Wheel nut threads

[roon]

Any place for these in F1? Reduced unthreading time.

[Jolle]

could be something, but they need to be lined up perfectly. F1 wheels use now something like three windings, the "twist" is really milliseconds, the final torque takes up the most time, and that still has to be done with this system.

Lining up the unthreaded bits probably takes longer then winding up the three twists it takes now.

[roon]

I thou

could be something, but they need to be lined up perfectly. F1 wheels use now something like three windings, the "twist" is really milliseconds, the final torque takes up the most time, and that still has to be done with this system.

Lining up the unthreaded bits probably takes longer then winding up the three twists it takes now.

Alignment is a good point. Tapered entries might suffice. The loss of thread interface might necessitate a taller/deeper nut and hub.

[Jolle]

I thou

could be something, but they need to be lined up perfectly. F1 wheels use now something like three windings, the "twist" is really milliseconds, the final torque takes up the most time, and that still has to be done with this system.

Lining up the unthreaded bits probably takes longer then winding up the three twists it takes now.

Alignment is a good point. Tapered entries might suffice.

So it takes two twists from undone to done, with the speed of the wheel guns that time is always less then any system to align the nut to the axle.

[roon]

I thou

could be something, but they need to be lined up perfectly. F1 wheels use now something like three windings, the "twist" is really milliseconds, the final torque takes up the most time, and that still has to be done with this system.

Lining up the unthreaded bits probably takes longer then winding up the three twists it takes now.

Alignment is a good point. Tapered entries might suffice.

So it takes two twists from undone to done, with the speed of the wheel guns that time is always less then any system to align the nut to the axle.

There's also the issue of snagging the threads. The gun would have to stop unthreading after 90* or risk re-engagement.

[AJI]

This is probably a stupid question, but the cars currently use a left hand thread for one side and right hand for the other, yeah?

[Jolle]

This is probably a stupid question, but the cars currently use a left hand thread for one side and right hand for the other, yeah?

Yes. Mix them up and you're pretty, umm... f@cked...

[strad]

I've never understood why they don't use a Higbee thread like on fire hydrants. Can not be cross threaded.

The Higbee is a modification to your existing thread that makes it thread much smoother and without possibility of cross threading. They're also called “Quick Start Threads” or “Blunt Start Threads”.
If you have a CNC lathe, it almost makes sense to put a Higbee Start on every thread. They’ll certainly be a lot cleaner and nicer if you can afford the time and the tool change.

https://john5293.files.wordpress.com/20 ... =545&h=409

[roon]

I've never understood why they don't use a Higbee thread like on fire hydrants. Can not be cross threaded.

The Higbee is a modification to your existing thread that makes it thread much smoother and without possibility of cross threading. They're also called “Quick Start Threads” or “Blunt Start Threads”.
If you have a CNC lathe, it almost makes sense to put a Higbee Start on every thread. They’ll certainly be a lot cleaner and nicer if you can afford the time and the tool change.

https://john5293.files.wordpress.com/20 ... =545&h=409

Thanks for that, strad. It seems they might. The thread start looks blunt in this photo.

[strad]

If they used a true Higbee they could not cross thread the wheel nut.
I'd have to see more of the first thread to know if that is a Higbee.
Maybe, not sure but maybe they run a loose fit and it's able to "jump" the first thread.

The goal is to remove the final part of the thread which is usually a small fin on the turned 45 degree angle portion of the part blank up to where it is a full profile 60 degree thread form. To do this you use a grooving tool (or a parting tool) after you are done with the threading cycle.

https://www.youtube.com/watch?v=KXyoX4hXb2A

[PhillipM]

A highbee start doesn't stop cross threading, merely reduces the chance of it by preventing damage to the thinned start*, which could then be picked up and gall, or send the nut in at an angle.

But you can still cross thread one.


*You can see that that is indeed a higbee thread start even without a photo of the end further around - precisely because you don't have the thinning.

[strad]

If you say so. "“The Higbee is a modification to your existing thread that makes it thread much smoother and without possibility of cross threading." "
I suppose maybe with the speed and power of F1 wheel guns it makes it possible.
I was put onto this more than a decade ago by a machinist friend.
It is used to prevent cross threading on important things like fire hydrants and certain emergency equipment.
As such I have wondered for over a decade why they haven't used it on wheel nuts in F1.

[PhillipM]

They have, it's right there in the photo, the thread is already machined like that.

It prevents cross threading on hydrants, etc, because you have a positive start that can be felt and you can't damage the start of the thread any more with hand torque, because the weak portion has been machined away.
You can, however, still start a thread at an angle if you're not careful, depending on tolerances.

The problem is it also makes it more likely for the thread start faces to just hit each other if you're using a fine thread (as F1 used to do when time didn't matter as much because of refuelling) - so then you end up going with a much coarser pitch - again, like the 3 thread setup pictured above, and running a lot more torque on the gun to get the required preload.
That kind of speed and torque available on the guns can still quite happily wind a thread on that's misaligned at an angle, or mushroom the start of even a highbee'd thread if they hit square on and cause damage.
The nuts are only aluminium, the guns have enough power to rip the whole thread clean out without blinking if it's not properly engaged.

The main problem is getting your tolerances exactly right so the wheel and nut still go on easily even when everything is hot, but still being tight enough to try to prevent engaging at an angle, and further shaping (axially this time, rather than radially like the highbee) of the thread end to deflect end-to-end strikes into engagement with minimal damage.
The nut and spindle coatings play a big part too.

[PlatinumZealot]

what are those ribs to the right of the thread in the photo?

[strad]

They have, it's right there in the photo, the thread is already machined like that.

Whatever
But it looks to me like the first thread is the same pitch as the second thread and that's where the difference lies. IMO