I’m looking at alternatives for the original 2.0L exhaust nuts.
Has anyone seen these, copper nut with a steel helicoil insert?

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I’m getting ready to help a friend replace his clutch along with a few “while you’re in there” items.
I’ve tried the ovaled copper nuts and destroyed to many head studs upon removal.
The inserts are steel as a magnet proved.
Any experience would be helpful.

Steel vs. copper. The copper probably has a higher CTE (coefficient of thermal expansion) which will make the steel bite more poorly. I wouldn't trust them for a high temperature & high vibration application. Those babies might be good for low temperature applications such as spacecraft. Hmmm...

That copper portion appears to have a prevailing torque feature

Not sure that will work any better than what you previously experienced.

What is a prevailing torque feature? Is that the notch?

Prevailing torque fasteners have a deformation that causes the nut to grip the stud - retaining torque (but not necessarily clamp load) even when the stud elongates from thermal expansion.

In this case it’s the indented notch (I think). If that copper notch has to be deformed in order to thread the nut onto the stud (not free spinning), it’s a prevailing torque fastener.

Sometimes it’s ovalaled slightly by intentional deformation as notes in the original post.

Sometimes they have the last thread or two smashed slightly closer together than what the normal thread pitch is.

Basically meant to keep the nut from vibrating off if/when there is a loss of clamp load.

In this case it looks like that indention is meant to hold the steel insert in place and not be a locking feature for the stud.

Yeah - hard to tell. Sort of strange though becuase Heli-coil doesn’t usually need a retaining feature. Because of the shape and coiled spring action of a Heli-coil it bites into the hole when the tang is broken off.

Never used these before so I can’t be sure which it is. Unless it’s free spinning - it’s prevailing torque.

Let me dig out a factory one tomorrow. Thinking they have heli-coil insert. Lots of copper coated steel nuts out there.

The factory ones on my 75 were long flanged nuts. They appear to be self-locking and did not have a Heli-coil in them.

All of my true Heli-coil inserts are of a high enough quality of stainless to be non-magnetic.

I found the nuts I'm going to use from Clips and Fastners in California

https://www.clipsandfasteners.com/

Part #PM80001-25 is an 8X1.25 yellow zinc plated flange nut with a 10mm hex size.
They look like the will work great. They are $5.86 for a bag of 25 so 24 cents each.

They have better ones as well.
Same dimensions but class 10 and 12point 10mm heads, black zinc
14.30 for 5 so $3 each.

That site is hard to navigate but has shitload of really neat fasteners.

Ferro-magnetic stainless steel is used in a variety of applications. It's no reflection on quality.

Here’s free spinning version with small hex to better fit exhaust flanges

http://www.914world.com/bbs2/index.php?showtopic=365634

I used these;

https://www.demon-tweeks.com/demon-tweeks-m...mp;gclsrc=aw.ds

They don’t seize but do tighten up!

Here’s another option, got them from Bel-Metric


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Nut on the bottom is one of the no longer approved copper nuts. These seat fully against the exchanger ears.

I can only wish I could get $5.91 a pop for mine. I wonder what shipping would be for 8 of them? Priority? Highly doubtful. I don’t think they would accept a personal check either. Or you would have to WAIT for the check to clear if they do. Perhaps….highly doubtful. Highly….

Factory Exhaust nuts have 13 mm head and 16mm flange(round up). They appear to have Heli-coil in them. All I have are used. Some have been replated and the other used.