How hig is too high for clutch engagement, and what's up with the bang on engagement?

[shredjim]

For info on the engagement banging see the thread "Nasty rough clutch engagement" post reply now on page 2 of this forum by Mr. BB. This is one cure.

Here is what you wrote in the thread you list above

"Once you get your belt deflection correct you'll likely still have a banging, not as pronounced , but still sounding like it could be causing some damage. If you want to smooth it out here is one way that has been used on at least 10 M sleds around here. It was accomplished by grinding a flat spot 1/2"+ long on top of weight centered on the spider roller bearing. I've ridden 2 sleds with this mod . 1-my '09. 2- my buds '08, both were equally obnoxious beforehand and now are smooth. We do a lot of on & off the throttle riding and this banging became very aggravating. If you want more information about this call Jon at Jon's Golf & Ski in Yakima, Wa. (509) 575 0159. He's an ardent snowmobiler, with a 1100 BB and a M7 turbo and works on a lot of snomobiles. I mention this because the name of his business doesn't sound very snowmobilly"

Will you please explain in more detail what you suggest and why it works, pics would be great!

 

[Frostbite]

I agree, more infor please. Pictures would be wonderful.

I have to assume the 1/2" is measured from where the weight initially touches the roller toward the direction the weight rotates when the clutch is engaged?

 

[Rms Rydning]

I have CPC weights and 158/290 primary spring.
And this is a problem even with perfect adj belt.

I had to take out 1 shim in the primary on my 07 m1000 to solve the hard engadement.

 

[Mr. BB]

I agree, more infor please. Pictures would be wonderful.

I have to assume the 1/2" is measured from where the weight initially touches the roller toward the direction the weight rotates when the clutch is engaged?

Nope, the center of the roller is the center of flat spot. Roller only comes in contact with 1/4" of flat spot as arms shift out. Don't know how to post pictures, need to get my 11 y.o. grandson over here I suppose, but hate to admit it. As far as what's with the banging,the general consensus seems to be that the DD rollers are having a dust-up with the helix. The slot in the helix is 1.5" and the roller is .75" leaving plenty of room for the roller to pull away from the helix ramp ( which it does, as you know, in reverse). I think what happens when you let off the throttle , the belt drops to the bottom of the primary and leaves the belt down in the secondary a little causing the rollers to pull away from the helix ramp and then when the throttle is pulled the roller slams against the ramp times 3 , causing the offending bang. And/ Or when the primary disengages and the sled is still in motion, the track is turning the secondary, maybe this will allow the rollers to pull away from the helix ramp. All I know is that this mod helps smooth things out. This was tried on a team secondary and smoothed it out alot. He couldn't believe how much noise was eliminated. Much better thru the trees getting to the next bowl. By the way it isn't just the reverse notched helixes doing this. My riding bud's '08 was just as rowdy as my '09, much better now. Now I hear the occasional click and clack that I had grown use to in my pre DD sleds, which I'm sure is just the slack being taken up in the drive train such as the track clips and the driver cogs and there is a little play in the DD. For the do-it-your-selfers a table belt sander works good and if you have a jig for holding all three arms in perfect alignment while grinding(sanding) that's even better. If you are using (practicing on) some used arms the center where the roller rests will be evident, possibly even have a nice little groove worn in the arm. Mark 1/4" on either side of center mark. Actually it doesn't have to be exactly a 1/2" long flat spot or even centered on roller. Close will work fine. Rounding off the edge where roller transitions from flat spot to original surface seems like it would be better. Probably the most important thing is keeping the flat spot perpendicular to the sides of arms so pressure is distributed evenly along contact between roller and arm. As a disclaimer I should say that so far nobodys noticed any down side to doing this such as affecting the holeshot or whatever? But who knows you might be the one to find something. It seems like it would prolong the life of the rollers as a bonus. Why this works I don't know. Have fun!