The Legacy has been Subaru's best-selling car since its inception in 1990. There have been a wide variety of Legacy models since that time, including sedan and wagon models as well as the equally popular Legacy Outback. Models come in both automatic and manual transmissions. If the clutch in the manual transmission of a Legacy starts to go bad, there are multiple things to look for.
If the clutch is slipping severely, you will notice the engine speed accelerating dramatically while the car only slightly increases in speed. Several problems can cause the clutch to slip.
The clutch disc could be going bad. Check the back of the engine and look for any oil or coolant leaks. If there are any, it could be leaking down onto the clutch disc and causing it to slip. You can also check the disc itself to look for wear, but you may want the help of a mechanic to do that unless you are a proficient mechanic yourself.
The clutch could also slip if the disc is overheated. Let the car cool for about an hour and see if the slipping stops.
If the clutch makes a lot of noise when it is depressed, that may indicate that the pressure plate is going bad. If a spring in the pressure plate breaks, it can result in a lot of vibration and noise. It is not feasible to simply replace the plate, so the entire clutch would require replacement. Noise could also mean the clutch disc is going bad with a broken spring or a bad rubber diaphragm. The clutch would also need replacement in this case. If the bearings are going bad and causing the noise, the clutch must be disassembled to replace them.
If the clutch pedal feels soft as you depress it, it could indicate air inside the clutch system. The usual cause for this is low brake fluid in the reservoir. Check your brake fluid level and add fluid as needed. Bleed the clutch after adding fluid and it should regain firmness.
Seal leaks are a common cause of cylinders going bad. Inspect the slave cylinder for any signs of fluid or leakage. The clutch master cylinder should be inspected as well. If a leak is found, the faulty cylinder will need to be either rebuilt or replaced.
Test the master cylinder by pushing down the clutch pedal while someone else watches the level of the brake fluid reservoir. If the level of brake fluid rises with the clutch depressed, the cylinder is faulty.
Sometimes you may have leaks in the hoses or fittings. Check the condition of the hose from the brake fluid reservoir to the clutch master cylinder and look for any fluid leakage. Also check for leaks in the fittings surrounding the master cylinder and the hose from the master cylinder to the slave cylinder.
Subaru has also had some complaints about the car shifting being awkward or more difficult than it should be, especially in Legacy GT's from 2005. The clutch is located right next to the firewall and this can impede shifting action somewhat or give it a clunkier feel. However, this is standard on those models and not considered a repair defect.