Fixing a rattle - welded nut loose

[Jordie Barretts sock]

My wife's MX5 NC has a couple of tin guards protecting the underside of the car.

A week or so ago, while replacinging the exhaust centre section I'm undoing the bolt into the chassis when, you guessed it, the nut that must be spot welded inside the chassis, let go. So I have a stiff half undone nut and bolt that rattles at low revs. That I can't access without major agg.

In view of this not having any weight bearing and there being the three other bolts, could I grind this errant bolt off and cable tie the plate to stop it rattling? No heat anywhere near it, so I'm guessing this would be OK?

Of course, any other suggestions welcomed.

[steveo3002]

cut it , push the half bit inside then fit a nutsert into the hole ?

[Jordie Barretts sock]

Forgive my ignorance, what's a nut insert?

[Vintagejock]

Its a special type of nut that enables you to fit a bolt without having to use a spanner to stop the nut turning. Usually needs a special tool to install it though. I suggest a cable tie wouldn't work because of the heat from the exhaust.

[Jordie Barretts sock]

The place where the offending article is, is a good six inches from the exhaust pipe. I'm hopeful a cable tie will silence it for a short term fix until I can get a nut insert (just Googled) which seems the ideal solution.

I'll post up a pic of the bar steward thing in a bit when I get under the car.

[5s Alive]

You don't need the insert tool either if you have sufficient space to work.

[Jordie Barretts sock]

Brilliant! I think (even lying on my back underneath) there's room to do that.

[Jordie Barretts sock]

Well that went surprisingly easily. I didn't even need to jack up the car. Managed to get a hacksaw to the thread of the nut and bolt, cut that off. Turns out there's a good 12 inches to any hot bits, so I've cable tied it for now. Luckily there was another hole in the chassis right next to where I cut the bolt.

Apologies for the iffy pic, I was on my back and at arms length.



A bit of pre bending of the cable tie, in one, out of the other around the plate and all sorted! No more rattle!

When I can get it on a ramp, should be straightforward getting a riv nut in there.

[wildoliver]

Knowing the underside of the NC fairly well the picture worries me. I'm hoping it's the alloy x plate under the gearbox held in with 4 12mm headed bolts with 2 being in to slots and 2 holes in the plate. If so that's fine even if it drops off it's not going to be catastrophic, half the time they are missing.

My worry is incase it's the front brace with the 17 and 19mm bolts through it where the 19 also hold the front subframe to the car.

[Jordie Barretts sock]

No, you're right the first time.