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Andy Seesemann
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Joined: 16 Jul 2001
Posts: 3289
Location: United States, California, Fullerton
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Jeff Stamper
Joined: 18 Dec 2008
Posts: 1415
Location: United States, Illinois, Plano
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 Posted: Tue Mar 24, 2009 2:57 pm Post subject: |
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Thanks guys, I will get the new clutch package now. This way I am covered if something happens like stated before
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Adi RocK
Joined: 07 Feb 2009
Posts: 63
Location: Brunei,
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| Posted: Tue Mar 24, 2009 7:30 pm Post subject: |
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| Andy Seesemann wrote: | | You may use the new steel gears with the old clutch |
that will give slower lap times. |
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Chad Stapleton
Joined: 19 Jul 2001
Posts: 4403
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| Posted: Tue Mar 24, 2009 8:23 pm Post subject: |
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 RocK RocK ??  who ?
but logically putting more rotating mass into the motor is not likely to make it faster 
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"Those of you who think you know everything are annoying to those of us who do !!" |
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Jeff Stamper
Joined: 18 Dec 2008
Posts: 1415
Location: United States, Illinois, Plano
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| Posted: Wed Mar 25, 2009 3:12 pm Post subject: |
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Well, then you will have slower lap times with the new clutch then by that reasoning ! Right ?
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John Savage
Joined: 30 Jan 2002
Posts: 1252
Location: United Kingdom (Great Britain), not USA state,
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| Posted: Wed Mar 25, 2009 4:07 pm Post subject: |
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Our experience with the new clutch is positive, 2 meetings this year:
Race 1, old clutch - win
Race 2, new clutch - win
Race 3, this weekend, new clutch - ?
No difference on the stopwatch between the two types.
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Carlos Calderon
Joined: 16 May 2006
Posts: 890
Location: United States, California, San Jose
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| Posted: Thu Mar 26, 2009 11:04 am Post subject: |
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| Jeff Stamper wrote: | | Well, then you will have slower lap times with the new clutch then by that reasoning ! Right ? |
No, not necessarily. Remember, the new clutch kit is really two different sets of parts. One set is the actual clutch & drum (+ parts); the second set is the steel gears one is required to run while running the new clutch.
I'm guessing here, but ... The internal plastic gears where replaced by the steel gears to increase the life of these gears. Of course, the steel gears are heavier and induce a greater moment of inertia.
To compensate for the greater moment of inertia, the new clutch is actually smaller, in terms of diameter, than the old clutch. So the weight is centered closer to the axis of rotation, decreasing the moment of inertia over the old clutch.
So, if you run the heavy steel gears with the heavy old clutch, it will probably be a bit slower. However, from John's comments, testing shows that running the new gears & new clutch is about equivalent to running the old gears & old clutch.
Make sense?
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Carlos Calderon
Joined: 16 May 2006
Posts: 890
Location: United States, California, San Jose
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| Posted: Thu Mar 26, 2009 11:24 am Post subject: |
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| Carlos Calderon wrote: | | I'm guessing here, but ... The internal plastic gears where replaced by the steel gears to increase the life of these gears. Of course, the steel gears are heavier and induce a greater moment of inertia. |
| Mark Miller wrote: | | The clutch has more overall weight, yet is more compact so overall it puts more strain on the drive gears - resulting in a reduced life of the plastic gears. |
Ok, so maybe I was a little off. The new clutch is heavier and produces greater momentum, but still a smaller moment of inertia (easier to spin up & down), like I said above. And hence, the heavier clutch necessitated the new steel gears (not the other way around like I had assumed).
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Chad Stapleton
Joined: 19 Jul 2001
Posts: 4403
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| Posted: Thu Mar 26, 2009 3:56 pm Post subject: |
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| Carlos Calderon wrote: | | ...Ok, so maybe I was a little off. The new clutch is heavier and produces greater momentum, but still a smaller moment of inertia (easier to spin up & down), like I said above. And hence, the heavier clutch necessitated the new steel gears (not the other way around like I had assumed). |
NO... you cannot have "greater momentum" with "a smaller moment of inertia" ....they are one and the same.
It could have more mass (weight) ..with a smaller moment of inertia, but then it would have less momentum also. !
So it either has more inertia or it doesnt..which is it ?
Sure as hell those gears are a bunch heavier though 
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"Those of you who think you know everything are annoying to those of us who do !!" |
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Carlos Calderon
Joined: 16 May 2006
Posts: 890
Location: United States, California, San Jose
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| Posted: Thu Mar 26, 2009 4:33 pm Post subject: |
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| Chad Stapleton wrote: | | Carlos Calderon wrote: | | ...Ok, so maybe I was a little off. The new clutch is heavier and produces greater momentum, but still a smaller moment of inertia (easier to spin up & down), like I said above. And hence, the heavier clutch necessitated the new steel gears (not the other way around like I had assumed). |
NO... you cannot have "greater momentum" with "a smaller moment of inertia" ....they are one and the same.
It could have more mass (weight) ..with a smaller moment of inertia, but then it would have less momentum also. !
So it either has more inertia or it doesnt..which is it ?
Sure as hell those gears are a bunch heavier though |
This is off topic, so I don't want to go down this path, but I will say, my statement may be incorrect, but momentum is not inertia. Angular Momentum = Moment of Inertia * Angular Velocity (L=Iw). They are not the same.
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Alan Dove
Joined: 10 Jun 2005
Posts: 983
Location: United Kingdom (Great Britain), not usa state,
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| Posted: Thu Mar 26, 2009 5:48 pm Post subject: |
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There have been a issues with the new clutches that have somewhat been influenced by a trick being used with the previous one. Basically before the race some people allegadly covered the clutches with WD40. This gave extra slip in those early laps. if you were starting from the back of the grid you can imagine the advantage gained by having a slippy clutch.
The worrying thing however is that this WD40 trick has only really been clamped down on in the UK recently. It's rather dissapointing to think that this trick has probably been done for years unknown and unchecked:( We don't have this problem with the direct drive engines though  hehe gotta get one in there !
With the new clutch however you are required to grease the needle bearing. Now naturally some grease could possibly slip onto the clutch drum or element. Now some drivers have been excluded from races because of grease on the drum with the new clutch when they were perfectly innocent. Anyway the UK rotax dealers JaG and ABkC had to release this statement on it
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Rotax New Steel Clutch: The Rotax classes are affiliated to J.A.G, the importer, and the ABkC, and they jointly wish to clarify the situation regarding grease or oil on the new steel clutch as follows.
The regulations for the clutch are shown in the MSA Kart Race Yearbook B.1.5 (Junior Max), B.4.5 (MiniMax) and C.2.5 (Max). The clutch is a dry centrifugal clutch, with engagement maximum at 3,000 rpm. That means that the kart must start to move at no more than an engine speed of 3,000 rpm with the driver seated in the kart. The clutch must have standard unmodified components as per the fiche.
BRP Powertrain advise that as the needle bearing for the clutch drum must be lubricated by use of grease (according to the service manual), it cannot be avoided that some grease may get into the clutch drum and onto the clutch element. The existence of oil or grease at the inside of the clutch drum, or on the clutch element, is not in itself a reason for technical disqualification. They state that oil or grease inside the centrifugal clutch will not result in any technical advantage or in an improved lap time: Issued 20.3.09 |
No doubt drivers will be testing different oils/greases to see if laptimes could be improved anyway.
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Carlos Calderon
Joined: 16 May 2006
Posts: 890
Location: United States, California, San Jose
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| Posted: Thu Mar 26, 2009 6:04 pm Post subject: |
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| Quote: | | They state that oil or grease inside the centrifugal clutch will not result in any technical advantage or in an improved lap time |
Interesting.
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Chad Stapleton
Joined: 19 Jul 2001
Posts: 4403
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| Posted: Fri Mar 27, 2009 6:16 pm Post subject: |
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| Carlos Calderon wrote: |
This is off topic, so I don't want to go down this path, but I will say, my statement may be incorrect, but momentum is not inertia. Angular Momentum = Moment of Inertia * Angular Velocity (L=Iw). They are not the same. |
Not the same numerically, but directly proportional.
IE : a higher Moment of Inertia = a higher Angular Momentum ( at any set speed)
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"Those of you who think you know everything are annoying to those of us who do !!" |
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Brian Degulis
Joined: 13 Aug 2012
Posts: 415
Location: United States, Florida,
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| Posted: Thu Jan 24, 2013 9:31 am Post subject: |
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Hello all We just got a very low time kart with Rotax max it's an 05 engine with 15 minutes time on it. Of course it has the old style clutch and gears. Should I replace them now or just use it until the old clutch starts failing.
Just to be certain this upgrade does not involve breaking the seal so it's something we can do ourselves right?
Thanks
Brian |
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Rodney Ebersole
Joined: 20 Jul 2001
Posts: 595
Location: United States, Colorado, Grant
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| Posted: Thu Jan 24, 2013 10:29 am Post subject: |
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Well I think you should replace your new clutch with The new clutch and sell your old new clutch and gears to me for 50 bucks so I can run it till it's done for. Yes no seal is broken when servicing your clutch and balance gear cover. 
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