Exhaust Manifold nuts - copper or stainless?

[timman42]

I'm going to replace my single downpipe with a dual DP and manifold. I was wondering if I should use the copper nuts from GAP, or locate some stainless ones?

Any input is appreciated.

[ABA Scirocco]

I vote copper nuts on stainless steel studs. I think you might have problems with stainless nuts vibrating loose.

[salz2135]

I prefer copper nuts and anti seize paste for the studs.

[shurik06_83]

copper will turn green and stick and copper is really soft rusted threads on the studs will file away at the threads in the nuts and make the thread really loose

stainless will never stick and is much harder so u can reuse them many times and u can get them at home depot for under $5 for the whole set

as for vibrating loose u can use lock washers and all will be fine

[ABA Scirocco]

Copper exhaust nuts are not copper through and through, they're steel nuts with a heavy copper plating and the last couple of threads are crimped slightly to grip the stud so they loosen off. I've had these nuts turn green in storage but never while on the car, I think the heat of engine prevents that.

BTW, these are the nuts and studs I used on my car along with a few other fasteners.

[timman42]

Thanks ABA for the info. I've looked on NGP, ECS, and GAP and didn't find any exhaust stud kits. I'm not aware of anyplace around here that offers studs like that either.

Hardware is M8x1.25, correct?

[timman42]

So it looks like M8x1.25 by 35mm long. Maybe I can find a hardware store nearby. Im thinking of trying the route using stainless nuts with lock washers, over stainless studs. I'd like to easily remove things if needed, in the future.

[antichristonwheels]

the studs are a standard Dorman item. Any NAPA or Carquest will have them. Stainless studs will actually be weaker than the stock stuff. Stainless also has a tendency to gall.

[ABA Scirocco]

Yes, it's M8x1.25. I had to call around a fair bit to find stainless studs locally, a couple places could have ordered them for me if I'd buy a full box of 50, Fabory would let be buy as many or as few as I wanted, I didn't go in there looking for copper nuts, they actually had them in a display out front. Fabory was a great place to deal with, they have just about every fastener you could ever need for a VW with the exception of specialty stuff like head or rod bolts, I'm not sure but I think they do mail order too if you don't happen to be close to one of their locations.

BTW, Those studs are a little longer than they really need to be, if I were to buy another set, I'd get the 8x30mm studs instead.

[ABA Scirocco]

the studs are a standard Dorman item. Any NAPA or Carquest will have them. Stainless studs will actually be weaker than the stock stuff. Stainless also has a tendency to gall.

I REALLY like my stainless steel studs. As far as I'm concerned, strength isn't an issue with a brand new fasteners and I haven't noticed any galling on my studs, they look very much like they did the day I installed them

[RandallCunninghamJrIII]

Thanks ABA for the info. I've looked on NGP, ECS, and GAP and didn't find any exhaust stud kits. I'm not aware of anyplace around here that offers studs like that either.

Hardware is M8x1.25, correct?

GAP has them. look @ the left column and click on 'hardware'.
it's not a kit, but they have exhaust studs/nuts in various sizes

[Eric D]

I use BMW shouldered copper exhaust nuts on my 8v.
I got them from James at http://www.fourseasontuning.com/

[timman42]

You're right Randall, I must have overlooked that. Thanks to all for the comments.

[Seax_Smith]

copper lock nuts and aluminum washers and as much "never seize" as you can squeeze in and run a die down the studs before hand if you are not replacing them.

Don't for get to order 16 of each (10 for the mani & 6 for the dual pown pipe).

[Black92EightValve]

as for vibrating loose u can use lock washers and all will be fine

Only problem with that is the heat from the exhaust will destroy any wave to any washers you use, rendering them useless as a lock washer, you'd need to use the star design lock washers if you're gonna go that route.

IMO you're still better off going with a copper nut, if you want to get a shouldered nut, go to your local VW dealer and get part # N 90200201

[timman42]

So I ended up just getting OEM steel studs and copper nuts from GAP. Thanks for all of the input.

[Brian.G]

Copper exhaust nuts are not copper through and through, they're steel nuts with a heavy copper plating and the last couple of threads are crimped slightly to grip the stud so they loosen off. I've had these nuts turn green in storage but never while on the car, I think the heat of engine prevents that.

BTW, these are the nuts and studs I used on my car along with a few other fasteners.

Thank god you pointed that out, I was getting edgy reading the posts until I saw yours
The amount of guys that think they are ''pure copper'' is insane.

BG

[Dave926]

ARP sells metric stainless bolts that can be used for the exhaust.

[piledriver]

You can get BRASS 8x1.25 exhaust nuts in 11mm OD, commonly used on acvws with large exhaust pipes for clearance, but they are solid brass hex stock and will not rust, bust or corrode.(OK, maybe lightly corrode, but they stay dry due to exhaust heat)

Jegs/CB performance and many others sell them, sometimes called header nuts

SS nuts on SS studs is likely to gall w/o antisneeze, but SS studs with ~anything else probably wont if anyone ever wanted to go that route.

[antichristonwheels]

stainless will be weaker. If you got a stuck stainless stud it will snap off easier than a good hardened steel one

[ABA Scirocco]

stainless will be weaker. If you got a stuck stainless stud it will snap off easier than a good hardened steel one

The main reason exhaust fasteners tend to get stuck in the first place is due to corrosion and that's FAR less of an issue with stainless steel fasteners, in my fairly limited experience with them, I've never had a stainless fastener get stuck so breaking them, thus far, has been a non-issue for me.

[Glegor]

So it looks like M8x1.25 by 35mm long. Maybe I can find a hardware store nearby. Im thinking of trying the route using stainless nuts with lock washers, over stainless studs. I'd like to easily remove things if needed, in the future.

STAINLESS IS WEAKER THAN NORMAL STEEL!!

stainless exhaust hardware just SCREAMS bad idea to me..

the only time you should use a stainless bolt over a rregular steel bolt, is when you need corrosion protection..

stainless at the exhaust manifold has got to be the worst idea ive ever heard..

stainless will gall to stainless, and steel..

copper nuts will not gall, and almost always come back off..

copper nuts, and regular steel studs (with copious amounts of high-temp anti-seize) is the way to go..

the copper plated nuts dont turn green unless you touch them, or leave them exposed to salt air for too long.. when they are on a car, i defy you to tell me that they turn green?

[ABA Scirocco]

STAINLESS IS WEAKER THAN NORMAL STEEL!!

stainless exhaust hardware just SCREAMS bad idea to me..

the only time you should use a stainless bolt over a rregular steel bolt, is when you need corrosion protection..

stainless at the exhaust manifold has got to be the worst idea ive ever heard..

I would agree with you IF exhaust manifold studs were a highly stressed component but on a street driven car, they're simply not, 8- new M8 fasteners of any grade would be plenty strong enough to secure an exhaust manifold and corrosion is very likely the only thing that would cause them to fail. I'd say stainless steel studs with stainless steel washers and copper plated nuts are an ideal choice to secure the manifold to the cylinder head unless perhaps you happen to be running a turbo with very high boost.

The studs that hold the down pipe to the exhaust manifold get a LOT more heat and vibration, I'm a little more circumspect about using stainless steel studs there.