Rear Axle - double failure

[blitz11]

I have a feeling a lot of people over tighten their axles trying to error on the side of caution. In 45 years of wrenching on MC's I have never used a torque wrench on an axle. Just get it tight, that's it, it's not going anywhere. Also that pinch clamp on both axles is just there to hold the axle snug. Those clamps are probably the most abused parts of a MC. I've had bikes come in and the clamp had been tightened until both side of the clamp touched. On the front it really causes trouble because that clamp side bottom part of the fork needs to be loose enough in the clamp that it doesn't get pushed to the inside when the axle goes through causing the brake caliper to be out of alignment with the disc. I live in the coalfields where the mine mechanics are used to dealing with torque settings in the hundreds of ft lbs, you won't believe how bad they can screw up putting 6mm side cover screws into an aluminum engine case.

Amen. Thank you.

The only bike where axle torque really mattered were older bmws with tapered roller wheel bearings. Those bearings/axle spacers had to be shimmed properly for correct preload at a particular axle torque. Other than that, just snug up tight. No need to be Hercules.

 

[markjenn]

Just my opinion, but I think the discussion to not use a torque wrench and that the axle nut "doesn't need to be that tight" may be going a bit too far. The torque on this axle nut is what causes the entire axle assembly (axle, spacers, inner bearing races) to behave as one unitized assembly on which the wheels rotate on the bearings. The forces are immense and you don't want this assembly to have any looseness or movement due to torque and road impact.

Assuming I have access to one, I do use a torque wrench in this application. And the torque is pretty darn high, higher than most would torque it if they're doing things by feel. Everything that is gettin torqued is hardened steel, not aluminum and is designed to handle the spec'ed torque with a safety factor. If you have an issue here, it is usually due to thread contamination and it is a great idea to clean the threads before bolting things back up.

- Mark

 

[limey]

I tend to use a torque wrench sparingly, for some very specific applications like tightening the steering head bearings, where too little or too much can be a bad thing. Because so much stuff on a bike involves aluminum threads, I tend to go with tightening things by feel. Usually I go to the point where I meet resistance, and then just a little bit more.

I torque as much as I can, working in power stations all my career I’ve see what can happen if over and under torqued can do.

 

[tomatocity]

I think it was Tomatocity's '16 that did the same thing.

It was my 2012. The axle was shipped 2 Day from Japan.

 

[Don in Lodi]

It was my 2012. The axle was shipped 2 Day from Japan.

::008::

 

[BadNews]

Thanks for the link - interesting article!
And thanks to everyone for your thoughtful input and advice. I've never done maintenance on my bikes, being a 'left handed' writer, but maybe it's time to ease into it.
On another note, I see that several of you are in or near the Mid-Atlantic area. Perhaps we can put together a Super Tenere meet/ride in the spring. Cheers.

There is an annual thing in Romney, West Virginia. Link here:
http://www.yamahasupertenere.com/index.php?topic=23216.0

 

[bob dirt]

This thread got me thinking. I just bought my second 2016. This one was used and has aftermarket tires on it that were installed by others. I already have new Dakars but am waiting to wear out the existing tires a little more before changing them . I bumped the axel nut with my 18 volt impact wrench today just to make sure all was good...and all was good. Re-installed nut finger tight and threw a torque wrench at it.

 

[Dirt_Dad]

I've had the axle/nut fuse together this way on the Spyder we had a few years ago. Took it to the dealership where they had to cut it off. Not a cross-thread. I was having a problem getting the belt aligned correctly so was loosening and re-tightening several times in a row, never taking the nut all the way off. On the last one it welded itself as described in the galling link. A very annoying situation.

 

[2daMax]

Sometimes when the nut and bolt are reused a few times, the thread pitch will change due to metals yielding and permanently deformed. This is where the likely hood the galling will take place due to unmatched pitches. Done it before on other things and lesson learned was to use anti seizing or any grease u may have handy.

Hope my axles are good. Will find out next month when tires get changed. Note to self is to ask the mech to put some grease on the threads.

 

[BadNews]

Sometimes when the nut and bolt are reused a few times, the thread pitch will change due to metals yielding and permanently deformed. This is where the likely hood the galling will take place due to unmatched pitches. Done it before on other things and lesson learned was to use anti seizing or any grease u may have handy.

Hope my axles are good. Will find out next month when tires get changed. Note to self is to ask the mech to put some grease on the threads.

Doesn't the torque specification take into account the friction on the threads, and won't greasing the threads upset that specification?

 

[RCinNC]

Doesn't the torque specification take into account the friction on the threads, and won't greasing the threads upset that specification?

Yes. When the threads are lubricated with anything, it will change the torque specifications. It's difficult to find a consensus on how much difference there is;. I've seen opinions that it can lower the torque specs by anywhere from 10 percent up to 30 percent. Some of the differences in torque values may depend on what lubricant is on the threads. It's kind of a crap shoot;. Do I use dry threads in a high torque area like an axle nut and risk galling, or do I use anti seize and drop the torque values by 10 percent and take whatever risk may be associated with that?

 

[Checkswrecks]

Torque values are given for dry assembly. Anti-sieze is a form of thread lubricant and I've heard rules of thumb to reduce torque by anywhere from 10% to a third. The value can be really critical when the threads will be subject to heat, like in engines. To show how muddy this can be, the following is a post from BobThe Oil Guy:


LUBRICANT OR PLATING TORQUE CHANGES
Oil, Reduce torque 15% to 25%
Dry Film (Teflon or moly based), Reduce torque 50%
Dry Wax (Cetyl alcohol), Reduce torque 50%
Chrome plating, No change
Cadmium plating, Reduce torque 25%
Zinc plating, Reduce torque 15%


My guidance is this: Because there are so many types of anti-seize and such a wide range of anti-seize, it is important to look up the manufacturer guidance for the product you are using. Spark plug manufacturers usually have guidance on their web-sites and I've seen notes in maintenance manuals for a number of vehicles.

 

[Checkswrecks]

RCinNC and I posted at the same time.
fwiw, I do use anti-seize because threading a fastener together damages the plating on the threads and can lead to galling.
Personally, using a torque wrench depends on what I'm putting together.

 

[EricV]

The torque on this axle nut is what causes the entire axle assembly (axle, spacers, inner bearing races) to behave as one unitized assembly on which the wheels rotate on the bearings. The forces are immense and you don't want this assembly to have any looseness or movement due to torque and road impact.

While the axle nuts are an area I do always use a torque wrench on, (dry threads), I make sure my axles are lubricated, not the threads. Just a thin smear of moly grease, though any grease would work fine. They do grease them at the factory for assembly, though typically it's the Yamaha standard of barely enough to do the job.

In response to Mark's comment above that I quoted; I do agree that the parts behave as one unitized assembly. I disagree that the this is a function of the torque value given to the nut. If it's 'tight', there is no significant slop in the assembly. Torquing it higher isn't going to change that. There isn't anything in that assembly that tapers or would change. The wheel bearings and spacers fit over the axle that slides though them. They will spin on the axle in some circumstances, but those are uncommon. (seized bearings)

Hopefully the people reading this thread understand that the correct tightening procedure is to insert the axle, spin the nut on, tighten the nut using two tools, one on the nut, another on the axle, then when you are satisfied with how tight the nut is, lastly tighten the pinch bolt in the swing arm, (or the pinch bolts in the forks for the front). The pinch bolts are NOT there to hold the axle while you tighten the nut! (or when you loosen it!!)
When people attempt that, its not uncommon to find the pinch bolts abused and also to find that the axle was not correctly/fully seated into the assembly, (as others have mentioned already).

I've had a '12 and now a '15. The OP pictures show a nut that does not look like either of my OEM rear axle nuts. Neither of mine have had those small slots cut into the flats. This makes me wonder if the OP is the original owner of the bike, and if he has two or more bikes that were being worked on at the same time. While it's completely possible that several different vendors are used by Yamaha for this part and it is the OEM nut, I can't help but wonder of at some point in time the incorrect nut was installed on the axle, (different bike's or non-OEM).

I have known a couple of riders that forgot to torque the axle nut, or tried to use the pinch bolt to hold the axle while torquing the nut, and subsequently had the nut fall off during a ride. ???

 

[RCinNC]

Torque values are given for dry assembly. Anti-sieze is a form of thread lubricant and I've heard rules of thumb to reduce torque by anywhere from 10% to a third. The value can be really critical when the threads will be subject to heat, like in engines. To show how muddy this can be, the following is a post from BobThe Oil Guy:


LUBRICANT OR PLATING TORQUE CHANGES
Oil, Reduce torque 15% to 25%
Dry Film (Teflon or moly based), Reduce torque 50%
Dry Wax (Cetyl alcohol), Reduce torque 50%
Chrome plating, No change
Cadmium plating, Reduce torque 25%
Zinc plating, Reduce torque 15%


My guidance is this: Because there are so many types of anti-seize and such a wide range of anti-seize, it is important to look up the manufacturer guidance for the product you are using. Spark plug manufacturers usually have guidance on their web-sites and I've seen notes in maintenance manuals for a number of vehicles.

I've always used Permatex 81343 to lubricate both the axle and the threads. Thanks to your suggestion, Checkswrecks, I went to Permatex's site and downloaded the technical data sheet for that product, and found that Permatex recommends that you use the original torque values after the anti-seize application. I was surprised, to be sure. I changed a tire the other day, so now I can go back out and re-torque it back to 92 ft/lbs. All this torque talk has gotten me paranoid....

 

[jbrown]

Every motor vehicle internet group I've belonged to has at some time had at least one thread arguing about dry or lubed torque specs.
There are always members with definitive proof that contradicts some other member's definitive proof.
The end result usually being that the real answer depends on the specific fastener and how the manufacturer specifies the value.

The Yamaha manual does state that unless otherwise noted, all torque specs are for clean, dry threads. Then in the list of torques specs, there are plenty that specify loctite or oil, either of which can have an effect on the clamping force at a given tightening torque. The rear axle torque spec does not add any lube or locking agent requirement, so I'd assume it really is a dry spec. I don't claim this to be a definitive proof

 

[RCinNC]

They probably don't specify any torque specs for lubricated threads because there are enough different anti-seize products on the market, with new ones being added, that it would be a pain in the butt to keep up with all of them. Since galling isn't what you'd term a common occurrence, Yamaha's engineers may feel there's no need for a preventative measure against something that doesn't occur regularly, or with any predictability. Picking a standard and sticking with it means Yamaha doesn't have to be responsible for all the different times when guys put lithium grease, or moly paste, or Permatex, or sheep fat on the threads.

I was very surprised when I read Permatex's data sheet and found they recommended using the original torque specs when using their anti-seize; definitely didn't expect that.

 

[RonH]

It takes quite a bit off effort to goof up the thread on a bolt the size of an axle. Somewhere some botched work has been done previously to start the process in my opinion. Another reason I do all my own work.

 

[RCinNC]

Thread galling doesn't necessarily involve goofing up the threads by doing something wrong; I think it's one of those things where the conditions have to be right, and if they are, you can gall the threads on an axle (especially with dissimilar metals, or metals like stainless steel) without much effort at all. It's a common enough occurrence on the V-Stroms that it has its own thread on the Stromtroopers forum. You might tighten and loosen an axle nut the exact same way a hundred times without doing anything abusive to the axle nut, but if the galling process started at some point in those first hundred cycles, on the 101st attempt the nut will cold weld itself to the axle. Heat, friction and pressure can cause it, and heat, friction and pressure are exactly what you generate every time you tighten an axle nut (especially at a high torque like 92 ft/lbs); it's unavoidable. Even when you're aware of it, and take precautions to prevent it, it can still happen.

 

[Checkswrecks]

It takes quite a bit off effort to goof up the thread on a bolt the size of an axle. Somewhere some botched work has been done previously to start the process in my opinion. Another reason I do all my own work.

The threads are plated on the axle and nut and every time one is threaded on the other, the plating is damaged. The plating serves both to aid in sliding the threads against each other to prevent galling and to provide corrosion protection. In critical engine applications this is one of the two main reasons for using a threaded fastener only once. (The other reason has to do with torque stretching the metal.) Add just a little contamination or a corrosive environment (rain water, stream crossings, living near the water, etc.) and the bad result happens a lot faster.