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Product Review Sherms Gorilla Clutch

Friday, October 3, 2003
After our project Kawasaki Mean Streak was waxed at the drag strip by the Sherms Cycle Products' Meanie, we figured we would follow the age-old motto: If you can't beat 'em, join 'em.

Our Mean Streak project bike has turned into a versatile machine, with good looks for profiling and more ponies for that high-performance snap we all enjoy, including some amateur drag racing that is proving to be popular with many cruiser owners.

Our 2002 mean Streak is easy to handle at the strip but dipping into the 12 second range was not as easy as it sounds.
Our 2002 mean Streak is easy to handle at the strip but dipping into the 12 second range was not as easy as it sounds.
The Sherm's boys kicked our collective butt when we pitted the two Kawis against each other, and it was mostly due to the hard launch from the Sherm's-modified bike that put the power to the ground at the moment the clutch engaged thanks to its Gorilla clutch kit. Whereas our Mean Streak seemed to take a moment to really start accelerating, Sherm's bike would get with the program almost immediately. At the strip this can equate to tenths of a second faster E.T., and those slivers of time can be the difference between winning and losing.

We wanted to see how much of an advantage the clutch offered, so we decided to install one of the $190.95 Gorilla clutch kits in our bike. Sherm's lead technician Guy Mobley assisted during the installation process.

There are a few items you will need to make installation of the kit go smoothly. The most useful is an impact wrench and 27mm socket. Also, bring along two new exhaust gaskets, oil, oil-filter and axle. A new clutch cover gasket is good to have, although you can re-use the stock one if you're careful.

The first step is to soak the fiber plates in new oil for about 20 minutes. That's about how much time you will need to remove all the hardware between you and the clutch. The steps are the same for the replacement of an OEM clutch, so we suggest you get a factory Kawasaki maintenance manual.

Start by draining your oil and removing the exhaust. After that, the right side lower frame support will need to be moved. You can do this without disassembling the rear brake components, so leave them attached and just take out the four allen bolts that connect the lower frame tube to the main frame. The bolts that hold the radiator on the right side will also need to be removed at which point you can swing the entire set-up forward and out of your working area.

The Sherms Gorilla Clutch kit retails for  190.95 and includes a Barnett heavy duty diaphram spring  new fiber and thicker steel plates.
The Sherms Gorilla Clutch kit retails for $190.95 and includes a Barnett heavy duty diaphram spring, new fiber and thicker steel plates.
Remove the engine cover to reveal the clutch. A small thrust washer usually falls out of nowhere when you remove the cover; place it over the starter shaft when you reassemble the bike. Take a look at how the throw-out bearing and outer clutch assembly goes together because there are a few components in there that are a bear during the re-assembly process. The pressure plate is held in place by a snap ring which can be removed easily with a screwdriver. The OEM diaphragm spring you're looking at is the component that causes the biggest slippage problem. The tiny fingers wear quickly under the abuse of hard acceleration. Expect about 12,000 miles from a stock clutch with above average abuse that comes from racing, towing or aggressive light-to-light riding. Typical cruising and touring can expect the life of a stock clutch to go over 20,000 in most cases.

Remove the 27mm clutch-hub nut with an impact wrench. Carefully extract the pressure plate assembly. Take a good look at this when you have it in your hand because it is tricky to put back together. Take note of how the stock diaphragm spring and collar and the three torque-limiting springs (warped-looking washers) look. Putting this back together is the tough part.

Remove the stock clutch plates and separate the steels from the fibers because you will need to use two of your best looking factory steels along with the Gorilla clutch kit. If the steels are blued, crosshatch-sand them back into shape. Now it's time to install the new clutch. If you don't know how to install a clutch properly by now, please have a reputable shop like Sherms or your local dealer do this for you. Otherwise, read on.

The first steel plate needs to be one of the thin stock steel plates. The five thick new plates are next, alternating with fibers, with the last steel plate being the second of your OEM plates. Make sure the last fiber plate is in the correct spot. It does not go into the grooves the other fibers are in, instead fitting into the shallow groove (ON WHAT?) per the OEM manual. This was the easy part. 

Assembling the pressure plate and trio of torque-limiting springs along with the new Barnett heavy-duty diaphragm can be tricky.
Assembling the pressure plate and trio of torque-limiting springs along with the new Barnett heavy-duty diaphragm can be tricky.
Assembling the pressure plate and trio of torque-limiting springs along with the new Barnett heavy-duty diaphragm spring can be a tricky job. Hopefully this will make it easier for anyone doing this on their own. Install the new diaphragm spring that came with the kit along with the OEM collar through the front of the pressure plate. The three torque-limiting springs (these are the warped-looking washers) go in a particular order on the back side of the plate. The first spring should cup towards the engine. The second one cups away from the engine with the third one over the second with the cup facing towards the engine. This creates a little flying saucer shape. Use a tiny bit of axle grease to hold them in place on the backside of the collar while you slip the assembly over the main shaft. Use the impact wrench and tighten the 27mm clutch-hub nut to spec.

Once you have the pressure plate in place you will need to push it in with your hand, keeping steady pressure as you force the fluid of the hydraulic clutch back up the lines. Keep pressure on as you reinstall the snap ring. It is always good to give the clutch lever a pull to inspect that you have assembled everything correctly. Expect about 1/8th inch of movement in the clutch assembly while it engages and disengages. The clutch lever requires a bit more effort than the low-effort stocker.

Make sure to put the tiny thrust washer back in place before reinstalling the clutch cover then tighten it down. Reassemble the frame and reattach the radiator making sure all brake lines and hoses are not kinked in any way and are routed properly around the frame rail.

With our Muzzys megaphone exhaust, it is necessary to have it removed it in order to change the oil, so change the oil before reinstalling the exhaust system. Replace the exhaust flange gaskets to ensure a good seal. A little trick offered by Sherms is to use Harley-Davidson Evo exhaust flange gaskets here because they can be reused. This saves a bit of money for do-it-yourself owners.

After the Gorilla clutch was installed we took the Mean Streak out for some real world street testing. What we found was that the effort it takes to engage the clutch lever was increased. The clutch lever effort was increased significantly, and it now feels much like a pre-2004 model H-D clutch. Once you drop the hammer, though, the bike feels like it accelerates with more authority than before.

The only thing left to do now is to take it back to the drag strip to see what difference it makes in our quarter-mile times. If you remember from our drag racing installment, Sherm's bike was able to break into the 12.9 bracket while we were stuck in the low 13s, so we are eager to see if it helps us dip into the 12s as well.

Installing the Gorilla clutch kit turned out to be more complicated than we were expecting, so we were grateful to have a real mechanic perform the job for us; unless you are not a competent mechanic, you won't want to tackle this job yourself. We recommend you have a professional shop like Sherms do this procedure unless you have more than a few clutch changes to your credit. It's better to get it done right the first time, and the extra hundred bucks it will take to install is well worth the peace of mind that comes from knowing a certified mechanic wrenching on your ride.

Stay tuned for our upcoming Mean Streak features which include the following articles:
MCUSA Mean Streak goes Gorilla at the drag strip.

Results from Sherms grudge match versus Thunder MFG's Mean Streak at the VROC reunion in Arkansas.


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