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Thread: Transmission / Centrifugal clutch for drag racing seems to be a proving winner?

              
   
   
  1. #1
    Old EV Racer EVcycle's Avatar
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    Transmission / Centrifugal clutch for drag racing seems to be a proving winner?

    I have been contemplating this change for some time and its benefits seem to have been proven. I recently saw a AC Dragster out if California add a
    10 disk from a Top fuel harley and dropped their 60 foot time from 1.7 to 1.2 sec. That is a big difference.

    Due to our drag bikes size, a two speed is not practical, but the Centrifugal clutch is. If I can find one for a 1 1/18" Bore.

    But why do you ask?

    I have run DC and AC motors and the AC motor still has a softer (relatively speaking) launch compared to the DC. My 60 foot times are poo poo.

    Think of it as "Dropping the clutch" at the launch of a drag race. It may be 100% torque, but it is still not moving at launch.
    It does not have to be 5000 RPM, Just enough rotation before the launch to make the vehicle hit ....hard.


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    EV Ed
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  3. #2
    Senior Member Ted Dillard's Avatar
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    Do you have a link to anything about that AC dragster? I'd love to read more!

    This is awesome, especially since I got lectured about how "spinning it up and dumping the clutch" wouldn't make any difference because electric motors don't have any sort of inertia force that would give you a benefit. It totally ran against my gut feeling, but the guy was a pro engineer and all that.

    Dying to see how it goes for you!
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  5. #3
    Old EV Racer EVcycle's Avatar
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    Quote Originally Posted by Ted Dillard View Post
    Do you have a link to anything about that AC dragster? I'd love to read more!

    Dying to see how it goes for you!
    I will do you one better....A video!

    https://www.youtube.com/watch?v=bdLXdCbe0Jg&t=922s

    From the engineering aspect, I think they are close. The just need some more runs to fine tune it.
    From the drag racing side, they need to get some more input on car setup. (We have run Bracket to Blown dragsters)
    They were off on their setup and the track was not holding all of their power.

    Our issue will be finding a inboard clutch that will fit a 1 1/8" motor shaft and be light, but strong enough to take the all the Juice.

    They had to go to a 10 disk (twice the normal size) Harley Nitro clutch!
    Last edited by EVcycle; 3 Weeks Ago at 1710.
    EV Ed
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    I thought Steve built that with the idea of using the lock-up right off the bat. Does he say his old 60' times were 1.7? I must have missed it..

    Sent from my SM-T380 using Tapatalk

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  9. #5
    Old EV Racer EVcycle's Avatar
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    I got the 1.7 Sec from the video.

    They said that they had set the clutch at 5000 rpm. That seems a bit high for a electric motor. I hope they are not using ICE logic for this application.

    The trick is to have the right amount of battery power (more than needed is just extra weight) in the right spot on the vehicle for weight distribution.

    In racing, every ounce counts.

    ICE drag racers have had a long time to get it right. This has a different power and weight design so the vehicle needs to be set up to make use of all the power.....correctly.

    A 4 link rear would help due to the battery placement..... but that would add more weight... everything is a trade off. "Power is useless without control"

    They had much larger rear slicks on it early on, They wisely went to a 10". I think the 10" are good as we ran a blower car on the same size tires with no issues.
    The may want to go to 12"s but no bigger. The way they were trying out different tire pressures (big difference in the pressures from start to finish) leads me to believe
    that there is more engineering that experience with the drag racing part of their testing.

    I have no doubt they will get there. It takes laps and making ONE change at a time,


    Ed
    Last edited by EVcycle; 2 Weeks Ago at 1349.
    EV Ed
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    It's likely that 5K is the break speed of the motor i. e. speed where max power is achieved. Snowmobiles used for drag racing run a 2-step with the lower limit just below the point where the clutch really grabs (most of them hold the brake on so as not to accidentally red light). I looked at a snowmobile setup for my drag bike a few years back but decided a bigger controller would be better.

    Sent from my SM-T380 using Tapatalk

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    My point is that you might find a sled clutch that could work for you....

    Sent from my SM-T380 using Tapatalk

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  14. #8
    Old EV Racer EVcycle's Avatar
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    Quote Originally Posted by Frank View Post
    My point is that you might find a sled clutch that could work for you....

    Sent from my SM-T380 using Tapatalk
    Thanks, I am pretty much locked into this combination due to the bikes size and I don't want to spend too much more on it. It runs well, I just think that if I find the
    proper clutch I can knock down the ET some. I have found a few possible contenders, but they all use a spline setup. The search continues !

    Ed
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    Senior Member Stevo's Avatar
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    would a slipper type clutch work, like a Rekluse?
    Current rides: '96 Honda Ohlins VFR, '03 Cannondale C440R, '03 Cannondale Cannibal, '06 Yamaha 450 Wolverine 4x4
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  16. #10
    Old EV Racer EVcycle's Avatar
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    Quote Originally Posted by Stevo View Post
    would a slipper type clutch work, like a Rekluse?
    I think those are wet clutches...
    Last edited by EVcycle; 2 Weeks Ago at 1635.
    EV Ed
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