Hydraulic Clutch System Repair
Clutch giving you a hard time? Let's look into diagnosing loose pedals, hard to engage gears and mushy pedal feel. The clutch master and/or slave could be your problem!
What is needed?
- Socket Set
- Wrench Set
- Empty Container
- Jack & Jack Stands
- DOT3 or greater Brake Fluid
- Locate the slave cylinder on the side of the transmission (GTS=Right side / SR5=Left side) the slave cylinder will have a bleeder valve (circled in green). Use your wrench to loosen this valve. Your assistant will manage the pedal; simply pump the pedal until all the fluid has left the system. It is helpful to have a clear tube you can connect to the valve; this will allow you to direct the draining fluid.
Slave Cyl. Replace
- After the system is drained, remove the two bolts that hold the slave cylinder in place. Follow by removing the soft line. Once the old unit is removed, replace the new unit by installing in reverse order. Take care when removing/replacing the clutch line. The threads are often soft and can be stripped very easily.
Master Cyl. Removal Prep.
- With the slave cylinder replaced it is now time to begin removing the master cylinder. Begin by removing/loosening all bolts on the brake booster. You will need to slide the booster forward to allow ample room for access to the nuts on the master cylinder. All four nuts can be found by following the brake pedal up to the firewall. (Tip: Use a swivel bit for your ratchet and use a small handled ratchet)
Master Cyl. Removal
- Remove the pin from the fork that connects the master cylinder to the clutch pedal. The pin is held on with a cotter pin and just needs to be pulled downward and the locking pin can then be pulled out.
On the left side tucked in the corner is a 12mm nut that anchors the clutch master from the inside, remove the nut.
Master Cyl. Removal
- After removal of old unit, install the new unit in reverse order.
- After the new unit is installed, bleed the system. This is done by leaving the bleeder valve on the slave cyl open and filling the master cyl as an assistant pumps pedal to allow the system to fill. Follow up by bleeding the system entirely.
Remember, brake fluid is nasty on paint and skin/eyes etc. If you get some anywhere on the car or on yourself, clean it off thoroughly and quickly.
To bleed a Hydraulic the system, simply use these steps:
#1) Build pressure by pumping the pedal (5-10 pumps)
#2) Hold the pedal to the floor.
#3) Loosen bleeder valve valve 1/2 - 3/4 turn (Overturn and air can enter through the threads)
#4) Watch the fluid coming out for air.
#5) Close Valve
--Repeat until the fluid coming out of the valve is pure liquid and no air. Remember to check the master cyl. reservoir often to ensure that you don't run out of fluid and allow air to enter the system again.
To explain why you are doing this in case you don't understand; the system is full of this fluid, when you depress the clutch you are driving a piston in the master cylinder that is creating a build in pressure. The only other moving part in this system is the slave cylinder. This cylinder has a piston in it that will drive outward when the pressure in built, the exposed end of the piston rests against the clutch fork and this fork has the throw out bearing on and this goes onto releasing the clutch. If air is in the system, when the initial piston moves, the only thing that moves are the air bubbles. The air moves much more freely then the fluid and it will not move the piston in the slave cylinder. Thus not driving the throw out bearing to pressure plate.
So if you have air in it for whatever reason, this is why you bleed it, to introduce more fluid into the system and keep it full while at the same time forcing the air bubbles out. So when you pump the pedal it drives all the air bubbles together and when it's held the pressure is released by the opening of the valve and the air will come out.
Clutch Master Cylinder; Exploded:
Clutch Slave Cylinder; Exploded:
Toyota OEM Clutch Master Cylinder; GTS PartNumbers:
Clutch Slave Cyl. - 31470-12050
Clutch Master Cyl. Zenki - 31410-12092
Clutch Master Cyl. Kouki - 31410-12182
Note when purchasing:
The Zenki and Kouki Clutch Masters' are different, Kouki had a bushing in line with the rod that drove the piston, thus preventing an annoying squeak that often comes from Zenki master cyl. Remember this when making your purchase!