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Discussion Starter #1
OK, I've downloaded the manuals, searched through posts, scanned the Uberpost, and I couldn't find the following information:

1) Torque specs for driver/passenger seat bolts.
2) Torque specs for undertray/diffuser bolts and screws.

Am I blind, or is this information top secret? Or are they just not critical enough to merit documentation?
 

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1) Haven't found in over a year and when I asked here 6 months ago no one else knew them either.
2) Haven't found in over a year. 1st service tech said "Just tighten them down and don't forget to put anti-seize on the bolts.

:shrug:
 

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Discussion Starter #3
1) Haven't found in over a year and when I asked here 6 months ago no one else knew them either.
2) Haven't found in over a year. 1st service tech said "Just tighten them down and don't forget to put anti-seize on the bolts.

:shrug:
Thanks, I guess that makes me feel less foolish... :up: nice tip on the anti-seize
 

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I searched too....found nothing. Over-torquing seems to be a real issue though. Seems like they're easy to strip (and cross-thread).
 

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I searched too....found nothing. Over-torquing seems to be a real issue though. Seems like they're easy to strip (and cross-thread).
My thoughts exactly. I purchased a 1/4" drive micrometer-style torque wrench calibrated in in/lbs just for the occasion, too (OK, I really didn't need an excuse to buy more tools, but it sounded reasonable, didn't it?). I really don't want to strip the M8 diffuser threads, since the captive nut is part of the crossmember -eek-
 

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don't overtighten... that seems to be about as good as it gets.

and if you think stripping the nuts for the diffuser is a bad situation, try shearing the undertray bolts off.
 

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don't overtighten... that seems to be about as good as it gets.

and if you think stripping the nuts for the diffuser is a bad situation, try shearing the undertray bolts off.
Were they sheared during removal (hence the previous recommendation of anti-seize)?
 

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Were they sheared during removal (hence the previous recommendation of anti-seize)?
my story is here:
http://www.lotustalk.com/forums/showthread.php?t=46296

it happened during reinstall of bolts. the threads were gritted up (read the linked thread) and the bolt sheared with very little force being applied. the bolt had obviosuly already been weakened. two shops have taken that panel off... one i trust and the other is the local lotus dealer.

the suggestion of anti-sieze may exacerbate the problem of junk in the threads, but that's just my guess.
 

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the suggestion of anti-sieze may exacerbate the problem of junk in the threads, but that's just my guess.
I always clean the bolt and insert thoroughly prior to applying new anti-seize and refitting the bolt. If you don't clean them, I believe you are 100% correct.
 

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For the under tray I use a German torque wrench, it is calibrated in units of Gut-N-Tights. I think Harbour Freight, the southern locals, sell one that uses Bout-Rights.
 

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Discussion Starter #11
For the under tray I use a German torque wrench, it is calibrated in units of Gut-N-Tights. I think Harbour Freight, the southern locals, sell one that uses Bout-Rights.
rotfl

Did the German one come with your S4? I didn't get one with mine... :shrug:
 

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I always clean the bolt and insert throughly prior to applying new anti-seize and refitting the bolt. If you don't clean them, I believe you are 100% correct.
you're so thorough. :up:

i'll bet your garage is clean too. ;)
 

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you're so thorough. :up:

i'll bet your garage is clean too. ;)
HA! but I can't spell even with the speelchicker turned on :).
As for the second comment, I think there is a space under one shelf that's almost clean -- if you don't count the oil spots and paint overspray :p.
 

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apk919, I also searched this long ago and was unable to find the specs, so I consulted an engineering web site that has a torque calculator.

I'm sure it is not perfect, but I found it to be reasonably accurate when cross-checking bolts with known torque and grade specs. Go to this link and use the "Torque Calculator" (see the right margin near top of page):

http://www.rockcrawler.com/techreports/fasteners_torque/index.asp#

Here is what I came up with:

- 5 ft.lb. (assumes grade 5) for the numerous 8mm diffuser bolts and 8mm undertray bolts...I don't have a torque wrench that goes that low accurately, so I just snug 'em up;

- 22 ft.lb. (assumes grade 5) for the two larger bolts located in the center of both the undertray and diffuser panels.
 

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Discussion Starter #15
apk919, I also searched this long ago and was unable to find the specs, so I consulted an engineering web site that has a torque calculator.

I'm sure it is not perfect, but I found it to be reasonably accurate when cross-checking bolts with known torque and grade specs. Go to this link and use the "Torque Calculator" (see the right margin near top of page):

http://www.rockcrawler.com/techreports/fasteners_torque/index.asp#

Here is what I came up with:

- 5 ft.lb. (assumes grade 5) for the numerous 8mm diffuser bolts and 8mm undertray bolts...I don't have a torque wrench that goes that low accurately, so I just snug 'em up;

- 22 ft.lb. (assumes grade 5) for the two larger bolts located in the center of both the undertray and diffuser panels.
Nice work, thanks. Now I've got a reason to use my 1/4" drive torque wrench, calibrated in in/lbs :D
 

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Cool.

While we are at it, does anyone know the factory torque specs for the engine mounts?

I did various LT searches and went through the the Lotus download manual and found no obvious mention...including in the section that discusses engine removal and reinstallation.
 

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Lotusmotion, when you made those calculations, did you use the lubricated or dry coefficient?
Thanks for the link, btw.
 

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You are welcome.

Out of curiosity, I calculated both wet and dry.

However, the torque specs I used for installing diffuser and underpan bolts were based on the dry coefficient.
 
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