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.
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
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.
Last edited by ABA Scirocco; 02-06-2011 at 10:42 AM.
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.
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).
Working on Shell #4 with 14 donor cars scavenged for parts.
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
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.
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?
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.
I agree completely with the above. DO NOT USE STAINLESS NUTS! If it is a stud, go with the factory stud (for strength), and copper clad deformed thread nuts with lots of anti-seize compound and you will have no problems. Stainless due to its nature can seize. I had case once where I hand screwed a stainless nut on a stainless bolt, and it seized at room temperature in just a few minutes. It took a wrench to remove the nut, and the threads were ruined. VW knows what they are doing here. The whole exhaust system is stainless, so if stainless nuts were better, then VW would have used them.
An aside: I found one of the nuts on the flange between my Touareg's DPF and Cat not tightened all the way (1/4" gap) causing a slight exhaust leak. I tried to tighten it up but the stud broke off. I removed the DPF to replace the stud. What I found was that the dealer replaced the CAT at one time and used steel nuts instead of the copper clad nuts. These destroyed the studs. The copper clad nuts on the other end (which the dealer didn't touch) came off with no issues.
My experience is that about 40% of the time, the dealer will make an error. That is better than allot of other shops, and they have more accountability so I continue to go to the dealer but check their work.
Say what you want with stainless but not all grades are the same. If you used a stainless nut and stud and it seized hand tight, you did not use the right stainless. Probably more like Chinesium stainless.
I've twisted wrenches far longer than most here. The best hardware is not cheap. I know Mercedes used a stainless stud/nuts on their older 617 turbo diesel engines and they were seriously expensive. They rarely seized at all. I used to do a lot of trap replacements and I know. What really sucked about their hardware is if you dropped it, it was hell to get out out of a tight space. Magnets were not any help.
When it comes to antiseize, the nickle stuff is by far the best. Most people stick with the copper, that is a waste of money as far as I'm concerned.
Not certain why you wanted to bring this back from the dead.