I have seen many videos on YouTube and heard it from some friends who work on their M3s. The myth is that for the VANOS to operate to its full range, it's important to insert the slanted tooth on the VANOS splined shaft which requires the least amount of rotation of the hub. My understanding is that this is simply not true.
The range of motion you see when the hub bolts are undone has nothing to do with the range of motion of the VANOS when the engine is running, right? I mean when the bolts are tight and the engine is running the bolts aren’t moving anymore in the slots on the camshaft sprocket ring. These slots aren’t the factor limiting the angular motion of the cams or the linear motion of the VANOS pistons on their axes during VANOS phasing. With the engine running, your camshafts will be phased (slightly rotated relative to the camshaft sprocket rings) by the VANOS pistons moving in and out of the VANOS. The only thing limiting this motion is the allowed range of linear motion of the VANOS piston limited only by the caps at the end of the vanos and the camshafts on the other end. So whether you used a sweet spot or not will not affect that range, but it is still desirable that you do not overturn that hub upon VANOS shaft insertion, because if you did you may run out of range and not be able to fully insert the vanos or force the cams to turn as you push it (which will affect timing and you won’t be able to insert these dowel pins anymore). While the "sweet spot" thing is a myth, you should not skip a tooth that would have been aligned when turning the hub until a tooth catches, and should aim to use the first set of matching teeth.
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The range of motion you see when the hub bolts are undone has nothing to do with the range of motion of the VANOS when the engine is running, right? I mean when the bolts are tight and the engine is running the bolts aren’t moving anymore in the slots on the camshaft sprocket ring. These slots aren’t the factor limiting the angular motion of the cams or the linear motion of the VANOS pistons on their axes during VANOS phasing. With the engine running, your camshafts will be phased (slightly rotated relative to the camshaft sprocket rings) by the VANOS pistons moving in and out of the VANOS. The only thing limiting this motion is the allowed range of linear motion of the VANOS piston limited only by the caps at the end of the vanos and the camshafts on the other end. So whether you used a sweet spot or not will not affect that range, but it is still desirable that you do not overturn that hub upon VANOS shaft insertion, because if you did you may run out of range and not be able to fully insert the vanos or force the cams to turn as you push it (which will affect timing and you won’t be able to insert these dowel pins anymore). While the "sweet spot" thing is a myth, you should not skip a tooth that would have been aligned when turning the hub until a tooth catches, and should aim to use the first set of matching teeth.
Discuss
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