Subframe nuts!

[Nuvo]

You can't access the captive nuts through those plugs unfortunately as they are way too high for a start.
You need to cut out a square panel into the chassis leg to expose the nut and pry open the cage to release it. It would be a nice little upgrade to accept the larger bolts but the work involved is too great in my opinion. Then again, if you have the workshop equipment and the desire then have at it.

[Nuvo]

m10 captive nuts are 30x27x9mm, the hole is offset along the length ~2.5mm. HTH

[Bowie69]

Thanks Nuvo, will see what I can do

[nribs]

Thanks Nuvo, will see what I can do

Take pictures for posterity.

[Bowie69]

Take pictures for posterity.

Always!

[steve briance]

Just a thought but, is it actually the hole thats going 'soft' or is it the thread on your bolt or, the bolt itself? They are stretch bolts and can be re used maybe once or twice but, if they have been torqued more than that they actually get quite a lot thinner. Could be the bolt have necked down so much while stretching that its not gripping the female thread?

Whatever happens, im watching what happens here as im sure it will be put right properly

[Bowie69]

New bolts when I did the rest of it! There is a small amount of thread damage, which I put down to the nut being mullered...

[steve briance]

Aaaah nuts. (pun intended)

[Mikes2]

You might be able to tap the threads to repair

[Bowie69]

At this point, if I have to cut the chassis I will likely back out and tap to M12, and re-drill the polybush spacer to suit.

Hopefully won't get that far