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Frequently Asked Questions
Q. I bought a single disc Vortex clutch for my son who runs purple plate flat head. It came with a 14 tooth sprocket. Do I have to buy a certain brand sprocket to go up in teeth or would any brand work?
A. Save yourself some grief and stick to OEM parts. One sure way to go slower is to use a clone sprocket. For example, Bully sprockets are wider than SMC sprockets and consequently cause a lot of unnecessary drag.
Q.Which name is it: sprocket, gear or driver?
A. Sprockets connect to chains. Gears connect to other gears. Drivers wear helmets.
Q. What is the correct engine engagement rpm?
A. Clutches should be set to the engine's maximum torque rpm. If you don't know the peak torque rpm, set the clutch to a low rpm. Acceleration will be lazy but you'll do no damage. Adjust upward in small increments. If you don't know the peak torque rpm and set the clutch too high you will have lazy acceleration and a fried clutch. The two biggest reasons why clutches overheat are wrong engagement rpm and bad sprockets.
Q. Does a clutch sprocket require any kind of maintenance?
A. Sprocket bearings must be clean and properly lubricated. Dirty or dry rollers skid rather than roll and cause drag on the clutch and generate heat. Chlorinated brake cleaner and Mobil 1 Synthetic Grease are recommended. Read more...Speed Secret #2
Q. I installed new SMC Roller Levers in my three disc Bully clutch. The issue I'm having is they are all tight in the actuator plate. I put the original levers back in and they fit fine. What's the deal?
A. Get some new dowel pins from either SMC or Buller. The old ones are probably corroded and consequently a bit oversize.
If you look closely at the pin holes in the two levers you will see big differences. The original lever has a punched hole that is large and rough. The hole in the SMC lever is drilled and reamed to a closer tolerance.
Q. Any chance that SMC Roller Levers will fit a Tomar TD43 ?
A. The Tomar lever plate has a slot width of only 0.175 inch and a pin groove diameter of 0.156 inch. The SMC roller levers have a thickness of 0.250 inch and a 0.250 pin diameter. It would take a lot of machine work on the Tomar lever plate to make all the parts fit, but it is possible.
Q . I was just informed that SMC will not be sending out the vortex clutches with the conventional levers anymore. All new SMC Vortex clutches will have the roller levers in them. Why?
A. SMC Roller Levers are made of steel. The original levers were made of brass (which is 15% heavier than steel). Although the old Vortex levers had advanced metallurgical and kinematic features, they are no match for the new roller levers. Roller levers offer a huge improvement in clutch efficiency i.e. more acceleration and less heat, but add only $45 to the cost of a new Vortex clutch.
Q. I want to go to a eight-tab disc. This is on a Vortex single disc. What all parts do i need to buy?
A.
SMC manufactures eight-tab discs ( P/N 4931) and eight-slot drums (single disc clutch: P/N 4825). Be advised that the four-tab discs and drums are faster. The chain contacts only half of the sprocket teeth causing the sprocket and drum to wobble on the engine's crankshaft. The four-tab configuration operates as a universal just just like the ones on your car's drive shaft and compensates for the angular speed variations. Eight and three tab geometries have a trigonometric disadvantage i.e. the pivot axes are not mutually perpendicular consequently there's a lot of friction between discs and drums that waste horsepower.
Q. Why was the SMC Bullet clutch discontinued?
A. The "hard-pulling" Vortex clutches were outselling the "hard-hitting" SMC Bullet clutches by a factor of 30 to one. The smoother engagement has proven to be faster.
Q. What is the minimum thickness for a Vortex clutch disc?
A. There is no minimum thickness. (New discs are .125 inch thick.) SMC clutches are not sensitive to air gap. A lot of perfectly good discs are discarded because they look worn out. APPEARANCE IS NOT A CRITERIA. Heat and pressure will eventually change the frictional properties of the disc. How well did the discs perform on the race track? That determines when to replace.
Q. If you were needing higher RPM's for a Open motor, which would be the better choice for a 4 stoke open? 1-axle clutch, 2-arena style clutch, 3-jack shaft.
A. Axle clutch because big engines need big clutches.
Q. Does the Vortex need to be rebuilt after every season? We ran on a purple plate for fourteen races. I scuffed the plates after every other race. Does anything else need replaced other than the plates and discs?
A. If you start to notice the engagement RPM being lower and lower over time, then change the springs. Make sure the pivot pins and hole in the weights are kept clean.