Locking nut

Restoring a motorcycle I've come across a type of locking nut I've not seen before. Usually they use ones that have a spring steel type insert in them and the others on the bike are that type but this one on the swingarm spindle is different with slits on the flats .

Are these classed as a one shot use or are you "allowed" to crush/close up the slitted area so it grips the thread again?, it just spins on and off loosely like a normal nut at the moment.

I would replace it with a nyloc but it's M14x1.25 and I can't find any, no one seems to do any below M14x1.5 fine.

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What bike is it Mike.?

Nick

Hi Mick, generally speaking just about any thread locking nut, including Nyloc's, are only designed to be used once and when they are removed should be discarded and new ones fitted.

M14 coarse available at **LINK**

Sorry I think you are after Fine http://www.spaldingfasteners.co.uk/metric-fine-a2-stainless-steel-nyloc-nylon-lock-full-nuts-m12-m14/

Regards Nick.

Edited By Nicholas Farr on 05/07/2015 23:47:09

Nick G it's a Suzuki GT750 "Kettle"

Nick F thanks they don't give the pitch I'd have to ask, there's plenty of M14x1.5 fine about but mine is M14x1.25 fine(r)

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Mick,

Aside from being Spark-Plug thread [which doesn't really help]; that's fairly common on German cars ... it might be worth checking your friendly local BMW dealer, if they have a Spares man who knows his stock.

MichaelG.

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Edited for typos

Edited By Michael Gilligan on 06/07/2015 00:26:56

Hi Mick, M14 x 1.25 is probably a none preferred size for lock nuts and you may have to go to a firm that will make them to order, e.g. **LINK**

Regards Nick.

**LINK**

ebay

As a last resort you could put a tube over the end and knock it to close the "petals." Unlike Nyloc they aren't deformed when fitted.
Failing that, if there is enough thread you could add a spring washer to it.

Why not use Locktite? It actually works better than most sorts of lock nuts. It even used to work on my Triumph single.

We used to call them a Waterbus. (The GT750)

I am guessing it is for the end of the swinging arm pivot bolt ?

When I restored a 1972 Honda XL250 recently, I managed to find a supplier of genuine new old stock parts that had an original one on the shelf. Have you tried this route yet.

It may be that other makes or models used the same size as well.

Phil

These nuts are called 'Marsden nuts' and I remember them being used to secure a fluid flywheel to the crankshaft in AEC buses, we used to reuse them after hitting the nut with a hammer squarely to close the petals a bit, all very crude but it worked. Regards Pat

Fairly common on Suzuki bikes as well, drain bolts, some head bolts etc but no others I know of with a locknut.

Thanks for the suggestions I'll probably use locking washers AND loctite to make sure. I had thought of expanding the slots to make it a proper castle nut then drilling the spindle to suit but 14mm isn't that big and I don't want to weaken it too much.

We used to use nuts like that , and others that had on the top side an oval hole(squeezed in a bit) for engine fittings on aircraft, Nyloc nut don't do heat too well. For non aircraft stuff it's OK to give it a bit of a whack with a hammer, you can do that with a Nyloc nut(once), although on a critical bolt on a motor bike I would use new, or Loctite.

Ian S C

I think they just date from the days before people thought everything but everything has to be plastic or contain plastic. Just took a few off the old Ransomes gang mower. Keeping them for when the oil and plastic runs out when they will be considered a fantastic new invention. (or I find some not usted through 5/16 UNF bolts)

The early stiff nuts had a fibre insert where the newer ones have nylon.

Ian S C

Hi Pat

I served my time in late 50s early 60s with the local bus company Grimsby Cleethorpes Transport and our AEC MK 111 Regents had castle nuts and split pins, I remember having to fit them with there heads with rotation otherwise they would come out.

Stan

Surely even if a nyloc nut has been used, it can be used again, provided that it goes back on stiffly. The same applies to the other types. If they are doctored and go on tight , then they are unlikely to loosen off. The proof of the pudding is in the eating.

All thread locking types have as set of parameters to which they have to meet in the case of nylon be it nyloc nut, nylon patch or insert two of these are prevailing torque and break away torque these fall each time they are tightened and untightened so in a nut shell aero industry would only use it once or industries would use it until the prevailing torque falls out of thier perameters.

H

Hi Thomas, compare an unused nyloc to one that has been used only once. You will see the unused one is plain and the used one has the form of the thread cut into it. So now the nylon has been distorted, not once, but twice, because it will distort a second time on removal and therefore will not meet the design parameters if it is used again, yes it will probably still grip the bolt, but not to spec. and you would not be able to claim it not being fit for purpose on subsequent use if it came loose. Not something I would want to happen on my car for instance. The same goes for any type of lock nut.

Regards Nick.

Lets look at how this nut was made in the first place .

Bar turned and threaded from hex with a semi domed end.

Mounted in miller , 3 cuts with slit saw at 120 deg to give six castleations.

At this stage there is no thread locking property, I would suggest that the next process is to crush the castleations slightly to give a certain amount of locking, by tightening the threads up.

Zinc plated and sent to the stores.

The nut has now been off several times since it was made in 197? ( I have an identical nut on my 1973 Honda XL too) so the castleations will have deflected back somewhat thereby reducing their pinch on the threads.

Would it not be possible to re crush the castleations by squeezing them up in a 3 jaw chuck , or indeed clobbering them with a hammer until the required amount of pinch is acheived.