Clutching help

[nherbst454]

Finally got a chance to ride in the UP this past weekend and the clutching was great down low as the acceleration felt better but my issue is on the top end I'm hitting the rev limiter (9200) at around 80 - 85 MPH. I've got a GWG spring with a 2mm spacer as well as the 8FP weights and a 17.2mm steel rivet in the tip. Off the line when punching it, it comes up to 8700 - 8800 and pulls well but you can feel it start cutting out and the tach is running over 9100 as you get around 80 MPH The middle and heel holes are empty, do I need to add weight to the middle hole? If so, any idea how much?

 

[shagman]

Finally got a chance to ride in the UP this past weekend and the clutching was great down low as the acceleration felt better but my issue is on the top end I'm hitting the rev limiter (9200) at around 80 - 85 MPH. I've got a GWG spring with a 2mm spacer as well as the 8FP weights and a 17.2mm steel rivet in the tip. Off the line when punching it, it comes up to 8700 - 8800 and pulls well but you can feel it start cutting out and the tach is running over 9100 as you get around 80 MPH The middle and heel holes are empty, do I need to add weight to the middle hole? If so, any idea how much?

What helix are you running.

 

[nherbst454]

Stock helix, machined secondary spring pocket to eliminate binding, 8DN conversion and OSP Belt adjuster to get the belt height correct. Secondary spring initially set at 3-3, then changed to 6-1, didn't notice much of a difference.

 

[shagman]

Add 3.2g in middle hole.

 

[shagman]

Or go to 46/40 dalton helix. The 40 at the end will lower rpm and give more mph.

 

[Studroes144]

Could u simply take the primary shim out and bring the rpm down?

 

[shagman]

No that is part of what makes this clutching work so well.

 

[titanrcr]

Could u simply take the primary shim out and bring the rpm down?

That would be my first move.

 

[stingray719]

That would be my first move.

As shagman said the stiff spring with the shim is the secret to this setup, either multi angle helix and/or adding weight I strongly suggest leaving the shim in.

 

[titanrcr]

As shagman said the stiff spring with the shim is the secret to this setup, either multi angle helix and/or adding weight I strongly suggest leaving the shim in.

It may be working for some but not for nherbst454 apparently. Removing the 2mm shim will have the same effect as adding weight to the arms so "I" would try that first. Very quick and simple to do. Without driving the sled myself I would not be in a position to make any suggestions on tuning his clutches.

 

[shagman]

The reason it's not spot on is because the helix change wasn't done with the rest of the parts. Yes it can be done by removing the shims. But that will also change the shift because of less spring pressure. The best way to fix rpm is to add weight. If he was running the 46/40 helix his rpm would not be high on top end. He needs more force with the weights so it will pull through the shift with 43 helix. Also 43 helix will not pull as much top end as a 46/40. Believe me I have a lot of hour doing testing with this setup.

 

[titanrcr]

The reason it's not spot on is because the helix change wasn't done with the rest of the parts. Yes it can be done by removing the shims. But that will also change the shift because of less spring pressure. The best way to fix rpm is to add weight. If he was running the 46/40 helix his rpm would not be high on top end. He needs more force with the weights so it will pull through the shift with 43 helix. Also 43 helix will not pull as much top end as a 46/40. Believe me I have a lot of hour doing testing with this setup.

Well you sure can't run half a setup. Helix will have a huge effect.

 

[stingray719]

It may be working for some but not for nherbst454 apparently. Removing the 2mm shim will have the same effect as adding weight to the arms so "I" would try that first. Very quick and simple to do. Without driving the sled myself I would not be in a position to make any suggestions on tuning his clutches.

"Without driving the sled myself I would not be in a position to make any suggestions on tuning his clutches"

Yet you did?

And just to clarify adding a shim has very little effect on rpm, some but very little. Adding weight adds roughly 200 rpm per gram. Not high jacking another's thread to go through clutching science here though please start a thread and we can take it there.

 

[titanrcr]

"Without driving the sled myself I would not be in a position to make any suggestions on tuning his clutches"

Yet you did?

And just to clarify adding a shim has very little effect on rpm, some but very little. Adding weight adds roughly 200 rpm per gram. Not high jacking another's thread to go through clutching science here though please start a thread and we can take it there.

Yes I did and still would remove the shim even without riding the sled. And just to clarify, at a spring rate of 2.75 a 2mm shim will effect the full shift rpm a lot more than you think.

 

[newtron]

Or go to 46/40 dalton helix. The 40 at the end will lower rpm and give more mph.

Correct me if I'm wrong but doesn't a lower/shallow angle increase rpm?