Steering head socket vs spanner for setting torque

[Gitbox]

I've seen the specs on the Yamaha spanner tool for setting the steering nut torque, but if I have the socket that looks like a castle nut, what are the torque specs for that?

Thanks.

 

[mikerider]

Same.

 

[Gitbox]

Even though it's extended away from the center for the spanner?

 

[Ignacio]

Even though it's extended away from the center for the spanner?

I didn't do that well in Physics, but do know Yamaha doesn't publish specs for different torquing devices, distances, angles, etc......just the one spec for each fastener. Truth is I don't know if the spec they published assumes the Yamaha spanner thing or just a pure number assuming center point of the fastener. If I understand correctly, you want to adjust for the difference iget into adjusting torque then start Googling and finding discussion and calculators like this that you could finnagle the offset and see it's probably not much to worry about.

 

[lnewlf]

easy...I use this..tighten until the bars don't flop///

https://www.mscdirect.com/browse/tnpla/84965052?cid=ppc-google-New+-+Hand+Tools+-+PLA_s2q4Qu0st___164110844130_c_S&mkwid=s

 

[Mr_Canoehead]

IIRC, the torque spec is 37ft*lbs at the Yamaha tool. Assuming that your torque wrench is 2' long, you would be applying a force of 18.5lbs. That 18.5lbs at the handle of the torque wrench (assuming the Yamaha tool is 3" from the center of the nut to the centre of the drive hole) would give an effective torque of 18.5 * ((24+3)/12) or 42ft*lbs at the center of the nut. YMMV depending on your torque wrench and the actual length of the Yamaha tool.

 

[RossKean]

NO!

The torque wrench is placed at 90° to the Yamaha tool so it is effectively the same as being right on the center of the nut. There is no added mechanical "advantage" due to the length of the Yamaha tool.

Someone posted a good reference to that somewhere here...

Edit:https://www.cncexpo.com/TorqueAdapter.aspx

Edit: Link is dead, but there are others out there...

 

[Brodie]

^^^^^^^^^^ BINGO !!!

If you study the service manual it specifies exactly this 90 degree relationship between the torque wrench and the hook spanner attachment.

By the way, if you have a left over rear shock preload adjuster from an old Honda tool kit from the late 60s you have the makings for an excellent Yamaha steering nut tool. All you need to do is drill a 3/8 hole near the end of the handle, then file the 4 corners into it for the 3/8 socket drive. I did mine decades ago for my 90 Venture Royale.

Brodie

 

[Ingie]

The tool you're all referring to is called a crow foot and you should be able to buy it at any NAPA, Lordco, or snap on vendor.

 

[Gitbox]

Thanks for the replies guys.

Ross nailed it - no change in torque when the spanner is at 90* to the fastener. Effective length of lever arm is unchanged.

That link is exactly what I needed.

 

[RossKean]

The first time I encountered the Yamaha spanner tool, my thoughts were the same! Someone pointed out the service manual procedure and with a little research, I managed to get my head around the physics of the situation. The little calculator I posted helps - try some number sets with varying angles...

 

[SLK50]

Just a reminder: The torque values stated in the FSM are for

the OEM bearing and do not apply if you have swapped them

for tapered rollers.

 

[Mr_Canoehead]

NO!The torque wrench is placed at 90° to the Yamaha tool so it is effectively the same as being right on the center of the nut. There is no added mechanical "advantage" due to the length of the Yamaha tool.

Someone posted a good reference to that somewhere here...

Edit:https://www.cncexpo.com/TorqueAdapter.aspx

You are correct. The manual shows torquing at 90* - I missed that. That would mean no increase in torque applied since the moment arm is unchanged.

 

[Mr. BR]

Valid point, SLK50... (balls vs tapered)

I installed tapered bearings on my '05 last year and honestly, I didn't follow the FSM at all since I didn't have a crow foot/hooked/spanner tool (at least not one that fit).

So I just ensured the bearing races were fully seated in the steering head and then snugged it all up.... the "test" being how easy the bars flopped from side to side. Too tight and there was obvious resistance in the side to side movement of the bars (sans fork tubes still) so I just found a nice middle ground. After a few weeks of riding, I checked them again and tightened up the bearings just a little. Not exactly scientific but it works (at 60K miles, my OEM ball headset didn't look bad at all but I got a deal on the tapered set so I installed them).

Regards,

Mr. BR

 

[saread]

NO!The torque wrench is placed at 90° to the Yamaha tool so it is effectively the same as being right on the center of the nut. There is no added mechanical "advantage" due to the length of the Yamaha tool.

Someone posted a good reference to that somewhere here...

Edit:https://www.cncexpo.com/TorqueAdapter.aspx

Nope. That's not right. What that link shows is the adjustment in torque setting based on wrench angle on an offset tool, like the Yamaha spanner. It shows that if you place your wrench at 90 degrees to the tool (as noted in the Yamaha service manual) there is no increase in torque applied over that supplied by the offset built into the tool. If you use a socket, you will have to adjust the torque setting on the wrench to account for the leverage that the offset in the Yamaha tool provides.

Torque is defined as force times length of lever arm. The offset in the Yamaha spanner provides a lever arm as long as it is used to apply force. Placing the torque wrench at 90 degrees to the tool merely applies the force roughly along a tangent to the circle described by the attachment point on the spanner in relation to the center of the steering head. In short form, it doesn't add to the lever arm already built into the tool. As you move that attachment point towards the center of the steering head, you have to increase the applied force to get a the same torque to account for the shortened lever arm. That's just math.

The above is crap. I did what my engineering professors always told me to do and sat down and drew the free body diagram (which I know I should have done first). The quoted information is exactly correct. If you place the torque wrench at 90 deg to the spanner, it is the same as if you'd be using a socket. The moments have to balance and if you apply a torque at the connection to the spanner without adding a moment arm (like placing the wrench at 90 deg) it has to be balanced by the identical torque at the nut or the whole world will spin out of control. Not like I ever have control of my world anyway.....

 

[C&C]

The only number that I have seen on this thread is 37 ft-lbs; this is the initial tightening torque, after that you need to loosen and re-torque to the final torque value of 13 ft-lbs. Forgive me if I missed this important number (somewhere earlier in this discussion).

 

[RossKean]

I beg to differ... (Post #15)

Using the calculator, consider the calculator with the angle "A" at 90° as per the Yamaha manual. You can make the length "E" any length without affecting the required force/torque. There is a difference as a function of the length "E" if the angle is greater or less than 90°.

 

[SLK50]

Ross is correct.

If the length of torque wrench, measured from center of stem,

parallel to wrench, doesnt change, then torque values are

the same with crows foot or socket.

 

[Brodie]

Look at it another way...

With the attachment in line with the torque wrench extending beyond it, the attachments length is added to the leverage ratio. With it in line but under the torque wrenchs beam, its length is subtracted from the leverage ratio. There has to be a crossover point where it is neither added nor subtracted, and that is exactly at 90 degrees from the beam.

This logic is kind of like the stopped clock (analog) is more accurate than one which gains or looses a couple of seconds a day.

Brodie