sheave "off-set", what does it do?

[Weasel]

Some of you here already know I'm the idiot thats going to run an 83 V-Max motor on a mini buggy. While trying to weed out the potential probems before hand I came across the "sheave off-set" requirement stated in the V-Max owners manual.

I'm fabbing the engine mounts at this time and I'm giving them the same adjustment that the sled mounts had before. I had a machinist friend that did some earlier machine work
and he also runs sleds, (Ski-doo) and he said ,"for the buggy, you won't need any off-set, don't worry about it",, he said,"my secondary actually floats". I'm assuming he was meaning that his seconary clutch can move on the shaft that it runs on. Being somewhat perplexed by that statement I thought I'd run it be you all here before I followed his advice.
Any thoughts?

[jefflanthier]

I think that if your secondary can float then it will find center by itself.

[opsled]

Offsets are measured from the outside faces of the clutches. Those measurements you find in owners manuals for offsets are for 2 specific clutches that are being used together. Different clutches can have different thicknesses from the inside edge where the belt rides to the outside face where the measurement is taken. So if you arn't using the same clutches as the book is refering to those offset measurements mean nothing. Most secondarys are allowed to float a small amount to compensate for any movement needed to keep the belt in alignment because of engine mount flexing or secondary shaft flexing. The Vmax 540 book calls for .040 clearance on either side of the secondary clutch once it is properly aligned and shimmed for clearance. To much clearance can allow the secondary to walk "out" of good alignment during backshift and then will need to be pulled back "in" to good alignment when you get back into the throttle. When riding in conditions where you are "on" and "off" the gas, to much clearance can cause problems. Secondary shafts can also flex and actually "bend" a certian amount under hard acceration and to much clearance can allow missalignment in those cases as the secondary clutch will want to walk to the end of the shaft while the movable sheeve on the primary is moving in the opposite direction.

You're dealing with steel and/or aluminum components with different mounts that are strong and stable but do need the ability to move some because things that won't bent break.

opsled