Damaged front sprocket thread. Curvy.

[Giddsy]

Hi all, first post, guess what? Problems.

I recently acquired my first sv650 - 2001 naked.. Cracking bike but needed new chain and sprocket. Easy job I thought.

However, it seemed last person who tried to remove front sprcket nut took an angle grinder to it and half cut the bolt off. Think this caused my problems. As it was coming off it became stiff towards the end of the bolt. I know now I probably should have stopped and reassessed the issue but I didn't. So now the bolt is stripped at the end.

So question is how do I go about re-thredding it? Never done this before but looks relatively simple except getting the die in there as all the sets I have seen have massive gert handles on them and I obvioulsy can't remove the offending bolt.

Are there tools that perhaps fit into a socket?

Secondly does anyone know the thread details for this bolt so I can buy a specific die rather than a whole set?

Thanks in advance.

Jim

[Giddsy]

Bit more research tells me I need to know the thread pitch. Any ideas?

[Sid Squid]

By "bolt" I assume you mean the thread on the gearbox shaft, yes? If so then unless the thread is completely destroyed, in which case the shaft will need replacing, the easiest way to tidy the thread would be with a thread restoring file.

[rictus01]

I presume you're talking about the single 36mm main shaft nut? if so there are two options the way to do it properly is to take the engine out, strip it down and get the output shaft out; then getting it rethreaded is a simple matter.

the cowboy way of course is to weld the sprocket on (used on track bikes sometimes), but it'd obviously need welding each time.

[Giddsy]

http://tapatalk.imageshack.com/v2/15/01/21/04118f0599fa74b5f54cd6ec82961abd.jpg

[Giddsy]

Yes you are right it is the gearbox shaft.. showing my inexperience here!

This is really the worst of it, there is another nick on the otherside but as you can see the most part seems ok.

Really hoping sid's idea will work, don't fancy dropping the engine out.

Had a look online and seen you can get various pitches I believe it's called. Do you know which one I will need?

[Giddsy]

Looking and thinking about it, I'd say that's been ****ted with a hammer. The nut I got off had definitely been smacked around..

[jambo]

I'd say that's a fair candidate for repair, but I'd possibly order a new nut if you're not sure how that one has fared.

Thread restorer files usually have a number of different gauges, one on each face I got a set of thread restorer nuts and a file in a neat kit from Halfords years ago that have had good use.

Jambo

[maviczap]

As above

Thread file first, as Sid suggested, it doesn't look too buggered. Its the cheaper option

Here's a 36mm thread restorer nut, as Jambo suggested. Its expensive, but compared to getting the engine out, its cheap

http://www.ebay.co.uk/itm/DORMER-M36-METRIC-COURSE-THREAD-CUTTING-AND-RESTORING-36MM-DIE-NUT-/320841749604?pt=LH_DefaultDomain_3&hash=item4ab3a89464

_UtfMOhK-Eo

[Giddsy]

OK thanks for the responses all. Will have a go with the file and let you know how I get on..

[Bibio]

if it was me i would just file the offending part flat so it was no longer causing an obstruction. as long as the leading edge of the thread is in good shape then all is well. think about it, the stem on the yokes has a dirty great big groove cut into it for the tab washer and the nut still goes down.

[dean0n0]

6 or 8 inch half round file (fine) to dress the damaged parts of the thread until the new nut spins on easily.
Patience is required.

[Giddsy]

Thanks all for your help.

A combination of thread file and fine file worked a treat. New sprocket on nice and snug.