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How to replace a clutch

We keep our ongoing restoration project moving forward by installing a new clutch in the old Jeep

Project CJ3A keeps inching toward completion. The chassis is now fully rebuilt and finally ready to accept the engine and transmission. But before we reinstall them, we need to inspect the clutch to make sure it’s in good condition. That means unbolting the transmission bell housing from the back of the engine. There is certainly no better time to do that than when they are out of the vehicle. As it turned out we’re glad we took the time to check. We didn’t like what we found.

The clutch was a little worse for wear, so we ordered a full replacement kit from a specialist supplier. Here’s how the installation process went.

Before we did any serious wrenching, there were decades of grime to scrape out of the bell housing — along with an abandoned mouse nest. It’s impossible to see what you’re working with when components are thickly caked with dirt, grease and oil.

With the tidying up completed, we started the job by replacing the clutch components that ride on the transmission input shaft. Those are the throwout bearing and sleeve it rides on. This bearing and sleeve slide back and forth on the shaft and contact the pressure plate, disengaging the clutch. The clutch fork, which is connected to the pedal linkage, pushes them toward the pressure plate when the clutch pedal is pushed down. A spring pulls them back when the pedal is released.

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The old bearing grumbled when we spun it, so it was clearly on its last legs. We pressed the new throwout bearing onto the new sleeve and slipped it onto the input shaft, connecting it to the return spring.

Our replacement kit didn’t include a new fork, but the old one was still serviceable. It simply pivots against pin with a rounded head. Putting a dab of grease on the pivot bin helps reduce wear.

Next, we unbolted the old pressure plate from the engine flywheel. Only six bolts hold it on. With that off, we inspected the flywheel surface. It wasn’t perfect, but we decided it was OK and didn’t need to be resurfaced. There were no signs of excess heat or stress cracks. If there were, we would have had to replace it as well. A good scrubbing with brake cleaner removed all the grime without leaving a residue that could cause excess slippage.

The first step in bolting on the replacement is to use a clutch alignment tool to position the friction plate. The end of the tool fits into the pilot bushing on the flywheel and centres the friction plate. Some clutch kits come with an alignment tool specifically for each application, but ours didn’t. We used a Lisle 55500 universal type, which is designed to work for almost any clutch job. A spare input shaft from an old transmission would have worked too, but we didn’t have one lying around.

Next the pressure plate is fitted over top of the friction plate and bolted to the flywheel. We found the correct toque setting for the bolts in the service manual and gradually tightened them down in stages, using a star pattern to avoid deforming the pressure plate.

Because the flywheel uses a pilot bushing, rather than a sealed bearing, we placed a dab of grease in it to minimize wear from the transmission input shaft.

Bolting the engine and transmission back together can be a bit awkward. Our neighbour, Cory, agreed to stop by for a few minutes and help me manhandle them back into place. Then, the unit was dropped back onto the chassis. Connecting the pedal linkage to the fork was the last step in the process.

About the author

Machinery Editor

Scott Garvey is the machinery editor for Grainews.

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