Do you have am older Honda motorcycle that is equipped with a hydraulic clutch system? Are you starting to notice clutch issues like trouble getting in and out of gear? When you shift into gear, does the bike creep forward or lurch and stall? Maybe you noticed a spongy clutch lever and have gone as far as to flush the clutch fluid only to open the reservoir cap to a muddy, half empty clutch master cylinder.
Here, you will learn professional to knowledge diagnose, service or repair the number one faulty hydraulic clutch component…
The clutch slave cylinder.
Below are some pretty important facts to learn as well as a “how-to” video of me rebuilding a faulty clutch slave cylinder STEP BY STEP with NO STEPS SKIPPED.
Hydraulic clutch systems were introduced to Honda’s motorcycle line-up in the 1980’s. Keeping the principles of the hydraulic brake system, they added a “slave cylinder” that made the motorcycle’s clutch operation buttery smooth and super easy to operate.
(They also implemented the hydraulic clutch system on many bigger sized bikes in the 90’s and today, keeping the exact same design.)
Like any other moving part or liquid, sprinkle in time, temperature changes and daily use, that hydraulic clutch system becomes one of the main causes of slipping clutches, broken transmissions, and road side assistance. One day your hydraulic clutch system operates flawlessly, the next day you cant get out of first gear…
Why Slave Cylinders Fail
– Contaminated brake fluid:
Hydraulic fluid overtime can develop moister in the system from heat cycles and begin to loose its ability to reduce corrosion, displace heat and lubricate moving parts. Failure to flush this system periodically can get ugly quicker than you can say “I’ll do it next year”.
– Age and normal wear and tear:
The slave cylinder in comprised of rubber seals to keep a tight seal on the pressurized hydraulic system. Rubber parts as you know, when introduced to moister, temperature fluctuations, and mechanical wear will eventually fail and leak hydraulic fluid. This is an unavoidable repercussion.
*Pro Advice
Hydraulic Clutch fluid doesn’t just disappear on its own. If you notice that the reservoir is oddly low, don’t try to just top it off and dismiss the issue. 9 out of 10 times it’s leaking at the slave cylinder, hidden behind covers or buried on the back of the motor…(Thanks GL1500)
Just Take It On The Chin
Honda uses the same hydraulic fluid (DOT4) in these clutch systems as they do in their hydraulic braking systems. I’m here to tell you that the brake fluid is not the problem. It’s actually a beautifully crafted lubricant that functions perfectly until it’s worn out (check your owners manual for your bike’s suggested flush period). For some reason, most motorcycle owners put brake and clutch fluid flushes at the bottom of their maintenance to-do lists right there next to coolant flushes and checking tire pressures.
Failed Slave Cylinder Symptoms
– Trouble finding neutral or difficulty shifting between gears
– Hard shifting, gear selection can become more audible
– With the clutch lever pulled in while in gear, the bike may try to creep forward or even lurch forward and suddenly stall
– Spongy clutch lever as if there is suddenly air in the system
– Low fluid level in clutch master cylinder reservoir
“What If It’s Just a Worn Out Clutch?”
The truth is, some of the symptoms mentioned above can be closely related to a burnt or worn out clutch but with some slight differences. More than likely, it is MUCH easier to pop the slave cylinder off or clutch reservoir cap first, for a quick visual inspection. If the fluid looks disgusting, flush the system thoroughly and be positive that a slave cylinder and hydraulic system is perfect. Test ride the bike again and verify that the problem has or hasn’t been fixed before proceeding into the clutch.
Common Worn Clutch Symptoms
– Once positively shifted into a gear, RPM’s increase but speed does not
– Typically under load (heavy acceleration in a high gear 4th or 5th) RPM’s increase but not vehicle speed
– With cable operated clutch system, if clutch cable is adjusted perfect, warped steel plates or worn friction disks can cause the motorcycle to creep forward once shifted into gear
– In worse cases, when you shift into any gear, nothing happens.. The image below is why!
*Pro Tips
When dealing with brake fluid ALWAYS keep extra towels and cloths around to cover and protect your painted or plastic parts.
Wear rubber gloves and keep them clean to avoid accidental drips as well as that annoying texture of brake fluid between your finger tips…. It’s the worst.
I always have a spray bottle of soapy water near by in case of a spill or drip. If an accident occurs, QUICKLY douse the area with the soapy mix and wipe dry. It only takes SECONDS for paint or plastics to be stripped of their color or shine.
Always replace the rubber cap seal when you crack the master cylinder reservoir open for the first time. ONE TIME USE.
Always replace the crush washers between hydraulic brake line fittings. ONE TIME USE.
Towards the end of the video I mention the clutch pivot bushing. Be sure to inspect, lube or replace this part if yours in worn. Image below is a comparison of a old vs new bushing.
PARTS NUMBERS I USED FOR THIS HONDA V65
-MAIN CUP/PISTON SEAL: 22865-MB0-003
-PUSH ROD SEAL/SMALLER SEAL: 91209-MB0-003
-MASTER CYLINDER CAP SEAL: 45520-MA5-672
-BANJO BOLT CRUSH WASHERS (x2): 90545-300-000
Hope you riders enjoy this video and gain the confidence you need to get the job done!
Please share the this article if you found it helpful or useful in any way! ENJOY!
