Axle lock nut

[docc]

When I replaced my rear axle, I also tried to replace the lock nut and washer. The nut had to come from Italy, so I bailed. Now, it seems the thin washer has >gane ryte agly  I suppose if this is the only thing I've lost in all the things I've had apart on this bike in the last year, that's *not too bad*. (Bad, but "not too bad")

 

So, I sourced a 14 gauge "machine bushing" in SAE. But it stands the nut off more than the original, thinner axle washer. I've ordered a factory part (95004219), but is the locking nut safe to run in this state?  At what point should these lock nuts be replaced?

[docc]

[The web gives me the heebie-jeebies]

 

"A P-51 Mustang airplane collided with the airport ramp in the spectator box seating area following a loss of control during the National Championship Air Races. The investigation found that the trim tab attachment screws could be rotated through the nuts by hand, and the fiber inserts were visibly worn and displayed the full thread form. The degraded nuts allowed the screws to repeatedly loosen at race speeds, . . ."

 

Later on that page, "When in doubt, throw it out."

[68C]

You should have 1 1/2 threads showing.

[MartyNZ]

You have some options.

1. Leave the washer out. Not good practice, but better than having the nut come off.

2. Get a thinner washer. Any washer. Or make a washer with a rotex punch.

3. Get a thinner nut, or grind the existing nut thinner.

4. Torque the nut to the standard torque listed for that size, ride, carry tools, and check the witness marks you made. 1 mile, then 5 miles, then 20 miles. If no rotation of the nut, you should have adequate locking.

5. Bore a hole through the nut and axle, install split pin.

To my mind #2 is best, and only 2 & 5 could be a permanent fix.

[docc]

"4. Torque the nut to the standard torque listed for that size, ride, carry tools, and check the witness marks you made. 1 mile, then 5 miles, then 20 miles. If no rotation of the nut, you should have adequate locking."

 

Haha, yeah, you can see I marked the nut for that purpose. But, jeez, I don't need that kind of noise in my head trying to ride, navigate, and be responsible to the riders behind.  So, I ordered a Guzzi replacement washer and sourcing new lock nuts locally for front and rear. Mine have been off and on dozens of times.

[docc]

I don't want my P-51 spiraling into the bleachers!

[MartyNZ]

You should know that fiber lock nuts have not been used for decades, so reading about an event on a vintage plane is not useful. Nylon locking (nyloc) in your axle nut is much better, and more durable. 

You can check how good the locking is by measuring the "run-on' torque. As the nylon bites on the threads, the increased torque is measurable. Perhaps another 5-10 Nm. I bet there is an online calculator to help. Having low run-on torque means that you should discard the nut, or use alternative locking methods.

[docc]

So, there is a "no-go" threshhold for run-on torque? Worth checking on our axle nuts as they age . . .

 

For now, I feel better with the nut fully seated. Used a bit of Klüber Staburags grease under and torqued the axle "from the drive side" as the manual prescribes.

[docc]

"Run-on torque" . . . a procedure for the Wheels Off Maintenance Checklist . . .

 

????

[Chuck]

You should know that fiber lock nuts have not been used for decades, so reading about an event on a vintage plane is not useful. Nylon locking (nyloc) in your axle nut is much better, and more durable. 

You can check how good the locking is by measuring the "run-on' torque. As the nylon bites on the threads, the increased torque is measurable. Perhaps another 5-10 Nm. I bet there is an online calculator to help. Having low run-on torque means that you should discard the nut, or use alternative locking methods.

 

I'm sure that 51 had nyloc nuts. A close friend was just narrowly missed by the debris, btw. Nyloc nuts "can" be reused, but the number of times is up in the air so to speak. It's up to the mechanic that puts it on. Back in the day, fiber lock nuts were one use only.

[docc]

Are we in a position to reference a limit to the "run-on torque", re-use limit, or any other measure for when the V11 locking axle nuts should be discarded?

[Lucky Phil]

Are we in a position to reference a limit to the "run-on torque", re-use limit, or any other measure for when the V11 locking axle nuts should be discarded?

Axle "Locking" nuts are really not required. My bike is fitted with Titanium non locking nuts front and rear with no issues as have been a hell of a lot of production motorcycles over the years including every Ducati I've ever owned including race bikes that have competed in the IOM. Its just another analy retentitive Guzzi idea thats not really necessary.

 

Ciao

[68C]

Of course a new nyloc nut does not have a thread in the nylon part, it cuts itself one the first time the nut is used. In extremis one can make a quick pass over the nut with a blowlamp, to partially melt the nylon, allowing it to return to a semi new condition. This technique best left for lawnmowers and other folks bikes/P51 etc.

 

P.S.I What is a 'bleacher'?

[Chuck]

 

 

P.S.I What is a 'bleacher'? 

Rows of seating, normally around a sporting event. Each row is successively higher.

[Pressureangle]

Options;

Look through the bin at the hardware; often, different lots of nuts have different heights. Yours looks to be pretty tall, you might find a new one a thread shorter.

Look for a non-nylon locking nut. 'aircraft nuts' or 'pinch nuts' are usually shorter than nyloc. 

Since it's a non-load bearing component, I'd feel safe even with a low-clearance nyloc, which may have 1/2-2/3 the thread engagement. 

A last, but hard-to-find option is to source a nut (or make one, if you have a light touch and cobalt drill bit) with safety wire holes and wire it.