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clutching explained

donbrown

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Without mentioning names.

Told my buddy bought a kit for 2018 154 3" track with 966 ramps

Buddy bought a kit all the same parameters except 165" track using 967 ramps.


What the difference between 966 and 967?
 

Dynamo^Joe

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IF he has my clutch kit, THEN the 966 ramp will work.
  • The 965 ramp is 50.7 grams
  • The 966 ramp is 51.0 grams; it is only 0.3 grams heavier than the 965 ramp.
If the guy has bone stock clutching he can remove the 965 ramps and install the 966 and they will work.

My kit works with the 951, 990, 967, 965, 968...AND the 966 ramp.

Because every ramp is a different mass, all you have to do is get the right pivot bolt weight for the elevation.

Example
At 7000 feet need a total of approximately 89.0 to 90 grams of complete ramp weight.
  • Complete ramp weight is the weight of the ramp (left arm+ramp+right arm) plus the pivot bolt weight.
On my clutch kit...
A 990 ramp uses 17.5 grams pivot bolt weight to get approx 90 grams
A 968 ramp uses 16.7 grams pivot bolt weight to get approx 90 grams
A 967 ramp uses 19.3 grams pivot bolt weight to get approx 90 grams
A 966 ramp uses 14.2 grams pivot bolt weight to get approx 90 grams
A 965 ramp uses 15.4 grams pivot bolt weight to get approx 90 grams
A 951 ramp uses 17.0 grams pivot bolt weight to get approx 90 grams

The 965 ramp is 50.7 grams
The 966 ramp is 51.0 grams; it is only 0.3 grams heavier than the 965 ramp.

So if the 966 only 0.3 grams heavier than the 965 ramp, then what reason would it not work in place of of the 965?

I just ran the 966 ramps last week in Revelstoke in Keystone before the "shovel out" at 7190 feet and did just fine with them. Correct engine speed and superb engine braking.

If a guy has bone stock clutching, he can remove the 50.7 gram 965 ramps and install the 51.0 gram 966 ramp. You’ll observe the engagement speed is 100 rpms lower with the 966 than the 965. The mass is in a wider displacement across the ramp and pull a little harder through the bottom to midrange.

https://www.dootalk.com/forums/topic/1542981-new-ramp-966-low-elevation/

The race handbooks say 47g for the 965 but i've weighed a lot of them and they were 50 grams. I did not use a triple beam but my ohaus scale is a $200 scale and i calibrate it every once in a while.
 
Last edited:
A

ak

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My 965 weigh 47.4 grams on my scale and my 990 ramps weigh46.9. So my scale reads a little higher than what skidoo list. 50 grams for 965 seems really high.
 

fugly27

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IF he has my clutch kit, THEN the 966 ramp will work.
  • The 965 ramp is 50.7 grams
  • The 966 ramp is 51.0 grams; it is only 0.3 grams heavier than the 965 ramp.
If the guy has bone stock clutching he can remove the 965 ramps and install the 966 and they will work.

My kit works with the 951, 990, 967, 965, 968...AND the 966 ramp.

Because every ramp is a different mass, all you have to do is get the right pivot bolt weight for the elevation.

Example
At 7000 feet need a total of approximately 89.0 to 90 grams of complete ramp weight.
  • Complete ramp weight is the weight of the ramp (left arm+ramp+right arm) plus the pivot bolt weight.
On my clutch kit...
A 990 ramp uses 17.5 grams pivot bolt weight to get approx 90 grams
A 968 ramp uses 16.7 grams pivot bolt weight to get approx 90 grams
A 967 ramp uses 19.3 grams pivot bolt weight to get approx 90 grams
A 966 ramp uses 14.2 grams pivot bolt weight to get approx 90 grams
A 965 ramp uses 15.4 grams pivot bolt weight to get approx 90 grams
A 951 ramp uses 17.0 grams pivot bolt weight to get approx 90 grams

The 965 ramp is 50.7 grams
The 966 ramp is 51.0 grams; it is only 0.3 grams heavier than the 965 ramp.

So if the 966 only 0.3 grams heavier than the 965 ramp, then what reason would it not work in place of of the 965?

I just ran the 966 ramps last week in Revelstoke in Keystone before the "shovel out" at 7190 feet and did just fine with them. Correct engine speed and superb engine braking.

If a guy has bone stock clutching, he can remove the 50.7 gram 965 ramps and install the 51.0 gram 966 ramp. You’ll observe the engagement speed is 100 rpms lower with the 966 than the 965. The mass is in a wider displacement across the ramp and pull a little harder through the bottom to midrange.

https://www.dootalk.com/forums/topic/1542981-new-ramp-966-low-elevation/

The race handbooks say 47g for the 965 but i've weighed a lot of them and they were 50 grams. I did not use a triple beam but my ohaus scale is a $200 scale and i calibrate it every once in a while.
965 gram weights are 47.08 grams
 

Dynamo^Joe

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My 965 weigh 47.4 grams on my scale and my 990 ramps weigh46.9. So my scale reads a little higher than what skidoo list. 50 grams for 965 seems really high.

Ok...we can use your weights, not mine, and adjust the pivot bolts.

965 @ 47.08 grams + 15.20 gram pivot = 62.28g to make 7900 @ 6000 feet.
966 @ 51.00 grams + 11.28 gram pivot = 62.28g

...Will the 966 ramp work at 6000 feet to make 7900 rpms, yes or no? :face-icon-small-hap
 
Last edited:
A

ak

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Dec 7, 2007
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Ok...we can use your weights, not mine, and adjust the pivot bolts.

965 @ 47.08 grams + 15.20 gram pivot = 62.28g to make 7900 @ 6000 feet.
966 @ 51.00 grams + 11.28 gram pivot = 62.28g

...Will the 966 ramp work at 6000 feet to make 7900 rpms, yes or no? :face-icon-small-hap[/

Yes it will at that elevation with your kit. What if it’s not your kit? How about s sea level kit at 10,000 ft in the sierras that's no good.
 

Dynamo^Joe

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Howdy. If a guy was stuck, I would use the 966 ramps and the standard H.E. primary spring and pivot it to have the correct overall weight for 7950ish. I would not use the L.E. primary spring higher than 4000 feet.

I'll look to see if i have a titanium pivot bolt to do that on stock clutching.
The 965 ramps are rite mint though as it is. he he he :becky:

On bone stock clutching, the high elevation clutching works mint at low elevation. The only thing you have to do is get about 5 grams more pivot weight on the ramps. Example; I ran the stock H.E. 967 ramps with stock clutching down here at 900 feet with heavy tungsten spacers on the pivot bolts.

Its basically old fashioned Aaen clutch tuning, nothing fancy. Just getting the correct weight with whatever cam arm for whatever elevation. Im not doing anything different than clutching a latest cat or 30 year old polaris.

Aaen's law carved in stone...
  • Weight determines engine speed - need more engine speed, reduce weight. need less engine speed, add more weight.
  • Change spring end force to straighten out shift "if needed".
 
Last edited:

PaulAnd

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Howdy. If a guy was stuck, I would use the 966 ramps and the standard H.E. primary spring and pivot it to have the correct overall weight for 7950ish. I would not use the L.E. primary spring higher than 4000 feet.



I'll look to see if i have a titanium pivot bolt to do that on stock clutching.

The 965 ramps are rite mint though as it is. he he he :becky:



On bone stock clutching, the high elevation clutching works mint at low elevation. The only thing you have to do is get about 5 grams more pivot weight on the ramps. Example; I ran the stock H.E. 967 ramps with stock clutching down here at 900 feet with heavy tungsten spacers on the pivot bolts.



Its basically old fashioned Aaen clutch tuning, nothing fancy. Just getting the correct weight with whatever cam arm for whatever elevation. Im not doing anything different than clutching a latest cat or 30 year old polaris.



Aaen's law carved in stone...

  • Weight determines engine speed - need more engine speed, reduce weight. need less engine speed, add more weight.
  • Change spring end force to straighten out shift "if needed".



Is Kanedog your evil twin?


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