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Old 02-08-2009, 08:51 PM   #1
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Default FM turbb manifold modification (studs)

I've heard that some people have been having issues with the studs on their FM turbo manifolds backing out. This has sometimes necessitated track cars to have to have their manifold nuts retorqued after each session during track days. There have even also been reports of stud failure because of the repeated retorquing of the nuts. So here's my proposed solution...

My solution is threefold:

-First, the size of the manifold studs were upgraded from M8 to M10.
-Second, nuts that are prepped to be safety wired in place will be used so that they can't back off. Each nut will be safety wired to TWO other nuts on the manifold.
-Third, setscrew holes were drilled and tapped into the turbo manifold. Setscrews are then put in place which screw into the manifold's M10 studs, locking them in place and preventing them from backing out.

Other typical hardware is also used (ie the special lockwashers) as are found on other installs.

Here's a pic. It's just hand tightened, not safety wired, and the turbo orifaces are still taped...but you should get the idea:

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I'm open to any opinions/suggestions/criticism on this solution. Thanks!
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Old 02-08-2009, 08:58 PM   #2
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Totally badass. Damn. You could have drilled through the nut/stud and then just wired them, then you wouldn't have needed to setscrew the studs into place. I did this, only I used bolts so I just drilled through the head of the bolt. I actually haven't wired them all together yet though, but it shouldn't be a problem.

Did you cut a flat on the studs for the set screw to hit? This would be ideal. Also, where did you but those nuts?
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Old 02-08-2009, 09:13 PM   #3
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I'll offer one improvement possibly...

I was gonna do studs before I realized they wouldn't fit. Meaning, if they were installed int the manifold, I couldn't put the turbo on. My turbo already hangs off the side a lot, so if I used studs, I'd have to install them while holding the turbo in place. But assuming there was no fitment issues with the studs already installed, I was going to drill through the manifold and through the stud, and then press a locking pin in. That would be a bit more bullet-proof reliable than a set screw as it too could back out.
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Old 02-08-2009, 09:19 PM   #4
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Set screws aren't going to come out. There's no force pushing/pulling on them. They WILL seize in place, however, so good luck removing them when the time comes.

That is pretty cool, though. Safety wire is the way to go for sure.
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Old 02-08-2009, 09:28 PM   #5
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Quote:
Originally Posted by Savington View Post
Set screws aren't going to come out. There's no force pushing/pulling on them. They WILL seize in place, however, so good luck removing them when the time comes.

That is pretty cool, though. Safety wire is the way to go for sure.
Meh, they push on the stud, the stud pushes on them per Newton's third law. Manifold expands and contracts with temperature change, and there's a lot of vibration as the manifold has an engine and turbo bolted to it. I could see a set screw backing out possibly. Cutting a flat on the stud for it to seat against will reduce the chances of the set screw backing out though. My experience is set screws like to seize in mild steels, not cast irons. I rebuilt a bunch of lathes, three bandsaws, and a printing press a few years ago and I can honestly say I probably removed a thousand set screws. The ones in cast are easier to get out vs. mild steel or aluminum. I used to know why too, something in the iron (maybe lead?) keeps it lubricated in a sense.
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Old 02-08-2009, 09:30 PM   #6
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Old 02-08-2009, 09:50 PM   #7
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Quote:
Originally Posted by mazda/nissan View Post
That's pretty cool, but it still uses M8 stud hardware. I'd have used this hardware but didn't want to face the possibility of broken M8 studs as the next weak point.
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