Grinding When Letting Off Clutch

[sk47]

Hello; I am going to follow this thread to see what happens as I am interested in a manual shift trans.
Two things come to mind when reading thru. First is the springs in the clutch disc on most vehicles. It has been my understanding those springs are in place to cushion engagement of the clutch. The springs absorb some of the forces when you let out the clutch and it starts to lock up against the pressure plate. I think it makes for a smoother engagement.

As to why this might an issue with this clutch is a question. I watched a video about dual clutch manuals. In the video only one clutch disc has those small springs while the second clutch disc does not have them. I have no clue if the two clutch discs being different will make a difference such as the OP reports. Just a WAG at this point.

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[friedmud]

Hello; I am going to follow this thread to see what happens as I am interested in a manual shift trans.
Two things come to mind when reading thru. First is the springs in the clutch disc on most vehicles. It has been my understanding those springs are in place to cushion engagement of the clutch. The springs absorb some of the forces when you let out the clutch and it starts to lock up against the pressure plate. I think it makes for a smoother engagement.

As to why this might an issue with this clutch is a question. I watched a video about dual clutch manuals. In the video only one clutch disc has those small springs while the second clutch disc does not have them. I have no clue if the two clutch discs being different will make a difference such as the OP reports. Just a WAG at this point.

Interesting - thanks for brainstorming on this... the springs are definitely something else to look at...

 

[Sivi70980]

I get the exact same sound occasionally in my car, it has done it since I bought it two years ago. It only happens at high rpm shifts if I let the clutch out slowly and start to get on the gas while still letting the clutch out. I've adapted my driving style to avoid it.

To me, it sounds like something vibrating very loudly, like a metal bracket. I can sometimes get the sound on demand if I get RPM up and put some pressure on the clutch pedal. I have never had it diagnosed, and it hasn't had any effect on how the car drives. I'm very interested in finding out what your dealer determines, though!

I can make my car do this too. Also driven manuals for 20+ years and not afraid to admit I had to learn what this car likes. If you granny it or go full send, you're good. In between that, you need to be more precise and weird things happen when you aren't. You're still super new to the car and I recommend driving it more and let your hand/foot timing calibrate to what the car likes. What Conman is explaining here happens occasionally to me when I go a little harder than I usually do without going all out. When you hit in any gear and calm down mid shift to the next, as I release the clutch with a higher engine speed it vibrates and makes a grinding sound till its fully hooked up. Obviously I try to avoid this happening. Hope this helps and hope nothing is wrong with your car, these things are tons of fun!

 

[NGOT8R]

This may be way off base, but could this noise possibly be caused by the shifter support bracket being loose and moving around (grinding against the transmission tunnel) during shifts?

 

[friedmud]

I can make my car do this too. Also driven manuals for 20+ years and not afraid to admit I had to learn what this car likes. If you granny it or go full send, you're good. In between that, you need to be more precise and weird things happen when you aren't. You're still super new to the car and I recommend driving it more and let your hand/foot timing calibrate to what the car likes. What Conman is explaining here happens occasionally to me when I go a little harder than I usually do without going all out. When you hit in any gear and calm down mid shift to the next, as I release the clutch with a higher engine speed it vibrates and makes a grinding sound till its fully hooked up. Obviously I try to avoid this happening. Hope this helps and hope nothing is wrong with your car, these things are tons of fun!

Thanks for adding your experiences here - good to hear from others about similar issues and how they've dealt with it. It is possible that what I'm experiencing is "normal"... but it really doesn't feel that way. Maybe I should go test drive another one to see (but I don't see any other manuals on any lots around me currently).

This may be way off base, but could this noise possibly be caused by the shifter support bracket being loose and moving around (grinding against the transmission tunnel) during shifts?

Interesting - would it make a difference that I can _feel_ this more in the clutch vs in the stick? It's a distinct grinding feeling in the clutch as it is let out.

 

[NGOT8R]

Interesting - would it make a difference that I can _feel_ this more in the clutch vs in the stick? It's a distinct grinding feeling in the clutch as it is let out.

I’m not sure, but was just wondering if this could be a possibility, as the engine/transmission will move around to some degree with the mushy stock motor mounts and transmission crossmember bushing, unless perhaps stiffer motor mounts, a shifter bracket and the polyurethane trans insert are installed to help lessen most of the movement.

I can say that the factory shifter support bracket and rubber bushing are super flimsy compared to the billet one in my previous pic. Have a look here at the stock bracket snd bushing. Maybe upon release of the clutch the movement could be causing the brief grinding sound.

I’m not saying this is the case with you, but as for me, I’m always listening to and feeling for abnormal sounds and vibrations when I’m in my car, especially after a modification. Sometimes I’ve gotten tunnel vision and only picked up on half of a problem because I may have been focused on a specific noise more so than a vibration too. The more I listen, feel and evaluate things, the clearer the picture becomes to me.

 

[Matti777]

I couldn't determine whether the sound was gear crunch or something else. I would start with an inspection of all driveline mounts and the shifter mechanism. After that it will require some dissassembly.

ps I have had rev hang due to a clutch disc hanging up on the shaft. It didn't cause any other issues....just annoying. (not a Ford)

 

[Elp_jc]

In the video I'm shifting without any throttle input at all.

So it's definitely the rev-hang induced, along with the dual clutch, I guess. Anyway, I'm giving the engine a chance to come pretty close to where it needs to be for the next shift, but I'm sure if I release the clutch quicker, it'd make the same sound... but since don't know what it is, and if it can be detrimental to something or not, I'm just 'granny shifting', even at higher rpm. The rev hang could be eliminated with a tune, by simply closing it quickly, but the video you posted explains why it's there (and yes, it's because of emissions).

Hey, found the other thread I mentioned for you : https://www.mustang6g.com/forums/threads/2019-gt-mt82-weird-sound-question.116475/

Hey, at least you have official company. Ha ha. Hope it helps, brother.

 

[Conman1138]

Rev-hang is NOT the cause of the sound we've been discussing. If that were the case, we would see A LOT more people coming to the forums to complain about this weird noise. Yes, rev-hang can contribute to the conditions that produce this sound if you try to shift quickly, but the actual cause of the sound is something mechanical. Since it only occurs at high RPM, my theory is something vibrating at the right frequency at partial clutch engagement, or the clutch spinning at the right speed to create loud chatter. If a tune fixed this, I wouldn't still be hearing it in my car occasionally.

 

[Elp_jc]

Of course rev-hang is not the root cause of the noise, but what reveals it. On a prior thread about that, It was attributed to the dual clutch plate, dual mass flywheel, or both. So in other words, 'normal', just like many other disturbing and unflattering noises like the infamous '2K rpm rattle', and 'BBQ tick'. At least there's a way around it, letting the engine drop close to the rpm needed for the next gear (rev-match does that for you).

 

[friedmud]

Long overdue update. It took a long time for the dealer to get back to me (but I have to admit that it didn’t matter much since it’s pretty much been too cold here to drive anyway)…

When they did: they said that Ford thinks it’s “normal”. However, the dealership is not convinced and they want me to bring it in once it’s warmer so they can hear it first hand. They also want me to drive another one to see if it’s doing it too.

So: not much to report - I’ll have to wait a month or more before I can drive back up there to do all of that. I will definitely report back when I do.

I can say that I have been able to drive it some since then - and the only real way to avoid the sound is to wait for the RPMs to drop completely (to where the rev-matcher holds it) before letting off the clutch. It’s a ridiculously long time (especially going 1st to 2nd… why aren’t those gears a little closer?). But - I still haven’t driven the car hard (only 750 miles so far)… so I don’t know if it will be a bigger/smaller deal once I actually do some spirited driving…

 

[Sivi70980]

Long overdue update. It took a long time for the dealer to get back to me (but I have to admit that it didn’t matter much since it’s pretty much been too cold here to drive anyway)…

When they did: they said that Ford thinks it’s “normal”. However, the dealership is not convinced and they want me to bring it in once it’s warmer so they can hear it first hand. They also want me to drive another one to see if it’s doing it too.

So: not much to report - I’ll have to wait a month or more before I can drive back up there to do all of that. I will definitely report back when I do.

I can say that I have been able to drive it some since then - and the only real way to avoid the sound is to wait for the RPMs to drop completely (to where the rev-matcher holds it) before letting off the clutch. It’s a ridiculously long time (especially going 1st to 2nd… why aren’t those gears a little closer?). But - I still haven’t driven the car hard (only 750 miles so far)… so I don’t know if it will be a bigger/smaller deal once I actually do some spirited driving…

I also recommend taking the tech for a drive. It really does sound like you're trying to shift too fast. After a little bit of driving I learned the timing the car likes and no issues but I can make it do what you describe by shifting too fast or man handling things. Gotta be precise with this one.

 

[friedmud]

I also recommend taking the tech for a drive. It really does sound like you're trying to shift too fast. After a little bit of driving I learned the timing the car likes and no issues but I can make it do what you describe by shifting too fast or man handling things. Gotta be precise with this one.

Man - I can’t see it all. In the video I’m not shifting fast at all… definitely not “man-handling” it. But - it may be too fast for this transmission. Maybe this is one of the reasons all the guys that drag mustangs get the autos now… I can’t imagine trying to drag with this car (luckily that’s not my purpose).

I used to have a 2002 WRX… I could absolutely _rip_ that through the gears… nothing was too fast.

At any rate - needing to be a bit slower will be fine… maybe after the warranty is up I’ll look into a replacement…

 

[ice445]

Man - I can’t see it all. In the video I’m not shifting fast at all… definitely not “man-handling” it. But - it may be too fast for this transmission. Maybe this is one of the reasons all the guys that drag mustangs get the autos now… I can’t imagine trying to drag with this car (luckily that’s not my purpose).

I used to have a 2002 WRX… I could absolutely _rip_ that through the gears… nothing was too fast.

At any rate - needing to be a bit slower will be fine… maybe after the warranty is up I’ll look into a replacement…

Its not too fast lol, I can rip redline 1-2 with no unusual noises.

 

[Sivi70980]

Its not too fast lol, I can rip redline 1-2 with no unusual noises.

I meant and should have said too fast for how much you're sending it. If it's full send, and shifting at redline, of course you can blast through the gears. When you do a second gear pull and then shift to third staying off the gas, if you let out the clutch too fast while RPMs are high, it makes the described sounds/vibrations till they nominalize. I did this a few times when I first got the car and have since learned how to avoid it. Maybe something is broken or maybe not. I believe 98% of the MT-82 issues are people not bothering to learn how to drive it. It operates differently than any other manual transmission I've driven over the years.

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