge-Whitworth model that dates back to the early 1900s. The most noticeable and eye-catching feature of this design are the eared spinners (nuts) that affix the wheels to the car. These spinners are marked “LS” and “RS” to indicate their proper placement on the car and also have an “AB” marking along with an arrow to indicate the direction the spinners must be rotated for removal.

Rudge hubs are not interchangeable from side to side of the car as they are designed and machined in both right-handed and left-handed threaded versions. The proper orientation of right-handed thread on the left side of the vehicle and left-handed-thread on the right side of the vehicle must be adhered to if the spinners are to be self-tightening and not fall off as the wheels rotate. Why is this?

Over the years many misconceptions, aided and abetted by loose terminology and a competing brand of center lock wheel (Lotus) that tightens in a different direction, have combined to create an aura of mystery that confounds even seasoned engineers. Let’s try to simplify the issue beginning with the terminology.

All center lock wheels consist of three basic parts: 1) a splined hub at the end of an axle that terminates in either a right-handed or left-handed threaded male fitting; 2) a wheel with a splined center section that slips over the splined hub; and 3) a nut or spinner with either a right-handed or left-handed threaded female fitting that screws onto the splined hub to secure the wheel.

Difficulty with understanding the reasoning behind “right” and “left” threads on different sides of the car begins when one tries to include the theory behind the “self-tightening” feature for the spinners into the discussion.  Generally, spinners or nuts tighten or loosen themselves because of tiny rotational movements between the parts described as “relative motion.”  Compounding the difficulty with understanding the process is something called “mechanical precession,” which describes the forces that come into being when a round object of a smaller diameter rotates within a round object of a greater diameter.

To make this all easier to understand, think of the Hula Hoop, A child’s waist might have a diameter of 25 inches while the Hula Hoop might have a diameter of 36 inches. In order to keep the Hoop in motion the child (the smaller diameter) must rotate faster than the Hoop (the larger diameter). This relative motion between the two diameters also imparts a circular rotational movement to the Hoop itself.

If anyone wishes to demonstrate this action (and still has access to a Hula Hoop), wrap a piece of tape around the Hoop as a marker, put the Hoop in motion around your waist and watch how the tape marker moves right or left showing the rotational movement of the Hoop. Depending upon the direction the Hoop is turning this motion equates to the self-tightening or self-loosening of a threaded fitting albeit on a much larger scale.

Returning to the Rudge wheel, we note that the center portion of the wheel has a smaller exterior diameter (like the child) than the interior diameter of the spinner (like the Hula Hoop). Because of this difference in diameters the wheel center rotates infinitesimally faster than the spinner in order to travel the same distance (just the same as the child with the smaller diameter must rotate his hips faster than the rotational rate of the Hula Hoop with the larger diameter). This difference in rotational speeds and the direction of the rotation is what accounts for self-tightening or self-loosening of a nut or spinner.

As viewed from the side and since the predominant direction of travel for an automobile is forward, the center portions of the wheels (the smaller diameter) on the left side of a car are rotating faster in a counter-clockwise direction than the spinners (the larger diameter) are rotating in the same counter-clockwise direction.  Since the left side of a Rudge wheel equipped car has right-handed threaded fittings, the relative motion between the wheel center and the spinner causes the spinner to self-tighten.

To help visualize this relative movement, grasp a standard right-handed bolt in your left hand and a right-handed nut in your right hand. Rotate both in a counter-clockwise direction but rotate the bolt faster than the nut and notice how the nut tightens onto the bolt. You have just demonstrated the self-tightening of a threaded fitting as a result of relative motion.

Turning our attention to the right side of the car, the wheels are still moving in a forward direction, but the rotation of the wheel center and the spinner is now clockwise as viewed from the side.  If we were to utilize right-handed threaded fittings on the right side of the car, the relative motion between the center of the wheel and the spinner would create a self-loosening force.  Hence the need for left-handed threaded fittings on the right side of a car.

Again, if there are doubts, grasp the right-handed threaded bolt in your left hand and the nut in your right. Rotate both in a clockwise direction being sure to rotate the bolt faster than the nut and you will see that the fitting loosens.

Several pertinent observations:

           1) The relative motion we are describing is of a very, very small magnitude and when the threaded parts are well and truly tightened together it is negligible. It is the possibility of this motion however that provides the mechanical reasoning behind right-handed threaded fittings on the left side of a car and left-handed threaded fittings on the right side when following the Rudge model.

            2)  The interface where the relative motion takes place is between the wheel center and the spinner nut, not between the spinner nut and the threaded hub. It is the relative motion between the wheel center and the spinner nut that causes the spinner nut to tighten or loosen itself with regard to the threaded hub.

            3) Some discussions on the topic of knock-off or center lock wheels confuse the issue beyond all comprehension by introducing the term “taper” to describe the interface between the wheel center and the spinner.  Forget about the word “taper” and simply remember that with the Rudge design the outside diameter of the wheel center is smaller than the inside diameter of the spinner and it is those different diameters that are responsible for “relative motion.”

Winding down this discussion, someone somewhere is bound to ask about the Lotus SE that has right-handed threads on the right side of the car and left-handed threads on the left side.  Why don’t the Lotus wheels fall off?  The answer lies with the relative diameters of the wheel center and of the spinner. 

Unlike the Rudge design where the spinner has a larger interior diameter than the wheel center, the Lotus spinner has a conical protrusion that fits inside the Lotus wheel center effectively giving the Lotus spinner a smaller interior diameter than the Lotus wheel and that design change reverses the direction of relative motion between the parts, i.e., the Lotus spinner having a smaller interface diameter rotates faster than the larger diameter of the Lotus wheel center. Since the relative diameters of the hubs and wheel centers have been reversed from those of the Rudge model, the orientation of right and left-handed threads on different sides of the car must also be reversed to allow self-tightening feature to function.

Finally, and contrary to some popular belief, the Lotus spinner does not present with a male thread that screws into the hub.  It has female threads just like the Rudge spinner, the difference being the conical protrusion of the spinner that fits inside the Lotus SE wheel center whereas the Rudge spinner lies outside the Rudge wheel center.

 

Edward Boyd, Southold, New York

June 25, 2018                                                                                                                                                       

 

[brasscarguy]

So Some years back I sold a set of  quick change wire wheels and hubs and nuts. These were a very good original condition set of wheels just clean and paint and mount. I sold this set to a well known brass era collector.

 

He calls me a few weeks later mad as hell telling me I screwed him by selling junk wheels and if I did not refund his money he was going to tell everyone on the net what a bad guy I was. I asked him what the problem was and he told me he could only drive the car a couple of blocks and the wheels almost fell off the car. 

 

I told him to go out to the car and look at the hub nuts and see that they were on the correct side of the car.  Stamped into the face of the hub nuts,  is "right or left side" and an arrow with the word off so you know which way to remove the caps.

 

I never heard back from this well known brass car collector with an apology, so I could only assume he had installed the hubs on the wrong side so when he drove the car the hub nuts loosened up as he drove. His embarrassment for being so ignorant was so bad he could not fess up and tell the truth.  I so badly want to share his name but discression is the better part of valor, my lips are sealed. brasscarguy

 

 

 

 

[Curti]

Does the 'well known' brass car guy frequent this board ?

[R W Burgess]

This comment has nothing to do with Cobras, but my 1965 Corvette has knockoffs and I had never changed my tires after purchase when I had "an occurance"! On the show field many years ago, "an educated" car show participant suggested that I should probably retighten the knockoffs on my car. Of course thinking about it all the way back home, I decided to do just that. The next week I went all around the car and retightened all of them. 

 

The next week was a local car show, and on the way down, the right rear wheel tried to come off my car. After fixing this, the next week I checked all of the wheels again, and upon taking the "hubcap" off I noticed little slots all around the inner part of the knockoff and the hub. Unnoticed by me were the "lock-slots" put in each wheel with "pins" that you would put in the nearest location to "lock the knockoff". DUH! I had broken one off as I retightened without first pulling the "pin". Live and learn!

 

So called car show experts are not what they are cracked up to be!  :-)