How many times have you been to the doctor or hospital for some ailment and the diagnosis was wrong? Getting to the root of most any problem within a complex situation is tough-even for professionals. And while you may take a trip to the emergency room for a pesky or persistent headache that could be some sort of allergy or worse, the symptoms can be all too similar for a number of scenarios.
Mechanical problems are quite comparable. If your truck doesn't start, it could be something as simple as an empty gas tank, clogged fuel filter, bad coil, or a multitude of other possibilities, but in order to diagnose the cause, we must rule out what we know it's not.
Last month we covered the basics on clutches as far as the most popular for street use, how they work, and the parts that are used in conjunction, like pressure plates, flywheels, and throwout bearings. This month we are looking into common clutch failures and how to diagnose the problem that caused the damage in the first place. If your clutch did more than just wear out and failed prematurely, it's very important to figure out why, instead of just replacing the parts and having them fail again; wasting lots of time and money-especially if you farm the work out!
The assembly and installation of the clutch components has plenty to do with the success and life of the parts; the other main factor is your personal driving style/habits. If you are working on the stock-type clutch for your truck, it's always wise to have a copy of the factory manual for its installation/maintenance specs, like bolt torque specs, pedal freeplay, if any special tools are required, and of course the actual R&R of the parts. While under your truck with the transmission out, be sure and check all related clutch parts for wear or possible problems. The clutch linkage starting from the clutch pedal bushings, to the bell crank (aka Z-bar), to the clutch fork and pivot ball, should be inspected for wear or damage. If you find any questionable parts, they should be repaired or replaced. If your truck has a hydraulic release system, check for any hydraulic leaks in the clutch master and hoses. If your vehicle is cable equipped, the cable should be checked for damage, stretch, fraying, excessive resistance, or binding. If any of these conditions are found, replace the clutch cable and always inspect the throwout bearing collar for signs of wear or galling.
Here's a list of do's and don'ts when it comes time to replace your clutch:
It's simple and obvious, but make sure you have the correct replacement parts before installing any of them, as well as the proper clutch alignment tool. Failure to use a pilot tool to align the clutch disc could result in damage to the disc during installation of the transmission.
Always check the new clutch disc for proper fitment on the transmission input shaft prior to installation. Make sure the input shaft splines are free of wear and twisting.
Whenever you have the clutch out, even if you don't replace it, it's usually a good idea to replace the old throwout bearing and pilot bearing while you're there. They are inexpensive compared to pulling the clutch out again, and I speak from experience! About 10 years ago, I had a '50 Ford I replaced a clutch in. I bought an old but N.O.S. throwout bearing that started squealing no less than three days later, and I had to replace it again.
Never combine a worn pressure plate with a new clutch disc or vice versa. Always replace both the pressure plate and clutch disc with new components.
Replace any worn components such as input shaft collars, clutch forks, slave /master cylinders, etc.
Always properly resurface or replace the flywheel. Resurfacing a flywheel with any device (say an angle grinder) other than a dedicated flywheel-resurfacing machine is not recommended. Also, always clean the surfaces of the pressure plate and flywheel with brake parts cleaner or acetone before installing.