Tech Article - Clutch - Inspection
All vehicles that have a manual transaxle need to use a single dry-plate, coil spring clutch 1972 and earlier models or diaphragm spring clutch 1973 and later models. The clutch disc has a splined hub that allows it to slide along the splines of the transaxle input shaft. The clutch and pressure plate are held in contact by spring pressure exerted by the coil springs or the diaphragm spring in the pressure plate.
The clutch release system is cable operated. The clutch pedal, the clutch cable, the clutch release lever, the clutch release shaft and the clutch release bearing, are all included in the release system.
When the clutch pedal is depressed, its movement is transmitted by the cable to the clutch release lever. The forks on the release shaft push against the release bearing, as the lever pivots, which slides along the input shaft toward the flywheel. The release bearing pushed against the release ring, on earlier clutches, which pushes on the inner ends of the three release levers, which releases the pressure plate from the clutch disc, which allows the clutch disc to disengage from the flywheel. The release bearing pushes against the fingers of the diaphragm spring of the pressure plate assembly, on later clutches, lifting the pressure plate off the clutch disc and allowing it to disengage from the flywheel.
When discussing the clutch components, terminology can be a problem because common names are in some cases different from those used by the manufacturer. For example, the driven plate is also called the clutch plate or disc, the clutch release bearing is sometimes called a throwout bearing, etc.
Always perform the flowing preliminary checks to pinpoint the source of clutch problems, unless you re planning to replace obviously damaged components.
a Check clutch inchspin down time inch. Run the engine at normal idle speed with the transaxle in Neutral and the clutch pedal up. Disengage the clutch depress the clutch pedal, wait several seconds and shift the transaxle into Reverse. You shouldn t hear any gears grinding. A grinding noise indicates a problem in the pressure plate or the clutch disc.
b Verify that the clutch releases completely. Run the engine with the parking brake applied to prevent the vehicle from moving and hold the clutch pedal about ?-inch from the floor. Now shift the transaxle between 1st gear and Reverse several times. Something in the clutch release mechanism is broken if the shift is hard or the transaxle grinds.
c Look over the pivot bushing between the clutch pedal and the pedal shaft for binding or for too much play.
d The most likely cause if the clutch pedal is difficult to operate, is a faulty clutch cable. Remove the cable and check it for kinks, frayed wires, rust and other signs of corrosion. Replace it if it s in bad shape. Lubricate it with penetrating oil and try it again if it looks like it s in good condition.
Note: Any time the engine is removed for major overhaul, check the clutch for wear and replace worn components as needed. The relatively low cost of the clutch components compared to the time spent gaining access to them warrants their replacement - unless they are new or in near perfect condition - anytime the engine is removed.
Take out the engine.
Scribe or paint alignment marks on the pressure plate and the flywheel to make sure of proper realignment of the pressure plate during reassembly, if the old pressure plate is to be reused.
Loosen the pressure plate-to-flywheel bolts by turning each bolt only a little at a time. Work in a criss-cross pattern until all spring pressure is relieved. Now hold the pressure plate securely and completely remove the bolts then by the pressure plate and clutch disc. Caution: Remember that the pressure plate is under tremendous spring pressure. If you work your way around the cover, removing each bolt one at a time, it will warp.
Normally, clutch problems are caused by a worn out clutch driven plate clutch disc. It s a really good idea to look over eh other components too, just in case any of them are worn or damaged.
Look over the flywheel for cracks, heat checking, grooves and other obvious defects. A machine shop can machine the surface flat and smooth highly recommended, regardless of the surface appearance, if the imperfections are slight. If you need to, replace the flywheel.
Clean the needle bearings inside the flywheel gland nut the large nut in the center of the flywheel. Inspect the needle bearings using a small flashlight. Replace the gland nut if they re flattened from too much wear or otherwise damaged. If you are going to re-use the old gland nut, be sure to repack the bearings with multi-purpose grease just enough to coat all needles lightly. Now put a little oil onto the felt ring just in from of the needle bearings. Note: In view of the low replacement cost for a new gland nut, it s a good idea to replace it anytime the clutch is removed, even if the needle bearings look okay.
Look over the lining on the clutch disc. There should be at least 1/16-inch lining above the rivet heads. Check over for loose rivets, cracks, distortion, broken springs and other obvious damage. As mentioned, normally the clutch disc is routinely replaced, so if you re not about the condition, replace it with a new one. If you re planning to re-use the old clutch disc, it s a good idea to check it for runout.
Carefully look over the splines inside the hub of the clutch disc and the splines on the input shaft. They can t be broken or distorted. Lubricate the splines in the disc hub and the splines on the input shaft with graphite, then make sure that the clutch disc slides freely on the drive shaft splines without too much radial play. You re probably going to replace the clutch disc anyway, but if the splines on the input shaft are damaged, you ll have to replace the input shaft as well.
Look over the friction surface of the pressure plate for wear, grooves and cracks. Alternating dull and bright areas indicate a warped plate. You can remove light glazing with a medium grit emery cloth. Inspect the friction surfaces of the release ring and the release levers for too much wear on earlier coil spring type plates. Inspect the diaphragm spring fingers for too much wear and make sure they re not distorted on later diaphragm spring type. Shake the pressure plate assembly and verify that the diaphragm spring doesn t rattle. Replace the pressure plate with a new or rebuilt unit if it is damaged or worn in any way.
Look over the release bearing. If it is noisy or rough, replace it. Also look over the bushings for the clutch release shaft and replace if needed. Note: Like the gland nut, the release bearing should normally be replace anytime the clutch is replaced.
If removed, install the flywheel.
Clean the flywheel and pressure plate friction surfaces with lacquer thinner or acetone. Caution: Don t use oil or grease on these surfaces or on the clutch disc lining. Make sure to clean your hands before handling the parts.
With the clutch held in place with an alignment tool, position the clutch disc and pressure plate against the flywheel. The best alignment tool is an old input shaft. Make sure the clutch disc is installed properly most replacement clutch plates will be marked "flywheel side" or something like that. If it s not marked, install the clutch disc with the damper springs toward the transaxle. Make sure the marks you made on the pressure plate and the flywheel are matched up if you re using the old pressure plate. Tighten the pressure plate-to-flywheel bolts finger tight, working around the pressure plate.
Center the clutch disc by ensuring the alignment tool extends through the splined hub and into the needle bearing in the gland nut. Wiggle the tool up, down or side-to-side as you need to, to bottom the tool into the gland nut. Working in a criss-cross pattern, tighten the pressure plate-to-flywheel bolts a little at a time. This will prevent distorting the cover. Tighten them to the torque after all of the bolts are snug.
Remove the alignment tool.
If removed, install the release bearing. Make sure to lubricate the bore of the release bearing and on 1971 and later models the outer surface of the central guide sleeve with high-temperature grease, and apply multi-purpose grease to the contact areas of the forks on the release shaft.
Now install the engine.
Adjust the clutch pedal freeplay