Tightening the Monster Axle Nuts

[techyiam]

10 hours ago, RagingGrandpa said:

Well, not actually... with 2WD vehicles and nothing to clamp the brakes, we can't put final torque on the front wheel using hand tools... and impact guns are imprecise and risky... so my habit is "snug in the air first, torque on the ground later"

The exercise I suggested was just a simple way to prove to one self whether or not my claim was true: that is with flex, under torqueing would result. So with any stick shift, put it in gear (no hand brakes if at rear), torque one lug nut (or bolt) on one of the driven wheels while the wheel is off the ground. Put the wheel back on the ground and recheck the torque. No risk nor harm would result. There, you will have your answer.

Going back to the axle nut on the euc, my main point was that to apply a much higher tightening torque with the shims going plastic would not be prudent, it is not unlike torqueing wheels up in the air.

 

10 hours ago, RagingGrandpa said:

(For EUC axles, the technique of multiple passes at 110ft-lb, with tapping/rapping the wedges between passes, has proven practical and effective throughout multiple installations, for me.)

Now, this changes everything. You managed to find a series of steps to work-harden the shims while the shim are still installed on the wheel. Kudos to you for making the discovery, and thanks for sharing.

As I mentioned in my previous post, torqueing some where just north of 100 ft-lb, the area of the shim where the stress is highest may start to go plastic. This area would be where the shim makes contact with the axle (along edges of the flats on the axle).

Optimally, work hardening is done at a higher temperature, but in your case, it looks like it is still sufficiently effective. Work hardening occurs when the metal is strained until it goes plastic, and the dislocations in the crystalline structure of the metal are forced to pile up, making the metal harder and stronger. However, there is a caveat. It becomes less ductile, and will crack and thus fracture easier.

The steps that you took are all critical. The steps you took successively bunch up the dislocations through iterations. The 110 ft-lb of torque is also critical. Too low, and you would not be able to work harden, and too high, you would damage the shims.

The shims need to be ductile in order to produce the proper wedging action. However, in your case, you have only work hardened the part of the shim that makes contact with the axle. The rest of the shim is not affected, and thus stiil ductile. The work hardened area of the shim is now stronger, and will wear better. Perfect outcome.

Although the stand-alone crescent wrench approach  may be limited in how high a tightening torque one can apply, your method didn't need it. Very clever.

Edited February 18, 2022 by techyiam

[Boris Lämpel]

Well, sadly Locktite is of no use. At least not for me. I fastened it with locktite as hard as I could. It became loose again and again.

So I will probably weld some kind of axle-nut-protector...

[alcatraz]

There are different strength loctite. It's better not to use a stronger one than you need or you'll get the opposite problem: you can't get the nut off.

[RagingGrandpa]

I'm in the "don't trust loctite" camp... the flats cut into the stub axle reduce the contact area that locking compound can act on. 

@Boris Lämpel: After dozens of retightenings across a handful of stub-axle Gotways, the only reliable method I've discovered is below: 

On 2/11/2022 at 3:56 PM, RagingGrandpa said:

Socket:
The only appropriate option that doesn't require removing motor cables is cutting your own 24mm socket. 
We're going to a very high torque- "sensor sockets" are too flimsy.

Driver:
A 1/2"-drive click-type torque wrench is the only ergonomic and repeatable method.
My torque recommendation: 110 ft-lb for the cable side; 120 ft-lb for the solid side; with rapping the wedges until torque is held consistently.
I've had local riders loosen nuts after installation to 120 ft-lb, but we're scared to go any higher. The Gotway 101 ft-lb spec is insufficient for trail riding & jumping.

Holding:
I recommend the big crescent:  https://forum.electricunicycle.org/topic/8050-tightening-the-monster-axle-nuts/?do=findComment&comment=356306 
Torque it with the motor and hangers installed in the EUC shell- it will help ensure relative alignment, and the crescent will bear the tightening torque, not the plastic. The flats in the axle shaft ensure the hanger alignment can't become very far off.

Threadlock: 
... will never be strong enough in this application, because of the partial threadform and irregular clamping surface.
Go for red, such as Loctite 263. It will still come loose eventually.

Edited May 1, 2023 by RagingGrandpa