Replace Head Studs?
Thread Starter
Former Vendor
Joined: Feb 2005
Posts: 15,228
Likes: 2,530
From: Anaheim
Thanks for your input Greg,
I found that when backing them off 90 deg and re-torquing them, that after a couple times they did not turn further and gain degrees turned indicating that the gasket was at full compression.
Brendan,
I agree, I took two days to do the last motor I did.
I found that when backing them off 90 deg and re-torquing them, that after a couple times they did not turn further and gain degrees turned indicating that the gasket was at full compression.
Brendan,
I agree, I took two days to do the last motor I did.
Rennlist Member
Joined: Nov 2009
Posts: 8,659
Likes: 426
From: Dubuque, IA
So does the wait a day, back off and re torque (by angle) apply to the 32v cars as well? Or is this just a stud question. I'll be putting my engine together this weekend and want to know if is should just do the 20nm then 90, 90 or should I back off after the last 90 a day later and re torque to the 90 again? Manual doesn't say this.
Nordschleife Master
Joined: Apr 2003
Posts: 9,601
Likes: 39
From: Abbotsford B.C.
Jeffrey,
No, you cannot retorque by angle without backing them all the way off and starting again.
So when using the bolts I would use the factory angle method. Or convert to studs (Simard??), and do something similar.
No, you cannot retorque by angle without backing them all the way off and starting again.
So when using the bolts I would use the factory angle method. Or convert to studs (Simard??), and do something similar.
Thread Starter
Former Vendor
Joined: Feb 2005
Posts: 15,228
Likes: 2,530
From: Anaheim
I love this!
This is what Rennlist should be about. People helping people with these cars we love.
Not everyone has every answer...not everyone is always going to be correct in how they do things.
Colin stepped up here, shared his method for everyone to see. Makes total sense and solves almost any problems anyone could be having with studs.
That's classy!
This is what Rennlist should be about. People helping people with these cars we love.
Not everyone has every answer...not everyone is always going to be correct in how they do things.
Colin stepped up here, shared his method for everyone to see. Makes total sense and solves almost any problems anyone could be having with studs.
That's classy!
Rennlist Member
Joined: May 2010
Posts: 48
Likes: 0
From: GREECE
HELI-COIL
I would say studs everytime, irrespective of wether they are designed to yield or not and wether they are replaced every time or not.
For one reason. Studs are screwed into the block with no load on them. Bolts are screwed into the block with load on them. There is lots of chance that the bolt threads could gall against the alu threads in the block while being tightened and damage the threads in the block = mucho problemo.
For one reason. Studs are screwed into the block with no load on them. Bolts are screwed into the block with load on them. There is lots of chance that the bolt threads could gall against the alu threads in the block while being tightened and damage the threads in the block = mucho problemo.
Thread Starter
Former Vendor
Joined: Feb 2005
Posts: 15,228
Likes: 2,530
From: Anaheim
And I'm told that there is a particular BMW model that requires inserts if the head is ever removed. I don't work on these cars, so I'm not familiar with the model that is involved, but this is very common knowledge, in the BMW crowd.
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Nordschleife Master
Joined: Jul 2003
Posts: 7,743
Likes: 78
From: Minneapolis
Not the studs themselves. It's the way they're installed.
Studs can be run all the way into the holes. Good to back them off a bit so the tips aren't touching, though.
Tightening bolts wears on the threads in the block. Those can get heli-coils but it's work. The Al has to hold the strain eventually and a stud doesn't work better with a helicoil.
With the studs sticking out you can also get better torque results as the cleanliness and lube condition is much easier to control.
Studs can be run all the way into the holes. Good to back them off a bit so the tips aren't touching, though.
Tightening bolts wears on the threads in the block. Those can get heli-coils but it's work. The Al has to hold the strain eventually and a stud doesn't work better with a helicoil.
With the studs sticking out you can also get better torque results as the cleanliness and lube condition is much easier to control.
Team Owner
Joined: May 2004
Posts: 31,239
Likes: 4,223
From: Philly PA
I just put my 85 Euro 16V back together and used the suggested way by Colin it worked out well
first the 20NM then 2 X 90 degrees.
I waited a few hours then 1/4 turn loose,
then torqued to 67 ft lbs ,
all of the nuts went back to the original 2nd 90 mark that I made with a marker
first the 20NM then 2 X 90 degrees.
I waited a few hours then 1/4 turn loose,
then torqued to 67 ft lbs ,
all of the nuts went back to the original 2nd 90 mark that I made with a marker
Rennlist Member
Joined: Feb 2003
Posts: 29,828
Likes: 218
From: saratoga, ca
I just put my 85 Euro 16V back together and used the suggested way by Colin it worked out well
first the 20NM then 2 X 90 degrees.
I waited a few hours then 1/4 turn loose,
then torqued to 67 ft lbs ,
all of the nuts went back to the original 2nd 90 mark that I made with a marker
first the 20NM then 2 X 90 degrees.
I waited a few hours then 1/4 turn loose,
then torqued to 67 ft lbs ,
all of the nuts went back to the original 2nd 90 mark that I made with a marker
As i mentioned a few years ago on this thread, Bill and I did the angle torque method and with the cometic gaskets, the resulting torque was almost hand tight (exaggeration) when it settled in. we re -did it and verified the re-angle torquing method actually had near 80ft-lbs of torque the second time around... engine has been running for 8 years now and no issues, so i guess that worked.
i still am puzzled with the angle torque method.. seems if you dont have new hardware, that final value is going to be way off.
I guess the hybrid method that Colin found makes more sense, as you end up at the same torques and you get there in a safe way too.
Addict
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Rennlist Member
Joined: Sep 2010
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From: Boulder Creek, CA
IIRC...studs are better...
Because the stud threads go into the block relaxed..which is important..
As you tighten the nut..the stud distributes force better along more threads, but the nut...is more efficient because only about 6 threads of a bolt or a nut when torque is allied to it, do anything.
Past 6 threads, there is almost no grip at all.
A long bolt as you tighten it, grips no more than the nut.
Read that in an engineering book a long time ago...
Because the stud threads go into the block relaxed..which is important..
As you tighten the nut..the stud distributes force better along more threads, but the nut...is more efficient because only about 6 threads of a bolt or a nut when torque is allied to it, do anything.
Past 6 threads, there is almost no grip at all.
A long bolt as you tighten it, grips no more than the nut.
Read that in an engineering book a long time ago...