EPIC nuts/studs loosening thread (reposting stupid stuff without reading = warning)
#401
I actually went back and read the entire thread. The damage is definitely from over expanding the joint.
Is there a spacer available for the T-3 flange? a half inch there, and a couple of standard teeth washers on the otherside of that flange would lengthen up the stud quite a bit and probably fix it for good. Then torque to 30-40 percent of maximum. Use grade 5 hardware so there is some flexibility in the hardware. Grade 8 is too hard.
The spacer would be better off made of ceramic or something along those lines so that it doesn't expand.
Is there a spacer available for the T-3 flange? a half inch there, and a couple of standard teeth washers on the otherside of that flange would lengthen up the stud quite a bit and probably fix it for good. Then torque to 30-40 percent of maximum. Use grade 5 hardware so there is some flexibility in the hardware. Grade 8 is too hard.
The spacer would be better off made of ceramic or something along those lines so that it doesn't expand.
#402
What temperature do those studs get to anyways?
#403
I've seen stacked B-washers suggested before, and them written up to be used that way (I think it's Carrol Smith's book - though in the end he's always a fan of 1) get the right size/stregnth for the application, and 2) torque it right, so that you're well below yeild under the worst conditions. He's also a fan of "biting" lock washers, which is the same every single thing I've read out of NASA and MIL-specs agrees on. All forms of spring washers don't buy you much.
The large spacer idea would be good, EXCEPT: I can't even get a box end in there, it's so tight. I can't use just any old washer (when I was still using them) because it's too fat. So, if by "large spacer" you mean "something 1 or 2 threads tall" you might be onto something. :-)
The different coeff of expansion isn't a bad idea. Stacking B-washers might be the best, but I've yet to find any which hold up to temps. Really I think a big part of any answer is going to be design the turbo and collector to accommodate sensible fasteners. If you allow for big bolts, good washers, locking, etc, you might have a chance. 8mm bolts are just enough to hold it together when cold, and that gets back to the v-band thing.
I'm still curious about the 10mm-wired thing. Bracing might help - I used to lose fuel rails all the time because I'd removed the intake manifold brace, and the vibrations would kill ANYTHING I put on there. It's certainly not helping.
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.
The different coeff of expansion isn't a bad idea. Stacking B-washers might be the best, but I've yet to find any which hold up to temps. Really I think a big part of any answer is going to be design the turbo and collector to accommodate sensible fasteners. If you allow for big bolts, good washers, locking, etc, you might have a chance. 8mm bolts are just enough to hold it together when cold, and that gets back to the v-band thing.
I'm still curious about the 10mm-wired thing. Bracing might help - I used to lose fuel rails all the time because I'd removed the intake manifold brace, and the vibrations would kill ANYTHING I put on there. It's certainly not helping.
#404
a half inch there, and a couple of standard teeth washers on the otherside of that flange would lengthen up the stud quite a bit and probably fix it for good. Then torque to 30-40 percent of maximum. Use grade 5 hardware so there is some flexibility in the hardware. Grade 8 is too hard.
The spacer would be better off made of ceramic or something along those lines so that it doesn't expand.
The spacer would be better off made of ceramic or something along those lines so that it doesn't expand.
#405
I have to get back to projects, and the COP systems, but if I have time I'll run the calculations the people who manufactured these units and are supposedly all powerful should have already ran. Just from a face run. at 1200 degrees the rod would stretch an additional .006 inches to accomodate the temp, which is ALOT. It may just not be even designed correctly enough to be functional.
#408
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In that case I may effectively be testing this idea. Repeating myself here but since I have the S4 I am able to go to a through-bolted design instead of a stud. This effectively doubles the grip length of the fastener; the S4 flange is about the same thickness as the T2 flange on the Garrett. We will see if it works.
#410
In that case I may effectively be testing this idea. Repeating myself here but since I have the S4 I am able to go to a through-bolted design instead of a stud. This effectively doubles the grip length of the fastener; the S4 flange is about the same thickness as the T2 flange on the Garrett. We will see if it works.
I don't have a lot of room on the backside, but on the turbo side, I could probably add 1/2" or maybe 1" of spacer under the bolt head to increase stud length.
One other option that I have is because my flange is tapped, I could use bolts through the turbo flange (with or without spacer under the head), threaded into and through the mani flange and then STILL run a locking nut on the backside of the mani flange onto the bolt that protrudes through, essentially "double nutting" it. That's what I have on my current studs. It would eliminate the extra nut/lock washer on the front side that I have now.
#414
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Yeah that is what I did. A stepped-bit worked great though it did take some psyching up to drill out the threads on my shiny new S4 manifold. If you can wait you might want to see how mine works out first.
#416
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The problem is there is no good way to get two of the four bolts through the turbine flange, at least not on my turbo. The only way to do it I could see is to notch out the flange.
With the through-bolt, I can bring the bolts in from the S4 side, and put the nuts on the turbine side.
With the through-bolt, I can bring the bolts in from the S4 side, and put the nuts on the turbine side.
#417
The problem is there is no good way to get the bolts through the turbine flange, at least not on my turbo. The only way to do it I could see is to notch out the flange.
With the through-bolt, I can bring the bolts in from the S4 side, and put the nuts on the turbine side.
With the through-bolt, I can bring the bolts in from the S4 side, and put the nuts on the turbine side.
#418
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Yes, that is basically how the S4 manifold works, minus the stud tack welding.
Two problems:
- One, it does not increase the grip length per the above discussion.
- Two, it is still a mega-PIA to tighten the nuts on the turbo side when it is in the car. With the through-bolt arrangement, all I need to do is get a wrench on the nut to hold it (not easy, but no rotation required) and then rotate the cap screw which will be easily accessible from above. Hell I will probably even be able to use a torque wrench on it.
Two problems:
- One, it does not increase the grip length per the above discussion.
- Two, it is still a mega-PIA to tighten the nuts on the turbo side when it is in the car. With the through-bolt arrangement, all I need to do is get a wrench on the nut to hold it (not easy, but no rotation required) and then rotate the cap screw which will be easily accessible from above. Hell I will probably even be able to use a torque wrench on it.
#420
I don't really meet all the requirements to post, but I'm gonna ask anyway...
about the only thing I can think of with the same orientation as a standard Miata cast set-up from the factory is a Dodge Cummings I just went and looked at one to verify, and they use a stud with a nut. if the studs on a Miata stretch you would think they would have the same issue, which I've never heard before. they run more boost and I would think the chipped ones see much higher EGT's than a track set-up especially towing. does anyone know the material they use for those studs?
about the only thing I can think of with the same orientation as a standard Miata cast set-up from the factory is a Dodge Cummings I just went and looked at one to verify, and they use a stud with a nut. if the studs on a Miata stretch you would think they would have the same issue, which I've never heard before. they run more boost and I would think the chipped ones see much higher EGT's than a track set-up especially towing. does anyone know the material they use for those studs?