Over threaded 13mm subframe bolt hole, ideas on fix?

[sonny172cup]

As reported in a other thread when dropping my subframe I manage to sheer 13mm bolts that hold the small triangle support brackets in place. I manage to drill out one of the bolts, but one of the others threads has been over bored. The bolt is located in the subframe where there is no way of getting a nut in there, so im guessing this is a common problem as the bolts was brittle as hell.

I was thinking of cutting a small inspection hole in side of the subframe, enough to slide a spanner end and nut in, then use that to tighten the bolt up, would this be fine?

Sods law that the one that came out easy was the inner one where its open and can see the bolt end grrrr

 

[Cup_Phil]

Rivnut?

Or is the old welded nut still in there?

 

[sonny172cup]

I overshot the drilling out and sheered of the inner thread so the bolt just slides in, so was thinking of putting a nylon nut in there, just need to get inside the frame.

The other bolt is half drilled out, Im chewing up HSS bits!

Will a rivnut be strong enough?

 

[Cup_Phil]

I would have thought so - the subframe is held on with some seriously bulky bolts - those triangular supports just seem to tie the chassis into the subframe and shouldn't be under too much load.

I'm not sure I'd want to be cutting holes in the subframe to get to the nut TBH

 

[sonny172cup]

My thoughts exactly, there are some holes in there already, but to far from the bolt. This must happen all the time with these cars so what do the traders do?

 

[mark123]

You could drill the nut out completely and weld a flange nut in the hole from the outside and grind down the weld to be level. Never tried it myself though.

 

[sonny172cup]

ok thats an option, I have no weld kit so will have to drop it off somewhere. Thanks Mark