Output Shaft Thread Damage

[squirrel_hunter]

Well I've hit a slight issue. Tightening the front sprocket nut on my '99 SV650 the nut will tighten up against the sprocket but any torque (145nm is required) will see it spin loose. Thus the thread is stripped or otherwise damaged. Tried with a different nut just in case and the problem persists. I cant see any obvious damage to it at the moment but something is wrong there.

My options are once I've finished crying 1) Weld the sprocket on 2) Replace the shaft 3) Try and repair the thread.

Option 1 is a bit of a bodge and only stores up the problem for later, so I'd prefer not to. Option 2 requires a full strip and rebuild of the engine, not a small job as I've finally just completed it. Option 3 is worth a shot then.

Trouble is with option 3 the size of the shaft isn't in the standard tap and die sets. So a quick search of eBay for "32mm thread restorer" throws up some wheel stud repair kits, worth a shot I think. However I'd like to be sure I'm going to get a kit with the right size, M12? M14? 1.25mm? 1.5mm?

So what size is the output shaft please? Or how do I measure to find out?

[rictus01]

Can't really help with size, but if it was me I'd be off round the local engineering place as they would do it in place for a few £'s as buying a "set" to do it would probably be a single use and then sit in a toolbox.

[glang]

wot a bummer! Any idea how it got damaged or was it just down to a lot of sprocket changes? Unfortunately with the torque thats required I cant see you being able to repair it. Would it not be possible to use a thick washer between the nut and sprocket so allowing you to tighten onto a different bit of the shaft thread....
Sorry cant answer your thread size question.

[maviczap]

Simple thread pitch gauge will get the correct pitch.

http://simplybearings.co.uk/shop/pro...N6cRoCZmrw_wcB

As for the die size? If its not staying on at the high torque, is there enough material on the output shaft to cut a new thread?

[andrewsmith]

Get the vernier caliper out SH.
For the thread pitch, use a thread feeler.

I would personally measure the nut, not the shaft

Die Look at this on eBay http://www.ebay.co.uk/itm/281408012408

I've never personally done it, but the words that were used by a friend weren't repeatable

Sent from my E2303 using Tapatalk

[johnnyrod]

Post a pic Squirrelo. Could be something like the threads as knackered there but fine further out so you could pack a spacer under the nut and use the good portion of the threads.

[Bibio]

Originally Posted by johnnyrod

Post a pic Squirrelo. Could be something like the threads as knackered there but fine further out so you could pack a spacer under the nut and use the good portion of the threads.

what he said.

thread repair die wont work, they only work for x'd threads and even then its dodgey.

unless you know the shaft is damaged, I think the cheapest place to start is a new nut. It says here 21mm thread but that's not enough info and if it is M21 (fine at a guess) you're going to find it very difficult to find a tap and die set. https://www.discountbikespares.co.uk...GSX-RF-SV.html

[squirrel_hunter]

I've investigated further and it looks like the thread on the shaft is more or less fine. I can feel a couple rough nicks but nothing stands out as being seriously amiss. The thread on the nut(s) however is showing signs of wear.

Cause is unknown, they didn't feel bad going on only on tightening. The nut is also a bit of a unique design in that the thread is slightly recessed in the body of the nut as it sits over the splines of the shaft and against the sprocket so I'm not sure if padding it out will help, I think I'd also lose the tab washer which is useful on this.

I would post pictures but there isn't really anything to see as the flash washes out against the reflecting metal and without it the you can't see anything either.

So my plan now is to get a replacement nut and a die for the thread to ensure its tidy. To get the correct size I measured the diameter of the shaft, which came in at 20mm and using a thread feeler I get a good match from a 1.5mm pitch. So that's a M20 1.5mm die I need. Not in your standard tap and die set...

A search gives me the Laser 5924 Wheel Stud Thread Restorer - HGV for about £40 on eBay. I think I'll order one of them get a nut and see what happens.

[NedSVS]

£40 sounds like a lot to spend when a little time with a triangular needle file might suffice. Why not wait till your nut arrives and try it on before spending all that money for a tool you may only use once. Also, perhaps worth checking, is the thread undercut? If so, just check that the nut is not going on too far and too many of the threads ending up in the undercut.