Author Topic: Help! Why does my nut keep coming off?!  (Read 1822 times)

Offline Sam C

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Help! Why does my nut keep coming off?!
« on: 10.05. 2016 11:33 »
All

New to this, so please bear with me. This bike is 20 years older than I am!

I also just tried to post all this a minute ago, and lost it somehow, so apologies if this is appearing twice! Anyway:

I have a 1959 A10 Golden Flash. I have had a recurring problem of the 'sleeve nut' coming loose (the big nut that you tighten with a C Spanner / punch and a hammer - and which holds the cush drive / 'shock absorber' on).

My question is: How do you stop this from happening?! It seems rather odd that there is no tab washer in there, and that the nut seems to tighten a good 1/4" beyond the split pin hole (mine is completely loose, can be tightend by hand, and it's still a good few mill beyond the split pin which is sat in there safe and sound). Shouldn't the split pin hold the nut in the tightened position? And if that's not what it's for, then shouldn't something else do that e.g. a tab washer or something?

So the question is: What does everyone else do to hold this nut on properly, and stop it from working its way loose?

Taking the primary chain case off, and tightening everything up, is a pretty involved job. So I don't want to have to keep doing it (this time it lasted 100 miles since the last time! And the last time it was tightened up by an 'old bike' mechanic, so I think it was done properly!)

Quite confused by it all to be honest. Do people use Loctite or something?

Cheers

 

Offline Greybeard

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Re: Help! Why does my nut keep coming off?!
« Reply #1 on: 10.05. 2016 11:45 »
If your nut keeps coming off you need to tighten your helmet strap!! *smile*

From: http://www.bsawiki.com/chaps/9-engine/16-chapter08
'Place the cush-drive sleeve over the engine shaft, followed by the cush-drive spring over the sleeve, and screw the mainshaft nut on to the engine shaft with a C Spanner, tightening the mainshaft nut up as securely as possible. Put a split cotter pin through the hole in the engine mainshaft, and spread open the split ends.'

I believe the split pin is just a back-stop in the case of the nut working loose and gouging into the primary case. It is very important that the big nut is very tight as it makes sure the crankshaft doesn't float. Mine has never worked loose. Threadlock might be a safeguard. Any other comments chaps?

Offline kiwipom

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Re: Help! Why does my nut keep coming off?!
« Reply #2 on: 10.05. 2016 12:03 »
hi guys, is it the nut that holds the handlebars???  ha, cheers
A10.G.Flash(cafe racer)Honda 250 vtr. Yamaha Virago XV920.

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Offline a101960

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Re: Help! Why does my nut keep coming off?!
« Reply #3 on: 10.05. 2016 12:12 »
Converting to an SRM nut makes life a lot easier. You can use a socket to get a better purchase when tightening. In the BSA GOLD STAR book a chapter entitled "Gilding the Lily" from an article taken from The Motorcycle published in Nov/Dec 1963 Eddie Dow advocates using a soft drift and hammer.
John

Offline Sam C

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Re: Help! Why does my nut keep coming off?!
« Reply #4 on: 10.05. 2016 12:46 »
Thanks for the help so far gents, keep 'em coming!

The SRM nut is currently out of stock, but I'll buy one once it's available again. I don't suppose there's any sort of tool (apart from a C Spanner) out there that makes it easier to tighten the nut is there? I really dislike the idea of using a punch, the thing looks pretty deformed from years of that as it is!

A related question: when re-fitting the primary chain case, do you soak the gasket in oil first? No idea what I think that's the right thing to do, but I'm sure I've seen it somewhere. Apologies if I imagined it?!

Cheers

Offline RichardL

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Re: Help! Why does my nut keep coming off?!
« Reply #5 on: 10.05. 2016 13:13 »

Absent an SRM nut, the link below is a description of a home-made tool from one member. The suggested torque is 65 ft-lb, which might be hard to get and harder to measure using a conventional C-Spanner.

http://www.a7a10.net/forum/index.php?topic=8752.msg62594#msg62594
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Offline a10gf

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Re: Help! Why does my nut keep coming off?!
« Reply #6 on: 10.05. 2016 13:36 »
About tightening, many possibilities, avoid the hammer! See http://www.a7a10.net/forum/index.php?topic=5800.msg39713#msg39713, & different home-made tools pictures somewhere in posts on the forum.

About the nut coming loose, drill a hole (or two at 90 deg.), thread them, and fit unbrako set screws, like the SRM I've got here, see pic. Scared of the screw itself coming lose, apply half a drop (or less) of blue loctite.

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Offline Greybeard

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Re: Help! Why does my nut keep coming off?!
« Reply #7 on: 10.05. 2016 13:40 »
I don't suppose there's any sort of tool (apart from a C Spanner) out there that makes it easier to tighten the nut is there?
Confession is good for you: I'll come clean and admit that I use a pipe wrench, (Stilson) to tighten mine.

Offline Sam C

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Re: Help! Why does my nut keep coming off?!
« Reply #8 on: 10.05. 2016 13:54 »
Well one thing I'm learning about these old bikes is that perhaps back then it was not expected that the average owner would have the full range of technology / tools that are expected today i.e. 'whatever is knocking about, plus a big hammer, ought to do it'!

I've ordered a tab washer from a local supplier, which I think should have been fitted all along (Vintagebike in Wiltshire: very helpful chap!). I'm also leaning towards threadlock. However, I will also get us much torque as I can onto that nut without breaking anything, one way or another!

I can dremel out / angle grind out an old socket - which I think is my best bet, since I can't weld. But I'll tentatively try the punch and hammer route first. I can't make it much worse than it already is!

In terms of gripping everything, assuming I get a socket onto it: What's the consensus there? Is the general view that 'sticking it in top gear and standing on the rear brake is fine' or should I be more careful / is there a tool for fixing things. For example a few people have mentioned a tool for removing (I think) the clutch basket - maybe that's something that would help me?

Cheers


Offline RichardL

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Re: Help! Why does my nut keep coming off?!
« Reply #9 on: 10.05. 2016 13:57 »
E,

I took a look at the C-spanner in the link you posted. That thing has about a 4" moment arm. To get to 65 ft-lb using that you would need to apply about 195 lbs of force right at the end of the spanner.  Then, the spanner is flat, which would make it brutal using your hand, if you could even apply so much.

GB,

Before getting an SRM nut, I too used a pipe wrench. At least, with a pipe wrench, you can get some leverage. If you wanted, you could even calibrate to get to an accurate 65 ft-lb. I pull with a fish scale when I want to simulate a torque wrench.

Richard L.
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Online metalflake11

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Re: Help! Why does my nut keep coming off?!
« Reply #10 on: 10.05. 2016 14:00 »
Quote from: Greybeard
[/quote
Confession is good for you: I'll come clean and admit that I use a pipe wrench, (Stilson) to tighten mine.

Me too.
England N.W
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England

Offline RichardL

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Re: Help! Why does my nut keep coming off?!
« Reply #11 on: 10.05. 2016 14:07 »
In gear and foot on the brake is one method to lock up (or nearly so) but it gets pretty awkward when trying to apply real force with a less-than-perfect spanner for the nut. You can buy or make your own locking disk for the clutch. Not knowing about the disk at the time, I used this approach:

http://www.a7a10.net/forum/index.php?topic=368.msg58817#msg58817

Richard L.
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Offline a10gf

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Re: Help! Why does my nut keep coming off?!
« Reply #12 on: 10.05. 2016 14:14 »
E, I took a look at the C-spanner in the link you posted. That thing has about a 4" moment arm. To get to 65 ft-lb

Just an example of a non-destructive tool, picture for the plunger cush, needs some force but far from 65 ftlb needed to get the nut in enough to fit the split pin lock (so no self-screw-off problem on the plunger).


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Offline bikerjohndavies

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Re: Help! Why does my nut keep coming off?!
« Reply #13 on: 10.05. 2016 17:05 »
There is a chap on EBay who has a socket that fits over the cush drive nut and then allows you to use a 7/16" whit socket on it. May help you.

www.ebay.co.uk/itm/321951841308
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Offline Greybeard

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Re: Help! Why does my nut keep coming off?!
« Reply #14 on: 10.05. 2016 17:25 »
Seems a good idea so I've ordered one. Thanks for the heads up.