moto_mixon Posted August 22, 2006 Share Posted August 22, 2006 I was looking at spec's to tighten the oil drain plug, and found this: Initial torque, 23 Nm (17 ft-lbs) Final torque, 32 Nm (24 ft-lbs) Can anyone explain what initial torgue, final torque refers to? TIA Link to comment
mmmoore Posted August 22, 2006 Share Posted August 22, 2006 Basically it is a torqueing process that tightens up part way then to the end value in the second sequence. Typical rational is more equal stress on part being torqued (reduces possibility of warping - especially V8 heads). On oil pans it tends to keep the gasket from slipping out on one side, or getting cut on one side, expecially with the red silicone aftermarket gaskets (more used on airhead valve covers). If using the silicone gaskets make sure all surfaces and gasket are oil free/dry. Other tribal knowledge may apply... Link to comment
moto_mixon Posted August 22, 2006 Author Share Posted August 22, 2006 Ok, that makes sense for a piece that has multiple fasteners to attach it. But with a drain plug, one single screw-in plug, what else can one do except tighten it in action all the way to the final value? Link to comment
planepaul Posted August 23, 2006 Share Posted August 23, 2006 The first torque establishes the sealing pattern, the second torque partially crushes the washer. It is a poor setup compared to most Japanese bikes. Link to comment
duckbubbles Posted August 23, 2006 Share Posted August 23, 2006 My question is- how do they want you to implement this? Do you go to initial torque, back it off, and then go to final torque, or go to initial, followed by final torque? Seems like I end up pausing in between there to reorient the torque wrench most times anyway. Either way I don't see where it would make much difference if you don't have a leak. Frank Link to comment
planepaul Posted August 23, 2006 Share Posted August 23, 2006 That's what I do.......Torque to initial torque, then back it off, go back to the same torque, then final torque. The contact area of the washer is really small, so the crush factor is critical. The first time I changed oil, I just did a torque-torque. It leaked. I now make sure that the washer is centered on the plug before and after I go to the first torque. No problems since. Another example of BMW's unnecessary over-engineering. Link to comment
Emoto Posted August 23, 2006 Share Posted August 23, 2006 No, no. Do not "back it off". That defeats the purpose of the intitial torque value. 1. Tighten to the first value. 2. Tighten to the second value. 3. Go ride. Link to comment
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