Grabbing Gears: Clutch, Pressure Plate & Flywheel Tips Part 1
Wayne Scraba
Today, clutch equipped cars are the exception rather than the norm. No secret we’re sure. But there are still folks who prefer to shift gears for themselves. There’s good reason for this (aside from the potential of a unique anti-theft device!). Winding through the gears is fun. You’re physically involved with the car in more ways than one. But the transmission isn’t the only piece of the puzzle. Clutches are essential too. And they can very well be the key to having fun with your stick shift combination. Given that, we come up with a couple of dozen clutch, pressure plate and flywheel tech tips and tricks. Some are tried and true. Some you may have never heard of. Bottom line? There’s something here for everyone who likes to grab gears. Check out Part One with twelve tips:
It’s always a good plan to incorporate new high-strength fasteners for the pressure plate with a new installation. Never use lock washers or flat washers on the pressure plate cover! Use the fasteners provided or recommended by the manufacturer or a high-quality aftermarket piece (for example, ARP). In some cases, the manufacturer might recommend the use of a good thread locker such as Loctite.
Prior to reassembly, clean the flywheel and pressure plate disc surfaces thoroughly with a non-petroleum-based solvent (brake cleaner works perfectly by the way) and then dry with compressed air. Cloths and shop towels shouldn’t be used to dry parts. It’s also important to thoroughly clean the bell housing and the back of the engine block before lubing and reassembling the parts (brake cleaner works great here too).
In the course of driving your car, a squeaking noise may come from what seems to be the clutch, even when the clutch pedal is not engaged. This noise might stop when a slight amount of pressure is applied to the pedal. Sounds like it could be the start of a bad release bearing? Maybe not! This noise is usually caused by a dry clutch fork pivot ball stud, which results in metal-to-metal contact with the clutch fork. Obviously, this can cause extreme wear, which eventually causes the pivot ball to go out of round. As a result, the fork will not rotate properly causing release problems. The fix is easy: Lightly lube the pivot ball surfaces.
Prior to fly wheel removal, it’s a good idea to mark the location. This allows you to reinstall it in the same position. This is very important in certain applications where a no dowel pin is incorporated. Why is this important? In some applications, the engine is balanced with the flywheel. In this situation, if it isn’t indexed correctly, then engine balance is messed up.
Should the center of a clutch disc break out, there are a couple of potential causes: If the hub and the two plates are still riveted together, but the plate, which the facings are riveted to, is broken out, then there is a serious misalignment in the transmission. This can be due to a bad pilot bushing or it can spell out trouble with the transmission input shaft. On the other hand, if the hub comes out and the two plates are not riveted together, then the clutch manufacturer did not install the rivets correctly.
If a new throw out bearing looks like it is off-center does that mean you bought a bad bearing? Not necessarily. The way some throw out bearing work, they self-align to a certain degree. This means a bearing that might appear a bit off center will actually center itself during normal use. By the way, if you can manually move the bearing on the collar, you have a self-aligning bearing.
It is possible to install a clutch disc backwards and in many situations, it will fit just fine. The catch is, it won’t live very long. New discs almost always have a decal or some other mark indicating the side that faces the flywheel. If the disc doesn’t have a decal, then install the hub assembly toward the transmission.
If you’ve had a flywheel resurfaced, it’s a good idea to inspect the mounting hole bore depths. If excess material was removed there’s a chance the pressure plate mounting bolts may run out of thread. In turn, this means might not be possible to properly torque the pressure plate hardware.
When adjusting the air gap on the clutch with a feeler gauge, push the pedal all the way to the floorboard (or to the pedal stop). Next, slide a feeler gauge between the disc and the pressure plate. Turn the clutch adjustment rod until you have approximately 0.050-inch air gap. When the air gap is set, release the pedal.
Occasionally when the clutch is removed for maintenance, you’ll discover the springs on the disc are loose or even missing. There is a reason they’re gone: The hub springs are designed to absorb torque. After use, they normally become looser than they were when new. This doesn’t create a problem unless the spring starts to wear the drive plate or back plate of the disc. Some cheap discs have springs that are so weak; they’ll depart from the disc, even though the facing material still looks perfectly fine. The fix is pretty simple: Next time around, buy a better-quality disc.
Even if the flywheel hasn’t been removed from your engine during a clutch swap, re-torquing the mounting bolts by way of a criss-cross pattern (to OEM specifications) is a good idea.
If you have the transmission our while performing a clutch job, check the mount. Most original equipment rubber trans mounts deteriorate over time, and should be replaced regularly. By the way, don’t even think about using solid mounts on the street. You’ll live to regret it. And so will your transmission. By the way, urethane examples such as this are a good option.
