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lower pully torque value

mquinn66

New member
Simple question - torque spec on the crank pulley (bottom front bolt on the crank of the pulley that drive the alternator on a belt). Could use metric spec ( 75 nM for 10.9 ). (with blue locktight - reduce 10%?)

BMW R1100RT 2000
 

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My book says 50 nM ( = 36.87 lb-ft) in two places; screen shots attached.
View attachment 87972

About right, no manual, rule of thumb puts me at 35 ft/lbs..

Don't reduce for blue loctite and if you use red loctite, sell the bike if you have to take it apart again.

I might have a concern that oxidation will compromise that torque value.

Best to make sure washers, pulley face, internal/external threads are clean.
 
Don't reduce for blue loctite and if you use red loctite, sell the bike if you have to take it apart again.

I might have a concern that oxidation will compromise that torque value.

Best to make sure washers, pulley face, internal/external threads are clean.

There is but one way to effectively break red Loctite: exposure it to a temperature over 500 degrees Fahrenheit. Theoretically you could get that bolt to that temperature, but I would not want to be in that situation if at all possible.
Blue is the choice for almost every automotive application.

Also, relevant to this thread and to the problem of oxidation, I did a minor mod to my own machine regarding this bolt. I don't understand why BMW gave it a 16mm hex head when there's no tool in the tool kit that lets you touch that fastener; standard M10 bolts have a 17mm head and there's a 17mm wrench in the tool kit for the rear wheel lugs.
I bought a pair new replacement M10 bolts of the same length (I believe it's 35mm), with a 17mm head, from my local auto parts store for about $4. The original definitely had a bit of corrosion on it so the new yellow zinc oxide one was less crusty. Reused the original washer.
Now, if I have a Hall sensor issue out on the road or my alternator belt pops and damages the pulley, I'd be able to remove it with the on-bike tool kit. The rear wheel lug wrench is definitely capable of getting it up to the required 36 pound-feet of torque.
 
Spec from BMW CD is 50nm, no oiling, no loctite.

Lock the crank at tdc with a 5/16" pin in the hole above the starter.
Don't attempt to lock the rear brake in 6th - not solid enough to get a reliable torque reading.
 
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