Top steering head nut

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ballisticexchris

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Yes RC, I always buy the service manual at the time I purchase the bike. I'm pretty sure you orientate the wrench just like any "claw foot" style. I alway set those tools at 90 degrees from the torque wrench to get proper torque.
 

steve68steve

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I'm with Chris on this one....if you're going to be doing maintenance jobs like the steering head, a service manual is just as valuable of a tool as anything else in your tool box. ...

That socket shown in gv550's post would be a lot easier to use than the Yamaha tool I have. It reminds me of the bottom bracket tool on one of my bicycles.
Haven't given it much thought, but it seems like if the torque specified for use with the spanner-style tool is X, one might need to calculate a different equivalent torque Y for a socket style tool. I don't have the brainpower right now to follow this thru, but it rally violates my intuition. Hopefully someone will know.

The spanner hole is spaced some distance away from the axis of the fastener, and torque is applied at 90deg to the spanner itself. To my mind, that means the actual torque received by the fastener is not the same as the indicated torque being applied by the torque tool. 50% of the torque is vectored away from rotation, and it's centered around a lever arm which is a distance away from the fastener.
If you push against the end of a 10" long wrench with 10 lbs of force, you're applying 100in-lbs of torque. If you move your point of force to the midpoint of the wrench (5"), applying 10 lbs halves the torque to 50 in-lbs. To get the same 100 in-lbs at the midpoint, you'd need to double the force to 20 lbs to account for the shorter lever.

To my small brain, the spanner-type tool is exactly this situation. The torque specs in the service manual apply to using the Yamaha tool.
 

Nikolajsen

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Yes and no.
I are correct in your calculation in your middle section.

But your last section...if Yamaha specifies a torque, then you need to use a spanner that shows the torque (or "click over" when reached), when you use such a spanner, it does not matter is the spanner is 5" or 10". The spanner is calibratet to its own lenght.
 
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ballisticexchris

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And the reality is You really don't have to use a torque wrench on that top nut. It's not a critical part that requires precise torque such as a camshaft.
 

RCinNC

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If you mean that big cap nut that sits on the very top of the stack, Chris, that's set for (I believe) 94 ft/lbs, I don't know how critical I'd say it is, but when I see an engineer set a high torque value like that for a part, I really do have to wonder why. At 94 ft/lbs, I'd say it must be doing something fairly important. That's an awful lot of stretching and clamping force; about the same as on the rear axle nut. There must be an engineering reason that it's set so high.
 
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RCinNC

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Haven't given it much thought, but it seems like if the torque specified for use with the spanner-style tool is X, one might need to calculate a different equivalent torque Y for a socket style tool. I don't have the brainpower right now to follow this thru, but it rally violates my intuition. Hopefully someone will know.

The spanner hole is spaced some distance away from the axis of the fastener, and torque is applied at 90deg to the spanner itself. To my mind, that means the actual torque received by the fastener is not the same as the indicated torque being applied by the torque tool. 50% of the torque is vectored away from rotation, and it's centered around a lever arm which is a distance away from the fastener.
If you push against the end of a 10" long wrench with 10 lbs of force, you're applying 100in-lbs of torque. If you move your point of force to the midpoint of the wrench (5"), applying 10 lbs halves the torque to 50 in-lbs. To get the same 100 in-lbs at the midpoint, you'd need to double the force to 20 lbs to account for the shorter lever.

To my small brain, the spanner-type tool is exactly this situation. The torque specs in the service manual apply to using the Yamaha tool.
I actually had these same questions myself in a thread back in 2017. The thread has some links to handy on line torque calculators.
https://www.yamahasupertenere.com/index.php?threads/steering-head-disassembly-question.21829/#post-310667
 

steve68steve

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I actually had these same questions myself in a thread back in 2017. The thread has some links to handy on line torque calculators.
https://www.yamahasupertenere.com/index.php?threads/steering-head-disassembly-question.21829/#post-310667
BOOM!

That's it. The equation is a few posts up in that other thread.

Since the torque spec is specified in the service manual using the Yamaha spanner wrench, that is "the" spec. I bought an Ebay laser-cut wrench so I wouldn't have to think.

Those using a socket might want to spend a few minutes of noodle time on it. The torque directly applied over the axis of the fastener is probably significantly less than the value applied via the offset "built in" to the Yamaha wrench.
 
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ballisticexchris

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If you mean that big cap nut that sits on the very top of the stack, Chris, that's set for (I believe) 94 ft/lbs, I don't know how critical I'd say it is, but when I see an engineer set a high torque value like that for a part, I really do have to wonder why. At 94 ft/lbs, I'd say it must be doing something fairly important. That's an awful lot of stretching and clamping force; about the same as on the rear axle nut. There must be an engineering reason that it's set so high.
Errrm.... I rather think it is a “critical part that requires precise torque”!
You guys do have a point. That's a lot of torque!!
 

RCinNC

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BOOM!

That's it. The equation is a few posts up in that other thread.

Since the torque spec is specified in the service manual using the Yamaha spanner wrench, that is "the" spec. I bought an Ebay laser-cut wrench so I wouldn't have to think.

Those using a socket might want to spend a few minutes of noodle time on it. The torque directly applied over the axis of the fastener is probably significantly less than the value applied via the offset "built in" to the Yamaha wrench.
I bought that same eBay wrench. I shudder to rehash that old thread, but i agree with you that I think the torque values would change based on which tool you use.
 

Mzee

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I bought that same eBay wrench. I shudder to rehash that old thread, but i agree with you that I think the torque values would change based on which tool you use.
If this reasoning is true then it means that different torque wrenches would obviously yield different torque measurements, but this defies common sense. Is it not true that whatever wrench one uses should have submitted itself to some common standard? Otherwise every manufacturer will have his instrument not compatible with the others in the industry? I am so confused.

Those of you in the know, why don't you also help by showing what needs to be torqued using a diagram that shows the different pieces in the steering mechanism.
 
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RCinNC

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If this reasoning is true then it means that different torque wrenches would obviously yield different torque measurements, but this defies common sense. Is it not true that whatever wrench one uses should have submitted itself to some common standard? Otherwise every manufacturer will have his instrument not compatible with the others in the industry? I am so confused.

Those of you in the know, why don't you also help by showing what needs to be torqued using a diagram that shows the different pieces in the steering mechanism.
No, I don't think it does mean that.

All torque wrenches are calibrated to provide a specific torque at a specific setting. The force is calculated based on the distance from the head of the wrench, where the force is applied to the fastener, to the handle of the wrench where the force is applied to the wrench. An 18" torque wrench calibrated to apply 25 ft/lbs is going to apply the same force as a 26" wrench calibrated to apply 25 ft/lbs. Look at it this way; a Yugo and a Ferrari are two totally different cars with totally different dimensions, but if both of them have calibrated speedometers, 25 mph is the same in both of them.

The difference between the in line torque wrench and the special Yamaha tool used to tighten the steering head in this case is the the torque settings for the special tool are calculated where the force is offset from 90 degrees from the head if the torque wrench, and also that the point of application of the torque was moved away from the head of the wrench to a point somewhere on the special tool. Any time you add a type of extension to a torque wrench that moves the application of force away from the center of the head of the wrench, it changes the torque value. Even if you could use the special tool in line with the wrench rather than at a 90 degree angle, the length of the extension has moved the point where the force is applied from the center of the head of the wrench to a some point located on the extension itself. You've effectively lengthened the torque wrench and increased the leverage without recalibrating the wrench for the additional length. That's why there are torque conversion calculators on line that you can input values for torque wrench extensions to get new torque values.
 
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steve68steve

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If this reasoning is true then it means that different torque wrenches would obviously yield different torque measurements, but this defies common sense. Is it not true that whatever wrench one uses should have submitted itself to some common standard? Otherwise every manufacturer will have his instrument not compatible with the others in the industry? I am so confused.

Those of you in the know, why don't you also help by showing what needs to be torqued using a diagram that shows the different pieces in the steering mechanism.
Torque is literally a force applied tangentially a distance away from the center of rotation.

Imagine a rusted lug nut on a car wheel. You put a lug wrench on it and push down on the end of the lug wrench. If the lug wrench is 1' long, and you push on it with 100lb of force, you're applying 100 lb x 1 ft, or 100 ft-lb of torque to the fastener.

It's still stuck. In desperation, you put a pipe on the end of lug wrench, which makes the lug wrench effectively 2' long - doubled in length. If you now apply the same 100 lb force to end of the now 2' long wrench, you get 100 lb x 2 ft or 200 ft-lb of torque on the fastener. The added wrench length increases the mechanical advantage (leverage) of the twisting force you're applying to the lug nut.

The design and calibration of torque wrenches accounts for their length. If one torque wrench is twice the length of another, it will only require half the force to actuate.

Our bike's service manual specifies a torque to apply to an offset spanner - a special short wrench - NOT directly to the fastener itself.
To abuse the lug wrench analogy more, cut your lug wrench into two pcs, then weld the two pcs back together at a 90 degree angle to form an L shape... with a weld that will fail at 100 ft-lb.
When you push on the end of the lug wrench, what happens? Well, the weld breaks when it reaches 100 ft-lb... but just before that happens, how much torque is the lug nut getting?

Answer: I don't know - but there's an equation to figure it out in the thread linked a few posts up. It's not necessarily 100 ft-lb, tho, because your pushing force is no longer tangent to the fastener, it's tangent to end of the offset spanner.
 

Gigitt

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If you use a torque wrench with an extension/adapter then actual torque values change when you ONLY change the pivot length.
So if you put the extension/adapter at 90deg you do not change the length of the pivot so the torque values are not changed.

When I was using the eBay copy of the claw adapter, the 3/8 square was rounding out when i was applying force on the torque wrench. This means that the pivot length is changing as the adapter is now not 90 deg but say 80deg.... The Adapter is Stainless Steel but it is soft!

Have a play with this torque calculator - dont forget to change the extension length E if you change angles
http://www.cncexpo.com/TorqueAdapter.aspx
 

Mzee

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Thank you very much. Each of your contributions has illuminated my mind. I am happy to learn from you. I will report back what I have done. waiting for the nut from Ebay.
 

Mzee

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Report back.

The steering nut came by post, the new steering bearings also came by post. Somewhere on the forum someone had posted pictures of how he serviced the steering column. Never done it before, but the instruction and the picture as well as the service manual made it easy.

I found that both the two nuts EricV describes in his thread above were completely loose. I took them off without using any instrument. I was surprised because I had the steering head serviced about 10 month ago by a Yamaha dealer.

52NM torqued the lower nut, then loosed it and torqued it again to 18NM. Put back everything else then torque the outer top nut 130NM (these are the ones I used, but the something tells me the ones I have discussed below would be the ideal one?).

What confused me is that the goose nut socket is obviously different from the Yamaha OEM spanner. So no adaptation is required since it directly sits on nut. Don't the above calculations change to lower values? I have roughly calculated them as follows: see picture, or do I maintain the ones specified in the service manual? Won't someone help clarify this for me.

Thank you.
 

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