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Discussion Starter · #1 ·
I have read everything I could find about the exhaust studs, and only confused myself even more.

I bought 8 new studs and 8 new nuts from Bob's yesterday, and they are ready to go in.

* Do I use anti-seize, oil, or anything at all on the stud, specifically the part that threads into head? (all recommendations I have seen)

* Or, do I use threadlocker, loctite, etc, on the stud to keep it from ever coming out again? (seen these recommendations as well, in contrast to the above)

* Do I bottom out the stud in head? (some say yes, some say no and to leave a gap.)

* I know about the 22nm or 16ftlb torque, but that is listed for the nut, not the stud itself, so that is my biggest question. If I obviously thread the stud into engine first, I need to know what kind of torque I'm using. Clymer manual says on page 258, step 13 e. "If a stud was removed from the cylinder head, separate the stud and nut and reinstall the stud into the cylinder head. Refer to Service Methods in Chapter One." Pg 20, in Service Methods, under Stud Removal/Installation, says use threadlocking compound, and step 8 says "Install the stud to the height noted in Step 1 or its torque specification." I didn't measure the height, and they were all not the same anyway before I took them out.

Ironically, the copper plated nuts (plated to prevent seizing) I attempted to remove were fused with the stud and the clean, dry stud threads in the cylinder head slid out with minimal effort.

Any and all advice, tips, thoughts, etc are welcome. Please stop me before I just use my impact wrench to seat these things. (I will record video for that if it happens)

Thanks
 

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I use Anti-Seize on both ends of the stud. If your installing new copper sealing rings you can use grease to hold them up in the head. You will need to retorque the nuts several times waiting a little between retorquing.
 

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I like using anti seize on both ends but I would reduce the nut torque by at least 15% (about 14 ft/lbs) due to the lube effect of the anti seize on the nut torque. I would also install the studs using to regular nuts locked together and use that to insert the stud to bottom and tighten slightly to about ten foot lbs.
Take a few moments to read on the web about effects of lube on a bolt. The BMW manual calls out whether to add loctite and what type when needed. A few locations get anti seize, mostly on bolt shanks though and in some cases the outer heads of allen bolts that have no knurling and are intended to move or have something around them move. (bolts that hold shocks comes to mind like the bottom bolt on the front shock of K1200RS.
 

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Discussion Starter · #4 ·
Thanks guys. I used anti seize. I don't see it being a big deal if stud comes out. Only problem I have now is that studs are in a little too far. I didn't put any significant torque on them, just tightened till the doubled up nuts started to spin.
After torquing nut down, the top (bottom) of nut is flush with end of stud. The ones I took off had a few threads exposed, giving the split in the lock nut more room to work I'm guessing. Not going to take it all apart though, I'll see what happens and re-tourque later.
Used grease for the gaskets also, worked great.
 

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Be careful if you are using the Clymer manual torque specs as they ARE INCORRECT. They are printed at 44 Ft Lbs but if you do the coinversion from the NM, you come up with 16 Ft Lbs. I almost stripped out all my exhaust bolts trying to get them to 44 Ft Lbs.
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I have read everything I could find about the exhaust studs, and only confused myself even more.

I bought 8 new studs and 8 new nuts from Bob's yesterday, and they are ready to go in.

* Do I use anti-seize, oil, or anything at all on the stud, specifically the part that threads into head? (all recommendations I have seen)

* Or, do I use threadlocker, loctite, etc, on the stud to keep it from ever coming out again? (seen these recommendations as well, in contrast to the above)

* Do I bottom out the stud in head? (some say yes, some say no and to leave a gap.)

* I know about the 22nm or 16ftlb torque, but that is listed for the nut, not the stud itself, so that is my biggest question. If I obviously thread the stud into engine first, I need to know what kind of torque I'm using. Clymer manual says on page 258, step 13 e. "If a stud was removed from the cylinder head, separate the stud and nut and reinstall the stud into the cylinder head. Refer to Service Methods in Chapter One." Pg 20, in Service Methods, under Stud Removal/Installation, says use threadlocking compound, and step 8 says "Install the stud to the height noted in Step 1 or its torque specification." I didn't measure the height, and they were all not the same anyway before I took them out.

Ironically, the copper plated nuts (plated to prevent seizing) I attempted to remove were fused with the stud and the clean, dry stud threads in the cylinder head slid out with minimal effort.

Any and all advice, tips, thoughts, etc are welcome. Please stop me before I just use my impact wrench to seat these things. (I will record video for that if it happens)

Thanks
Most threadlockers start getting soft around 250 degrees and generally are ineffective above 350 or so. These studs likely see temps like that now and then so thread locker is likely a waste of money. I would tend to use anti seize as others have said and back off the torque 15-20% to accommodate the loss in thread friction.
 

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Discussion Starter · #7 ·
So I went back and re-installed the studs. Out of the 8, 7 of them came out when I first pulled the exhaust to do the clutch job.

I'm attaching a pic of the studs when I installed them and they quit turning at about 10ftlbs, because the double nut would just keep spinning.
You can see in the pic the nut barely fits fully on the stud. I measured the original stud, and it sticks out 35mm, leaving a few mm of exposed threads past nut. I then measured the hole the stud goes into, and it is ~27.5 mm deep. So only about 20mm of stud is sitting in the cylinder head, with 7.5mm or so of empty space.

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Once I put anti seize on the the stud, I could finger tighten it past a depth that allows you to even get a nut onto the end of it. I backed them off to 35mm exposed, put the exhaust on, and threw the nuts on. The nuts would not fully seat on the stud, because the stud would just start screwing in instead of me being able to torque nut onto the stud. The top of nut where the split is, would not go past the first thread. In other words, the threads of the nut were barely grabbing the end of the stud before I hit 16ft lbs. So I used needle nose pliers and needle nose vice grips to grab stud in middle (on threads not going into anything) and was able to get nuts further onto stud, then torque to 16ft lbs. Second pic is after getting the nuts further onto the stud and torqueing them down.

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I didn't reduce the torque, because any less, and I can get the nut spinning off with almost no effort at all. Feels like it will just fall off before I have chance to re-torque it after running for a bit.
 

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You don't put anti seize on your stud?
 
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Sure you got the correct studs? They should be 55 mm long
 
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Discussion Starter · #12 ·
Yes, I measured, re-measured, and compared to the ones that came out. I thought maybe the end of the pipes not seated, but they match the pics I took before removing, and the old bolts also match the new ones as far as how far in they were and nut placement.
 

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Discussion Starter · #13 ·
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You can see the old one, that looks like the other ones I took out, was only seated about 20mm as well, going by unexposed end of stud. Any further into head, and no room for nut to seat on threads. I wasn't having any exhaust leaks or anything, only reason they came out was to do the clutch surgery.
 

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You did remove the old crushed copper gaskets before you installed new ones?
 
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Discussion Starter · #17 ·
I should have gone that route with the set screws, to ease my paranoia of not knowing if mine are set properly. I saw a post you made in 2019, about the M8 x 55 not being exactly 8mm, so I was hesitant to try hardware store studs requiring me to run a tap through threads on the head.
 
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