tim996

So I have changed both air con pipes that run under the sill. The problem is those clips. They are held on by a plastic hollow bolt onto a welded thread onto the car floor,
Problem is the welded threads rust and become smooth, the new plastic clips have nothing to bite onto. So they rattle about.

Has anyone solved this? I was thinking silicone glue between the clip and floor

Paul Waterloo

That or use some construction adhesive, I personally like Locktite PL Premium that stuff is the bomb. If you ever need to get it off, you could chip/grind it off....but it doesn't sound like something you would do soon.

Just put it on, and let the car sit for 24 hours and you'll be set.

http://www.loctiteproducts.com/const...dhesives.shtml

There is other stuff on the same page that is clear. Anything like this will work.

mharrison

Pop rivets?

5CHN3LL

I'd go with the silicone, since when it cures it will be rubbery and help damp vibration. Anything that sets up very hard is another vibration opportunity...

Rubik

^^^ +1

Paul Waterloo

If it's going be rubbery, it will allow the pipes to flex more, which would create more of a low stress, high cycle fatigue. I personally would want the fasteners tight to the body to minimize relative motion between the pipes and the body. Rubbing is not good.....unless you are with a hooker in Reno!

tim996

Thanks all, great advice,

5CHN3LL

Cyclical fatigue can happen regardless of the viscosity of the adhesive. Since we don't know the resonant frequency of the lines in their original state, and we have no idea about the degrees of freedom provided by the original fasteners, postulating that a non-rigid adhesive will result in fatigue failure seems a little...intentionally academic.

In my unscientifically-founded opinion, a good-sized gob of silicone is going to work just fine for damping the AC lines. They're already bouncing around unrestrained and haven't failed; securing them in some manner is probably better than leaving them alone. You could also argue that since these pipes undergo a fairly significant thermal delta (given what they're used for), using an adhesive that completely limits longitudinal movement for a body that regularly increases and decreases in length due to thermal expansion could also fatigue the metal.

If this was my car: I'd plop down a blob of RTV and check it off as "good enough."

I wish I had something as clever as the Reno Hooker analogy to polish this off with - that's good stuff...