Manual transmissions are a bit of a dying breed these days, but there are still at least a few modern cars where a manual is still available and plenty of older cars still on the road that use manuals. Even though dual-clutch automatic transmissions shift way faster than manual transmissions, a manual is still considered the transmission of choice for the real driving enthusiast.
The clutch is one of the most important components of a manual transmission, and you should be familiar with the symptoms of a bad clutch in order to know when it might need your attention. Bad clutch symptoms include difficulty shifting, a clutch pedal that feels weird in some way, and a burning smell coming from the transmission.
In this article, we’ll be taking a comprehensive look at clutches and how they work. We’ll also cover the symptoms of a bad clutch in greater detail, and we’ll share with you some of the things you can do to prevent your clutch from failing prematurely.
What Is a Clutch and How Does It Work?
A clutch, as we’ve mentioned, is one of the most important parts of a gearbox. Whether you have a manual transmission with a single clutch or an automatic transmission with a torque converter or a dual-clutch setup, having some sort of clutch is essential for the transmission to work properly.
The purpose of the clutch is to disengage the crankshaft from the gearbox in order to allow the engine to continue running when the car isn’t moving. The clutch also allows you to transfer torque between the crankshaft and the gears without damaging your transmission, even if the crankshaft and gears are turning at different speeds.
As for how a clutch works, it’s actually fairly simple. Inside a clutch, you have a pressure plate and a clutch disc. The clutch disc is connected to the flywheel (which is in turn connected to the crankshaft) and the pressure plate is connected to the transmission.
When the clutch is disengaged, the pressure plate is pressed up against the clutch disc, which is then pressed up against the flywheel. The resulting friction causes the pressure plate to lock to the flywheel, which allows the transfer of torque from the engine through the transmission.
When you engage the clutch by pushing in the clutch pedal, this pushes a piston against the center of the pressure plate. The center of the pressure plate is lined with a series of flexible pins, and as the piston pushes on the pressure plate, these pins flex in such a way that the pressure plate is pulled away from the clutch disc.
With the pressure plate no longer contacting the clutch disc, the transfer of power through the transmission is interrupted, and the engine can now spin freely.
Bad Clutch Symptoms
Now that you’re a little more familiar with how a clutch works, let’s go over the symptoms of a bad clutch. Knowing what to look out for can make it way easier for you to diagnose clutch problems early on, which can help you avoid more costly repairs. These symptoms apply to both manual and automatic transmissions, apart from those which are inherently part of a manual transmission system.
Soft-Feeling Clutch Pedal
If your clutch is starting to fail, you may notice that it feels unusually soft or spongy when pushing the clutch pedal. Paying attention to how your clutch normally feels when it’s working properly can help you recognize the feel of a spongy clutch more easily.
There are a few possible reasons as to why your clutch might feel this way. It could be that your clutch fluid is low, which can prevent the pressure plate from being able to fully disengage from the clutch disc. It could also be that your release bearing or your clutch fork has become damaged.
Sticky Clutch Pedal
A sticky clutch pedal is more serious, and can severely compromise the drivability of your car. If your clutch pedal gets stuck to the floor or stuck in its default position, you’ll basically be unable to shift gears.
Related: Why Won’t My Car Shift Out Of Park?
If your clutch pedal gets stuck, that’s a sign that there’s a problem with the linkage connecting the clutch pedal to the clutch itself. The release bearing may have failed, or it could be that the springs within the linkage have become overstretched.
Vibrating/Pulsating Clutch Pedal
A properly functioning clutch should always feel reasonably smooth to operate. If you find that your clutch pedal isn’t feeling as smooth as it once did, it could be a sign that something is going wrong.
Pay attention to how the pedal feels when engaging the clutch. If it feels like it’s vibrating or pulsating, this could be a sign of a number of issues related to your transmission (and not necessarily problems with your clutch specifically).
A vibrating clutch might be a sign that the friction material on your clutch disc has become worn out, burnt, or contaminated. It could also indicate that your pressure plate has become warped or otherwise damaged, and it could even be a sign that your flywheel has become warped somehow.
A bad clutch can also make it difficult for you to shift the transmission into the gear you want. In particular, you might find it especially hard to shift your car into and out of reverse and first gear.
This tends to happen when the clutch disc fails to fully pull away from the pressure plate. As you might expect, there are a few possible reasons why this can happen.
If your car uses a hydraulically operated clutch, this could be a sign that the clutch fluid in your reservoir is low or you have a leak somewhere. It’s also possible that your pressure plate is wearing out.
In all likelihood, this increased shifting difficulty will be accompanied by other symptoms of a bad clutch like a spongy-feeling clutch pedal.
You already know that for a clutch to work properly, the clutch disc has to make proper contact with the pressure plate. The material that the clutch disc is made with gives it the friction it needs to properly grip onto the flywheel.
When this material gets worn down, however, an inadequate amount of friction is produced, and the clutch will start to slip. A slipping clutch feels exactly like you’d expect; when accelerating, you’ll start getting the sensation that the car is slipping in and out of gear.
Basically, when pressing the gas pedal, you’ll notice that the engine revs higher but the car doesn’t actually move any faster. You may also find it unusually easy to release the clutch.
There are several causes of a slipping clutch. The degradation of the friction material on the clutch disc is the most common cause, but it could also be caused by a warped pressure plate, damaged clutch linkage, broken motor mounts, or an excess of oil in the transmission due to an oil leak.
Unusual noises are almost always one of the symptoms of a failing clutch. The source of the noise could be a loose moving part coming into contact with another part of the transmission, or it could be caused by various parts sticking together when they should be coming apart.
As for what noises you’ll actually hear when your clutch is failing, such problems usually cause grinding or squeaking noises. You may hear such noises when shifting gears or when the transmission is in neutral.
Any number of problems can cause your transmission to make strange noises, but in any case, a noisy transmission means that something is definitely wrong inside it.
Lots of issues can cause your car to emit a burning smell, and a failing clutch is one of these issues. We’ve already mentioned that clutch discs are coated with a friction material that helps them stick to the flywheel. When this friction material gets worn down, the clutch disc starts to slip.
When this happens, the flywheel starts rubbing on the clutch disc, which causes it to heat up. It’s this heat that causes the characteristic burning smell of a failing clutch.
The smell of a burning clutch is quite strong and pungent, and you’ll have a hard time missing it if you do smell it. This smell has been compared to burning sulfur or spent gunpowder, so if you smell anything like that while driving, you’ll probably want to have your clutch looked at as soon as you can.
How Long Do Clutches Last?
The clutch can last well over your cars lifespan, but it highly depends on the vehicle brand, as some are built more reliable than others. It also highly depends on the usage of the clutch. If you frequently switch gears and push it to its limits, it will definitely degrade faster than if you were just casually driving and keeping good maintenance. But generally, a car clutch can last as long as 175,000 miles (280000 km) or as little as 30,000 miles (48280 km), but usually around the ~125,000 mile (200000 km) range.
How to Extend Your Clutch’s Life
Repairing your clutch can be expensive, and ideally, you’ll want to avoid getting your clutch into a state where it really needs to be repaired. Luckily, there are several things you can do to preserve your clutch’s life and avoid too many unnecessary repairs.
In general, taking care of your clutch involves equal parts preventative maintenance and careful driving. Let’s get into more detail about what you should be doing for each.
Driving carefully will certainly help keep your clutch in working order, but ultimately your clutch is a mechanical component that is eventually going to wear down regardless. By performing preventative maintenance on your transmission before it starts experiencing major issues, you can keep it working for longer and also keep maintenance costs down overall.
In terms of what you should actually do to take care of your transmission, the main thing to remember is to have your fluids changed regularly. Manual transmissions need oil in order to work properly, and ensuring that your transmission oil is in good condition will help your engine last longer.
Your transmission also has a oil filter that needs to be replaced every so often as well. Try and have your transmission looked at every 25,000-35,000 miles or so, and have your oil and filters replaced if they need to be.
Lastly, pay attention to how your car sounds when it’s running normally. This can help you more easily identify when your car is acting up, while will let you deal with mechanical issues more quickly.
When driving a car with a manual transmission, you should take care to avoid certain habits that can damage your clutch. You can get away with doing this stuff with an automatic transmission, but manuals are a little more fragile and need to be treated a bit differently.
For one, you should never let your foot rest on the clutch pedal when you’re not actually using the clutch. This practice is called “riding the clutch”, and letting your foot rest on the pedal can cause the clutch to slip a little bit, which obviously makes it wear out more quickly.
For the same reason, you shouldn’t let your hand rest on the gearshifter when you’re not about to change gears. The small amount of pressure you’re putting on the shifter can actually cause some of its internal components to wear down over time, eventually causing it to jump out of gear.
You should also make sure to take your car out of gear whenever you’re stopped. Leaving your car in gear while stopped is fine to do with an automatic transmission because of the way a torque converter works, but with a manual transmission with a clutch, doing this will cause your clutch to wear out prematurely.