[Cloud9...68]

The pinch bolts that tighten the clamping sleeve around the driveshaft and the transaxle input shaft are M10's, and should therefore take a torque of about 47 nm. And yet the manual says the following about their torque requirements:



"Order of assembly of the clamping sleeve:



Start by fitting fitting one bolt each on left and right-hand side and tightening to 10 +/- 5 Nm. Fit opposite bolts and tighten to 80 Nm. Re-tighten the bolts fitted initially to 80 Nm."



This seems very high for M10 bolts; 80 Nm is close to the typical torque for an M12, such as the cross-member bolts. The manual calls for the clutch sleeve pinch bolt to be torqued to the same 80 Nm, so at least they're consistent, and I understand you definitely don't want these bolts coming loose, but 80 Nm just seems awfully tight for an M10 bolt. Thanks.

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[MB968]

What class are they. A higher class can take a greater torque.

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[MB968]

One table I have shows the normal zinc plated M10x1.5 class 10.9 at 75 Nm. If it is a higher class, 12.9, 80Nm could be OK.

________________



I see on further review this is the same socket head cap screw that is used on the coupling at the other end of the driveshaft. I just looked at mine, and it has a 12.9 stamped on the OD of the cap screw, explaining the torque spec. of 80 Nm. Just check your bolts to make sure they are indeed 12.9's.

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[Cloud9...68]

Yes, you're absolutely right - they're class12.9, so 80 Nm is correct. Thanks.

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[MB968]

I'm sure the 80 Nm is for dry threads. Make sure they are cleaned off, not lubed. If they are lubed you have to reduce the torque somewhere around 20% +/- depending on how much the lube affects the friction in the threads.



One of the better references I found (because it specifies % of proof load per an ISO spec) gives the following: An M10 x 1.5 12.9 with dry threads torqued to 84 Nm should take the bolt to 75% of proof load (as specified in ISO 898-1). For lubed threads, 64 Nm results in 75% of proof load.

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[Cloud9...68]

Thanks; the manual doesn't call for any lubricant on the threads, so I was planning to install these bolts dry. Another small challenge is going to be with the fact that the pinch bolts that secure the sleeve around the transaxle input shaft aren't quite accessible with a straight extension because the window partially blocks these bolts - the manual even specifies using a 16 degree offset socket (not sure if that's the exact wording - I don't have access to the manual at the moment), so I will have to do some math to figure out how much torque I need to apply to get 80 Nm to these bolts.

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[MB968]

If you're going through a u-joint, the torque transmitted will be esentially the same.

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[Cloud9...68]

Really? Even if the torque wrench is not normal to the bolt head? Also, I'm nervous about applying that much torque across my flimsy-looking u-joint.

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[flash]

don't be nervous - 59ft/lbs

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[Cloud9...68]

I'm not worried about damaging the bolt - but I'm not sure the u-joint can take the torque. I've broken a few in my time. Not a huge deal - if I break it, I'll find a tougher tool to do the job.

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[flash]

craftsman makes a u-joint with a hardened center



however, i don't think i have ever used a u-joint on that clamp.

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[MB968]

[quote name='flash' timestamp='1334618084' post='125303']



however, i don't think i have ever used a u-joint on that clamp.

[/quote]

Cloud, if Flash has never had to use a u-joint on the rear TT coupling, you may want to play with it more to see if you can get a straight shot at it.

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[MB968]

[quote name='Cloud9...68' timestamp='1334609583' post='125292']

Really? Even if the torque wrench is not normal to the bolt head? Also, I'm nervous about applying that much torque across my flimsy-looking u-joint.

[/quote]



I don't think I'm wrong in saying this. The only degrees of freedom that a u-joint is constrained in is rotational. It is free to move in all other directions. Of course many of the actual u-joints designs do have some resistance (not completely free) when significantly off angle. But, your note said 16 degrees off, so I wouldn't hesitate to use a direct reading.

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