Step by step: From general maintenance to complete restorations, we share tips and tricks for working on classic bikes.
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.
This 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 metal disc (left) and overheated original.
For parts, we turned to clutch specialists Barnett Clutches & Cables, picking up a complete set of plates — fiber and metal — plus new springs. All in, our Barnett clutch discs and springs cost $218. That may seem like a fair piece of change, but given Barnett’s reputation, quality is not going to be an issue. We sourced the missing clutch plate piano wire retainer, outer cover gasket and pressure plate bolt/washer from bikebandit.com for $19. Importantly, much of the process outlined here applies to other air-cooled Suzuki inline fours, including the GS650, GS850, GS1000, GS1100 and GS1150 from 1978 through 1986, as the basic design was used across the range. The GS750 models used a different setup.
This job is completely within reach of the average weekend warrior. Replacing the piano wire retainer complicates the process, but disassembly is otherwise straightforward. Draining the oil is optional (we doubled up for an oil change) — the clutch is on the right, the sidestand on the left; positioned on the sidestand, no oil will drain out when you remove the outer clutch cover. As always, we suggest having a good shop manual at hand. Happy motoring!
1. We did an oil change at the same time, so we started by draining the oil with the engine hot, then removing the oil filter for replacement.
2. To begin, remove the 10mm bolt securing the rear brake lever. Before removing the lever, note the small alignment punch mark on the lever shaft; it aligns with the pinch slot in the lever.
3. Next, remove the pin securing the clutch cable to the clutch release arm. Remove the 10mm bolt securing the clutch release arm, then lift the release arm up off the release shaft.
4. Using the proper JIS Phillips driver, remove the clutch cover bolts, working slowly in a cross pattern. They can be stubborn, making an impact driver highly recommended.
5. The clutch cover screws vary in length. To ensure proper location, sketch out the cover on a piece of cardboard, mark and punch out the approximate screw locations and then transfer the screws onto the sketch.
6. With the screws removed, the cover should break free easily. If it doesn’t, reinstall the release arm and pull it toward you to “push” the cover off.
7. With the cover removed, loosen then remove the six clutch pressure plate retaining bolts and springs, working slowly in a cross pattern until the bolts with springs and limiter barrels come loose. Remove the cover and set aside.
8. Next, remove the clutch plates, starting with the fiber outer and ending at the final metal inner. The plates alternate from fiber to metal. Use a pick and magnet as necessary to aid removal. If the piano wire is in place retaining the innermost metal plate and the plate isn’t blued from overheating, you can leave the innermost plate in place.
9. The piano wire was missing on our clutch. The wire holds the innermost plate in tension against a cone washer and the clutch hub. The hub must be removed to install a new piano wire. To remove the hub, fold back the locking tab washer, then remove the 34mm nut securing the hub.
10. To install the piano wire, install the cone washer and a metal clutch plate on the hub. Lightly clamp the plate to the hub. Feed the wire around the hub in its slot, then push the spring ends through the keeper hole in the hub.
11. Make sure the wire is properly seated around the hub. Reinstall the hub, the tab washer and retaining nut. Put the transmission in gear. Have an assistant apply the brake and torque the retaining nut to 50.5ft/lb.
12. Before installing the rest of the plates, soak the new friction plates in clean engine oil. Barnett suggests a 1-3 minute soak. After they’ve soaked, hang them from a hook to drain off excess oil.
13. Install the plates, alternating from fiber to metal and so on, ending with a fiber plate. This is how it should look before the clutch pressure plate is reinstalled.
14. Although not strictly necessary, we opted to replace the clutch pressure plate springs as we think it’s good practice. The full set only added $22.16 to the project. We also replaced the incorrect retaining bolt and washer.
15. Reinstall the pressure plate using the new springs. You can see our replacement bolt at the 11 o’clock position. Working slowly in a cross pattern, tighten the bolts until they seat, then torque to 9.5ft/lb. Rotate the center release rack so its teeth face rearward.
16. Install a new gasket on the cover face. The cover has two locating dowels that will hold the gasket in place. Sealant is not necessary, just make sure the sealing faces are clean and dry. Gently tap the cover home if necessary.
17. Next, transfer the cover screws from the paper or cardboard locating template. Using the correct JIS Phillips driver, work in a cross pattern until they all seat evenly and securely. Reinstall the clutch release arm, aligned as shown, and connect the clutch cable.
18. To finish, install the new oil filter then fill the engine with fresh oil. Start the engine and check for leaks, then let the engine rest and top off the oil as necessary. Assuming there are no leaks, you should be ready to ride.