Oil cooler line hose bolt torque value

[cross]

Hello,

I changed my oil cooler hoses but can't find the torque value for the bolts in the manual

Does anyone know what the torque should be?


Thank you
Sasha

[tevan]

New orings and snug them up. They are a small bolt

[cross]

Great, that's what i did


Thank you
Sasha

[divan]

The bolts on the oil hoses are 6mm. The manual (in the "General Info" section) lists standard torque values for nuts and bolts where no specific values are specified (as with these bolts). Torque should be 6-9 ft-lb (or 0.8-1.2 kg-m if using metric wrench). For these things it's a good idea to torque them after snugging up, to be sure you have equal compression on both bolts (and the o-ring), to avoid leaks. Shoot for a middle number (e.g., 7 ft-lb) to avoid stress on the aluminum threads in the case. HOWEVER -- see the note below.

Just as a side note: "back in the day" the advise was to always lubricate bolts on these bikes before assembling, since many of the joints are between aluminum case threads and steel bolts and screws. However, as many engineering guides on bolt torque point out, lubrication on anything other than stainless steel (where it's a must to prevent galling) actually reduces torque readings, sometimes by as much as 40%. That can lead to serious over-tightening which, in the case of our steel bolt to aluminum case threads, will almost certainly lead to stressed, if not stripped case threads. If someone in the past has over-tightened these smaller 5/6 bolts, screws, or stud/nut joints, stressing the internal threads, then torquing to specified value may not be a good idea; "snugging up" might be the better way to go. The only way I know to "test" whether a joint like this has been stressed is to thoroughly clean the threads on a good (preferably new) bolt and hand tighten most of the way in and then pull gently back and forth on the bolt. If it feels loose (moves a bit in and out or wobbles a bit), the internal threads are likely worn (stressed). Maybe some folks who are more experienced or knowledgeable could offer us some advise? There are lots of places, besides the oil hoses, where we run into this situation.

One final point: The manual's general torque values section clearly specifies where lubricants (and what kinds) should be used on joints; so I assume that anywhere lubricants aren't specified, the values refer to dry (non-lubricated) joints.

[NobleHops]

[Larry Zimmer]

Good on that final line, Nils. If the 'book' doesn't say anything, it assumes DRY threads. Also, note that dry zinc coated (galvanized) bolts should reduce torque 10% - 12%. Those 6mm are easy to strip the threads in aluminum; especially, when you encounter some porosity in the aluminum as often happens with castings. (Even more so with die castings.)