Rebuilding the L & T clutch

2010

Perhaps the hottest product to find its way onto the starting grids at kart tracks around the country is the L&T clutch. This clutch seems to have solved more performance problems than any other part recently introduced. Although this clutch is just starting to make a name for itself in the karting world, little is known about how it works or how to maintain this unit.
Racers can get this clutch in one, two or three disk models. We will examine the assembly of the three-disk L&T clutch.
After disassembly, all parts must be clean and dry. Tony Miglizzi, owner, designer and only employee of L&T Manufacturing, stresses that the clutch be cleaned with a ketone-base solvent, such as a brake cleaner. Miglizzi points out that during the assembly, care must be taken not to touch clean threaded surfaced with your bare fingers.
First, assemble the hub and flywheel. Miglizzi lays out a clean white piece of plastic, a bit larger than a place mat, to assemble the clutch upon. At this point you will need the flywheel, hub, lever support and four 8/32 X 3/8″ hub screws. Make sure the hub assembly and the flywheel fit together with no binding. Install the lever support, making sure the prongs face upward. Next, install two hub screws. Start the first screw opposite the keyway cut into the hub. Install the next screw 180 degrees opposite. Lightly tighten both screws. Check the assembly to make sure all the parts mate well together. Place a drop of RED Loctite near the bottom of the two remaining screws. Install these screws into the hub assembly. Remove the first two screws installed, loctite and reinstall. Using an inch pounds torque wrench and tighten each screw to 50 inch pounds.
Spring cups and adjusters are installed next. Lay out the spring cup, spring adjuster screw, spring adjuster nut and the spring. You should have four assemblies. Thread the nut onto the spring adjuster screw all the way to the top of the screw. Place the spring adjuster nut and screw into the spring adjuster cup head first. Now, place the spring into the spring adjuster cup. Repeat this process for the other three assemblies. Insert the assembly, from the bottom side of the flywheel, making sure the flat ground part of the spring cup mates against the flat ground side of the hub. You should see a tiny bit of daylight between the flats of the hub and the cup.
Assemble the disks and floaters. Stack onto the hub/flywheel assembly in this order: disk-floater-disk-floater-disk. Always make sure to hook the small inside radii of the floaters over the spring cups. Make sure floaters are free from binding the spring cups.
It is now time to assemble the pressure plate. Start with the pressure plate with the sharp edged holes facing downward. If you notice the pressure plate to be slightly warped, turn the pressure plate over from the original orientation. This will correct most of the warpage. Set out the four lever straps. Notice the notch on one side of the lever strap lets. This notch always faces outside. Notice the keyhole slot in the lever strap. This keyhole slot faces the top of the clutch assembly. Assemble all four lever straps into the pressure plate. Mate the hub/flywheel with the pressure plate. At this point, the L&T service tool is needed to finish the assembly. Place the service tool on top of the pressure plate with the counter-bored side against the pressure plate. The tool will sit on the top of the four straps. Insert the service tool screw into the top of the hub/flywheel and screw into the service tool on the bottom. This will compress the clutch. Once compressed, no gaps should be observed in the clutch pack.
Now it is time to assemble the levers. Place in front of you the four lever strap pins, sometimes called dog bones, and the 12 weights. Divide the weights into four groups of three. Grab a lever strap pin with a good set of needle-nosed pliers. Insert the pin into the keyhole cut into the exposed lever strap. Make sure pin is centered between the two straps.
Take the end of the pliers and gently move the pin up into the narrow part of the keyhole. This must be done to all four lever strap assemblies. Place the three weights together and slide the weights onto the lever strap pines. Make sure the weights go in far enough to allow the assembly to sit down into the flywheel. Once all four weight assemblies have been installed, remove the installation tool.
The last step is to put in one turn of spring pressure, which is what the clutches have when they leave the factory.
Now, check the lever strap pins by gently pushing up on the ends with the needle-nosed pliers. Test the levers by wedging them from the inside with a can opener or blunt blade screw driver. This will move the lever against the outer flange of the flywheel.
Check the air gap of the clutch. Miglizzi specifies >025-.030. If your gap is too large and you still have serviceable lining on the friction disks, use the special L&T shim kit. To install the shim, squeeze the flywheel and pressure plate with a pair of pliers and slide the shim into place. Make sure the shoulders of the shim face inward. After inserting the shims in each lever strap, look at the weights and lever strap pins to make sure they are in the right position. The weights must be out against the lip of the flywheel and the pins must be all the way up into the lever strap. Miglizzi recommends never letting the air gap go beyond .035. Excessive air gap could have very expensive consequences.
Maintaining the L&T clutch is simple. Check the oil every time the kart comes off the track. Recommended oil level is visible oil when the clutch inspection hole is either at four or eight o’clock. Miglizzi strongly recommends the use of L&T clutch oil. Change the oil frequently and after every other race day disassemble and inspect. Friction disks should be replaced every time they measure less than .085. The pressure plate should be replaced if they attain warpage of more than .010. Give all parts a good cleaning and visual inspection for nicks, grooves and chipped ends. Because Miglizzi uses a very durable 90 shore durometer reading gasket, if is very important to make sure the drum and the cover surfaces are clean and the screws are very well tightened. Failure to tighten these screws well will results in the clutch losing oil while in operation. Finally, check for wear on the drum sprocket and bushing.

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