The M8 A&S Clutch
Stellar HDF Member
Joined: Oct 2007
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From: Eastern PA
I just had my 2017 CVO Limited Stage IV with a catless headpipe and Street Cannons dynotuned. 128/128. The good news is that the HD High Capacity clutch with the 1200N (red) springs handled the torque with no slippage at all throughout all the dyno tuning. No need to upgrade to the 1275N springs for this build at least.
Nice #'s .. I could be wrong, did they speed shift on the dyno? how did they mimic 300+lbs of riders and gear on the dyno and shift thru the gears? That is the test if the springs are truly engaging the clutch in my saddle.
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Good questions but the dyno testing didn't check for full load luggage and 2 up riding. I don't know of any dyno testing that does! Mine was was done with an average rider, full tank and tourpack lightly loaded. HD rates the High capacity clutch with 1200N spring for 150ftlbs at the crank. Figure 132-135 ftlbs at the rear wheel.
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HD EFI Guru
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I just had my 2017 CVO Limited Stage IV with a catless headpipe and Street Cannons dynotuned. 128/128. The good news is that the HD High Capacity clutch with the 1200N (red) springs handled the torque with no slippage at all throughout all the dyno tuning. No need to upgrade to the 1275N springs for this build at least.
(How about a dyno sheet so we can see where your low RPM Torque is at.)not needed. Now that I've seen your chart in another thread its like all the others. A typical Stage IV kit produces most of it's Torque above 3000 RPM, as yours does. Since they ran the dyno from 2500 RPM up it really helps the clutch not slip. Pulls from 1500 RPM up show the problems with high Torque at lower RPM's. The dyno does NOT load the bike anything like the street does. Remember the dyno is a rolling drum on bearings that moves, the street is solid and doesn't move which puts a lot more load on the clutch that the dyno will never show you. The Dyno is just a tool and used properly it really helps, used improperly it can and will lead you wrong. If your happy with it enjoy it and go ride the heck out of it.
Last edited by Steve Cole; Apr 4, 2017 at 10:28 AM. Reason: found dynosheet in another thread
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HD EFI Guru
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Here's the Dyno for my 2017 M8 117 Stage IV 128/128. I would say the torque is pretty darn good across the entire rpm band. Starting with 105ftlbs at 2100rpms. Rising to 128ftlbs at 4700rpms and still over 110ftlbs at 6000 rpms. I'm very pleased that the high-capacity clutch with the 1200N springs (red) were sufficient. I wasn't looking forward to having to pull a tougher clutch spring if I needed to move up to the 1275N springs.
I would welcome anyone to post a better, longer, flatter torque curve on ANY Harley engine dyno in ANY year that has all MOCO internal parts in an engine that came on the bike from the factory. Putting the dyno aside, it rides terrific at ALL rpms. Miles of smiles!!
I would welcome anyone to post a better, longer, flatter torque curve on ANY Harley engine dyno in ANY year that has all MOCO internal parts in an engine that came on the bike from the factory. Putting the dyno aside, it rides terrific at ALL rpms. Miles of smiles!!
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Your dyno looks like plenty of others I have seen already from that dyno. The numbers are what they are, but it in no way shows the clutch short comings. Starting the pull down below 1500 RPM so that you have good data by 1500 RPM is what begins to show the issues. As I told everyone it's what happens on the Street that counts. The load on the street is much higher and the short comings of the clutch show up there much sooner. Your happy with what you have and that is all that counts, go enjoy it.
Road Captain
Joined: Jul 2016
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From: Ottawa
What are you talking about? Do you know who Steve Cole is and the extensive knowledge he has due to experimenting with things that most of us wouldn't even want to touch. All he is doing is highlighting is that a Dyno is a tool used in a very controlled aspect which doesn't really reflect real world conditions. I'm not an engineer or a rocket scientist but it doesn't take much to understand what he is saying. A Dyno won't tell any of us how good or bad the clutch spring is. He also states that if you're all happy with your Dyno's and your clutch's then ride the heck out of your scoot and enjoy.
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What are you talking about? Do you know who Steve Cole is and the extensive knowledge he has due to experimenting with things that most of us wouldn't even want to touch. All he is doing is highlighting is that a Dyno is a tool used in a very controlled aspect which doesn't really reflect real world conditions. I'm not an engineer or a rocket scientist but it doesn't take much to understand what he is saying. A Dyno won't tell any of us how good or bad the clutch spring is. He also states that if you're all happy with your Dyno's and your clutch's then ride the heck out of your scoot and enjoy.
I agree that the street is the best place to fully appreciate the "grip" of a clutch but its not empirical. A good starting point is being sure it doesn't slip under the stress of a "good" dyno tune. In my case, the dyno tuning started around 2100 and there was no slippage with the SE High-Capacity cltuch using the "red" 1200N spring. Which is exactly the info I was sharing for the benefit of others that might be considering this clutch setup.
Last edited by Heatwave; Apr 4, 2017 at 04:01 PM.
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I know exactly who Steve is....we've interacted for more than a decade. Talented developer of the originally HD Race Tuner which I used for many years. HD went in a different direction and Steve developed TTS with his deep knowledge. I just don't see the need for anyone, Steve included, to throw shade on the dyno tune of a competitor.
I agree that the street is the best place to fully appreciate the "grip" of a clutch but its not empirical. A good starting point is being sure it doesn't slip under the stress of a "good" dyno tune. In my case, the dyno tuning started around 2100 and there was no slippage with the SE High-Capacity cltuch using the "red" 1200N spring. Which is exactly the info I was sharing for the benefit of others that might be considering this clutch setup.
I agree that the street is the best place to fully appreciate the "grip" of a clutch but its not empirical. A good starting point is being sure it doesn't slip under the stress of a "good" dyno tune. In my case, the dyno tuning started around 2100 and there was no slippage with the SE High-Capacity cltuch using the "red" 1200N spring. Which is exactly the info I was sharing for the benefit of others that might be considering this clutch setup.
As I told you and everyone else the dyno is a good tool when used properly. Your line of the stress of a "good" dyno tune does mean squat. The dyno is a drum spinning on bearings and places very little load on the clutch, so it is not the best place at all to look for slip. While it shows it, when the clutch lets go completely it does not show clutch slip well. Hope you can go out and enjoy your bike now.