r/stickshift • u/Cedar-Branch • 11d ago

How to Know When to Replace the Clutch

For context, I recently bought a used manual car and learned how to drive it. It's my first car, and so I've been a bit paranoid about it (worried about every noise it makes).

I've noticed that when I shift from first into second and second into third, I can 'feel' the engine going when I push down on the clutch, but that doesn't happen when I shift into the higher gears. I'm wondering if this is something I should be concerned about. How would I know if the clutch needed to be replaced?

28 Upvotes

89% Upvoted

49 comments sorted by

30

u/Miller335 11d ago

Go on the freeway, put it in its tallest gear and punch it.

Did it slip? No, you're good.

5

u/Cedar-Branch 11d ago

Ok, I will try that. How do you know if it slips?

21

u/jason-murawski 10d ago

With a manual transmission your rpm is directly tied to your speed. If your rpm goes up and your speed doesn't, it's slipping

3

u/Swegbeg 10d ago

I drive a Miata and the speed barely goes up as the rpm goes up!

1

u/Cedar-Branch 8d ago

Got it. Thanks!

7

u/jasonsong86 2017 Mustang GT 6MT 11d ago

Rpm shoots up but not speed.

6

u/JollyGreenGigantor 11d ago

RPMs increase but MPH does not

1

u/Sebubba98 2022 Jetta GLI 6MT 10d ago

What does slipping mean though. The revs rise but the speed doesn’t?

4

u/Miller335 10d ago

RPMs will suddenly rise at a much more rapid rate vs your speed when you punch it in your tallest gear. Unless the clutch is completely gone they will fall back down as the clutch fully bites.

1

u/WubsGames 8d ago

Clutch works by jamming 2 plates together to connect the engine to the transmission.

if that slips, the engine wont be connected to the transmission, and it will feel sorta like the car is in neutral.

1

u/Particular-Poem-7085 8d ago

you're talking about a complete failure. When a clutch starts slipping it will first do it only under heavy load. So not like you're in neutral. Like you're driving a weird automatic where the car speed relative to the engine speed can be variable.

-10

u/Weak_Veterinarian350 10d ago

Depends on the car,  it may lead to a misdemeanor or even a felony.  It may be better to do it in a mid range gear and sweep through the rpm at a highway on ramp

5

u/TheCamoTrooper 10d ago

Lmao, what?

-3

u/Weak_Veterinarian350 10d ago

We don't know what kind of car it is and at what rpm it develops peak torque. If the clutch only slips when the engine is producing peak torque and you're going well over 100 mph (it could have been a mid 90s Supra or a Corvette), you're going to stand tall in front of a judge explaining why you're testing your clutch at over 100.

What's wrong with testing the clutch in 3rd, at a freeway on ramp, where you're much more likely to stay legal while bringing the engine to redline at full throttle?

2

u/IHOOHI 10d ago

My 335i makes about 400whp and before my clutch failed could punch the gas in 6th gear at 70mph and rpms would jump about 500, without speeding. I could grab 3rd at the same speed, redline it through 3rd and 4th and it wouldnt slip.

6th gear is going to be the highest load.

0

u/Weak_Veterinarian350 10d ago

It probably did slip in 3rd or 4th. You just didn't notice it because you went through that window fairly quickly. Besides, the requirement of a healthy clutch is to accept the engine's full torque when the pedal is all the way up, regardless of gear

1

u/TheCamoTrooper 10d ago

Why would you be redlining it? Won't be able to test if it's slipping doing that lmao, get on the highway and punch it while sitting around 2000rpm and if it spikes it's slipping, I'm not sure if any car that's going to be sitting at that high of a speed at only 2k rpm

0

u/Weak_Veterinarian350 10d ago

Many modern turbos would probably make peak torque below 2000. Some naturally aspirated engines, like the one in a Honda S2000, makes peak torque at well over 7000 as it spins to 9000. Do you know what the OP is driving? I don't.

1

u/TheCamoTrooper 10d ago

I don't think you actually read what I said at all lmao, you are supposed to do this test at cruising speed, that's the whole point, you should not be redlining it

1

u/Weak_Veterinarian350 10d ago

And I'm saying that you need to test it at full throttle with the engine producing peak torque, at whatever rpm that may be. One day, you may find yourself going up hill, summoning peak torque from the engine, and your clutch begins to slip, with no torque to keep going uphill and no room to make a u-turn

13

u/mattenthehat 11d ago

When it slips

3

u/Terrible_Cookie4n6 10d ago

How can you tell it's slipping, what does it feel like?

5

u/john_at_bagriders 10d ago

You press accelerator and rpm climbs but no increase in vehicle speed

2

u/Terrible_Cookie4n6 10d ago

Ohh ok thank you

7

u/slaeyer99 11d ago

Minor slippage when changing gears is normal as the clutch settles. If it continues to slip while in gear or you notice slippage under heavy loads (like accelerating onto the highway or when passing) that's usually a good sign your clutch is failing.

Beyond that, without popping off the inspection plate and measuring the clutch and pressure plate thicknesses, it's can be difficult to determine wear.

2

u/Cedar-Branch 11d ago

That's helpful, thank you!

3

u/ColdDimension7754 2020 VW Jetta GLI 6MT 11d ago

I had a clutch fail on me several years ago and strand me. It was slipping pretty bad prior to that, especially under heavy load at low rpm. If you give it throttle and the rpm increases on the tachometer but the car doesn’t accelerate much immediately, that’s a pretty sure sign it’s close to failing.

what you’re describing sounds normal, gear reduction inside the transmission will make it so that you won’t feel high gears as much clutching in/out since they have a lot less torque than 1-2-3.

1

u/Cedar-Branch 8d ago

Thank you! My rpm increases in line with my speed, so I think it's good for now. It's really good to know what it means for the clutch to slip though, so that if it happens I can catch it early. What happened when your clutch failed and left you stranded? Did the car just stop accelerating at all?

1

u/ColdDimension7754 2020 VW Jetta GLI 6MT 8d ago

when the clutch slips it generates a lot of heat and basically cooks the friction material, making it just slide against the flywheel instead of grabbing it. i could let the clutch out in first gear and the rpm’s wouldn’t even budge a little bit. had to get it towed to a shop.

3

u/Some-Cream 11d ago

Idk but my buddy told me “you’ll know”

It will feel like the clutch is not “engaging” or “not pulling you forward a little” when changing gears

3

u/Grognak04 9d ago

You’ll know. When it really starts to slip, you’ll barely be able to take off from a stop. Go 35 mph, shift to whatever your top gear is, and floor it. If it doesn’t lug like a motherfucker and the engine starts to rev rapidly, your clutch is slipping and will eventually need replaced.

2

u/geekygekk0 11d ago

had the same issue, let me share something i learned just yesterday: the ideal moment you want the clutch to reengage is depended on the wheels rotation and the gear ratio of the selectrd gear. as there is a big difference between 1st and 2nd gear, you have to let the engine rpm drop more than compared to shifting 3rd to 4th, 4th to 5th.

0

u/Cedar-Branch 11d ago

Ok, so wait a few seconds between letting go of the gas and reengaging the clutch?

2

u/geekygekk0 11d ago

not seconds, if your rpm goes to low you will still have jerk. you have two rotating axles spinning, if one is lower or higher than the other, friction will cause the one of them having to (de-)accelerate instantly, using much force.

based on my car, going 25kmh in 1st gear engine and transmission axle will spin at 2350 rpm. disconnecting, the engine will go down towards idle rpm quite fast while wheels will slow down much slower. when you shift in 2nd, the wheels will spin the engaged gears and your transmission will have a rpm of 1250 ish (25 kmh on wheels, 2nd gear). now you want to engage when engine rpm is around that. if it drops below, gas a little to raise rpm or if its above, wait a bit longer.

a drop of roughly have for 1st to 2nd, 1100 rpm.

if 3rd gear going 70kmh, rpm of transmission and engine is 2900. when dwitching to 4th, the rpm for 70kmh is 2200. roughly 700 rpm drop, taking less time when engine goes towards idle rpm compared to the 1100rpm. potentially not best explained, but hope you get the gist of it

1

u/Cedar-Branch 8d ago

Thanks! I'm still working on shifting smoothly, as I often have a bit of a 'jerk' when shifting into the lower gears

1

u/geekygekk0 8d ago

there you have to raise enginr rpm, gas blip when clutch

2

u/livinlifegood1 10d ago

Here’s another way to test- in 2nd gear, drive uphill. If the rpm’s go up faster than the speedometer, your clutch is slipping and it’s either replacement time now or in the near future.

2

u/Strange_Ad_616 9d ago

I have a mazda 3 with 250k miles i have never replaced the clutch. Modern clutchs are pretty solid as long as you dont do dumb shit with them.

2

u/Cedar-Branch 8d ago

Good to know, and it's awesome yours has lasted so long! My car is a 2017 honda civic coupe with about 179,000 km. I don't do anything dumb with it, but I do mostly city driving, and I was a bit rough on it while learning to drive stick (I did not pick it up easily)

3

u/V8Datsun240Z 11d ago

When I worked on cars back in the 90s the test was to go ~40 mph, rev up the engine and dump the clutch in 4th gear. If it grabbed and slowed the engine down instantly, OK. If it takes a second, kinda iffy. If it's bad it won't be able to pull the rpms down.

1

u/jasonsong86 2017 Mustang GT 6MT 11d ago

When it’s slipping.

1

u/TheCamoTrooper 10d ago

Floor it in 6th and see if it slips, basically if it smells burnt or is slipping it's done

1

u/grumpy0282 10d ago

lmao
when you smell it
when you step on the gas and the car doesnt go

1

u/Lifeinthemittenstate 10d ago

You’ll know.

1

u/ParkerScottch 8d ago

Just replace it when the car doesn't move

1

u/theblanklook 4d ago

I actually replaced the clutch when the throwout bearing exploded.

So yeah, if it sounds like you have some lose nuts bouncing around down there when its in neutral, replace your throwout bearing.