Stripped Thread

[seatkid]

I've been working for 4 or 5 days getting the old girl ready for another trans-european tour, and in my haste I overtightened the nearside back bolt that holds up the undertray - stripping most of the nut - which of course is welded inside the bodywork chassis member. I've effected a "temporary" repair by using a longer 8mm plain bolt -the original had a tapered end and put on some thread locking compound (blue - low strength) in the hope it'll hold onto the few threads that are left (probably only 2 or so). As a precaution to the bolt somehow falling out, I've duck taped the area, to stop it falling down at 90mph on the autobahn, possibly taking out my front/rear tyre.

 

What way to repair this damage?

 

I could tap the nut out to 10mm but I dont have a 10mm tap and dont really want a 10mm bolt - I might have to open up the hole in the undertray.

 

Drill out and fit an insert? Come to think about it, I have a selection of nutserts but they are for sheet metal.....

 

Any expert suggestions to a proper solution. (but it has to be cheap)

 

Thanks....

[chrispb123456]

Hi Seatkid

Apart from drilling and re tapping. what about one of the many cavity wall type fixings?

[seatkid]

Hi Seatkid

Apart from drilling and re tapping. what about one of the many cavity wall type fixings?

good suggestion, not thought of that one...

[cyborg]

My recipe :unsure:

 

use the over size length bolt cot off head put 2 nuts on end tightend against each other.

 

then put some instant steel or jb weld on other end and put into the hole

 

unscrew the 2 nuts then use one to fasten belly pan ...voila

[seatkid]

My recipe :unsure:

 

use the over size length bolt cot off head put 2 nuts on end tightend against each other.

 

then put some instant steel or jb weld on other end and put into the hole

 

unscrew the 2 nuts then use one to fasten belly pan ...voila

 

That sounds like a good "pitmatic" solution.

[nigel b]

either use a longer bolt and use a nut on top of the welded nut or remove the welded nut(grind it off)and use a rivetnut

[snowytop]

Hi Seatkid,

A good strong repair for stripped threads is to insert a helicoil. That way you keep the exact thread type that you originally had e.g 8mm.

Not sure what it would cost to have one put in, but couldn

[seatkid]

either use a longer bolt and use a nut on top of the welded nut or remove the welded nut(grind it off)and use a rivetnut

The nut is on the inside of the box section unfortunately.

Edited May 12, 2011 by seatkid

[seatkid]

Hi Seatkid,

A good strong repair for stripped threads is to insert a helicoil. That way you keep the exact thread type that you originally had e.g 8mm.

Not sure what it would cost to have one put in, but couldn

[gregers]

how about some heavy duty cable ties?

[seatkid]

One blind hole?

[nigel b]

helicoil might be your only option then

tapping drill is 8.3mm

helicoil tap will be near enough the same size as an m10 tap

make sure you get the right length helicoil

they usually come in sizes like 1d,1.5d,2d etc.. which is 1x diameter(8mm)1.5xdiameter(12mm)...