LM3 Steering stem head nut torque value

[MikeLemon]

First time poster here in Sussex, UK.  I've been working on my LM3 over the past 12 months, and by and large it's been going well. 

I've come up against a problem in that I can't work out from google, this forum's archives, and the web in general as to what torque to apply to the chamfered head nut on top of the triple clamp.

I know how to set the bush nut that sits on top of the bearings to give the correct load on the bearings, and I'v got the settings for the clamp bolts that hold the bush, but all I can find that might relate to the top nut is from page 33 of the workshop manual that says "Bush, steering lock - 122-130 ft/lbs".   As this nut is basically a lock nut, and the bush itself is only torqued to less than 20 ft/lbs, I can't see that 130 ft/lb on the chamfered retaining nut will do anything more than strip the thread.  (don't ask me how I know :( ).

Can anyone shed any light on this for me?

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[MikeLemon]

Here's a picture of the nut in situ.

If anyone can give me a definitive torque value for this I'd be very grateful.  Thanks.

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[guzzista]

Hi Mike. Sounds like your common sense approach works. I have tightened a few of the top chamfered nuts on Tonti Guzzis and asides from just normally tightening them with a (believe  32m ?) socket on a 1/2 inch ratchet wrench I have not torqued or over tightened and stripped anything. A little blue loctite wouldnt hurt if you  are worrying about it coming loose. Once the bearings have  been preloaded a bit ( Have a mate check for fork movement to and fro  as well as ease of turning left/ right with the front end off the ground and someone sitting on and weighing the bike down) . With that done you should be good to go

[Chuck in Indiana]

Hi, Mike.. welcome to WG. You will get more answers on the main board. That said, if I read this correctly, it's the jam nut you are talking about? Just snug it up. That's what jam nuts do. If you haven't figured it out yourself, take Guzzi torque specs with a large grain of salt. 

[Groover]

I also used the specs shown on page 33, (17-18 kgm or 122-130 ft/lbs). I stopped at about 110 ft/lbs on that top lock nut because I also thought that was way too much. I tightened all the top triple hex bolts first to specs, then did that one last.

I'd also say go less and it will be fine. I've had to do mine (for adjustments) at least twice at the 110 ft/lbs and there is no damage to the threads. If anything, use that as information if you've wondered if those threads can take it.

Anything you do, take care of those factory triples. Some are impossible to find, and I think that is one of them.

[MikeLemon]

I've snugged it up tight with a splash of loctite. Can't see it coming undone. Thanks Chaps!

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[Chuck in Indiana]

I've snugged it up tight with a splash of loctite. Can't see it coming undone. Thanks Chaps!

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Attaboy..

[rodekyll]

Hi, Mike.. welcome to WG. You will get more answers on the main board. That said, if I read this correctly, it's the jam nut you are talking about? Just snug it up. That's what jam nuts do. If you haven't figured it out yourself, take Guzzi torque specs with a large grain of salt. 

This.

Also, you speak of torqueing what you call the "bush nut", which sets the preload on the head bearings.  The bearings are taper rollers -- different than the ball bearings used in some other bikes.  They need slop, so the nut is not "torqued" to a spec.  What you want to do is raise the front end off the ground and tighten the bush nut gently till the forks bind tight.  Then loosen the nut until the front end just flops freely from stop-to-stop -- the point that any tighter and you feel a bind somewhere in the fork arc, or you have to push the handlebar to initiate a flop is just right.  If you start from too tight, the proper point of looseness can be easily found by doing the flop test. 

When properly set up and the front wheel bearing normal weight (all the way on the ground), you should be able to slip the big washer between the top bearing and the bush nut with a screwdriver, but you should not be able to perceptibly wiggle it up or down.  Years ago I learned from a guzzi guru that to be really anal about it, you want to work a 0.004" - 0.006" feeler gauge between the nut and the washer, but for his purposes the flop test and the washer wiggle were close enough.