2018 Mustang GT 6 Speed - Grinding while Shifting

[DickR]

These service techs are now telling me the noises are normal. Their reason: Another Mustang GT on the lot makes the same sounds.

I'll record the sound either this afternoon or tomorrow morning and upload it.

I owned and autocrossed a 2015 GT PP for 3 years and 31K miles. Oem gear oil. Shifted UP from 1st to 2nd MANY times at over 6500 rpm as fast as I could move the shift lever and the clutch. The only time there was a grinding noise (I know what gear grinding sounds like from over 50 years of driving manual transmissions) was when I either didn't depress the clutch fully, started to lift my clutch foot before moving the shifter all the way into 2nd, or didn't actually move the shifter far enough to engage 2nd before letting the clutch out.

With high rpm down shifts keep in mind that these are relatively heavy gears with a lot of inertia. The syncros have a lot of work to do to accelerate the lower gear via friction when you down shift at high rpm without "double clutching". This can make a noise which might sound similar to grinding.

I owned a Lotus Europa decades ago that fast 1 - 2 shifts over 7000 rpm with tired syncros would result in gear grinding simply because the whimpy syncros in those days couldn't keep up. This was called "beating the syncros" back in the day.

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[youra6]

I owned and autocrossed a 2015 GT PP for 3 years and 31K miles. Oem gear oil. Shifted UP from 1st to 2nd MANY times at over 6500 rpm as fast as I could move the shift lever and the clutch. The only time there was a grinding noise (I know what gear grinding sounds like from over 50 years of driving manual transmissions) was when I either didn't depress the clutch fully, started to lift my clutch foot before moving the shifter all the way into 2nd, or didn't actually move the shifter far enough to engage 2nd before letting the clutch out.

With high rpm down shifts keep in mind that these are relatively heavy gears with a lot of inertia. The syncros have a lot of work to do to accelerate the lower gear via friction when you down shift at high rpm without "double clutching". This can make a noise which might sound similar to grinding.

I owned a Lotus Europa decades ago that fast 1 - 2 shifts over 7000 rpm with tired syncros would result in gear grinding simply because the whimpy syncros in those days couldn't keep up. This was called "beating the syncros" back in the day.

Thanks for the post. I have been very meticulous in how I've been shifting. I've shifted aggressively, gently and everything in between. The car does make a louder grinding/clunking sounds when it is shifted aggressively, but the point is it always makes some sort of sound regardless of how I shift (past 5K). If I shift at 4.5K or at 5K or anything below, I generally hear nothing.

There is no issue when I'm down shifting, so the double clutch scenario doesn't apply to me. I do rev match every I down shift.

I even let the salesperson and mechanics drive my car and they all could reproduce the noise. It boggles my mind they can consider this noise normal.

 

[mustang1]

maybe there is a slight clutch drag that is affecting the synchros, resulting in a grind. You could try test driving another Mustang to see if its the same or different.

 

[youra6]

maybe there is a slight clutch drag that is affecting the synchros, resulting in a grind. You could try test driving another Mustang to see if its the same or different.

Could be it. Got my repair order and I'm going to call the dealer again tomorrow. If they tell me to go eat dirt, I'm going to a different dealer and submit a complaint to NHTSA.

Worst comes to worst, I'll gather up all my repair orders and get a independent ASE mechanic to take a look at it and drop the Lemon law on these sons of bitches.

 

[Optimum Performance]

I would be interested in this actual noise as well. If you can get a clip of it, it would be helpful.

 

[mustang1]

Could be it. Got my repair order and I'm going to call the dealer again tomorrow. If they tell me to go eat dirt, I'm going to a different dealer and submit a complaint to NHTSA. ...

the dealership may not know that much about manual transmissions and from the perspective of the mechanic or sales guy, your car is good enough. There is other things that can go wrong with a new car, so try not to upset the dealership. My next step would be to test drive another new Mustang and see if it is any different. Then you can weigh your options.

 

[youra6]

I would be interested in this actual noise as well. If you can get a clip of it, it would be helpful.

I will on my way to work tomorrow. Hopefully it will be audible on a cellphone video.

the dealership may not know that much about manual transmissions and from the perspective of the mechanic or sales guy, your car is good enough. There is other things that can go wrong with a new car, so try not to upset the dealership. My next step would be to test drive another new Mustang and see if it is any different. Then you can weigh your options.

I dont think the dealership would be so naive to think this is considered "normal", however I'm a pretty reasonable guy. I will keep everyone posted.

 

[Kong76]

How should one be shifting? Letting go of the clutch slowly while easing in on gas or let go of the clutch fast and press on gas as soon as clutch is at the resting position?

I let the clutch out and meet it with a tad of gas half way for a smooth transition but it's not slowly. More of a good clean sped up tempo. I don't let the clutch completely out and then get back on the gas except maybe for 6th. Way to jerky. Been driving manual like that since 92'. Not saying that's exactly how you are suppose to but it works for me.

 

[youra6]

Here is the video: This is a pull from second gear. I was a bit fast with the clutch here to make the sound more evident but you can still hear it regardless of how you shift.

[ame]

 

[Optimum Performance]

Sorry do not hear any grinding. Not really sure what you are trying to express. Sorry

 

[youra6]

Sorry do not hear any grinding. Not really sure what you are trying to express. Sorry

The video is taken from a crappy mobile phone with shaky hands. The sound you would hear is at the 4 second mark. There is a definite audible noise that occurs right after I move the shifter to second.

I doubt you hear the same sound when you shift past 5K RPMs on your Mustang GT...

 

[DickR]

In the video it doesn't sound like "gear grinding" but it doesn't sound "normal". Does it do it between 1 and 2?

In the video it looks and sounds like you do the shift and either don't get back on the gas as you let the clutch back out or you instantly get back off the gas. The "look and sound" are almost like the drive train is jerking as if you suddenly slowed down. If so can you do a video where you "follow through" and continue to accelerate hard in 3rd?

The below probably isn't the case but just to be sure:

It looks like you are in Colorado. If so how cold is it and what tires do you have. It "sort of sounds" like brief tire spin. What drive mode and are TC and Advance Trac "on"? With below 40 deg cold air and pavement summer tires or all season tires are very "traction limited". Snow tires even more so.

 

[youra6]

In the video it doesn't sound like "gear grinding" but it doesn't sound "normal". Does it do it between 1 and 2?

In the video it looks and sounds like you do the shift and either don't get back on the gas as you let the clutch back out or you instantly get back off the gas. The "look and sound" are almost like the drive train is jerking as if you suddenly slowed down. If so can you do a video where you "follow through" and continue to accelerate hard in 3rd?

The below probably isn't the case but just to be sure:

It looks like you are in Colorado. If so how cold is it and what tires do you have. It "sort of sounds" like brief tire spin. What drive mode and are TC and Advance Trac "on"? With below 40 deg cold air and pavement summer tires or all season tires are very "traction limited". Snow tires even more so.

Its 50 degrees in Colorado this morning so that it isn't it. I'm running stock P-Zeros.

When I drive home today, I'll post another video of me continuing driving in 3rd. I was hesitant to keep going as the speed limit is 40, and I was going near 60 in the video. We have lots of cops here lol.

It sounds a bit different in real life but that to me sounds probably more like a reverberation than a grind, but there is most likely some metal to metal contact there. And yes it does it too from 1st to second. If I shift the same way but do it at 4.5K RPM, there is no sound. I can't recall what drive mode I'm in but I thought that was a PP feature. Hopefully that answers all your questions.

 

[DickR]

I suspected that you had a "speed vs. speed limit" issue. ;)

I'm at a loss in regard to ideas. Do you have a trusted friend you can get let drive it when conditions and speed limits cooperate?

 

[NoVaGT]

Looks like you damn near went back into 1st, the car didn't let you, and it diverted you to 3rd.

Honestly, it looks like you can't shift.

Looks like you're trying to muscle the shifter, and that's going to damage stuff.

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