Shock mounts in a bad way - what are my options?

[Cigaro]

Whilst fitting the rear shocks back on to the GN last night I noticed that two of the nuts were very hard to get on, as in they kept slipping off the mounting stud when I first put them on.

I did eventually manage to get them on, but they were very stiff to tighten up.

Looking at it it actually seems that the right hand side top mount stud has had some of the thread snapped off and there is a smaller nut installed on it.

It seems sturdy now it's all bolted up (the nuts aren't going to come off the stud, in other words); is this dangerous? If so, I'm assuming I need to replace the shock mounting studs on the swingarm and frame; Can I just cut off the existing stud , drill the hole through and use a bolt with washers to get the spacing correct or does it need to be welded on (I'm assuming it probably does as otherwise the bolt will move around in the hole!)

Who will do this for me and how much will it cost?

Cheers.

[Cigaro]

Just to clarify what I'm on about, here is a lovely Paint diagram.

https://i1013.photobucket.com/albums/af255/thebassjunky/swingarm.gif

[ms51ves3]

Could you not run a die over the threads to clean them up?

[Cigaro]

I could, but it doesn't change the fact that one of them has been snapped at some point and is shorter than it should be.

[ms51ves3]

[Vincent]

Are al the mounting studs knackered? Might be an idea to pick up a cheap replacement swingarm for the bottom ones. I don't think I'd want use bolts instead.

[Cigaro]

Sorry to revive this thread, but I still have this problem.

The bottom mount is OK; I got the dome nut on and that's not going anywhere. The top one, however, seems to be stripped. It tightens up, you give it another turn and it just goes loose again.

My first thought is that the problem is with the dome nut rather than the thread of the stud, so I'm going to try replacing that - but if not then I think I need to get a new stud welded on; should I be able to find one of the right specification easily enough?

[Robby]

Are the studs removable like exhaust studs? You'll need to strip the paint around them and wire brush right back to see.

If they are, you can remove them and fit new ones. If they are welded or a part of the frame in some other way I would expect an acceptalbe fix would be to grind off the remains of the stud, drill the hole and tap it, and run a bolt of the correct pitch into that. This is assuming the stud protudes from a little cylinder of steel on the frame, not direct from the sheet metal of the frame.

[Vincent]

I'd be a bit careful with this one - those mounting points have to put up with a fair amount of stress. I'd seek the advice of a good and trustworthy welder first. I would even consider transplanting the subframe off another bike rather than try and make your own mounts.

[Cigaro]

Here's the offender:

https://img.photobucket.com/albums/v498/xen0morph/SANY0532.jpg

It actually looks like the stud might be seperate from the tube that it's in, but surely this is just wishful thinking.

Cheers.

[27cows]

I think I'd be tempted to have threaded bit recut to the next size down (maybe to take a non-metric nut). Using a bolt in place of the lug isn't an option - it's extremely unlikely to work and could make a nasty mess of your frame.

You should be able to do it yourself with no bother if you have a tap and die set (and the obligatory big box of assorted fasteners from many sources that most of us seem to acquire ). Obviously care would need to be taken. But this should work as it would only be the thread part that was being slightly thinned, while the main body of the lug, which takes the weight, remains untouched.

[finpos]

I'd agree the easiest thing to do is to cut it down one metric size and use a flanged nut or a washer - there's not really any lateral force on that nut so won't be a problem, however there's a lot of load on the stud itself so you don't want to go messing with it. The biggest problem you'll have is making the stud the right size to accept the smaller die, you'll probably need to file it down carefully.

If you care about the original look, cut it down 2 or three metric sizes, then thread it and epoxy a nut onto it. File that nut down to the original diameter of the stud, thread it and stick an new dome nut on it.

f.

[Vincent]

I think I'd be tempted to drill a hole in the end for a split pin or cotter pin then use a rubber and metal washer behind it.

[Frost]

I'd get the thread re-cut (probably cost about a fiver at an engineering place) and stick a nut with a flange on it. Replacing that with a bolt wouldn't be a nice idea.

[Ariel Badger]

They do not actualy need nuts, you could drill a hole and hold them in place with split pins and washers, that is how it was done on my Mk11a Landrover.
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[Damon]

[Cigaro]

I'm not sure about having no nut at all. I can pull the shock off myself fairly easily, so I wouldn't like it to be just sat there without a nut holding it on.

I suppose a splitpin might work. Wouldn't the MOT tester have a fit if he saw it, though?

The problem with cutting it down and rethreading it is that (despite what it looks like on the pic) there's only about 3mm worth of thread actually left on the stud. I don't know if that's enough to get a nut to grip.

Suppose it might be worth running a die over the existing thread to see if I can get the nut to grip on.

Thanks for the help everyone.

[Damon]

How about getting the original nut on it and then drilling through both the nut and shaft to accept a split pin. Best of both worlds

[27cows]

A far from ideal solution (but one that would work because I've done it myself on a couple of crossers in the past) would be to put a nut on as best as you can, then add a touch of weld at the end to keep it in place (this is assuming recutting a new thread doesn't work).

In a perfect world you'd have the means to cut a finer thread than standard, then add a fine threaded nut (meaning you'd get more turns per mm).

[Cigaro]

Cheers everyone. Well, someone I know who is an experienced mechanic and engineer is going to drill and tap the stud and put a bolt through the middle of it, that seems the best way to do it now.

Many thanks for your help