Please watch an ad – I get a penny. Replacement info for original electric clutch on a Craftsman lawn tractor. The original clutch was a Warner Electric Mag Stop MSS-60-LC, 5217-2 (the 5217-2 is the reference used to find a replacement).
IMPORTANT: Work on a level surface. Make sure the tractor will not move. Disconnect spark plug. Do not run the engine. Make sure clutch is cool. Remove the mower deck to have access to the clutch.
This material is a set of silent slides and a short video clip.
There are three major elements involved. The clutch assembly which includes the electric magnet and pulley for the mower deck. The transmission drive pulley assembly which includes a shaft and a pulley. The engine drive shaft into which a bolt goes to hold everything in place.
The clutch is bolted from below to the driveshaft from the engine. The slides show the side views of the clutch including the plug for the electrical connection and the pin from the frame that keeps the clutch itself from rotating. Make note of which clutch slot is mounted with the pin because there are two slots. If you use the wrong slot, the clutch will push against the tie rod (it may not be obvious unless you check). The clutch is heavy (8 lbs) so support the bottom pulley with a block of wood when you loosen the bolt holding it on the driveshaft.
To remove the clutch, support it, then use a large wrench (pipe wrench) to hold the straight sides of the bottom of the clutch assembly surrounding the bolt – it has two straight sides for this purpose. Use a large socket wrench to loosen the bolt – it turns in the normal direction. Once the bolt is removed, carefully hold the bottom of the clutch and wiggle it down. The clutch unit mounts to a transmission pulley shaft that then mounts to the engine driveshaft. A separate slide shows the trans pulley assembly and its pulley fully removed (the slide shows it upside down).
The clutch assembly has a key that fits in a channel in the trans pulley assembly. The trans pulley assembly has a key that fits into a channel on the engine driveshaft. These may be tight and you may need to work a bit to get the clutch to slide down. The trans pulley assembly will most likely come down with the clutch assembly and you can separate them when they are removed.
Once the clutch is off, disconnect the wiring from the top of it. Your replacement clutch may plug into the connector that dangles from the mower OR it may not fit that plug. My replacement plug did not. If yours does not, follow the wiring up to the engine area and you will find a second connector (about 9 inches along the wiring). The plug from your new clutch should fit that connector. Pry up the end of the outside part of the plug to release the small stop on the clutch side of the connector and pull the two apart. Space is limited for large hands.
NOTE: Illustrations of the removed clutch show an exposed set of ball bearings. This is not normal and it is why I had to replace my clutch. The bearing assembly is normally sealed and not visible on the top of the clutch.
To reassemble the new clutch, have your supporting block handy under the tractor. Slide the trans pulley assembly up onto the engine driveshaft. Make sure to slip the belt for the drive around the pulley and keep it inside the guide pins. Check where the key channel is on the shaft of that assembly. Rotate the clutch pulley so that the key on the inside of its opening will match the channel while at the same time the slot in the side piece of the clutch will fit up around the stabilizing pin from the frame. Remember which slot goes on the pin. Use the support block to help hold the clutch up while you mount it. You may need to align the slot with the pin first, then rotate the pulley on the bottom of the clutch to get the key to align with the key channel. The shaft inside the clutch may drop down an inch or so while you to do this. If it does, you must get it moved back up into the clutch assembly.
When the assembly is mounted all the way on the shaft, reinsert the bolt and tighten it. Retighten to the same torque it was when you removed the clutch – you may need both wrenches to keep the clutch from rotating. Unless you have a torque wrench, this is a matter of feel. Do not overtighten and strip the threads.
Before attaching the mower deck, you must “burnish” the clutch. Do this by running the engine at 50% power and engaging/disengaging the clutch for 10 second intervals – do it five times. Then increase power to 75% and repeat the 10 seconds on/off another five times. To be sure the clutch is actually working, you can stop the engine, attach a small piece of masking tape to the pulley, restart the engine and engage the clutch and look around the side of the tractor to see if the tape is spinning. If it is, you are ready to reattach the mower deck. Keep the mower drive belt on all the pulleys and inside its guide pins.