'24 6MT slapping sound

[wreck99]

Question for the group. It's a hard one to try and explain but I'll do my best. I drive a '24 JLUR 6MT and something I've noticed is if I press the clutch while the engine is still trying to go forward in 1st (like trying to stop/start in stop/go traffic), there's this slapping kind of sound that happens when I push the clutch in. I can't think of a better word to describe what I'm hearing but It's not a great sound. I've tried to get better about waiting for the engine to press the pedal in stop/go traffic to avoid this sound and gotten pretty good at it however a quick stop doesn't always give me that chance. Does anyone know what this is? Is this normal?

I ran Uwharrie yesterday and noticed it a lot more on the trail when i was in 4L. I didn't need to use the clutch hardly at all which was amazing. The Jeep just creeped over everything with ease but when it would crest over a hill or something and engine breaking/self throttle was happening, I'd hear that slapping sound...even not pressing the clutch. I didn't notice it in 4H. I'm assuming it has something to go with the clutch give but I'm no expert. I was wondering if anyone knows what's going on here.

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[Asuriyan]

Normal if you abruptly disengage the clutch under load in low gear. Pretty sure it's the flywheel shifting, but it could very well be the driveshaft... these things have quite a bit of slop built into the driveline, manuals are noisier in general than automatics, and there's not much in the way of sound reduction between you and the transmission tunnel.

 

[wreck99]

Normal if you abruptly disengage the clutch under load in low gear. Pretty sure it's the flywheel shifting, but it could very well be the driveshaft... these things have quite a bit of slop built into the driveline, manuals are noisier in general than automatics, and there's not much in the way of sound reduction between you and the transmission tunnel.

Thank you! This gives me some peace of mind I'm not breaking something. It doesn't happen often under normal driving circumstance now that I know when to expect it in 1st gear, but it was very apparent in 4L climbing stuff.

 

[OrneryBear]

If I'm thinking of the same sound, it's normal and I think as @Asuriyan said, it's the flywheel. We had a vw with a luk (luk makes the clutch assembly in the JL) dual mass flywheel and it made the same sound. I only ever hear it though when the engine rpms are too low. If you hear it a lot you're probably doing something wrong with how you are using the clutch and throttle, like trying to drive at too low of rpm with the clutch out.

 

[wreck99]

If I'm thinking of the same sound, it's normal and I think as @Asuriyan said, it's the flywheel. We had a vw with a luk (luk makes the clutch assembly in the JL) dual mass flywheel and it made the same sound. I only ever hear it though when the engine rpms are too low. If you hear it a lot you're probably doing something wrong with how you are using the clutch and throttle, like trying to drive at too low of rpm with the clutch out.

Not hearing it a lot during normal driving conditions. Only hear it when in 1st gear maneuvering very slow like around a parking lot or in stop/go traffic and just happen to catch it at the right time I guess pushing the pedal. Yes, it's at low rpms then.

However, it was happening more often during offroading yesterday when in 4L. I was letting the Jeep do it's thing crawling over the obstacles, no clutch engagement was needed. RPMs weren't super low, maybe 1500-2k? I can't recall. The slapping sound would happen once the Jeep crested a rock hill and on it's way down slap-slap! It would also happen when I would push the clutch to brake in between obstacles or while crawling over rocks and wanted to slow down where engine breaking wasn't quite enough. I didn't think I was driving wrong. I'm not new to manuals, just to this JL one. Again, that slap sound during offroading yesterday only occurred in 4L during an obstacle. Never heard it under normal driving conditions or even flat ground in 4WD. It's happened enough in 1 day where I wanted to question it. If I need to make an adjustment, I will just need to know what's going on. First time I ever had a manual do this lol.

 

[OrneryBear]

Not hearing it a lot during normal driving conditions. Only hear it when in 1st gear maneuvering very slow like around a parking lot or in stop/go traffic and just happen to catch it at the right time I guess pushing the pedal. Yes, it's at low rpms then.

However, it was happening more often during offroading yesterday when in 4L. I was letting the Jeep do it's thing crawling over the obstacles, no clutch engagement was needed. RPMs weren't super low, maybe 1500-2k? I can't recall. The slapping sound would happen once the Jeep crested a rock hill and on it's way down slap-slap! It would also happen when I would push the clutch to brake in between obstacles or while crawling over rocks and wanted to slow down where engine breaking wasn't quite enough. I didn't think I was driving wrong. I'm not new to manuals, just to this JL one. Again, that slap sound during offroading yesterday only occurred in 4L during an obstacle. Never heard it under normal driving conditions or even flat ground in 4WD.

I was not implying you would hear it normally driving. You’re lugging the motor it sounds like, and letting the clutch fully engage too early and not enough throttle before the clutch is fully engaged. Basically not balancing the clutch and throttle inputs enough. Dont take this as a critique, the flywheel on the JL is too light for the weight of the vehicle and power of the engine. makes the clutch chatter like an late 80s honda civic.

To be honest, it sounds like you would love the upgraded jp6 clutch kit from act with the heavy pro mass flywheel. Less having to ballerina dance with your feet, more just letting the clutch out and climbing obstacles.

 

[wreck99]

I was not implying you would hear it normally driving. You’re lugging the motor it sounds like, and letting the clutch fully engage too early and not enough throttle before the clutch is fully engaged. Basically not balancing the clutch and throttle inputs enough. Dont take this as a critique, the flywheel on the JL is too light for the weight of the vehicle and power of the engine. makes the clutch chatter like an late 80s honda civic.

To be honest, it sounds like you would love the upgraded jp6 clutch kit from act with the heavy pro mass flywheel. Less having to ballerina dance with your feet, more just letting the clutch out and climbing obstacles.

Yes, I may be going aftermarket clutch at some point but not for a while as it's not a priority or in the budget. Perhaps I'm not describing this sound and when it happens correctly though. You say fully engaging the clutch too early. The sound I'm hearing under normal driving conditions isn't when I'm letting off the clutch, it's when I have to depress the clutch and I guess engine breaking is happening? I'm having a hard time describing this so I apologize. During 4L that sound was happening on a descend from an obstacle. I didn't want to ride the clutch going down because engine breaking is awesome on obstacles. Maybe I was in the wrong gear doing the obstacle but I really don't think so. I spent some time fooling around with it yesterday to learn that crawling over some of that stuff in 3rd gear at 5-10 mph was great. RPMs weren't too low, or too high. I think around 2k. I just wasn't expecting this slapping to happen on the way down during engine breaking. To be clear, the Jeep wasn't bucking like it would if you were lugging the engine. No whiplash either lol.

 

[OrneryBear]

Yes, I may be going aftermarket clutch at some point but not for a while as it's not a priority or in the budget. Perhaps I'm not describing this sound and when it happens correctly though. You say fully engaging the clutch too early. The sound I'm hearing under normal driving conditions isn't when I'm letting off the clutch, it's when I have to depress the clutch and I guess engine breaking is happening? I'm having a hard time describing this so I apologize. During 4L that sound was happening on a descend from an obstacle. I didn't want to ride the clutch going down because engine breaking is awesome on obstacles. Maybe I was in the wrong gear doing the obstacle but I really don't think so. I spent some time fooling around with it yesterday to learn that crawling over some of that stuff in 3rd gear at 5-10 mph was great. RPMs weren't too low, or too high. I think around 2k. I just wasn't expecting this slapping to happen on the way down during engine breaking. To be clear, the Jeep wasn't bucking like it would if you were lugging the engine. No whiplash either lol.

Just to confirm we are on the same page with terminology (and maybe we are), when I say fully engage the clutch, I mean when the clutch pedal is fully depressed since when you let off the pedal, the clutch disk is able to fully engage the flywheel connecting the engine and transmission drive.

That said I'm not fully understanding what you're describing apparently.

So to clarify, you are decelerating down an obstacle slowly in 3rd gear at 2k rpms and it's "slapping"?

 

[wreck99]

Just to confirm we are on the same page with terminology (and maybe we are), when I say fully engage the clutch, I mean when the clutch pedal is fully depressed since when you let off the pedal, the clutch disk is able to fully engage the flywheel connecting the engine and transmission drive.

That said I'm not fully understanding what you're describing apparently.

So to clarify, you are decelerating down an obstacle slowly in 3rd gear at 2k rpms and it's "slapping"?

Yes in 4 low during engine breaking. Like it's rocking back and forth slapping at the same time. I wondered if I tried it in 2nd if that would happen but then I'd be going too slow over said obstacle.

Maybe slapping is too harsh a word? Clicking? But there is some feeling to it as well.

 

[OrneryBear]

Yes in 4 low during engine breaking. Like it's rocking back and forth slapping at the same time. I wondered if I tried it in 2nd if that would happen but then I'd be going too slow over said obstacle.

Maybe slapping is too harsh a word? Clicking? But there is some feeling to it as well.

Ahh...hmm ya I'm definitely not sure now. I have some steep descents on my property, I might test this out tonight and see if I can replicate. Do you know what angle you were at?

 

[wreck99]

Ahh...hmm ya I'm definitely not sure now. I have some steep descents on my property, I might test this out tonight and see if I can replicate. Do you know what angle you were at?

I don't recall, but north of 20 degrees I'd guess. FWIW it is the same sound that happens around parking lots and crawling in traffic when you press the pedal "too early" I guess. I might try to capture it on video if I can.

 

[Asuriyan]

Yes in 4 low during engine breaking. Like it's rocking back and forth slapping at the same time. I wondered if I tried it in 2nd if that would happen but then I'd be going too slow over said obstacle.

Maybe slapping is too harsh a word? Clicking? But there is some feeling to it as well.

If I had to pick a single descriptor for what I'm thinking of, it would be "clanking".

 

[gdeyarmond]

Question for the group. It's a hard one to try and explain but I'll do my best. I drive a '24 JLUR 6MT and something I've noticed is if I press the clutch while the engine is still trying to go forward in 1st (like trying to stop/start in stop/go traffic), there's this slapping kind of sound that happens when I push the clutch in. I can't think of a better word to describe what I'm hearing but It's not a great sound. I've tried to get better about waiting for the engine to press the pedal in stop/go traffic to avoid this sound and gotten pretty good at it however a quick stop doesn't always give me that chance. Does anyone know what this is? Is this normal?

I ran Uwharrie yesterday and noticed it a lot more on the trail when i was in 4L. I didn't need to use the clutch hardly at all which was amazing. The Jeep just creeped over everything with ease but when it would crest over a hill or something and engine breaking/self throttle was happening, I'd hear that slapping sound...even not pressing the clutch. I didn't notice it in 4H. I'm assuming it has something to go with the clutch give but I'm no expert. I was wondering if anyone knows what's going on here.

If it makes you feel any better, both my wife's 2024 Willys and my 2020 Tacoma do the exact same thing. The first reply to your post is exactly the reason.

 

[Apples491]

A clanking/clicking when in 4Lo is something I'm very used to driving manual transmissions. It happened in my Xterra as well. The way it was explained to me is, The transfer case is chain driven and there is, by design, a small amount of slop in it. As you change throttle while wheeling it loads and unloads the pressure on that chain causing the clanking sound.. You don't get the noise on an automatic because the torque convertor spends its entire life smoothing out changes in the driveline for that exact reason.

Now, I have never actually heard this noise when driving around town so I can't say for sure that it's what you're talking about, but it sounds like it to me.

 

[wreck99]

I was able to capture the sound. Messing around in 4 LO over a hill since I couldn't replicate it in 1st / 2WD like I sometimes can in parking lots. But it's the same sound.

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