Another Loose Sprocket Nut

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<!--quoteo(post=44243:date=Fri 15th Jun 2007, 11:02 PM:name=Toneski)-->QUOTE(Toneski @ Fri 15th Jun 2007, 11:02 PM) <{POST_SNAPBACK}><!--quotec-->sorry GG, buts thats exactly whats happened, its pulled over the thread, i can see that from the damage to the nut
trying to find where i put the damaged nut so i can post a pic

there does seem to be less movement on the splines with genuine yammie sprocket<!--QuoteEnd--><!--QuoteEEnd-->


In that case Toneski, you must have had a faulty nut with an oversize effective thread dia &/or core dia, or your shaft has a thread with an undersize effective thread dia, &/or undersize maj dia.

A correctly manufactured shaft & nut will never jump threads when torqued

I've worked in machine shops producing threads as Quality Control / Assurance.
Oversize core dia on the nut allows low torque thread stripping, as does a truncated thread on the shaft.
I have never, in twenty years of engineering, ever heard of a nut jumping threads after it was torqued up. When loose yes, but not when tight.


<!--quoteo(post=44273:date=Sat 16th Jun 2007, 11:22 AM:name=Toneski)-->QUOTE(Toneski @ Sat 16th Jun 2007, 11:22 AM) <{POST_SNAPBACK}><!--quotec-->is it possible the splines can wear over time?<!--QuoteEnd--><!--QuoteEEnd-->


Yes - I had an X7, where the sprocket wasn't clamped tight, merely held on by a splined washer that bolted to the sprocket.
The sprocket sat 'loose' on the output shaft, but could come off due the splined washer which was 1/2 spline width rotated

It used keep ripping the splines out of sprockets - I replaced the output shaft and it nver did it again. The splines on the shaft were worn allow it to destroy the sprocket splines

<!--quoteo(post=44318:date=Sat 16th Jun 2007, 06:22 PM:name=ChrisG)-->QUOTE(ChrisG @ Sat 16th Jun 2007, 06:22 PM) <{POST_SNAPBACK}><!--quotec-->Not convinced about this sprocket thickness isue but going for a Yam one just in case. Sprocket sits on the splines and there's a section of shaft behind, so the shoulder it sits against is probably too small to have another washer on.



I had 2 washers between the sprocket and the nut though so that should have the same effect as a thicker sprocket.

I've put the old sprocket back on for the time being with a new nut and locktight on the nut only. Should have the new chain and sprockets by next weekend which should be less than 700 miles away, I'll then use the locktight on the sprocket as well and accept that I'll need a bearing puller to get it off again.

The old chain is a DID X-ring has been on for 25-30,000 miles (with a scott oiler)<!--QuoteEnd--><!--QuoteEEnd-->

<!--quoteo(post=44289:date=Sat 16th Jun 2007, 01:29 PM:name=ChrisG)-->QUOTE(ChrisG @ Sat 16th Jun 2007, 01:29 PM) <{POST_SNAPBACK}><!--quotec-->Yikes, genuine yam front sprocket is nearly £50 compared to less than a tenner for a pattern one, and it's going to take a week as Fowlers haven't got any in stock.

Oh well, it's on order and my x-ring chain and pattern rear sprocket are on their way form M&P<!--QuoteEnd--><!--QuoteEEnd-->
I've never had an issue with JT sprockets

You will need a 3 legged puller to get it off after loctiting
A good one is available from Machine mart for about £10 (its the one I use on my DRZ)
http://www.machinemart.co.uk/shop/product/...le-150mm-puller

<!--quoteo(post=44286:date=Sat 16th Jun 2007, 12:32 PM:name=ChrisG)-->QUOTE(ChrisG @ Sat 16th Jun 2007, 12:32 PM) <{POST_SNAPBACK}><!--quotec-->Hmmm, Fowlers will only do genuine Yamaha parts, is the X-ring going to be noticable better than the genuine one?<!--QuoteEnd--><!--QuoteEEnd-->

X ring chains are a noticeable improvement over ordinary O rings for longevity - std will be an O-Ring. DID make the best chains
I had 30K miles out of an X ring, using just spray on lube

<!--quoteo(post=44270:date=Sat 16th Jun 2007, 10:33 AM:name=ChrisG)-->QUOTE(ChrisG @ Sat 16th Jun 2007, 10:33 AM) <{POST_SNAPBACK}><!--quotec-->edit: almost forgot, how tight should the fronty sprocket fit on the splines? Mine can rotate by a noticable amount, which could mean it allows it to slide around and wear.<!--QuoteEnd--><!--QuoteEEnd-->

Should be a sliding fit - with the minimalist amount of play. If you've got some rocking then your output shaft splines are worn
The locitite will hold it tight though once it has gone off - the Loctite cures to form a Thermoset plastic
Allow 24hrs for it to cure fully

This post was last modified: 16-06-2007, 06:14 PM by GuyGraham.