Hello. I have a comet clutch that went bad. I need a new clutch. My son is 100 lbs. my question is should buy a new 35# after market clutch or just by a new 35# hub for the stock clutch that i took off years ago? What is the difference between a 12 tooth and 13 tooth in the 35#? What is a good set up for clutch and sprocket #'s. I currently have a 13/46. We do a few fun non sanctioned races. Thanks
Might be hard to find Comet parts but not impossible. The more teeth you have on the clutch the faster you will go but the harder it is to take off. You give up low end torque as you add teeth to the clutch. The old stop watch is what you have to rely on. You have to see if he has gain any time advantage by going with the larger gear. A race is very short and if he is slow to get going but then he is a "bat out of hel_" but you run out of time to catch up to the pack then it definitely is working against you.
The Comet clutch couldn't take a lot of heat because they used music wire springs unless you spec out you wanted stainless steel. A certain snowmobile manufacturer in Canada found this out the first year and then they knew what to order the next time. We only use stainless steel because it will take more than twice the heat but it also cost 4 times what a music wire spring does but who cares what the cost is when you give the customer problems he doesn't need.
I would go with a 12 tooth and get the 13 tooth drum and sprocket at the same time. It is the freight that will cost you almost as much for the DR & SP later.
The secret to a clutch consistent performance is a spring that will take heat and shoe contact or pressure points to the drum The more shoes in a clutch the more efficient it is. (Also the harder to get back together but not impossible). To start with we have six shoes in the clutch, take and saw three of the shoes in half with a sawsall. Then cut three loops out of the spring and reassemble. A good video to watchin on YOUTUBE -- Max Torque clutch assembly video. The cut shoes would go in the position to the left of the slot in the drive plate. Leave the complete shoe over the slot. Now reassemble the clutch and give it a try. You will have a higher engagement because you have taken off weight (lighten the shoes) and you have shorten the spring. You can only do this with the lighter of the two shoes. This would not work with the wedge shoe that we normally supply to the snowmobile Mfg. This trick to cut the shoes is on the standard "SS" shoe that you would cut.
Another easier trick to do is take out three of the wedge shoes and replace them them with three lighter shoes. Every other shoe to balance the weight. You can do this without cutting the spring. This will also bring up your rpm.
If you want to e-mail me direct I will send you a picture of the two different style shoes. I don't know how to add pictures to the site. email@example.com
Post by Jim Donovan on Jan 13, 2011 8:02:01 GMT -5
Easy way to picture this is take the spring out of the equation. When the shoes start moving out towards the drum they only touch in one spot and as the rpms pick up then the rest of the shoe then is evenly pressed to the drum and the clutch is LOCKED turning as one piece of steel. Each shoe style clutch has its own wear pattern. Looking at at Max-Torque or the copies of our clutch they all with show a wear mark on the bottom 1/3 of the shoe. This is the initial "tick" of the shoe to the drum because the spring wants to roll the top of the shoe inward and thus it kicks the bottom out. 400 more rpm of the engine the whole shoe is locked against the drum and it doesn't slip any more. The more pressure points to the drum the smoother and quicker it will lock up. A two shoe clutch slips more and get hotter than a three shoe. A four shoe is better than a three , etc.
How hot does the clutch get? Plenty hot!! How much heat can a spring take before it gets anneal? Well according to the Spring manufacturers Institute, Inc (bible for the industry), a music wire spring will be annealed when temperature exceeds 250 degrees F while a stainless steel spring the temperature has to exceed 550 degrees. The spring is the heart of the clutch, once that is ruined the clutch will come in sooner and sooner to the point you have to hold the brake to keep the go kart or snowmobile from running away. Some clutches to keep them "fresh" and engaging at the same rpm you must change the springs on a regular bases if you want the same reaction times.
Understand how the clutch works that you own and what you can do to it to make it better. Learn what you have since the clutch doesn't make any horse power. The clutch can only transfer power to the axle.