When you find your manual transmission slipping when accelerating, it’s basically clutch slipping, which means it isn’t delivering the power needed to spin the wheels. A warped flywheel, worn clutch and pressure plates, or a leaking cylinder can all be reasons that can lead to this issue.
In my decade-long experience with manual cars, I’ve found that whenever this occurs, the transmission doesn’t shift, the gears don’t engage, and the vehicle’s speed doesn’t match the engine’s. You see the revs go up, but your car won’t surge ahead as you accelerate.
Let’s explore more details about the problem and show you how to diagnose and fix it.
Why Does the Clutch Slip in Manual Transmissions?
Let’s begin with what causes your clutch to slip. To understand it better, you’ll want to know how clutches work in the first place.
Manual cars’ clutches produce and retain the torque needed to push your car forward. With the pressure plate holding it snugly up the flywheel, the clutch spins your engine and keeps the speed in sync with the transmission input.
The clutch also has friction discs on either side, pretty similar to brake pads, to hold up against the pressure plate and the flywheel. And just like any material, these components can wear down over time.
So, inevitably, when that happens, the clutch fails to retain the running torque and begins to slip when you load up the engine.
Your car may hit the snag sporadically at first. For example, I’ve seen the clutch grinding down at the third gear or fourth. But things are well-destined to get worse over time as the wear continues.
How to Diagnose a Slipping Clutch in Manual Transmission?
It’s normal for manual car clutch components to suffer gradual wear and tear with use. But coming across dozens of slipping clutch issues over the years, I can tell you it still takes some mastering for new drivers to save some chunks of its life.
For example, those driving in congested cities shorten their clutch’s lifespan prematurely just through gridlock and regular shouldering from the standstill.
Hence, keeping a close eye on clutch engagements and slippage in certain situations can pay off big time.
Now, if you suspect a slipping clutch issue when accelerating your manual car, here are some things I’d recommend watching out for to diagnose the issue.
1. Inspect the Clutch Fluid
You should find your clutch fluid tank near your car’s brake cylinder. It should be perfectly filled or anywhere between the lowest and highest markings. So, you’ll want to fill it up as needed.
This should be your first step in diagnosing clutch slipping issues. After all, I’ve seen this to be the only fix some manual cars require.
2. Look Closely at How Your Clutch Reacts
When your clutch isn’t running well, you can literally feel it by watching how it responds to your actions. You’ll know it’s gone bad when:
- Your engine hesitates, or the speed barely changes, no matter how high you shoot the revs up.
- The clutch pedal shifts forward as you move into gear.
- The height of your clutch pedal changes where it should engage.
- The engine power decreases as you load it up. Your wheels barely get the forwarding power.
- Acceleration feels less connected to the gas pedal.
3. Smell for Burns
Do you smell something burning under the hood? While this may point to an oil leak or wiring damage, a burning smell from underneath your car or the engine can also signal a slipping clutch problem.
From what I’ve seen, this happens when the frictions go awry inside the clutch from persisting disengagements and produce excessive heat.
Do you have an automatic transmission slipping when accelerating? You might want to try these methods instead.
4. Press the Clutch Pedal Down
You’ll know for sure that your clutch will need a replacement when you notice the disengaging takes far less pedal movement than usual.
Ideally, you should be left with at least 1-2 inches of free pedal movement before the disengagement. So, if there isn’t that much space, your clutch isn’t riding when not depressed.
5. Drive Around
Drive around your car to see whether achieving a certain level of speed takes more engine RPMs than it should. If it does, it’s a telltale sign that you’ll need a new clutch.
You can just drive down in the third gear, putting the car in the second, before letting the clutch out. Dozens of times, I’ve seen that when you have a failing clutch, the engine RPMs never go up instantly, which should’ve been the case with a fine one.
Alternatively, you can test it by driving your car in the third or fourth gear while resting your foot on the accelerator. Just push the clutch down and release it. If the RPMs don’t go down with the release, your clutch has worn down badly, leading it to slip.
How to Replace a Slipping Clutch in a Manual Transmission?
Diagnosing hundreds of manual cars with slipping clutches over the years has shown me that a replacement is the only solution most of the time. Yes, filling up the fluid or replacing a leaking rear seal may do the job occasionally, but it’s rare.
Hiring a professional for the replacement job may cost anywhere from $300 to $2,500, depending on your car and how you drove it. So, if you want to save some hefty bucks, why not go hands-on when you have the know-how?
Having recently troubleshooted some Chevy 10-speed transmission problems, here is my recommended procedure for clutch replacement.
- Step 1: First, you’re going to locate the clutch between your car’s flywheel and the transmission.
- Step 2: Jack up your car somewhere level and remove the driveshaft by taking the bolts off at the back and pulling it out of the transmission.
- Step 3: Now, take out the gear shift by removing the console piece and unscrewing the gear shift knob and assembly. Also, unscrew the speedometer cable and move it out of the way.
- Step 4: Remove all bolts that connect the transmission to the engine, including the clutch slave cylinder bolt.
- Step 5: You’ll need a jack to hold the transmission in place while sliding it off the engine. Then just unbolt the clutch assembly and remove the old clutch disk.
- Step 6: Now’s the time to replace the old clutch with a new kit with all the necessary parts. Align the clutch assembly with an alignment tool and bolt it back on.
- Step 7: Slide the transmission in and wiggle it until it’s in place.
- Step 8: Finally, reattach the driveshaft and gear shift, and screw in the gearshift knob. Then lower the car and take it for a spin to test the new clutch.
Hopefully, this diagnosis and replacement guide will come in handy whenever you find the clutch in your manual transmission slipping when accelerating.
With proper maintenance, you can expect a standard clutch to last about 80,000 miles. While there’s so little to be done against the inevitable wear and tear, you can cut the damage noticeably with sensible driving.
When you stop riding the clutch and straining it, it’ll continue to serve you years down the line.
Peter Finn the Car Doctor
Certification: BSc in Mechanical Engineering
Education: Mechanical engineer
Lives In: 539 W Commerce St, Dallas, TX 75208, USA
Rasel is an auto mechanic student and writer with over half a decade of experience in the automotive field. He has worked with top automotive brands such as Lexus, Quantum, and also owns two automotive blogs autocarneed.com and taxiwiz.com.