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Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

Reassembly time is nigh. I am considering ditching the allen head cap nuts that hold the bearing housing to the bracket. . .they are so old, and made from such odd material, how can they not be worn out?

So, I have two questions. First, any reason not to use a locking hex nut? And second, how does one adjust for torque values when switching from a regular to locking nut?

TIA

rasta
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Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

fiat22turbo · Joined: 18 Jan 2006 Posts: 4040 Location: Portland, OR

I don't know that there is a difference in torque settings between a locking nut and a non-locking nut.
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Stefan
1979 924 Carrera GTS (clone-ish)
1988 944 Turbo S (Silver Rose)

!tom · Posted: Fri Apr 02, 2010 5:13 am Post subject:

Intuition would tell me that you would measure the torque required to "spin" the nut on, then add this to the published torque value for the fastner.

That is, of course, if you use the same thread as you did previously. The thread pitch largely determines the correct torque for any application, as it's the clamping force that is important. Bolt diameter is important too so that the bolt stretches the correct amount, to ensure the bolt is under continuous tension given the dynamic loads of the part.
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78 924 NA
5-lug

Cedric · Joined: 27 Aug 2004 Posts: 2826 Location: Sweden

I have regular hex bolts on my car (PO changed them and I continued to use them), works nice and is so much easier to assemble/disassemble than the allen ones.
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1980 924 Turbo
www.instagram.com/garagecedric/

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

Rich H · Posted: Fri Apr 02, 2010 8:28 am Post subject:

What he said, you need to add the run down torque to the desired torque

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1994 Lotus Esprit S4 - Work in progress...
1980 Porsche 924 S2 DITC Turbo - Original spec
1978 Homo-Sapiens - Tired spec
1953 Landrover S1 - Pensioner Spec

ic932 · Joined: 11 Feb 2005 Posts: 1104 Location: UK

Been awhile, but these are very low torque bolts no? Unless you feel its benificial to easy instalation (lock nuts) then I would just torque then to spec (whatever that might be) then nip them up a lil' more. I doubt I got a torque wrench that is that low...just feel when its good.

Min · Posted: Fri Apr 02, 2010 11:51 am Post subject:

If your going to be that picky about torque you better simply measure bolt elongation instead. Since such things as bolt coatings effect their friction factor as well as lubrication. Cadmium plating for example produces approximately 33% less friction than untreated steel. Were as lubrication only changes it by 5%. I'd suggest measuring elongation or you could also use load indicating washers to detect when the correct torque has been achieved.

Torque wrenches aren't really that accurate in the first place really. Their relative accuracy is pretty low.

http://www.boltscience.com/pages/tighten.htm for more information.

http://www.turnasure.com/direct-tension-indicators-turnasure-bolting-technology.shtml

for some tension indicating washers.

Min
_________________
Custom means it didn't come from a box.
1980 n/a with EDIS and Megasquirt II Injection. 7 different colors and counting.

Min · Posted: Fri Apr 02, 2010 11:57 am Post subject:

could also get yourself some 'squirter' DTI washers (direct tension indicating)

http://appliedbolting.com/squirters.html

They squirt out silicon when they are at the correct tension.

Min
_________________
Custom means it didn't come from a box.
1980 n/a with EDIS and Megasquirt II Injection. 7 different colors and counting.

Paul · Posted: Fri Apr 02, 2010 1:01 pm Post subject:

The stock ones work and I've reused them before.
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White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

I'm going to look at Stage8 locking bolts and nuts for the exhaust mani and turbo applications on my upcoming Euro spec engine build...
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erstwhile owner of just about every 924 variant ever made

Paul · Posted: Fri Apr 02, 2010 1:21 pm Post subject:

I'd stick with the stock ones, they were specified to withstand the red hot heat.
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.

Min · Posted: Fri Apr 02, 2010 1:24 pm Post subject:

personally if I was interested in locking those fasteners properly, I'd just use a jamnut method (assuming there is enough room)

http://www.boltscience.com/pages/twonuts.htm

Min
_________________
Custom means it didn't come from a box.
1980 n/a with EDIS and Megasquirt II Injection. 7 different colors and counting.

ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

Paul · Posted: Fri Apr 02, 2010 1:32 pm Post subject:

Alrighty then, but if you are wrong, what a PITA to swap out.
_________________
White 87 924S "Ghost"
Silver 98 986 3.6l 320 HP "Frank N Stein"
White 01 986 "Christine"
Polar Silver 02 996TT. "Turbo"
Owned and repaired 924s since 1977
Porsche: It's not driving, it's therapy.