This might explain difference in cost between the two. The 2.0 nut is used and the copper is new. Note the copper one has elongated hole.

I believe the elongated center in the copper nut is done to provide a self locking feature. Regular locknuts cannot work in the high heat exhaust area as the nylon ring in the locknut doesn't hold properly, but the deformed copper will.

Yup, the top threads are squished. It's the way most locking nuts are done. Nylock is fine for a lot of things, but if they're gonna be by a heat source, forget it. This includes clutch cables.. The squished thread lock nuts are destined with a certain amount of deformation, so they won't damage the studs...

Sixer, can you look at the OEM nut to see if there is a slice in the side anywhere? I remember one from the exhaust nuts I took off my car way back when...

--DD

I have one sitting right here. No slice, no deformity, no plating and no no. Just a steel nut with a thick flange on one end and Helicoiled threads on the inside. They are NOT self locking nuts, nor were they meant to be such.

The Cap'n

The copper nuts are awesome at pulling exhaust studs!

OEM nuts are great if you can find them.

I like the copper nuts BUT I run a 8X125 tap through the nut to eliminate the "pinch"

Again, you're joining the ranks of those who call those things "copper" nuts. They're NOT copper, they're STEEL, with a copper plating. Clearing out the "pinch" makes them regular nuts with a hefty price tag.

The Cap'n

Okay, so what's the proper replacement for the originals and install procedure? Sound like the copper PLATED ones aren't recommended for fear of stripping the threads that receive the exhaust stud.
And if a regular nut is recommended, what should one use to keep it in place? I recall Jake recommending milk of magnesia on the threads.

Correct ! I like them because they don't slip through a socket.

Force of habit as that is how they are advertised EVERYWHERE.

Personally if I can't find OEM ones I will go with these:

http://vwparts.aircooled.net/ACN-Flanged-R...-p/acn-nuts.htm

REALLY nice when dealing with larger OD header stubs.

James, you may find the nuts your are looking at are too small in diameter for the exhaust flange on HE's.

Exactly. The copper plated nuts are still in use on new Porsches as well. A good portion of the nuts used on the current cars have a pinch or dimple and are one time use.

These are the ones I went with. They worked fine with my SSi's and were no trouble to install.

I remember the same thing on the last ones I replaced. The slit allowed the nut to be slightly bent across the axis to create a locking feature instead of squashing the nut perpendicular to the axis.

I went through this myself last year when completing my /6 conversion. I read posts of people having problems with copper lock nuts pulling out the exhaust studs. Just not worth the risk IMHO.

I have a mix of flanged and regular nuts on my exhaust. It seems my MSDS headers have welds that get in the way of the flanges - so that was an issue but minor.

The flange is still 13mm. I have used them before.

As the Cap'n mentioned, OEM nuts were steel with a helicoiled thread. It's precisely this helicoil thread that keeps them from bonding to the studs in the first place which is why this nut type is so desirable. VW also used this type of nut on their motors as exhaust nuts from the factory albeit without the shoulder on them.

Unfortunately, I have found no where that this type of helicoil nut is now made. However, the same style of nuts are used to hold the transmissions together on the 914 (without the shoulder). Yes, the same 8x1.25x13 with the helicoil centers are likely holding your transmission together right now. Since the transmissions don't get hot enough to really need this type of protection, I replace the trans nuts with standard nylocs and save these special nuts for exhaust nuts.

Just an FYI for those of you wanting a real seize-free exhaust nut. . .

Or if your a hoarder your already sitting on a stash of em....

Is it appropriate to use something like this on the exhaust nuts?

Click to view attachment

From what I understand, Copper antiseize is the best to use.

http://www.amazon.com/Loctite-38650-Copper...ti-seize+copper

The Loctite product is rated 200 deg higher than the Permatex, so it looks like a winner. I have a bottle of the Permatex and have used it to keep spark plugs from seizing, but maybe the copper stuff is best for the exhaust side.

Thanks

Hmmmmm, if I'm not mistaken, Loctite and Permatex have been the same company for years.

The Cap'n

Kinda-Sorta.. Permatex purchases a few specific sealing products directly from Henkel and relabels it as their own stuff. Loctite however is a product line manufactured by Henkel, sold as straight up as Loctite.

Sorry, these are semantics..

I found these when I was installing the 914 motor into my 68 fastie. They have a 12mm head and are flanged. The flanged surface has locking ridges. I don't know of anyone using something like this so I'm keeping an eye on them. It's been almost 2000 mi. and all is well so far.



Above you can see one of the copper plated nuts with slit for locking. I bought a set of those too in case I need to go back but I don't like them.

I wonder if this is something we could put in a request for from McMaster-Carr? I would think since they have every other fastener known to man, they might be able to find the heli-coil nuts. I'd be willing to do the leg work.