If you drive a Mustang, more than likely it is equipped with some sort of manual transmission.  Because of the widespread popularity of the Mustang & the sheer number of cars produced, the aftermarket is teeming with multiple choices in parts replacement, & this is especially true in the clutch department.  Check out our Mustang Clutch Kit Buyers Guide to help you determine what clutch kit best suits your application.  Here we will cover the most common clutch-related problems that arise & the causes for each as well as the solution.
Clutch Chatter
Problem
- A "vibration" or "reverberation" felt as the pedal is being released & the clutch is engaging.
Cause
- Chatter is often caused by:
- A used flywheel that was not resurfaced before installation of a new clutch.
- Slippage that has caused the disc facing to glaze over, often caused by the clutch cable being adjusted too tight, or poor driving habits
- Excessive slippage that has caused the flywheel &/or pressure plate to develop "hotspots", often caused by the clutch cable being adjusted too tight, or poor driving habits
- Oil or grease contamination of the disc facing that caused slippage & glazing
- Engine power level exceeding the holding capability of the clutch that caused slippage & glazing
- Rear gear ratio higher than (numerically lower) 3.27.
Solution
- 9 times out of 10, once you experience chatter, the only way to get rid of it is to start over with a new clutch & maybe even a new flywheel.
- Some are lucky enough to be able to rectify their mistake of not turning the flywheel by simply disassembling everything & having the flywheel machined & rid themselves of chatter. A flywheel is considered machined when you drop it off at your local machine shop & the surface is mechanically ground parallel to the crankshaft mounting surface & you are given a receipt for the service being performed. Rubbing the surface of the flywheel with Scotch Brite does not count. You could always just opt for a new Flywheel.
- Once a clutch disc has glazed over, it is done for. Even if you correct your adjustment issue or driving habits, you are looking at purchasing a new clutch.
- Once a flywheel or pressure plate has developed "hotspots," they are done for. Again, you will need to start over with a new flywheel or clutch/pressure plate. "Hotspots" are now harder than the surrounding metal & will wear at a different rate, causing an uneven surface & chatter even if you have them machined. "Hotspots" are easily identifiable by their purplish-blue appearance.
- Leaky rear main seals wreak havoc on clutches as do leaky transmission input shaft seals.  If your Mustang leaks oil in the bell housing area - fix it, or you will cause your clutch to fail. Also, when installing a new clutch, clean the flywheel & pressure plate with brake parts cleaner & make sure your hands are clean when handling any clutch component, especially the clutch disc. Many people over-grease the input shaft splines that the clutch disc engages with, which in turn, will find its way onto the disc material. Use grease in this area sparingly!
- When selecting a new or replacement clutch for your Mustang, be realistic about the power output & future goals.  If you pick the right clutch the first time, you'll be rewarded with good manners & a long service life.
- Mustangs with 2.73 or 3.08 rear gears will experience a mild degree of chatter during certain driving conditions, period unless a very forgiving OE type replacement clutch is utilized. This is a good excuse to get new gears!
Clutch Slipping
Problem
- Your tach needle is climbing, but your speedometer isn't & the tires aren't spinning. Â Excessive clutch slip is often accompanied by a funny burning smell coming from underneath the car.
Cause
- A slipping clutch is often caused by:
- Incorrect clutch cable adjustment on your 1979-2004 Mustang
- Incorrect hydraulic release bearing setup on your 2005-Present Mustang
- Oil or grease contamination of the disc friction facing
- A used flywheel that was not resurfaced before installing a new clutch.
- Engine power level exceeding the holding capability of the clutch
Solution
- If you recognize the clutch is slipping immediately, you may be able to rectify the issue & allow your clutch to live a long life.
- Some are lucky enough to be able to correct their mistake of not turning the flywheel by simply disassembling everything & having the flywheel machined & rid themselves of chatter. A flywheel is considered machined when you drop it off at your local machine shop & the surface is mechanically ground parallel to the crankshaft mounting surface & you are given a receipt for the service being performed. Rubbing the surface of the flywheel with scotch Brite does not count. You could always opt for a new Flywheel.
- Ensure the clutch engagement/disengagement point is at or slightly above the midway point in clutch pedal travel. If the engagement/disengagement point is at the top of the pedal travel, the pressure plate never fully engages & allows the disc to slip under acceleration. Installation of an adjustable clutch cable & aluminum Mustang clutch quadrant may be necessary on a 1979-2004 Mustang.  We recommend one of these setups for all new clutch installations.
- If using a factory hydraulic release bearing in a 2005-Present Mustang, you'll likely not experience a problem. If using an aftermarket unit, be sure to follow the adjustment instructions to the letter.
- Leaky rear main seals wreak havoc on clutches, as do leaky transmission input shaft seals. If your Mustang leaks oil in the bell housing area - fix it, or you will cause your clutch to fail. Also, when installing a new clutch, clean the flywheel & pressure plate with brake parts cleaner & make sure your hands are clean when handling any clutch component, especially the disc. Many people over-grease the input shaft splines that the clutch disc engages with, which in turn, will find its way onto the disc material. Use grease in this area sparingly!
- When selecting a new or replacement clutch for your Mustang, be realistic about the power output & future goals. If you pick the right clutch the first time, you'll be rewarded with good manners & a long service life.
Transmission Stuck in Gear or Grinding
Problem
- Your transmission is stuck in gear or will not go into gear or grinds when shifting all gears after the installation of aÂ
new clutch.*
Cause
- Shifting problems after a new clutch install are typically caused by:
- Incorrect clutch cable adjustment on a 1979-2004 Mustang
- Incorrect hydraulic release bearing setup on a 2005-Present Mustang
- Leaking or improperly bled hydraulic release bearing on a 2005-Present Mustang
- Damaged or bent clutch fork
- Damaged, bent, or incorrectly adjusted clutch fork pivot stud
- Worn or ill-lubricated pilot bearing causing the transmission input shaft to bind or not move freely
Solution
- Luckily, these types of issues are apparent right off the bat & are often easily rectified without experiencing clutch or driveline damage.
- Ensure the clutch engagement/disengagement point is at or slightly above the midway point in clutch pedal travel.  If the engagement/disengagement point is at the bottom of the pedal travel, the pressure plate never fully disengages & it doesn't allow the disc to fully release from the flywheel.  Installation of an adjustable clutch cable & aluminum quadrant may be necessary on a 1979-2004 Mustang.  We recommend one of these setups for all new clutch installations.
- If using a factory hydraulic release bearing in the 2005-Present Mustang, you'll likely not experience a problem. If using an aftermarket unit, be sure to follow the adjustment instructions to the letter.
- A leaky hydraulic release bearing will be easy to spot; simply repair the leak. Be sure to bleed 2005-Present Mustang release bearings as per the service manual for OE applications &, per manufacturer recommendations for aftermarket units.
- If your clutch fork appears suspect upon disassembly, it is cheap insurance to go ahead & replace it.
- If your clutch fork pivot stud appears suspect upon disassembly, it is cheap insurance to go ahead & replace it.
- We always recommend replacing the pilot bearing when replacing the clutch. Doing so will ensure the transmission input shaft moves freely. If you are confident that your existing pilot bearing is still serviceable, a conservative daub of grease always helps.
*
If your transmission was already experiencing these issues before the clutch install, you might have internal transmission damage such as bent or broken shift forks or worn synchronizer rings. An aftermarket shifter with improperly adjusted shift stops will also cause you not to shift into gear.*
This about covers all of the common issues. You'll notice that there has been no mention of a defective clutch as the cause of these issues. This is because it is very uncommon for a clutch to be defective! It is imperative to pay close attention to detail when installing a clutch in your Mustang or to choose a competent shop to do the work. It is also wise to check with the shop to see if they are opposed to bringing your own parts. Some shops will only install their "own" product & often, their "own" product is at or below OE specifications. If you ever have a question or concern regarding a future clutch purchase or a clutch you've already purchased from us, please don't hesitate to call and speak to one of our highly trained sales staff. They will get you squared away in short order!
