Working out a locknut size?

[NJD]

Lexmoto arrow before we begin, before anyone asks and I forget.

Cutting a long story short so far I've spent one pond and seventy pence on two locknuts that aren't the right size based on the wrong advice and the interwebs are confusing me on the most simplest of matters. BCF's turn to educate me yet again.

So as per the pictures below I've damaged the seat locking nut (OEM) and want to replace it. The nut will tighten and loosen but it's easier just to replace since (and when the find the right size) they're cheap enough anyway. I'm struggling to work out what size I'd need. I've looked on the Lexmoto parts section but fail to find what I'm after.

All I can tell you is that it requires a 12mm spanner to undo.

Guy working in Homebase told me that a M10 = 10mm spanner, M12 = 12mm spanner as so on and so forth. Based on that advice I got confused what spanner size was required while shopping and purchased two m10 locknuts thinking that it would fit a 10mm spanner although it turns out they require something bigger than a 14mm spanner to get around the head so they're defiantly not the right size. And I'm lost.

Any ideas?

Also, and finally, is there a simple way to tell what way to undo nuts and bolts without having to find myself in a similar situation again with a more expensive part?

https://s16.postimg.org/gp74mqhlh/nut1.jpg

https://s21.postimg.org/p7adbu4nr/nut3.jpg

[sickpup]

It's probably M6.

As to head to thread size there are some notional standards but they vary by country of manufacture, best just to look and work out which comes with experience.

8mm head M5 thread
10mm head M6 thread
12mm head Japanese 13mm head British/Euro 8mm thread

But there is no hard and fast rule. Crankcase cover bolts for example are often M6 with an 8mm flanged head so experience is the thing.

[iooi]

[NJD]

[sickpup]

[Polarbear]

A lock nut will still turn the same way as any other nut. It's only on left hand threads anything is reversed.

What we were taught at engineering school (many many years ago) was (lifted from Wiki)

To apply the right-hand rule, place one's loosely clenched right hand above the object with the thumb pointing in the direction one wants the screw, nut, bolt, or cap ultimately to move, and the curl of the fingers, from the palm to the tips, will indicate in which way one needs to turn the screw, nut, bolt or cap to achieve the desired result. Almost all threaded objects obey this rule except for a few left-handed exceptions.
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Triumph Trophy Launch Edition

[tom_e]

[NJD]

[Monkeywrenche...]

just to clear, it doesn't matter where you're standing or where the bike faces, left and right are in relation to the fastener when viewed from its face looking straight at it...not where you stand or in relation to anything else..
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2001 Aprilia RSV Mille R -dead, 2016 XSR 700-gone, 2018 Dorsoduro 900

[grr666]

The guy working in Homebase should lose his job. I regularly find myself in DIY builders merchants often and the staff there
usually know absolutely nothing about what they sell except the price.

Try a trade counter next time, they tend to be manned by staff familiar with the things they stock and what they
are used for etc.I used to use a place called Cookes in Chadwell Heath for all my nut and bolt needs, I wonder if it's still there?
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Currently enjoying products from Ford, Mazda and Yamaha
Ste wrote: Avatars are fine, it's signatures that need turning off.

[chris-red]

[mauzo]

Get'chaself a socket set, you're much less likely to round off bolts like that. Even those 12-pointed rings most spanners have on the other end are better than the C-shaped end.

And yes, the M numbers are the diameter of the outside of the threads in mm; the size of the smallest hole the bolt will go through. (The spanner you need will obviously be bigger than that.) So you can find out what size nut you need by measuring the bolt it goes on to.

But if those nuts really are LH thread you won't be able to buy them anywhere normal. (I don't believe they are either. I think you're still confused somewhere.)
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'04 CG125, '07 CBF500

[NJD]

[MCN]

Use an adjustable.

Normally the diameter of the bolt shank and threaded part is 1/3 of head hex part AF (across opposite flat sides).

But some different bolts follow different rules.

Bolt manufacturers are arse and designers are arse and manufacturers are arse for not getting their collective shite together and sorting out this nonsense. (Main culprits are the muricans who don't do decimal. And they say they cannot afford to re-tool the USA and all who sail in her.)
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Disclaimer: The comments above may be predicted text and not necessarily the opinion of MCN.

[mauzo]

[MCN]

Those nuts and bolts will be standard thread direction. i.e. Right Hand thread.
Looking on top of the bolt or nut you turn socket/spanner CLOCKWISE to tighten

Or ANTI-CLOCKWISE to loosen.

Left Hand threaded stuff is Extremely unusual and very specific.

It is difficult to find LH thread taps and dies.

For nuts and bolts that are damaged you need to use 6 point/single hex tools.

Normal ring spanners and sockets are 12 point which can damage soft metal fastener heads that have been damaged or are rusted in.

Try to avoid using open end spanners to loosen nuts and bolts. They do not offer any grip and slip off. That will positively have a negative effect and fuk up your day.
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Disclaimer: The comments above may be predicted text and not necessarily the opinion of MCN.

[grr666]

[NJD]

[Raffles]

[tyler12]

https://www.chinesemotorcyclepartsonline.co.uk/partno_12M8FLNUT.php

pretty sure that's the nut you're after.

[NJD]

Just to clarify before I buy a 13mm spanner and apply some force I'd it normal to get resistance when attempting to tighten the locknut all the way down?

I haven't managed to try it on the bike but when I was testing out the different sizes with the bolt out I found it's an m8 but when I put a socket / spanner to it (they're both to big to try on the bike itself) it felt like it needed more force than what I wanted to give it and risk damaging the thread of the bolt.

Would it be ok to buy a 13mm spanner and just get on with it it is the design of the below locknut the wrong type?

https://www.halfords.com/webapp/wcs/stores/servlet/ProductMobileDisplay?storeId=10001&productId=753229&srch=m8+self+licking+but&categoryId=310504&langId=-1&catalogId=10151

[Islander]

Those look like nylock nuts - nothing wrong with that but the original was a flanged nut so you'll probably need washers to go under them.

Locking nuts don't run freely like a plain nut and will need a small amount of force to thread them on.

[NJD]

[quote="Islander"]Those look like nylock nuts - nothing wrong with that but the original was a flanged nut so you'll probably need washers to go under them.

Locking nuts don't run freely like a plain nut and will need a small amount of force to thread them on.[\quote]


Below is what it looks like. Only reason I asked is because I wasn't sure if the bolt was getting caught on the blue inner part of the nut or it just needed some force.

13mm spanner and M8 washers. Have to wait for another day due to work. The gift that keeps on giving.

https://s8.postimg.org/i4ycb97xh/image.jpg

Also is my phone browser special or is this site a pain in the rear to use on phones in general? Typing and the next moment I end up typing in the search bar along with many other quirks. Been writing this got about 10 minutes.

[tom_e]

Yep that's a nyloc nut and will require a little more force than normal as the bolt bites into the nylon as you tighten it.

[ondabike]

NUTS