Seems Yamaha made a boo boo on the drain plug torque spec

[klx678]

I found this in the Tenere 700 forum and don't know if it made it around the horn. I added the emphasis on some parts:

Just wanted to let you folks now I had an interesting and disappointing situation with my new Tenere. Last week I reached my 600 mile break-in so I changed the oil. The drain plug from the dealership was on really tight. After draining the oil I put the plug back in. I followed the instructions in the service manual which called for 32 ft-lbs of torque. However, I managed the strip the threads and partially squash the strainer cover assembly (the OEM name). Of course, I was surprised and horrified.

I rechecked my torque wrench about 10x and it was set to only 30 ft-lbs. Suspecting the wrench failed I checked it against another and it seemed to be okay. I did not "calibrate" the wrench, but merely checked it against the "feel" of another to determine they about the same.

I brought the bike to the dealer for repair and explained the story. In the meantime, I checked the torque specs on other motorcycles: KLR650 (17 ft-lbs); Husqvarna 350 (15 ft-lbs); Triumph Tiger (17 ft-lbs). Why does the Tenere call for 32 ft-lbs? Seems like a lot by comparison, even if the bolt is big. I can't send a picture because the bike is in the shop right now.

Long story short: Yamaha agreed this was too much torque for this plug, and said they will no longer recommend 32 ft-lbs. Yamaha will cover the cost of the part and the repair, but unfortunately, the part is on backorder with no ETA at this time. Bummer since the riding season is quickly coming to a close. I wanted to warn other Tenere riders to be careful with the plug.

I think it probably shows how few people actually torque drain plugs, but for those that do, make the spec 15 ft-lb or 180 in-lb, convert to N-m if needed. Those of you who do not use a torque wrench on the drain, remember that not everyone has "the torque wrench arm". Working in a shop for a lot of years I can attest to that fact with all the drain plug and spark plug holes that needed heli-coiled, not to mention fork axle cap studs snapped off.

Edited October 4, 2021 by klx678

[Triple Jim]

It's good that you posted this, but I have to think it's silly that someone would read 31 lb-ft  (the spec in my manual) and actually get out a torque wrench and try to tighten it to that value without questioning it.

(I realize you were quoting, but torque is pounds times feet, or lb-ft, or sometimes ft-lbs, not feet per pounds as "ft/lbs" means.)

 

 

Edited October 4, 2021 by Triple Jim

[klx678]

I didn't edit that part of the message, kept as in his post.  I will go in and edit it.  Thanks.

I definitely think it should be out there in any of the 700 forums.  Should actually be a notice emailed/mailed out to owners by Yamaha.

Edited October 4, 2021 by klx678

[shinyribs]

32ft is head stud range torque values! Ouch! I'm with Jim, I can't imagine someone pulling on a wrench THAT hard and not questioning it. 

 

Likewise, it seems the rear axle torque value is also insane in the manual. Something like 80 pounds. 80!!!! No wonder folks are killing those axle nuts! 

I swear, 90% of all stripped threads I see are preluded by a torque wrench. Just tighten it until it's tight, then stop. 

[seven]

Maybe coming from my car (Audi S4) big torque numbers don't make me question things. Wheel bolts are 88 ft-lbs, heck the bolt holding the rear shock is something like 120 ft-lbs! That rear axle nut on my MT-07 didn't even make me think twice...one nut holds the whole axle and wheel onto my bike so yeah I felt it should be good and tight. LOL

[7fold]

15 minutes ago, seven said:

Maybe coming from my car (Audi S4) big torque numbers don't make me question things. Wheel bolts are 88 ft-lbs, heck the bolt holding the rear shock is something like 120 ft-lbs! That rear axle nut on my MT-07 didn't even make me think twice...one nut holds the whole axle and wheel onto my bike so yeah I felt it should be good and tight. LOL

Same, honestly - I torque the lug nuts on my care to ~80 ft-lbs so I didn't think the torque for the axle nut was out of the ordinary. The drain bolt torque issue is definitely helpful though - my last oil change, I had a really hard time getting the crush washer off the drain bolt. I guess now I know why hahaha.

[ElGonzales]

Once that crush washer ended sticking between my thumb and it's nail >:/
I followed the Yamaha instruction of 32 ft-lbs only at my first own oil change. Then the next times I decided that 22 ft-lb should be enough. No problems until now

[Yakko Warner]

For non load bearing  fasteners, such as a drain bolt, too loose will only result in a few drops of oil leaking, and is easily remedied by tightening the bolt a bit more.  Too tight and the threads can strip, or the bolt can break, which results in a world of pain and misery.  So if in doubt, too loose is much preferable than too tight.  Again for non load bearing fasteners only.  My $0.02.

[Triple Jim]

Up to the point where it rattles out.  

I like to use Stat-O-Seals instead of crush washers on drain bolts.  They have a rubber O-ring built in, and seal without having to tighten a lot.

Edited October 5, 2021 by Triple Jim

[klx678]

On 10/4/2021 at 3:31 PM, shinyribs said:

32ft is head stud range torque values! Ouch! I'm with Jim, I can't imagine someone pulling on a wrench THAT hard and not questioning it. 

 

Likewise, it seems the rear axle torque value is also insane in the manual. Something like 80 pounds. 80!!!! No wonder folks are killing those axle nuts! 

I swear, 90% of all stripped threads I see are preluded by a torque wrench. Just tighten it until it's tight, then stop. 

Per my experience over 90% are caused by over tightening without a torque wrench from what I saw in the years at the dealership - and personally of course.     

Think about the size of the axle and nut, then consider automobile lug nuts are to be torqued from around 90 to 110 ft-lb.  More than that axle nut which is significantly larger.   The problem with the axle nuts was the kind of nut.

The key here is to have a good thought process on torque values too.  As noted, Yamaha went too high and it has caused damage.  One member here did the right thing, dropping down to 22.  The rider in the Tenere 700 forum actually did some research after his issues with the recommended torque and found the range around 15-17 ft-lb, which makes far more sense.  After all, it is just a plug, not holding anything in place other than the oil in the pan.   

I'm thinking I may drill the bolt for safety wire, which makes sense as a safety net should the 15 ft-lb or whatever my arm generates, is too loose.  Makes you wonder what Yamaha now thinks is a correct value.  

[shinyribs]

The axle is large diameter to handle sheer loads and prevent flexing. The nut is a by product of the axle diameter, not an indicator of how much torque needs to be applied to it. There are absolutely zero forces trying to unscrew the nut or trying to rip the axle out of the swingarm laterally. The nuts only job is to lightly snug the inner bearing races against the axle spacers. The nut is self locking. 

The problem I see is people don't understand the job of the fastener in question. They see an axle and freak out. " ItS kEePiNg My WhEeL oN!", so they tighten the beejeezus out of it, not realizing that it's useless. 

Torque values exist for the purpose of stretching the bolt in order to create clamping force to: 

A: supply sufficient pressure to keep the nut on.

B: supply sufficient to to retain a gasket.

We're NOT gonna stretch that rear axle, which is why Yamaha gave us a Fuji nut. The absolute premium of all locking nuts. 

 

And while you're not going to stretch that axle, you will deform and stretch the weakest part where it's threaded. Hence..." Yamaha uses shet nuts and now my axle is ruined". Because it's an axle, not a hardened bolt.

Edited October 7, 2021 by shinyribs

[klx678]

You point out the exact reason for the 80 ft-lb.  Stretching the axle and clamping parts together.   Same reason why some engines are built using a method of torque setting and another 90° turn on that.  The axle may strech a bit and the spacers and all will squeze tightly, plus it will reduce some flex in the whole swing arm wheel assembly.   Maybe not a major amount, but still some.   80 ft-lb is actually pretty light considering the size of the bolt (axle) and the nut.   Look it up in an engineering chart.  First thing I did after seeing the torque setting for the 14 mm drain plug.  Problem is it is hard to find torque values for material that has the internal thread.  Cast aluminum is certainly going to be less than steel, (Edit) but try to find that information online.  It ain't easy.  Spent time trying to do so along with looking in my old Statics and Strengths of Materials text book.

Edited October 6, 2021 by klx678

[shinyribs]

The threads on that axle won't take the torque of a bolt that size. That axle isn't a bolt and shouldn't be treated as such. I think the trending ruined axles will support that. 

A steel 14mm drain plug will take way more torque then the aluminum pan it's screwed in to, especially with it's shallow threads. You're not gonna torque stretch that bolt in that situation, you'll deform the aluminum threads instead. The drain hole is that big so that a viscous fluid can flow out in a reasonable amount of time, not because it needs to be tightened to 30+ lbs of torque. 

It's another case of the size of the fastener being a by product of It's job, not an indicator of how tight it needs to be cranked down. Same reason we don't bear down on 14mm spark plug threads. Spark plug bores are that big because the electrode and insulation take up space, not because it needs a fastener of that strength level. 

Edited October 7, 2021 by shinyribs

[klx678]

From an engineering stand point that axle meets the definition of a bolt.   Just check at Fastener Engineering  click here

You want to talk spark plugs, let's refer to NGK, the very first line says, "Torque is one of the most critical aspects of spark plug installation."  Yet I will bet a vast majority of riders do not do so and doubt many have ever read what NGK, or any other plug manufacturer has to say.  click here  I recommend the reading because they point out the problem if under torqued and over torqued.

I don't pull this stuff out of my butt.   I tend to research a bit.  That's how I found the torque value Yamaha had for the drain plug and how I found it was too high.  I really still wonder why nothing really has ever been said about it by Yamaha, even if just an email.

I already pointed out that cast aluminum is weaker than steel, only pointing out that the torque value of 31 ft-lb is really low for the thread pitch, problem is it is hard to find specs for torquing in various metals, like cast aluminum.  

From everything I've read about it, the axle nut issue is not a problem with torque, otherwise it would happen with replacement nuts.  I've not read where anyone has had similar problems with the threads after changing the kind of nut. Oddly enough my KLX250 rear axle nut torque is also 80 ft-lb and I've never heard of any of the KLX riders stripping out axles.  Plus, I've only read one thread where the recommendation is to drop the torque value and then only to 70 ft-lb made by some individual, not a company.  Nothing else other than the recommended value from Yamaha.  Here is a link to a quote in this forum from a reader who used Fuji nuts at work and had similar experiences with the nut locking on tight with the metal insert that bites into the thread.  click here  Check the thread out.

 

Edited October 7, 2021 by klx678

[blackout]

I would love to have a torque wrench with a shorter, more standard handle length.   That way you can feel the torque applied on the smaller fasteners. 

[Triple Jim]

You could just use a ratchet handle if you're going by feel.

[shinyribs]

7 hours ago, blackout said:

I would love to have a torque wrench with a shorter, more standard handle length.   That way you can feel the torque applied on the smaller fasteners. 

I think the long handles are part of the problem. It's easy to just keep on pulling on those things.

 

We could just move our hand up, but nobody is gonna do it

[Triple Jim]

46 minutes ago, shinyribs said:

We could just move our hand up, but nobody is gonna do it

I use the beam type... no moving hand up allowed.  

I don't understand the problem with a long torque wrench.  Depending on which type you're using, the idea is to either be watching the pointer and immediately stop when you reach the desired torque, or stop when it clicks.  Either way, length just makes it easy to get to the torque you need, and doesn't hurt anything unless you're not paying attention.

[shinyribs]

I only trust the beam type. I refuse to own wrenches that require batteries, and spring operated clickers just don't hold up. Wore out a couple clickers ( without trying hard) and went back to the beam wrench my grandpa gave me. There's just nothing to fail or go out of calibration. 

You're right about the length. What I meant, but I didn't make clear, was the idea of a person unfamiliar with tightening things could get carried away with the extra leverage.  And using a torque wrench with a "normal" length handle would help folks develop a feel for a particular tightness while using the toque wrench as their guide. Which is what Blackout was saying. 

[Triple Jim]

I admit I've had to use a mirror once or twice, positioned to let me see the pointer when I'm in some strange position under a car and can't see it directly.

My 3/8" drive beam torque wrench is in the category of "normal ratchet length" and it goes up to 50 lb-ft.  Normal for a 1/2" drive ratchet handle, that is.  If you put a 1/2" adapter on that wrench it would probably be what you guys are talking about.

Edited October 9, 2021 by Triple Jim

[klx678]

My old 3/8 drive inch-lb beam wrench is only about a foot long, so not too bad.

As for overtightening due to the length of the beam wrench, the user would have to be oblivious to the purpose of the tool.  The only real concern many might have would be if tightening with a click style wrench turning too fast, when the tool clicks turning too fast could overtighten the fastener.  The slow and easy approach is the thing to do, even if doing your work with your "torque wrench arm".

 

[foochi]

What are you all torquing your rear axle nut to? I've been torquing mine to spec (76 ft/lb) and everything has been fine every time I readjusted my chain slack. Yesterday, I tried to loosen the nut to adjust chain tension and it wouldn't budge either tight or loose, I got it off but it definitely stripped.

[klx678]

Hopefully the nut is stripped, not the axle.  It is that Fuji style lock nut.   Throw it away and get a nylock nut from some place like Fastenal if you can do so.  They aren't very expensive and will work fine.   Another avenue is to cross drill the axle to work with a castle nut.  

There are some trick nuts to work as well, like the one from I believe Gilles.   They may stock them at Bellissimoto.com

[foochi]

2 hours ago, klx678 said:

Hopefully the nut is stripped, not the axle.  It is that Fuji style lock nut.   Throw it away and get a nylock nut from some place like Fastenal if you can do so.  They aren't very expensive and will work fine.   Another avenue is to cross drill the axle to work with a castle nut.  

There are some trick nuts to work as well, like the one from I believe Gilles.   They may stock them at Bellissimoto.com

Sadly,  both were stripped.

Edited October 11, 2021 by foochi

[klx678]

Bummer, just don't order another nut.  They are crap.  Get the axle and do the nylock nut or a castle nut and drill the axle.