If clutch dies early, don’t blame speed
QI
am a 77- year-old Swedish grandmother who knows little about cars, but delights in learning by reading your column. I do not want to repeat the costly mistakes of the past, so please advise me.
I was driving at night on the freeway when the car, a 1999 manual-transmission Saturn with 59,000 miles of driving, lost nearly all momentum, slowing to 3 mph per hour because of a clutch failure. We had the clutch replaced for $400 because it was broken, and the flywheel fixed for $100 because it was pitted.
Why would a clutch break after 59,000 miles of careful driving? They said do not ‘‘ride the clutch.’’ What does it mean to ‘‘ride the clutch?’’ I try to keep my left foot on the floor to the side of the clutch while driving. Is it wrong to keep one’s foot near the top of the clutch when one is starting a trip? My husband has occasionally started at a stop sign at second gear or third gear instead of first gear and said it did not matter. Now he tries to start in first gear. How can we prevent a costly breakdown of the clutch in the future? How should we change our driving habits? I drive slowly, while my husband drives at 60 to 65. ALet’s
take a look at how a
clutch works, then we can see how to double or triple the life of that original clutch. Manual-transmissionequipped vehicles use a clutch to allow the vehicle to come to and from a stop with the engine running, and to allow smooth shifting between gears. Clutch parts include the engine’s flywheel, which is bolted to the end of the crankshaft. Astrid Orinda This part is similar to a very thick and heavy metal dinner plate. The clutch disc, about the size of a 45 to 78 phonograph record, contains friction material on each side, and a splined hub at its center. The clutch hub engages the transmission’s input shaft. The pressure plate or clutch cover, a spring-loaded mechanism resembling a casserole dish lid, bolts to the flywheel, clamping the clutch disc tightly between. A final component, the release bearing, presses against the pressure plate as the clutch pedal is depressed, causing it to loosen its grip on the clutch disc.
When a clutch fails to hold properly, due to worn clutch disc friction facings or a failed pressure plate, replacement of both parts is necessary. This involves removal of the transmission to gain access. Resurfacing the flywheel is a good idea, to restore a smooth and flat surface, as is renewing the release bearing.
What can one do to extend the life of a clutch? Always start out in first gear, and release the clutch pedal as promptly as possible to minimize clutch slippage. Try to find the magic engine speed/ release rate that launches the vehicle with minimum clutch slippage (slipping the clutch excessively is known as ‘‘riding the clutch’’). Also, as soon as the pedal is released, avoid pressing on the pedal — even slightly, as this accelerates releasewear. Driving speed is not an issue. It’s all about releasing the clutch smoothly and quickly when starting out. Brad Bergholdt is an automotive technology instructor at Evergreen Valley College in San Jose. Write to him in care of Drive, Mercury News, 750 Ridder Park Drive, San Jose, Calif. 95190; or e-mail to under-the-hood@juno.com. He cannot make personal replies.