Good Vibrations!

Rode out to the SA Owners Club meeting/bbq last night and had some serious shaking at 1500rpm. Upon arrival a fellow member noticed the rear guard moving around a bit and that was definitely loose but it ends up not the cause, more a victim I'd say. A quick parking lot repair with good natured ribbing from members fixed that though.
On the way home the vibes were still there, and then along a good twisty bit I found the handling to be terrible, twisting all over the place. My mate, who was riding with me, mentioned it could be the headsteady and I figured that was right on the money. Checked it tonight and 2 bolts are missing from the head! The left bolt was still there but not that tight. The centre bolt also fixes my earth so I'm surprised I didn't get any electrical symptoms as well. At least now I know what if feels like without a headsteady. I've checked out the threads in the head and they're good! Talk about lucky, eh. Will pick up some new bolts and washers tomorrow, the rubbers look good thankfully, and fit it all back together using PV's method
http://www.accessnorton.com/post119643.html?hilit=headsteady#p119616

Hello Loctite.

Loctite lets go with heat remember, is it possible to drill and lockwire them...like racing bikes do :roll:

Hmmm, very good point. Can't lockwire the bolts together as the steady is in the way, perhaps to the steady itself.

Anyone else have ideas on this one?

As I remember, there's a lock washer that works, belleville or wedgelock, it's sort of spring loaded.
http://www.mcmaster.com/#standard-washers/=f907lx
Dave
69S

Anyone know the exact length of these bolts? My local shop hasn't got the genuine items in stock so I thought I pick some up at the fastener place. I've got one left but given that the washers are incorrect I don't want to take a chance on the bolt being the correct length as well.

my Combat head steady bolts are 3.6" long. Still not installed so know not to whiz around too hard or cross paint lines at any angle or its wobble city to recover.

dan,

The allen head bolts in the head are a hard to get thread, BSF I think, they are the same length as the allen head bolts in the inlet manifold, but different thread form, just for fun eh! I have never had mine come loose, YET I bodge it with a sturdy flat washer against the head steady followed by a spring washer under the bolt head, it works okay. But if you are at a good fastener place, ask about Nord Lok washers, these are a neat looking set up that locks the bolt and doubles up for a flat washer. You may need to try a classic bike shop or a specialty fastener shop to get BSF threads.

Cheers Richard in Sydney

john robert bould said:

Loctite lets go with heat remember,

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Loctite 272 is save up to 200°C. If the threads on the head steady bolts see that kind of temperature you don't care about loose bolts as you're bike is burning then.

is it possible to drill and lockwire them...

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Lockwire is a precaution against losing fasteners - not against loosening.

like racing bikes do :roll:

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Racing bikes tend to be checked over regulary in short intervals. If you leave a lockwired fastener unattended for too long you don't need to replace the fastener but to helicoil the thread.


Tim

Neither lockwiring or loctite should be required on these, I only use flat washers and just tighten the bolts up properly. Never come loose. In fact I grease them lightly to prevent the steel bolt seizing in the alloy thread.

Hi Ludwig, nice to learn, all copy............

Never really had a problem with these coming loose. Probably someone forgot to tighten them.

It is normal for the rear fender and tail light to do the Norton dance while idling. That is why so many rear number plate brackets fracture and also it happens around the license plate bolts if you only use 2 bolts.

ludwig said:

Spring washers should never be used on something that moves or vibrates :

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I had a training by Loctite techs (NOT sales reps) a few years ago and they showed a Junkers test video of several different bolt securing methods - unsurprisingly the Loctite won but there was still a point in this video. They claim that the mechanism behind the Loctite is NOT primarily the chemical bonding but mainly the fact that the gaps in the thread are filled and thus the fastener can oscillate far less under vibration. The only thing apart from Loctite or similar stuff I like are Nord-lock washers, they work quite well.

However I agree that properly torqued down bolts at that application shouldn't need anything but a bit of anti-seize and the correct torque.


Tim

Hi

My 850 is in a Featherbed frame with out isolastics and I have never had any problems with them allen bolts come loose, but I do use spring washers, in the 31 years its been in the Featherbed frame never had one yet that was loose, but if I pull the head stay off for any reason I will put new spring washers on.

Ashley

Thanks for the replies everyone.
I managed to get some genuine bolts that'll do for now but I'm not too keen on the quality of them. I'll stop by the fastener shop tomorrow and see if they can find the right thread and length combo. I'll also ask about Nordlock, but if not just get some good washers and torque 'em all down correctly.
I was a bit worried this thread would open up into a 15 page heated debate on what headsteady is best.

Alright, had some delays but it's all back together now. Headsteady is in after getting correct bolts, some Nord Locks and large flat washers. I inspected the steady, plates and rubbers and all seem good with no visible cracks or holes out of round. I would like to verify all the bolts and nuts are to be done up at 12ft-lbs. Going by the service manual and the Old Britts torque list, I'm fairly certain that's correct for the 3 head bolts but what about the 2 studs/nuts and the rubber mounts?

Having done all this, the vibration is certainly better but not gone, it would seem the headsteady coming loose was a sympton, not the sickness. It's no longer a shake but is now a high frequency vibration pretty much at exactly 1500rpm, no more, no less. I've adjusted the idle to 1500 so I could go over the bike but I still I can't seem to find a definate source. I can see why the rear guard came loose though, the vibe seems to exit out that way.

Anyone ever experience something similar?

Haven't checked the clearance on the front and rear Iso's yet though, will try and find some time to do that before the famn damily arrives for Chrissy on Wednesday. Fat chance.

I'd like to take my nephew for his first street ride when he gets here, so I might throw caution to wind and ride anyway, just try to avoid letting it stay around 1500 for any period of time. 'Course I won't be able to sit him on the tank like my uncle used to with me!

Happy Holidays to everyone, just in case I don't post again! May all your Norton wishes come true.