EPIC nuts/studs loosening thread (reposting stupid stuff without reading = warning)
07-23-2009, 01:01 PM
#381
Spring washers effectively become... ineffective once the torque on the stud is reached. I think its a combination of problems.
One is that the studs are loaded to their torque maximums. This means the stud is stretched as far as it will reasonably go without plastic deformation. When they heat up two things happen. The maximum torque load allowable goes way down because tensile load is a function of temperature, and simultaneously the stud is stretched by the expanding steel under thermal stress. When the stud stretches it goes past the allowable load, and quickly into the region where the stud is permanently lengthened known as a plastic deformation. This happens over a 50-60 cycles, and suddenly... your **** is loose. So what do people do?? Go buy bigger studs, harder hardware, and torque the crap out of it, only to have it happen all over again, because (expanding steel)>(bolt) even when using adamantium.
Solution: Use a gripper washer, something with teeth, good hardware, and don't torque it to the limit. You might also try using a metal which expands at a different rate for a washer. Like copper, brass, or aluminum. Just make sure you don't make solder on your exhaust manifold by using something that will melt when used on the exhaust manifold. This other metal will help to take up the thermal expansion that the stud would normally be singularly subjected to.
One is that the studs are loaded to their torque maximums. This means the stud is stretched as far as it will reasonably go without plastic deformation. When they heat up two things happen. The maximum torque load allowable goes way down because tensile load is a function of temperature, and simultaneously the stud is stretched by the expanding steel under thermal stress. When the stud stretches it goes past the allowable load, and quickly into the region where the stud is permanently lengthened known as a plastic deformation. This happens over a 50-60 cycles, and suddenly... your **** is loose. So what do people do?? Go buy bigger studs, harder hardware, and torque the crap out of it, only to have it happen all over again, because (expanding steel)>(bolt) even when using adamantium.
Solution: Use a gripper washer, something with teeth, good hardware, and don't torque it to the limit. You might also try using a metal which expands at a different rate for a washer. Like copper, brass, or aluminum. Just make sure you don't make solder on your exhaust manifold by using something that will melt when used on the exhaust manifold. This other metal will help to take up the thermal expansion that the stud would normally be singularly subjected to.
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07-23-2009, 01:15 PM
#382
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Stein,
I think you might be onto something. It says here:
Belleville washer - Wikipedia, the free encyclopedia that they are used "where they aid locking a joint that experiences a large amount of thermal expansion and contraction. They will supply the required pre-load, but the bolt may have an additional locking mechanism (like Loctite) that would fail without the Belleville."
Actually they would prevent the stretch of the studs if you didn't overtighten the nuts. The flanges would expand and the belleville washers would deflect to take up the expansion and then keep things snug enough with pre-load to prevent leaks when cool.
Edit: The trick is not to tighten the nuts so much that the belleville washer is flattened out completely. I think that is what Travis missed on the idea.
I think you might be onto something. It says here:
Belleville washer - Wikipedia, the free encyclopedia that they are used "where they aid locking a joint that experiences a large amount of thermal expansion and contraction. They will supply the required pre-load, but the bolt may have an additional locking mechanism (like Loctite) that would fail without the Belleville."
Actually they would prevent the stretch of the studs if you didn't overtighten the nuts. The flanges would expand and the belleville washers would deflect to take up the expansion and then keep things snug enough with pre-load to prevent leaks when cool.
Edit: The trick is not to tighten the nuts so much that the belleville washer is flattened out completely. I think that is what Travis missed on the idea.
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07-23-2009, 01:21 PM
#383
Spring washers effectively become... ineffective once the torque on the stud is reached. I think its a combination of problems.
Solution: Use a gripper washer, something with teeth, good hardware, and don't torque it to the limit. You might also try using a metal which expands at a different rate for a washer. Like copper, brass, or aluminum. Just make sure you don't make solder on your exhaust manifold by using something that will melt when used on the exhaust manifold. This other metal will help to take up the thermal expansion that the stud would normally be singularly subjected to.
Solution: Use a gripper washer, something with teeth, good hardware, and don't torque it to the limit. You might also try using a metal which expands at a different rate for a washer. Like copper, brass, or aluminum. Just make sure you don't make solder on your exhaust manifold by using something that will melt when used on the exhaust manifold. This other metal will help to take up the thermal expansion that the stud would normally be singularly subjected to.
I like the belleville washer idea. I might head over to fastenal to pick some up.
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07-23-2009, 01:29 PM
#384
One is that the studs are loaded to their torque maximums. This means the stud is stretched as far as it will reasonably go without plastic deformation. When they heat up two things happen. The maximum torque load allowable goes way down because tensile load is a function of temperature, and simultaneously the stud is stretched by the expanding steel under thermal stress. When the stud stretches it goes past the allowable load, and quickly into the region where the stud is permanently lengthened known as a plastic deformation. This happens over a 50-60 cycles, and suddenly... your **** is loose. .
AFTER the stud is permanently lengthened (after 50-60 cycles), tack weld it ?
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07-23-2009, 01:32 PM
#385
http://ntrs.nasa.gov/archive/nasa/ca...1990009424.pdf
Goto page 15/104
You will be completely bottoming those washers under any torque you put on an 8mm. At 50% preload thats 4000lbs according to:Bolt Preload Calculation - Engineers Edge
I didn't run it by hand or check the constants, but I imagine its within reason.
Also from eng-tips a well respected site: http://www.eng-tips.com/viewthread.c...=231027&page=2
belleville's will be ineffective
Goto page 15/104
You will be completely bottoming those washers under any torque you put on an 8mm. At 50% preload thats 4000lbs according to:Bolt Preload Calculation - Engineers Edge
I didn't run it by hand or check the constants, but I imagine its within reason.
Also from eng-tips a well respected site: http://www.eng-tips.com/viewthread.c...=231027&page=2
belleville's will be ineffective
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07-23-2009, 01:42 PM
#386
There is another solution I had not thought of until just now. Use a longer bolt with a large spacer. This will effectively increase the distance the bolt stretches per tensile load. So with the longer bolt/stud you get more allowable stretch from a fixed amount of thermal expansion. Short fat bolts/studs are the worst with thermal expansion because the joint is so tight.
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07-23-2009, 01:46 PM
#388
http://ntrs.nasa.gov/archive/nasa/ca...1990009424.pdf
Goto page 15/104
You will be completely bottoming those washers under any torque you put on an 8mm. At 50% preload thats 4000lbs according to:Bolt Preload Calculation - Engineers Edge
I didn't run it by hand or check the constants, but I imagine its within reason.
Also from eng-tips a well respected site: Automotive Engineering other topics - Bellville Lock Washer
belleville's will be ineffective
Goto page 15/104
You will be completely bottoming those washers under any torque you put on an 8mm. At 50% preload thats 4000lbs according to:Bolt Preload Calculation - Engineers Edge
I didn't run it by hand or check the constants, but I imagine its within reason.
Also from eng-tips a well respected site: Automotive Engineering other topics - Bellville Lock Washer
belleville's will be ineffective
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07-23-2009, 01:52 PM
#390
http://ntrs.nasa.gov/archive/nasa/ca...1990009424.pdf
Goto page 15/104
You will be completely bottoming those washers under any torque you put on an 8mm. At 50% preload thats 4000lbs according to:Bolt Preload Calculation - Engineers Edge
I didn't run it by hand or check the constants, but I imagine its within reason.
Also from eng-tips a well respected site: Automotive Engineering other topics - Bellville Lock Washer
belleville's will be ineffective
Goto page 15/104
You will be completely bottoming those washers under any torque you put on an 8mm. At 50% preload thats 4000lbs according to:Bolt Preload Calculation - Engineers Edge
I didn't run it by hand or check the constants, but I imagine its within reason.
Also from eng-tips a well respected site: Automotive Engineering other topics - Bellville Lock Washer
belleville's will be ineffective
I have no patience to decipher the bolt preload calculator.
Eng-tips guy was looking for a locking device.
I think we're talking about two different things here. At this point I'm not looking for a locking device, I'm looking for a device that will only compensate for thermal expansion. If the preload is insufficient using one washer, they can be stacked.
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07-23-2009, 01:54 PM
#392
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There is another solution I had not thought of until just now. Use a longer bolt with a large spacer. This will effectively increase the distance the bolt stretches per tensile load. So with the longer bolt/stud you get more allowable stretch from a fixed amount of thermal expansion. Short fat bolts/studs are the worst with thermal expansion because the joint is so tight.
ding ding ding we have a winner. this is how it's done on large pressure vessels.
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07-23-2009, 01:55 PM
#393
Hey I got no dog is this battle, just throwing out opinions.
If you stack 4 of those on there, and they are flat from preload then they are going to act like one big hunk of steel putting the load right back on the stud. Mise well have skipped the washers and bolted it straight to the flange.
If you stack 4 of those on there, and they are flat from preload then they are going to act like one big hunk of steel putting the load right back on the stud. Mise well have skipped the washers and bolted it straight to the flange.
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07-23-2009, 02:00 PM
#397
How much does the assembly weigh? 50 lbs? At 1 foot from the head? Seems like a couple triangles could get that figured out...
I'd like to know that as well... Seems like I don't really have any coefficient of spring to temperature curves handy.
What temperature do those studs get to anyways?
I'd like to know that as well... Seems like I don't really have any coefficient of spring to temperature curves handy.
What temperature do those studs get to anyways?
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07-23-2009, 02:09 PM
#398
Those studs look small.
Look - its what I said before - if the stud doesn't break, it doesn't stretch, and the nut doesn't turn, it's working. If these are working for street use, but too weak for the track, the 50% increase in strength from size will help a lot. Pick up a bit more from good material, and there's your answer. You never see a railroad car assembled with REALLY FANCY lock nuts on 1/4" screws, do you? :-)
Just curious what size they are - in the video they looked smaller but you went bigger later, right? Have you tried tieing them when using large, high quality studs?
I've seen a lot of broken manifolds which stop breaking when they are braced. Not sure how much this would help the studs, but it's worth doing if you don't have something mechanically robust. Just keep in mind you're now moving one end from heat expansion, and holding the other end still so there needs to be room for that flexing.
Look - its what I said before - if the stud doesn't break, it doesn't stretch, and the nut doesn't turn, it's working. If these are working for street use, but too weak for the track, the 50% increase in strength from size will help a lot. Pick up a bit more from good material, and there's your answer. You never see a railroad car assembled with REALLY FANCY lock nuts on 1/4" screws, do you? :-)
Just curious what size they are - in the video they looked smaller but you went bigger later, right? Have you tried tieing them when using large, high quality studs?
has anyone considering a hard mount on the exhaust to the trans? I know it fails on the greddy kit, but I've discovered a lot of front/rear movement when the turbo parts are out. This is definitely a MAJOR binding stress on the turbo parts which aren't welded together and cast iron or studs don't like to flex.
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07-23-2009, 02:15 PM
#399
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Long bolts and springs like this have been used for manifold to downpipe connections for years, but there is no room for a bolt or stud this long on a turbo flange. Totally worthless to us, but maintains tension to keep a seal and allows for expansion. But the belleville washer won't require nearly as much space to work correctly. Again, you don't want torque it until you flatten it out. It would be useless at that point.
I can tell you what they use on large turbo diesel engines that I sell, but you don't want to hear it.
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07-23-2009, 02:19 PM
#400
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@Hustler: forget grade 8, please get stainless 304L studs. Im having made a few sets (M10x1.5 and M8x1.25) and may have some sets left to send out for testing in 2/3 weeks.
To all others: we're stretching studs due to wrong material. They not only stretch but become brittle. They look 'burned' and loose their strength. No spring washed, spring, Resbond of magic is going to fix that - we need to find the right material. Also, we need to look less into magic fasteners, and more into practical simple proven solutions that work on other tracked turbo cars - aside from v-bands.
I am now testing 304L stainless studs (M10x1.5) in ~40mm length. I will see if I can fit more inside the manifold. Travis makes a point on longer stud material, but there is simply very little room on the outside of the manifold, maybe 5mm more or it will hit the turbine housing. 5mm vs 40mm is only a 12% increase. I don't think a 12% increase in 'stretch resistance' is worth the effort. I'd be breaking them 30mins later during a track day.
If 304L doesnt hold up long enough - I dont reminder replacing them yearly. Next up is getting A286*, then Inconel, then v-bands.
*) if I can get them for a reasonable price in a reasonable time.
Someone, please edit the first post of this thread and clear up all bull ****. PLEASE.
To all others: we're stretching studs due to wrong material. They not only stretch but become brittle. They look 'burned' and loose their strength. No spring washed, spring, Resbond of magic is going to fix that - we need to find the right material. Also, we need to look less into magic fasteners, and more into practical simple proven solutions that work on other tracked turbo cars - aside from v-bands.
As steel rises in temperature it reaches a point, about 1400° F. (red heat), called the absorption point, at which it absorbs a perceptible amount of heat before its temperature again increases. Likewise, having been raised above the adsorption point and allowed to cool slowly, it reaches a temperature about 50° F. below the absorption point where it seems to give out more heat than is accounted for by loss of temperature. Its glow shows an increase of brightness if observed in a dark room. This is the recalescence point. Both of these points are known as critical points.
Heating to the absorption point brings the grain of steel to its finest texture. The higher the heating beyond this point and the lower the carbon, the larger the resulting crystals upon cooling. This may be seen, in many cases, by examining fractured specimens with the unaided eye. This enlargement of crystals reduces strength, hence the size of crystals is a visible sign indicating strength. The smallest crystals may be restored in high-carbon steel by heating it to the absorption point. It may then be cooled slowly or suddenly without change of grain.
Steel need never be heated above its absorption point except to have it amply hot for shaping in a single heat. If high-carbon steel is heated much above the absorption point, its strength is injured, its fracture looks dull, and it is said to be "burned." Such a condition may be impossible to remedy. However, low-carbon steel escapes injury at high heats in most instances, but becomes brittle if heated repeatedly below 1650° F. It is restored to its elasticity if heated above 1G50° F.
The crystalline structure of a piece of steel as affected by heat is determined by the five conditions as follows:
(1) Temperature, (2) duration of heating, (3) mass, (4) rapidity of cooling, and (5) whether or not steel cools without being rolled, hammered, or otherwise subjected to pressure or impact.
The presence of nickel, tungsten and other metals used to produce alloy steels have a marked effect upon the critical points of steel. These points are lowered, and the presence of the alloying metals seems to accomplish this by their influence upon the carbon which the steel contains.
Heating to the absorption point brings the grain of steel to its finest texture. The higher the heating beyond this point and the lower the carbon, the larger the resulting crystals upon cooling. This may be seen, in many cases, by examining fractured specimens with the unaided eye. This enlargement of crystals reduces strength, hence the size of crystals is a visible sign indicating strength. The smallest crystals may be restored in high-carbon steel by heating it to the absorption point. It may then be cooled slowly or suddenly without change of grain.
Steel need never be heated above its absorption point except to have it amply hot for shaping in a single heat. If high-carbon steel is heated much above the absorption point, its strength is injured, its fracture looks dull, and it is said to be "burned." Such a condition may be impossible to remedy. However, low-carbon steel escapes injury at high heats in most instances, but becomes brittle if heated repeatedly below 1650° F. It is restored to its elasticity if heated above 1G50° F.
The crystalline structure of a piece of steel as affected by heat is determined by the five conditions as follows:
(1) Temperature, (2) duration of heating, (3) mass, (4) rapidity of cooling, and (5) whether or not steel cools without being rolled, hammered, or otherwise subjected to pressure or impact.
The presence of nickel, tungsten and other metals used to produce alloy steels have a marked effect upon the critical points of steel. These points are lowered, and the presence of the alloying metals seems to accomplish this by their influence upon the carbon which the steel contains.
If 304L doesnt hold up long enough - I dont reminder replacing them yearly. Next up is getting A286*, then Inconel, then v-bands.
*) if I can get them for a reasonable price in a reasonable time.
Someone, please edit the first post of this thread and clear up all bull ****. PLEASE.
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