EPIC nuts/studs loosening thread (reposting stupid stuff without reading = warning)
#201
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^ Keith Verges? Ahh ok guys he knows a thing or two about racing Miatas. If A286 hardware works for him, it will probably work for you too. Keith where do you get your A286 fasteners from?
#202
A286 hardware
It is pretty hard to come by. I happened to find some from an aircraft mechanic on eBay.
I stocked up on 3/8-24 bolts and 5/16-24 bolts; I could not find metric. I use 3/8-24 bolts to hold the turbo to the manifold (and I safety wire the bolts and modify the turbo to accept bolts rather than studs), and I heli-coil the downpipe to accept 5/16-24 bolts, which I also safety wire. These fasteners hold as permanently as I can tell.
Someday I want to see how a Porsche 962 is held together. Anything that won 24 Hours at LeMans is good enough for me.
I stocked up on 3/8-24 bolts and 5/16-24 bolts; I could not find metric. I use 3/8-24 bolts to hold the turbo to the manifold (and I safety wire the bolts and modify the turbo to accept bolts rather than studs), and I heli-coil the downpipe to accept 5/16-24 bolts, which I also safety wire. These fasteners hold as permanently as I can tell.
Someday I want to see how a Porsche 962 is held together. Anything that won 24 Hours at LeMans is good enough for me.
#203
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It is pretty hard to come by. I happened to find some from an aircraft mechanic on eBay.
I stocked up on 3/8-24 bolts and 5/16-24 bolts; I could not find metric. I use 3/8-24 bolts to hold the turbo to the manifold (and I safety wire the bolts and modify the turbo to accept bolts rather than studs), and I heli-coil the downpipe to accept 5/16-24 bolts, which I also safety wire. These fasteners hold as permanently as I can tell.
Someday I want to see how a Porsche 962 is held together. Anything that won 24 Hours at LeMans is good enough for me.
I stocked up on 3/8-24 bolts and 5/16-24 bolts; I could not find metric. I use 3/8-24 bolts to hold the turbo to the manifold (and I safety wire the bolts and modify the turbo to accept bolts rather than studs), and I heli-coil the downpipe to accept 5/16-24 bolts, which I also safety wire. These fasteners hold as permanently as I can tell.
Someday I want to see how a Porsche 962 is held together. Anything that won 24 Hours at LeMans is good enough for me.
You know, it may not be an 'A286' spec bolt, but the Europeans have to have a spec bolt of equivalent strength made from a similar alloy, in metric. Searching for metric A286 fasteners may be the problem since they will all be standard threads by default. American standard, American threads. I'll check around here at work and see what I can find out.
Interesting that you are using bolts. I suggested this earlier in the thread, and am still considering it, good to hear that it works for you. Sounds like you are using hex-head bolts? Did they come drilled for safety wire, or did you drill them? I need to check the Rockwell C on A286 but if it has been through hardened to 160 ksi it is probably going to be difficult to drill. EDIT: A quick search shows it is about HRC 35, which is still machinable IIRC.
Once you install and torque them, do you have to retorque them later on? Seems like that would be a PIA to cut the safety wire, tighten the bolts, and rewire them with the manifold in the car. That is the only thing I do not like about the safety wire approach.
Last edited by ZX-Tex; 06-29-2009 at 02:14 PM.
#204
no re-torqueing required. I use 12-point head bolts, actually, and have to grind some of the head off and modify a box end wrench to tighten them but I promise you they do not come loose. In fact, you have to pull the manifold to R&R the turbine. Had to drill them with a special carbide bit.
#206
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The Young's Modulus (elasticity) for A286 and 316SS is about the same. But A286 has a much higher yield strength than say 316ss, about twice as high depending on the treatments. So yeah that is the idea, it will not yield (stretch) as much as a lower strength bolt.
While we are discussing exotic materials for bolts, titanium like 6Al4V (something I use a lot) is also very strong, with about the same yield/ultimate as A286, again depending on the treatment, and is in the same price range. And metric titanium fasteners are common. But, and this is a big BUT, its coeff of thermal expansion (CTE) is about 1/2 that of A286. That means, as it heats up, it does not elongate as much at the A286. This is bad since it means it would be loaded more by the expanding cast flange, more than the A286, all else being equal. For a metal, titanium is also a crappy thermal conductor, so it would tend to heat up/cool down slower than the parts around it, exasterbating the problem.
Keith thanks for chiming in, very helpful real-world experience on your part. Now I am thinking A286 (or equivalent) bolts, safety wired. Are you using regular stainless safety wire? Do you know the gauge?
While we are discussing exotic materials for bolts, titanium like 6Al4V (something I use a lot) is also very strong, with about the same yield/ultimate as A286, again depending on the treatment, and is in the same price range. And metric titanium fasteners are common. But, and this is a big BUT, its coeff of thermal expansion (CTE) is about 1/2 that of A286. That means, as it heats up, it does not elongate as much at the A286. This is bad since it means it would be loaded more by the expanding cast flange, more than the A286, all else being equal. For a metal, titanium is also a crappy thermal conductor, so it would tend to heat up/cool down slower than the parts around it, exasterbating the problem.
Keith thanks for chiming in, very helpful real-world experience on your part. Now I am thinking A286 (or equivalent) bolts, safety wired. Are you using regular stainless safety wire? Do you know the gauge?
Last edited by ZX-Tex; 06-29-2009 at 03:45 PM.
#207
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so you want a material that's expanding at the same rate as the flanges but has a very high elastic limit so it doesn't stretch permanently and leave your nuts loose...
I still wonder if a nickel-titanium super-stretchy alloy is the way to go. you get 6-8% stretch WITHIN the elastic limit.
I still wonder if a nickel-titanium super-stretchy alloy is the way to go. you get 6-8% stretch WITHIN the elastic limit.
#208
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I do not know what casting alloy Garrett actually uses for their turbine housings but I have put in an inquiry. The alloy they use could have a different CTE.
#215
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I'd rather take your word for it that **** swallowing is not a pleasant experience.
BTW I am still looking for A-286 (or equivalent) bolts in metric, no luck so far. I did find sources for grade 12.9 metric bolts that have the same tensile strength as A-286, about 150 ksi. But they are not corrosion resistant, just black oxide coated. That might be OK, though I would prefer the A-286.
I have ordered these, and will use them if I cannot find any A-286 equivalent metric bolts. These have a minimum tensile strength of 174 ksi. I'll either drill them for safety wire or use resbond.
http://www.mcmaster.com/#catalog/115/3085/=2jjwpq
BTW I am still looking for A-286 (or equivalent) bolts in metric, no luck so far. I did find sources for grade 12.9 metric bolts that have the same tensile strength as A-286, about 150 ksi. But they are not corrosion resistant, just black oxide coated. That might be OK, though I would prefer the A-286.
I have ordered these, and will use them if I cannot find any A-286 equivalent metric bolts. These have a minimum tensile strength of 174 ksi. I'll either drill them for safety wire or use resbond.
http://www.mcmaster.com/#catalog/115/3085/=2jjwpq
Last edited by ZX-Tex; 06-30-2009 at 11:59 AM.
#220
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The new BEGI manifolds are 10mm x 1.5, on the inlet side that is. The DP flange is 8mm, but that is determined by the threads on the turbine housing.
I am still going to use Stage-8 fasteners on the DP side, though I am using bolts, not studs/nuts. It should make it a lot easier to install. One of the reasons installation is such a PIA is having to separate the assembly past the end of the stud.
I am still going to use Stage-8 fasteners on the DP side, though I am using bolts, not studs/nuts. It should make it a lot easier to install. One of the reasons installation is such a PIA is having to separate the assembly past the end of the stud.