HOW-TO: Change a sport quad clutch
Before there were racing ATVs, former Honda technician Eric Crippa was Kent Howerton’s race mechanic at Husqvarna. The Rhinestone Cowboy’s factory Husky was down on power to works Hondas of the day, so Kent invented slipping the clutch through corners so the motor would pull the too-high gear through the turn. Other mechanics laughed and scoffed at Crippa for having to change the clutch plates out between motos, but Eric laughed back at them, saying, “Yeah, but who’s taking home the firstplace trophy?”
Today, every ATV racer worth his or her salt slips the clutch to get the most out of the sport ATV, whether in turns or when encountering an obstacle. Slipping is an integral part of the brakeslide pivot, and putting that much pressure and heat into the friction and drive plates wears out the clutch and the oil that bathes it. Modern 450s need new clutch plates so often that they’re manufactured with quick-change clutch covers. Simply unbolt the rear brake pedal to reveal the clutch-cover bolts and break out the T-handles to remove the clutch cover and pressure plate. It only takes a few minutes to have a brand-new clutch, so why put up with a slipping clutch?
Other sport quads don’t have quickaccess clutch covers, so you have to remove more components to remove the whole clutch-side outer case. Here’s how we replaced the stock 2004 Honda 300EX clutch plates and upgraded to Moose friction (driven) and steel (drive) plates and heavy-duty clutch springs.
We chose a 2004 300EX for this “How To,”and Moose Racing supplied the friction (#F70-5127-6, $73.95) and steel drive plates (#M80-7105-5, $32.95) and heavy-duty clutch springs (#FHDS4-4, $11.95) for the project. Clean the machine, warm up the engine to thin the oil, and drain the oil into your container for recycling. Remove the right footpeg and heel guard so the right case can be removed.
The 300EX brake pivot is the swingarm bolt, so we unbolted the rear-brake reservoir from the frame and rotated the brake pedal down and out of the way. Pro race mechanics usually turn the quad on its side so they can work on the clutch standing upright.
The 300EX has reverse, so it has to be unhooked before case removal. Remove the black metal guard protecting the reverse light wires, and unplug the two wires. We wrapped a zip-tie around the forward-most wire for identification later. Unhook the reverse-actuator cable and unbolt the cable anchor from the case.
Peel back the rubber clutch-perch cover and unlock the clutch adjuster nut. Turn the adjuster in and line up the grooves in the adjuster and lock nut as shown. Remove the clutch and reverse actuator cables from the perch. Unhook other end of the clutch cable from the lever on the case.
Loosen and remove the banjo bolt from the external oil line to the upper end. Remove the anchor bolt routing the oil line up the backside of the cylinder and head (shown). This might not be a step with other quads, but you may also need to remove the muffler and head pipe on others.
Some models have long oil-filter cover bolts that protrude into the inner case, so they have to be removed. This isn’t the case with the 300EX, nor do you have to remove the oil dipstick. Remove all the right-side case bolts (8mm heads, in this case). Find a spot on the case where you can pry the case loose without damaging the cover’s gasket.
The 300EX has a square screen that fits inside a groove in the inner case, but it came out with the outer case. Clean it and replace.
Remove the four 10mm hex bolts holding the clutch lifter plate, and inspect the needle bearings for wear. Slip washers over the four bolts and retighten the four clutch-spring bolts (see next photo).
Honda recommends you buy three tools: a clutch center holder (07JMB-MN50300), holder plate (07HGB-001010B) and holder collar (07HGB-001020B)—which is expensive. Instead, we broke out the impact wrench and 27mm socket to loosen the clutch nut (it’s not reverse threaded!).
Remove the clutch-spring bolts, springs, washers, nut and clutch-nut washer. Remove the inner basket (with the old plates) and inspect the inner and outer basket tongues. If grooved, the plate release can be affected, so remove the grooves with a flat file. Soak new friction plates in a pan of fresh oil.
Place the new friction and drive plates in the inner hub in the order you removed the old plates (friction, drive, friction). Replace the big washer between the outer and inner baskets, and then work the plates and inner basket
into the outer basket until it’s fully seated
Thread the clutch nut onto the shaft and finger-tighten. Replace the clutch springs, as well as your temporary washers and bolts. Impact the nut to 55 foot-pounds, remove the springs one more time, dump your washers and replace the clutch lifter plate.
We found it easier to put the reverse-engaging linkage into the inner case as shown. Remove the outer bolt and cable arm first.
Carefully line up the clutch case with the reverse-engaging shaft and bolt holes. Slide the case home, and thread a few case bolts to hold in place. Replace all case bolts and tighten, and then replace the reverse arm and bolt. Replace the reverse cable and mount, and plug in the reverse light wires. Replace the guard.
Attach the engine side of the clutch cable to its lever first, and then work the other end into the clutch lever. Anchor the cable housing/ end against the perch and pull the clutch lever. As you release the clutch lever, pull the housing into its slot in the perch. Adjust to 2-3mm of freeplay as shown. Do the same for the reverse cable.
Remove the wire or zip-tie from the rear brake pedal, and replace the master-cylinder mount bolts and footpeg heel-guard assembly. Remove the dipstick and fill the sump with fresh oil. We used Motul 20W50 and the 300EX took about 2.5 quarts. Enjoy the new clutch!
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