I have a 2005 T660 non turbo. I bought it last year, and now have the chain case cover off to do the speedo side bearing.
the official AC manual says the 3 drain plugs on the case need a torque of 35 ft lbs. It’s an aluminium case and 35 ft lbs seems ridiculous. I torqued them to 15 ft lbs and that felt very very tight. Can anyone give advice. I think 35 is gonna strip the case threads!
I’m not sure, I’d have to pull it again but hey… here’s the thing, Arctic cat official service manual, 36 ft lbs for the oil pan drain plug, 35 for the chain case drain plug.
THEN, I pulled out the owner’s manual booklet. It says for chain case plug, “ tighten securely”.
for the oil pan plug it says 16.5 ft lbs. The owners manual sounds reasonable. The service manual is way off and if I didn’t have experience, I would’ve just cranked them up to the torque value and stripped everything.
How irresponsible of AC to publish such bad and conflicting info.
I’ll go with tightly, and 16.5
Errors in manuals do happen! The secondary clutch is spec'd at 4.6 ft*lbs. in one of my manuals, when it should be 46 ft*lbs.
In general, the rule of thumb to ensure that the bolt breaks before the threads strip is 1x bolt diameter thread engagement for steel, and 1.5x bolt diameter thread engagement for aluminum minimum, though this depends a bit on the alloy of the threads, and gauge of the bolt.
If you're working on something where the torque spec isn't available, there are charts for the general specs for a given bolt diameter and strength, like the example below. In general, your aiming to achieve a clamp load of 75%-90% of the bolts yield strength, using the torque (friction) to measure it. That friction is heavily dependent on thread condition; most manuals spec the torque clean and dry by default and will specify lubrication if required. It's also not that consistent, with a given torque producing a typical variance in clamp load of around +-10%.