Frame swingarm pivot bolt thread gone!

[seastate]

Hi,

I though that I'd rebuild my NTV(P) as it was starting to get a little tatty and everything was fine until I removed the swingarm pivot bolts and found the thread on the right hand side of the frame had almost dissapeared..

Not sure how it could have happened as everything seemed ok. I think maybe a hard knock on the back wheel when I came off it once (or twice).

I know I could get an ebay frame but I thought I can probably do something - probably a Helicoil or similar but measuring the pivot bolt I get 22.76mm Dia. and I've been told there's no such thing as an M23 thread.

Has anyone else come across this please?

Heres a pic of it

[pikey]

It`ll `likely`be M24 metric fine:

www.engineeringtoolbox.com/metric-threads-d_777.html

Where are you measuring 22.76 mm at the damaged thread section?

It can definately be repaired, a new swingarm spindle with a smaller diameter thread may have to be manufactured though.
A helicoil couldn`t be used in such a structually important fixing but a hollow boss could be welded into the frame then reamed to size and a fixing made outside the frame boss with a washer and nyloc or castleated nut and R pin.

[ilegalalien]

i've just measure the bolt and it came out as 22.76mm.. so you got the right bolt n size

[seastate]

Thanks for the replies.

The torque on the bolt is really important as it pinches the swingarm bearing in and if I start changing threads I wont get the right torque. The best way would then be to remove the old spindle and weld in a new one but then I'd have to make a jig up first.

I am going to get an ebay frame....

[ilegalalien]

you could weld some steel in there on the bad parts and tap the same thread in.. a 1.0 tap is £23 on e-bay

[McF]

New frame is probably the most sensible decision
That swingarm pivot is a pretty serious part of the structure
If it has failed once imagine how easily something could go wrong with it again?

I cannot recall if the pivot bolt or locknut screws into the frame but the locknut has 90Nm of torque to set so there is a lot of force going into that before you start riding

[realnutter]

I have a very clean 650 frame with log book... yours if you can get to Reading to collect it........

[seastate]

Jul 3, 2012 9:30:49 GMT 1 realnutter said:

I have a very clean 650 frame with log book... yours if you can get to Reading to collect it........

You are fantastic

I'm just near Littlehampton and I'll definitely come up and get it..

I've PM'd you my details

Cool, now the rebuild can get under way and I need to decide colours..

I will start a new thread in restoration projects so you can see how its going.