- 29 Nov 2010
All of the power your engine makes has to go through some very small pieces in your clutches. Just think of how much force is created by a 160 HP engine, a 180 HP engine, or even more. With turbo mods being made to the Arctic Cat 1100 4-stroke, power levels of well above 200 HP are now common.
The primary clutch squeezes the drive belt and the secondary clutch hangs on to it, comparing the pull from the engine with the pull from the track. As it does this, the rollers and helix inside of the secondary are transferring all of this power from sheave to jackshaft, twisting and flexing along the way. This is why rollers break, this is why helixes break. Say what? Broken helix?
Yes. It happens. They can and do crack, and some actually break the arms, or towers. So, it is safe to assume that if high-powered engines can damage the tall thin arms of the helix, there is tremendous force being applied to a very small area. Then consider how tall the arms are on the helix and the amount of leverage being applied. Do you really think that little helix is going to stay perpendicular to the sheave? Do you really think the little stock bushing in there is going to be able to keep from binding on the shaft?
These are the things that clutch tuners worry about. The OEMs are always trying to make things work as good as possible at a fair price with acceptable durability. This is understandable. But this leaves room for the aftermarket to use better designs, better materials and better manufacturing processes. Does it add cost? Of course it does, and that is why the sled doesn’t come like this from the factory. They can’t make each and every part as good as possible, it would be cost prohibitive.
Companies that deal with clutching on a daily basis take calls all of the time from riders who are having issues with their machines. These guys hear what the needs are in the field, and they respond with solutions. Case in point, Lonn Peterson and Duane Watt at Thunder Products. Readers of SnowTech Magazine should all be familiar with both of these characters, as they have been providing solutions for clutching problems for a (combined) 60 years. That’s a lot of flyweights, springs and helixes. Duane is the patent holder of the encapsulated roller secondary that three of the four OEMs now use and Lonn is the patent holder of the adjustable flyweights, so this ain’t their first rodeo.
They looked at what was going on inside the Cat secondary with all of the big power sleds. What they saw was the factory helix was built light and inexpensively. It was made of cast aluminum. Looking at the tall, narrow arms that the ramps are cut into, they saw it was not very strong. They looked at the width of where the helix mounts to the sheave, and saw how little of support area there was. They saw a small, inexpensive bushing. They saw a gorilla compression spring that was over-sprung, placing excessive pressure on the drive belt (it’s that stiff to hold the belt during reverse operation). They saw great opportunity for improvement.
Enter the Hercules Helix. The name is appropriate as it provides a super-strength improvement to the torque-sensing secondary clutch, which the helix is the heart of. The Hercules Helix starts with a chunk of machined aircraft-grade billet aluminum. This alone provides stronger material and more exacting manufacturing so it is of the proper dimensions. The first thing you notice is how much thicker the arms are, compared to the narrow fingers of the stock helix. Then you notice how much more contact surface area there is with the helix where it mounts to the sheave, providing a solid platform. This eliminates twisting, flexing and binding as the clutch is shifting with all of the power running through the arms.
Duane Watt likes to use great big Oilite bronze bearings to provide extra support on the shaft of all of his clutching products, and the Hercules Helix is no different. Take a look at the stock helix on the clutch and notice how much of the shaft is captured with the clutch closed – the shaft is barely captured by the bushing, providing very little support at engagement! Where the stock helix uses a small 1/2” bushing, the Hercules is fitted with a 1.5” tall, providing a 300% increase in bearing area. This keeps the sheaves straight and parallel to each other, but also reduces friction and maintains smooth shifting. Typically it is the stock busing that goes bad and ends the usable life of a helix, but with this kind of bearing in there the usable life of the Hercules Helix is greatly extended.
Stock helix on left, Hercules Helix on right. Notice the width of the tall arms. Notice the height of the center support bearing. Notice the width at the top of the support arms. Notice the Hercules reverse notch. Cast vs. billet. Weak vs. strong.
Another thing you’ll notice is how the Hercules Helix has a very different reverse notch machined into it. The OEM helix relies on a super-stiff compression spring to maintain drive belt pressure in reverse, where with this reverse notch in the Hercules you are now able to run a much lighter compression spring. The difference from this alone will amaze you. Seriously, you can run a spring that has 100 pounds less of compression force. Yes. This reduces heat, and you do not have to worry about the secondary popping open with the lighter spring tension. Typically the belt will run 30-40 degrees cooler with a Hercules Helix installed, and we all know what this means for drive belt durability.
If you take a stock clutch and helix (without the spring) and open it all the way up, look and see what happens as the rollers travel to the very end of the helix slot. The rollers reach the end of the slot, but then actually travel across the slot and start to travel back down the slot as the clutch fully opens! Try it and you will see. Then install the Hercules Helix and do the same test. It travels to the end of the helix, clutch wide open, and it stops. The clutch is instantly ready to backshift.
And finally, the Hercules Helix has a twin-angle cut to the ramp angle. It shifts hard off the line and helps to keep your engine from over-revving. Suffice it to say that, with the rest of the performance upgrades in this design, you will immediately realize firm aggressive upshifting and smooth backshifting. This was dyno tested and field tested to determine the angles and their transition point, and it works.
If you want your clutches to work as good as they possibly can there are some simple steps to making the best of the power you have to work with. Keep the sheaves straight and parallel, get rid of drive belt heat and make the system shift smoother with less friction. The Hercules Helix is a huge step in the right direction towards these goals. The Hercules Helix sells for $299, with the compression spring going for $48.95. If smooth shifting with less binding makes sense to you, then be sure to check out their similar products for the primary clutch. Contact Thunder Products at 320-597-2700 or visit www.ThunderProducts.com