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Replacing a Hydraulic C4 Clutch System

Clutch Release Corrections

Andy Bolig Feb 1, 2002

Step By Step

It’s always a good idea to disconnect the battery to prevent any electrical problems. For this job, you’ll have to remove the battery to simplify access to the clutch master cylinder. If you have a ’90 or newer Corvette, you’ll also have to remove the computer from its mount. You don’t have to disconnect the wires for the computer—simply remove the mounting bolts and move it out of the way.

To get to the master-cylinder pushrod connection, remove the inner panel under the driver side of the dash. There are connections for the ALDL connector and an interior light under there, so take care when removing the panel so as not to damage the connections.

Removing the clutch slave cylinder is the first step. There are two nuts that hold the cylinder in place.

With the slave cylinder removed from the bellhousing, you can reach the fitting on the fluid line to the master cylinder. Always use a tubing wrench when loosening the fitting to prevent rounding of the fitting.

With the slave cylinder removed from the bellhousing, you can reach the fitting on the fluid line to the master cylinder. Always use a tubing wrench when loosening the fitting to prevent rounding of the fitting.

There are two bolts that hold the clutch master cylinder in place. Remove them. Once you can move the clutch master cylinder and you’re able to reach the line from the master cylinder to the slave cylinder, again use the tubing wrench to loosen the line.

This clip holds the original clutch master-cylinder pushrod onto the pedal assembly. Remove it and slide the pushrod off the pedal assembly. Then the clutch master cylinder can be removed.

We used a Wagner CM120165 master cylinder and a Wagner F103711 slave cylinder as replacements. They can be found at many auto parts stores.

Take note of this spacer between the firewall and clutch master cylinder. Make sure you don’t forget to install it with the new clutch master cylinder or you’ll have to tear it apart again to install it.

Hook up the line to the clutch master cylinder and bolt the new clutch master cylinder to the firewall with the aluminum spacer. The new clutch master cylinder has a clip already installed in the pushrod. You do not need to use the old one.

Using new brake fluid, fill the slave cylinder completely. Once the slave cylinder is full, fill the master cylinder. Notice that brake fluid will start to gravity-feed through the line down to where the slave cylinder should be connected.

While the fluid is draining through the tube, connect it to the slave cylinder. Make sure to keep the connection as the highest point until you get it tight. Keeping the connection pointed upward and the flow of fluid from the master cylinder should keep any air out of the system.

If you still have air in the system, there’s a bleeder on the slave cylinder. Make sure the bleeder is pointed straight up when you open it so the air will escape before the fluid. Typically, if you kept the line connection pointed up and the master cylinder didn’t run dry of fluid, this step shouldn’t be necessary.

With the hydraulic clutch system void of air and the slave cylinder installed and working properly, you can reinstall the battery and the side panel of the car.

After a short hiatus during the ’82 production year, manual transmissions were once again installed in Corvettes. The 4+3 transmission was the first to be introduced into the C4 line, later to be replaced by the ZF-designed six-speed. Both of these transmissions used a hydraulic clutch system that was new to Corvette. While there are a few minor changes that occurred during the C4 production, the system has remained the same, and the steps to repair this system are the same, regardless of what year C4 is being worked on. When replacing any components for the clutch system, it’s always advisable to replace the clutch master cylinder and the slave cylinder at the same time. Because both the slave and master cylinder are the same age, it’s only a matter of time until the other part will fail.


Corvette Clinic
Sanford, FL

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