Hi,

I have removed old nuts and cleared the threads of the old studs, they look fine to me, but some users reported snapping them when installing the new exhaust.

So for you here who have done this professionally or at least done more than 10 exhaust swaps on 911 turbos.

Do I really have to change the studs?

I have 10 studs ordered so that isnt the issue, I just want to know if the need replacement or not, I am aware that recommending to change them is a "safe" bet.

But after looking at the old studs I get the feeling that, trying to remove them might not be as easy as I would like to, it "feels" like removing them is a bigger risk than re-using them...

 

There is no right or wrong answer here. If the engine is still in the car I would suggest to leave them alone. If they look good to the eye then leave them. Often taking them out causes a bigger issue. If you are concerned still I suggest you find a steel spacer the thickness of the Exhaust manifold flange and test torque each stud, carefully. Use some anti friction grease as well. This way if any stud was to fail, it would without having to remove the whole Exhaust manifold.

 

Thanks, good advice on the test!

What is the torque in Nm for those?

 

8.00mm stud in Aluminum should be 18 FT/Lbs, 24.5 Nm. Use some anti Friction grease and start with less Torque and gradually go up to the final value. Go slow and deliberate. You do not want any to break. Make sure the threads are clean and the Nuts you are using are in the same condition. Use a plain nut(s) to do the test as I think the nuts used on the exhaust may have integral locking.

 

Planing to use bmw copper nuts (also locking) and cheramic grease (think its stable up to 1400ºC).

Thanks for the torque values and help!

 

Your welcome.

 

End result!

 

Are you sure the stud is aluminum?

 

What is the advantage of the BMW copper nuts vs the OEM Porsche ones? What BMW car are these off of and do you have a part number?

Thanks

 

He said the stud was "in" aluminum...he did not say the stud itself is aluminum

 

Thanks for pointing that out...misread.

 

The oem Porsche ones rust (badly) and have a "locking" feature making them pretty hard to get off. I dont know which model uses them, its a exhaust manifold nut.

 

I dont know why alu is mentioned, the turbo exhaust housing isnt alu nor is the nuts or the exhaust, only steel present....

 

Dissimilar metal corrosion is as natural as aging. Simply put, it is an electrochemical process that destroys metal, reducing its thickness and strength.

When dissimilar metals are in contact with an electrolyte - usually water from rain or condensation, or from sources like airborne particulates,dirt, and oil, an electrochemical reaction takes place that permits electron flow from one dissimilar metal to the other. By products of corrosion - sulfates, oxides, or hydroxides - take the place of the original material, although these byproducts may be carried away by the electrolyte.

Dissimilar metals such as steel and aluminum are most prone to corrosion, however corrosion can also occur in the presence of only one type of metal as well.

Bottom line is steel and aluminum are most prone to corrosion, while copper is still prone to a lesser degree.

 

And in winter the roads are salted creating horrible conditions for the exhaust nuts on our cars...