helpful comments, thanks all.
I got some of the flanged serrated nuts, but might have been zinc. since I already have the SS nylon lock nuts - by mistake - I might try using that in a “jam nut” arrangement if the bolt is long enough.
… meanwhile, going to keep the radar on for SS M8 lock nuts - or think of what I can do with 997 leftover M8 SS lock nuts if I order them from Fastenal.
What are you bolting together on a muffler?
I’m thinking about it, and a muffler is usually welded on either side to the exhaust pipe, then hung to a rubber mount, from a protrusion that was generally welded on by the manufacturer.
If you mean that you’re using exhaust clamps to attach the muffler to the exhaust pipe, just use the fasteners that came with the clamp. I agree with the many people who said that exhaust hardware rusts in place before you ever have to worry about it backing off.
I have seen black oxide serrated flange nuts at NAPA and have used them on exhaust systems and they don’t rust. It was a kit with the studs, also black oxide coated for replacing the manifold to front exhaust pipe studs.
BTW, if you are trying to put a SS nut on a mild steel stud, don’t do that. It will eat up the stud in no time.
@meanjoe75fan yes muffler.
@keith black oxide, eh? I’ll keep that in mind… what about zinc-plated serrated nut on a SS bolt?
My last-minute plan now is : SS bolt, SS nut + another SS nut (= jam nut), with 3M copper Anti-Seize on the threads. … unless the zinc-plated serrated nut is advisable on an SS bolt.
also FYI - I found a couple SS M8 1.25 all-metal lock nuts on ebay. And I ought to give Porsche another shot - just discovered the other day one of my bolts has a green tint to it - perhaps nickel?
SS on SS, better not to mix metals.
SS on SS you do need the copper anti-seize. Without it, they will seize. If you have the room, stick a lock washer between the jam nuts, holds even better.
Why on earth do you NOT want the exhaust hardware to rust?
Rust is like nature’s Lock-Tite! If you’ve ever had to take an exhaust clamp OFF, you’d appreciate how hard it is to break free the nuts, even after only a year. It quickly rusts enough not to move, but takes a LONG time to rust through…perhaps the ideal scenario.
I’ve never had an exhaust clamp fail due to rust, but I’ve had several where the 8mm U-clamp part sheared off before the nut backed off. That’s pretty secure!
Really, though, do it right and pay somebody $40 (or less) to weld that sucker on…
Hey! BelMetric has M8 1.25 pitch stainless steel “conical” lock nuts! Yayyyy!
Agree to just let it rust but if you must, I’m partial to Fastenal or Napa. The brother of a guy I worked with years ago started Fastenal. Who knew it would grow that much? I needed a little SS allen set screw for my faucet. No one had it except Fastenal. Had to order it. Had it the next day for 50 cents, no shipping charge.
I have never had a problem with ANY exhaust system nuts backing off. Maybe our rust locks them in place.
Headers on small block Chevrolet engines are notorious for working loose and blowing the gasket. There are quite a few ‘fool proof’ kits that advertise to end that problem.
I did the same thing before looking at this thread, but I installed them anyways and just tested to see how hot they got. On my 2006 sprinter they’re used to hold the exhaust into rubber clamps with a large washer. I found that after a 2 hour drive they were not hot at all in the back and not too hot to touch in the front.