How to: Actually use a torque wrench to tighten the alternator pulley nut
05-06-2022, 12:23 AM
#1
How to: Actually use a torque wrench to tighten the alternator pulley nut
Good day, Volks!
Time to give back, after extracting much from this fantastic website and its good people.
I’m a stickler for using torque wrenches and was determined to find a way to do it on the 24mm nut that holds the alternator pulley assembly on the alternator shaft.
That I could figure out, it isn’t practically possible to put a torque wrench on this nut— without a hollow torque wrench, OR, some decadent way of holding/stopping from turning the pulley in a way that doesn’t damage it or the belt.
It turns out the solution is quite straightforward. (Sorry if this is a repeat of someone else’s discovery, I didn’t search)
Don’t torque the nut. Instead, torque the shaft.
Hear read me out.
-Put a 10mm 12-point (triple square) driver on the torque wrench.
-Put a 24 mm wrench on the nut.
-Set the torque wrench to 50 Nm, in the loosening direction.
-Hold the nut still and loosen the shaft to 50 Nm.
Presto! Likely the first time this nut has been properly torqued since it left the factory.
In case it’s hard to visualize, you must apply 50Nm of torque in the tightening direction on the nut to counter the 50 Nm of torque being applied to the shaft in the loosening direction.
(For every action, equal and opposite reaction, yada yada thank you Mister Newtonmeter)
One small caveat:
Because my tool is rather long (ahem!), I had to remove the engine cover latch to have enough space.
So, barring a physics-rebuttal from any of the millions (and millions) of people smarter than me, I think we’re good to go.
Thanks again for all the sharing.
By the way, after nearly choking at the $420US price of the crankshaft holding tool, I had one made locally. Works a charm! If anyone is interested, I think I could have a batch made for a little less than half that cost.
cheers!
Time to give back, after extracting much from this fantastic website and its good people.
I’m a stickler for using torque wrenches and was determined to find a way to do it on the 24mm nut that holds the alternator pulley assembly on the alternator shaft.
That I could figure out, it isn’t practically possible to put a torque wrench on this nut— without a hollow torque wrench, OR, some decadent way of holding/stopping from turning the pulley in a way that doesn’t damage it or the belt.
It turns out the solution is quite straightforward. (Sorry if this is a repeat of someone else’s discovery, I didn’t search)
Don’t torque the nut. Instead, torque the shaft.
-Put a 10mm 12-point (triple square) driver on the torque wrench.
-Put a 24 mm wrench on the nut.
-Set the torque wrench to 50 Nm, in the loosening direction.
-Hold the nut still and loosen the shaft to 50 Nm.
Presto! Likely the first time this nut has been properly torqued since it left the factory.
In case it’s hard to visualize, you must apply 50Nm of torque in the tightening direction on the nut to counter the 50 Nm of torque being applied to the shaft in the loosening direction.
(For every action, equal and opposite reaction, yada yada thank you Mister Newtonmeter)
One small caveat:
Because my tool is rather long (ahem!), I had to remove the engine cover latch to have enough space.
So, barring a physics-rebuttal from any of the millions (and millions) of people smarter than me, I think we’re good to go.
Thanks again for all the sharing.
By the way, after nearly choking at the $420US price of the crankshaft holding tool, I had one made locally. Works a charm! If anyone is interested, I think I could have a batch made for a little less than half that cost.
cheers!
05-06-2022, 07:21 PM
#2
Three Wheelin'
Seems good! I put a crowfoot on my torque wrench pointing straight up along the shaft of the wrench and torqued the nut while using the factory tool to hold the alternator shaft. Paint marked it and it hasn't moved in a few thousand miles.
05-07-2022, 01:25 AM
#3
Rennlist Member
Just make sure your torque wrench can be used in that way. Some torque wrenches can only tighten and using them the other way round will damage them. So I was told.