Exhaust Stud Tightness Question?
- Thread starter Hoople
- Start date
Hoop,
I think this is normal and expected. I no longer use a torque wrench on the exhaust header nuts (is this blasphamy?), but rather use the "double grunt" method grabbing the "head" of the ratchet only and just using wrist to tighten. After the first run cool down, I reapply penetrating oil and retighten same way.
I think the fact that the aluminum and steel of the head and pipes are expanding differently then the lead/wire mesh gaskets as all that heats up is what leads to the repeating retorque since once the aluminum and steel cool, they contract away from eachother. But as soon as the next heat cycle starts, they expand and reseal very quickly. If you are worried about it, you can double nut the studs to ensure that they won't back off, but I have never had that problem.
As long as you don't have a leak, after the second "retorquing" I would not worry about it.
Having said all that, I did change from the HD lead/wire mesh gaskets to the Cometic C9540 Exhaust Gasket All Models 99 -UP "EXTREME PERFORMANCE". I like these a lot better.
TQ
I think this is normal and expected. I no longer use a torque wrench on the exhaust header nuts (is this blasphamy?), but rather use the "double grunt" method grabbing the "head" of the ratchet only and just using wrist to tighten. After the first run cool down, I reapply penetrating oil and retighten same way.
I think the fact that the aluminum and steel of the head and pipes are expanding differently then the lead/wire mesh gaskets as all that heats up is what leads to the repeating retorque since once the aluminum and steel cool, they contract away from eachother. But as soon as the next heat cycle starts, they expand and reseal very quickly. If you are worried about it, you can double nut the studs to ensure that they won't back off, but I have never had that problem.
As long as you don't have a leak, after the second "retorquing" I would not worry about it.
Having said all that, I did change from the HD lead/wire mesh gaskets to the Cometic C9540 Exhaust Gasket All Models 99 -UP "EXTREME PERFORMANCE". I like these a lot better.
TQ
Hoople
Account Removed
That's just it, I am not sure what it is doing. After riding the bike hard for just 1 single time, I can go back and tighten all 4 nuts 1 more time before the torque wrench clicks off at 120 in /lbs.
Granted they don't tighten much, maybe 1 flat or 60* of a complete turn, but they do rotate and they do tighten up a little bit. That just seemed strange to me. After about the 10th time of tightening them, I thought I would post a thread and ask.
With all the recent exhaust "popping" questions I have read, I wanted my header pipes not leaking and focused in on the gaskets/seals probably to an extreme.
TQ, What you say does make total sense. I am going to double nut it and leave it alone. As usual, I find myself getting carried away and fixated on something. Appreciate all the advice.
BUBBIE
Well-Known Member
Hoople, I have had my exhaust off and on many times recently as you may know, from all the apart and together I have done trying to find a problem in my Oil system... I will keep this Tightness in mind when It comes apart and together again.... I don't use a torque wrench when I do My exhaust..
I have found that once tightened and started for a Heat cycle and allowed to cooled and tightened once more, I QUIT there and don't touch again.. Put the heat-shields on and done. It never seems to leak doing it this way..
signed....BUBBIE
I have found that once tightened and started for a Heat cycle and allowed to cooled and tightened once more, I QUIT there and don't touch again.. Put the heat-shields on and done. It never seems to leak doing it this way..
signed....BUBBIE
Hoople
Account Removed
I am only rechecking the torque once the pipes are cool. (they sat overnight/cool to touch)
I am also using the upper torque value which may not be the best thing to do. The range is 100-120 inch-lbs. If I use the 100 inch range (8.3 ft lbs instead of 10.0) maybe the wrench would click off (?)
I am also using the upper torque value which may not be the best thing to do. The range is 100-120 inch-lbs. If I use the 100 inch range (8.3 ft lbs instead of 10.0) maybe the wrench would click off (?)
I doubt it, because each time you run the engine up to operating temp. (or not even that since your heads and pipes get HOT faster) and the metals expand, you are crushing your gasket due to that expansion. Once the heads and the pipes cool back off, they will contract, but the crush gasket will not expand back out much if at all, giving you the ability to snug back up to compensate for the amount that the gasket was deformed during the heat cycle.
Again, after the second "snugging" retorque, you should not need to fiddle with it any more (as long as there are no leaks at this stage) since the heads and the pipes will expand on each subsequent heat cycle to seal the exhaust flow. With gas temps over 1,000 degF, this doesn't take long!!
TQ
"Again, after the second "snugging" retorque, you should not need to fiddle with it any more (as long as there are no leaks at this stage) since the heads and the pipes will expand on each subsequent heat cycle to seal the exhaust flow. With gas temps over 1,000 degF, this doesn't take long!!"
TQ[/QUOTE]
I have to agree with this statement! Retorquing after each heat/cool cycle would be a bad thing,IMO, unless you have leaks. By the way, what is the range of the torque wrench you are using? I've been told that you should only use a torque wrench from 20-90% of the range.
TQ[/QUOTE]
I have to agree with this statement! Retorquing after each heat/cool cycle would be a bad thing,IMO, unless you have leaks. By the way, what is the range of the torque wrench you are using? I've been told that you should only use a torque wrench from 20-90% of the range.
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RibEye
Senior Member
Hoop,
I think this is normal. I believe that what is happening is that the mesh seals are displacing and working in. Each time you heat and run there is some vibration and toque loss (not interface loosening), due to the nature of the mesh. It is only slightly compliant, and will not come back once displaced. I believe if you continue, you will displace and crush the available compliance out of the seals and develop a leak over time.
The torque is not expected to remain so high, it is to initially crush and conform the seals to match the mating surfaces and seals. The manual says to torque them once, ride to full temp, let cool and repeat...once. The seals should then be mated to the surfaces to seal, retaining some minimal compliance.
If you are concerned about loosening from where they are, double-nut, to keep them where they are now. You shuold be good, unless the new seals have been over-crushed already.
I had concerns with my new SE seals, as I put them in, that they would not stay tight (nature of a fine wire mesh). It might be my nature to over-think things, but I these thoughts are what I came up with, and so far so good.
Enjoy,
Rich P
Took me too long to post, and others came to similar concusions. Like minds and such.
As you were,
Rich P
I think this is normal. I believe that what is happening is that the mesh seals are displacing and working in. Each time you heat and run there is some vibration and toque loss (not interface loosening), due to the nature of the mesh. It is only slightly compliant, and will not come back once displaced. I believe if you continue, you will displace and crush the available compliance out of the seals and develop a leak over time.
The torque is not expected to remain so high, it is to initially crush and conform the seals to match the mating surfaces and seals. The manual says to torque them once, ride to full temp, let cool and repeat...once. The seals should then be mated to the surfaces to seal, retaining some minimal compliance.
If you are concerned about loosening from where they are, double-nut, to keep them where they are now. You shuold be good, unless the new seals have been over-crushed already.
I had concerns with my new SE seals, as I put them in, that they would not stay tight (nature of a fine wire mesh). It might be my nature to over-think things, but I these thoughts are what I came up with, and so far so good.
Enjoy,
Rich P
Took me too long to post, and others came to similar concusions. Like minds and such.
As you were,
Rich P
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Hoople
Account Removed
There does not appear to be any exhaust leaks. The range of the torque wrench is 25-250 in lbs, so I should be somewhat in the sweet spot.
At this point I will double nut it and leave it alone to see what happens. I hope I didn't do any damage to the header pipe flared end or SS mesh gasket.
Great replies that all make sense. I was just too focused and could not let go. Tks!
At this point I will double nut it and leave it alone to see what happens. I hope I didn't do any damage to the header pipe flared end or SS mesh gasket.
Great replies that all make sense. I was just too focused and could not let go. Tks!