Replace Suzuki GS1100 Clutch Plates


| 8/13/2015 8:28:00 AM



1981 Suzuki GS1100EX

The clutch: Always used, often abused, it doesn’t get the respect it deserves. That’s somewhat ironic, given the clutch’s role in ensuring you get from A to B. Yet it’s somewhat understandable, as clutches are typically undercover and out of sight — and out of mind.

The typical motorcycle multi-plate wet clutch is made up of two sets of alternating discs; a fiber-faced set driven by an outer clutch drum and a set of metal discs keyed to an inner clutch hub. A spring-loaded pressure plate bolted to the inner clutch hub clamps the discs together, coupling the clutch drum and clutch hub together to transfer power from the engine to the transmission, and then the rear wheel. When you pull on the clutch lever, linkage pulls or pushes the pressure plate, overcoming spring pressure and uncoupling the clutches so you can shift gears.

BikeMasterThis constant coupling and uncoupling causes wear. If you’re nice to your clutch, bringing engine speed up lightly for launch and letting the clutch engage quickly and cleanly, the plates can last indefinitely. Stoplight drag races, on the other hand, are clutch killers. The high revs induced for a high-speed launch translate to longer and harder engagement. The clutch plates slip and heat up, resulting in wear of the fiber plates and overheating and warping of the metal plates.

The previous owner of our 34,000-mile 1981 Suzuki GS1100EX had installed “heavy duty” clutch plates. Clutch feel was poor, however, and there was no adjustment left in the cable, which was new. A tear-down showed overheated and blued metal discs and wearing fiber discs. More worrying, it also revealed a missing piano wire retainer for the innermost metal disc and an incorrect pressure plate bolt. That missing piano wire added about an hour to the job; replacement requires removing the inner clutch hub. Our advice? If the innermost metal plate is good (no signs of bluing) and the wire is in place, leave it be.



New and original metal discs

GTRider9
12/14/2017 8:34:42 PM

This is a well-done article; I do have a few extra thoughts: 1) The center hub nut is almost always loose; it's soft and chafes on the mainshaft threads. APE made a replacement that is much stronger and will actually stay torqued. Hopefully they still have them available. You should also have a new locking washer on hand as they are not always re-usable. 2) The rivets that hold the outer basket to the primary driven gear loosen up and the shock-damping springs sack out, creating a lot of slop. To check for this,grab the outer basket while the plates are out and try to rotate it back and forth. It should move only slightly, if at all, on the primary driven gear. If it rotates readily back and forth it needs to be replaced or rebuilt. There used to be several companies that could replace the damper springs and re-rivet the basket back together; hopefully some of them are still around. Both loose nuts and loose baskets can wreak havoc with shift quality and clutch feel, plus a loose basket will often make a knocking noise at idle. 3) If you do need to pull the basket, take a moment to verify that the oil pump (behind the clutch) mounting screws are tight. On early GS1100's the oil pump cover was held on by three small phillips-head screws, which can come loose and dry out the top end without triggering the low-oil-pressure light. Later models used the same bolts that secure the pump to the cases to hold the cover on, and are somewhat more reliable. Take it from me though--when you pull your valve cover and find that your cams and rockers are wasted, it will ruin the rest of your day!