Fixing a shredded bolt

jingeroo · Two Stroke Sniffer Joined: 08 Sep 2008 Karma :

I recently noticed that the washers behind the nut holding one of rear shocks was loose, so I tried to tighten it only to find both the nut and bolt are shredded.

Could anyone advise the best way to rethread the bolt (which is welded to the frame) or can a replacement be welded onto the bike at a garage? I have heard of tap and die sets but do normal garages have these?

The bikes a cg125 br-k

I would be grateful of any advice

Thanks

Cigaro · World Chat Champion Joined: 28 Mar 2007 Karma :

Being the master of bodgery, what I would personally do would be hacksaw it off, drill the bolt out, and put another one through of the same size with a washer and a nut on the outside of the frame, then torque it all up very tight.

It's probably not a good idea though, really. Very Happy

ravingriley · Borekit Bruiser Joined: 20 Oct 2008 Karma :

Thats sounds a good idea. Plus its hard to find tap and die sets with large thread peices.

Bass junky Thumbs Up

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Cigaro · World Chat Champion Joined: 28 Mar 2007 Karma :

Obviously you need to make sure you get a very strong nut and bolt, and get the spacing the same so you don't mess up the suspension geometry.

To be honest I see no reason for it to fail. IIRC the shock mounts on my cub 90 weren't welded on either side, they were just big bolts with washers to hold them in place.

stinkwheel · Bovine Proctologist Joined: 12 Jul 2004 Karma :

The nut is only welded to the frame for the conveniance of a) not being able to lose it and b) for being able to tighten it up using only one spanner.

I wouldn't necessarily even take the old nut off, once you have the bolt out, just fit a slightly longer bolt of the same diameter and put a nut on the outside of the knackered one.

Obviously if this makes it stick out so far it risks fouling something, the original captive nut might need to be ground off the frame. There is no real need to weld the new one on though, just nip it up good and tight with two spanners.

Use a mild steel bolt not a stainless one, use one that is the same diameter as the original and has the numbers 8,8 stamped onto the head of the bolt. This indicates it is strong enough to do the job and not some crappy monkey metal thing from B&Q.

For added security you could always use a nylok nut providing it doesn't stick out too far.
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syl · World Chat Champion Joined: 05 Dec 2005 Karma :

Stinkwheel's usually spot on, but now I'm confused. Which one is welded to the frame - the nut or the bolt?
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G · The Voice of Reason Joined: 02 Feb 2002 Karma :

BanditsHigh · Worse than a woman Joined: 21 Mar 2005 Karma :

Pete. · Super Spammer Joined: 22 Aug 2006 Karma :

I agree with Method 2, shold last a long time. Might not pass next-years MOT if the tester's a stickler.
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ZRX61 · Victor Meldrew Joined: 05 Nov 2003 Karma :

Good fucking grief, first fix should be run a thread chaser along the stud FFS Rolling Eyes

BanditsHigh · Worse than a woman Joined: 21 Mar 2005 Karma :

^^^ Calm pills run out did they?

Not everyone is perfect like you 'ZRX61', they don't all have the abundant knowledge that you do, but at least he's been smart enough to ask!

As for running a thread chaser along the thread ...

stinkwheel · Bovine Proctologist Joined: 12 Jul 2004 Karma :

Ahh, sorry, I misread it as a captive nut Embarassed

Consider my previous post as a load of bollocks.

I've never seen a twinshock with a fixed stud, mine have always had a bolt going through a lug on the subframe.

Although, if it is genuinely a bolt going through the frame with the head tack-welded in place *, grinding off the welds, knocking it back through and replacing it with a new bolt would be my preferred fix.

* Honda actually do use this method for a surprising number of studs, including those on the rear exhaust manifold on VFR750s as I was incredibly relieved to find when I sheared one.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

BanditsHigh · Worse than a woman Joined: 21 Mar 2005 Karma :

jingeroo · Two Stroke Sniffer Joined: 08 Sep 2008 Karma :

Thanks for the reply's.

I'm gonna take it to a local bike shop and see what they say. I will mention some of the methods yous have advised. I think restoring the original thread is not gonna work ( using a thread chaser) as there is hardly any thread left.

Cheers again for the advice.