School Boy error for engineering types

[steveatesh]

Damn, I took off the polished alloy tread plate yesterday and when putting it back on cross threaded one of the socket top bolts holding it in place. I was in too much of a rush becaus$e brass monkeys were running about the place looking for something they had lost, used an electric screwdriver without hand turning it in first

Anyway - I dare say the bolts are easy to source - A2 stainless steel, 20mm long thread length by 5mm width - but the bit that presses into the body sill where the bolt fastens into is actually loose now so its going to make it difficult to use a tap and dye to rethread it.

Anybody know how the tread plate fastners are held in place in the sill? can they be replaced at all without welding? They look like a push fit and I cant see any sign of welding there?

So engineering types - what do you suggest? Its not load bearing so at the end of the day I can grind off the thread from the bolt and drop it in the hole using loctite or similar to keep it there (or even blu tac at a push!). Or any secret ways of sorting this easily?

[Lunablack]

I've not seen under a tread plate, but I suspect what you're screwing te bolt into is a "nutsert" also known as a "rivnut"...

The reason I say this is that during my sill removal, they're all ov the place in the alloy chassis extrusions...

They can be removed and repaired, but I've never done one..... Loads of info on the net and youtube though.....that's where I'd start..

[Guycord]

st! I thought that was going to be a call to re-engineer the Queen Mary 2, The Typhoon Eurofighter or the O-rings on the Space shuttle booster rockets when I saw the thread.

Better put slide-rule back in case.

[steveatesh]

Guycord said:

st! I thought that was going to be a call to re-engineer the Queen Mary 2, The Typhoon Eurofighter or the O-rings on the Space shuttle booster rockets when I saw the thread.

Better put slide-rule back in case.

Na, they are easy compared to not wanting to damage your P+J when sorting out a polished alloy tread plate!

Thanks for the info Luna, looks like a Rivnut and removal seems to involve drilling them out and hoping the bit doesn't drop into the chassis. Think I'll just leave it and sort the bolt out instead. Thanks for your help! Note to self, remember Tolkein - short cuts lead to long delays!

[Lunablack]

If you decide to drill, and it drops in the chassis, you can squirt some silicon sealant down the hole, and it'll stick the insert to the alloy and stop it rattling around.... I've done this with rivet heads in the past, and its worked fine..

[Stonic]

Or get hold of a rivnut tool and see if you can get enough thread to bite so the tool will pull the rivnut tight again. Then use a tap and very slowly clean up the thread. You can try applying superglue around the edge of the rivnut whilst you clamp it tight. The problem drilling them out is that if lose, they just spin on the drill bit. Worst case I've had you use a small grinder wheel on a dremel! Not something I'd want to do on an Aston.

[drofnavi]

I have fixed these fasteners before, put some Araldite or JB weld around the insert and let it dry thoroughly before carefully re tapping the tread. Don't over tighten the bolt and it should work fine as it not a load bearing component.

If you are going to replacing it, try and grind the top off it so that you don't enlarge the hole on the body. Some of the tools for pulling them are better than others, best to look for a good professional use tool.

[steveatesh]

Thanks both, least I know it's not a lost cause. Does JB weld take paint off, as the sill is painted where the rivetnut is?

I Appreciate every bodies advice thanks.