The clutch system is a closed system and should never need "topping up" with fluid. If it starts losing fluid, it means there is a leak somewhere, and needs to be fixed. Especially in the GL1500, a clutch slave leak can be disasterous: if clutch fluid gets past the inner oil seal, it will get into the engine crankcase, and destroy the lubricating oil layer on the crank smooth bearings. Running the engine like this will very quickly destroy the engine!
We show in our video as well as our images below, how to remove, rebuild and reinstall a clutch slave cylinder.
Parts used:
Piston: 22863-MJ8-003
Spring: 22864-MB0-003
Piston Cup Seal: 22865-MJ8-003
8x18x5 Oil Seal: 91209-MB0-003
Vacuum Bleeder
Brake Cleaner
Hydraulic Brake Fluid
Shop Towels
Here is our video of the entire process:
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After removing the left side side panels, you can see the clutch bleed nipple, directly below the alternator:
After removing the left side side panels, we start by removing the bolt holding the drain hose stay, to give easier access to the clutch bleed nipple bolt:
Next, from below, remove the 10mm bolt holding the bleed nipple in place.
This is the clutch slave cylinder, on the back of the engine cover, viewed from below. There are three bolts holding the slave cylinder to the engine cover, and one bolt (on the right) for the banjo fitting connecting the hydraulic line to the slave cylinder.
Remove the banjo bolt. Hydraulic fluid will flow out once this is loosened, so have shop towels on hand to catch and absorb any spillage.
Next remove each of the three slave cylinder bolts:
Using a screwdriver, gently insert it into the telltale/weep hole on the bottom and pry the slave cylinder gently away from the engine cover.
Once it releases, you can pull it away easily by hand. Also remove the actuating rod from the back of the engine.
This slave cylinder was obviously leaking. The brown crystallized substance is dried hydraulic fluid.
Apply air pressure from a compressor to the banjo fitting on the slave cylinder to push the piston out of the cylinder.
Remove the piston assembly from the cylinder.
You will see lots of sediment and muck in the bottom of the cylinder.
Spray liberally with brake cleaner to clean out the residue.
With a clean shop towel, clean out the brake cleaner. Repeat as necessary until clean.
If reusing the old piston, remove the spring and seals. In this case, I am using a new piston.
This is the cup seal that fits over the piston.
Soak a clean shop towel with brake fluid.
Use the brake fluid on the towel to lubricate the cup seal as well as the piston itself.
Making sure the narrow end of the seal points to the front (away from the spring), gently slip the cup seal over the piston.
Ensure the seal is installed in the correct orientation! Very important!
Lubricate the oil seal and piston again with brake fluid, and gently press the oil seal into the end of the piston.
The seal should be level with the outer edge of the piston when fully seated.
Install the spring onto the back of the piston.
Lubricate the cylinder and piston liberally with brake fluid, and gently press the piston into the cylinder. Do not pinch the cup seal, and make sure the piston goes in level.
Using a small screwdriver, apply grease around the outside of the piston. The service manual has you do this before installing the piston, I prefer to do it afterwards, to avoid contaminating the interior of the cylinder with grease. Wipe any excess grease from the face of the piston.
Apply grease to the actuating rod and spread evenly.
Insert the actuating rod into the clutch on the back of the engine cover.
Install the clutch slave cylinder back onto the engine cover. There are dowels on the engine cover to locate the clutch slave cylinder properly.
Reinstall and tighten the bolts. Install new washers on the banjo bolt fitting, and reinstall the banjo bolt into the clutch slave cylinder.
Spread towels under your clutch master cylinder to catch any brake fluid - spilled brake fluid will DESTROY plastic bodywork and paint ON CONTACT! Do not allow brake fluid to touch your bodywork under any circumstances! Using brake cleaner and shop towels, spray out and clean the reservoir of any residue as shown here.
Loosen the bleed nipple with a 10m wrench or socket.
Install the end of the vacuum pump on the nipple.
Add brake fluid to the reservoir. Pump the vacuum pump to draw the fluid down to the slave cylinder. Make sure you continue to top up the reservoir so that you don't run dry and suck air into the system! You will also want to pump the clutch lever while doing this, to dislodge any air. Once all bubbles have been removed, close the bleed nipple while still applying vacuum. You may need several cycles of bleeding before getting full clutch pressure.
Once you have full pressure on the clutch lever, reinstall the bleed nipple clamp and close the reservoir.
