[lithdoc]

I'm having a new issue with my 2020 M6.

The car was built in 11/20, currently has 4600 miles.

Recently a gear grinding noise happens when trying to shift 1->6 or 2->6 at higher RPMs, usually after accelerating and RPMs being at above ~3k. When shifting at lower RPMs, I'm able to shift to 6th without noise.

Before I go to the dealership (whose competence is not great) I'd like to have a better idea what the problem is what I need to ask them to fix.

Please advise.

Thank you!

 

[2ndAmend]

Please clarify, you are shifting directly from 1st to 6th?

 

[lithdoc]

Please clarify, you are shifting directly from 1st to 6th?

Yes, that's how I usually drive in the city... Punch in in 1st, reach ~50 mph and then cruise in 6th. My third Challenger, second Hellcat, doing nothing different.

The issue seems to be shifting into 6th when RPMs are still somewhat high and engine has not revved down. I'm thinking it's either cluch, synchro, or shifter linkage issue.

Another issue is that sometimes I'll put it in 1st, it will seem like it's in, but when clutch is released the grinding appears and shifter knob is banging around. Acts as if I'm trying to get into gear without depressing the clutch.

 

[DevilsReject97]

I know a lot of the modern transmissions have a gear shift limiter, meaning you have to be in a certain RPM/speed range to shift... had this on my Camaro... that could possibly be it...

 

[lithdoc]

I know a lot of the modern transmissions have a gear shift limiter, meaning you have to be in a certain RPM/speed range to shift... had this on my Camaro... that could possibly be it...

Definitely no limiters or rev matching on this old fashioned machine... You can shift from anything to anything, as long as the engine does not redline.

 

[2ndAmend]

First:

My M6 will occasionally (1/100) "feel" like it is in 1st but when I let out the clutch is grinds because it is not in gear! The Serv Mgr said "muscle it" but that doesn't help because it feels in but not. The Barton helped but did not cure. Just today, at the end of my long driveway I shift 2-1 and it "popped" into gear, but I let out the clutch and grind!!! MF'er!!!

Apparently there was a huge change to the clutch at some time. My friends 16 had the "baby elephant" clutch but my 20 is a normal clutch. I sometimes wonder....

I would like to hear if any one else experiences this.

 

[DevilsReject97]

Definitely no limiters or rev matching on this old fashioned machine... You can shift from anything to anything, as long as the engine does not redline.

I know GM had it with their version of the TR6060, so wasn't entirely sure... good to know

 

[lithdoc]

First:

My M6 will occasionally (1/100) "feel" like it is in 1st but when I let out the clutch is grinds because it is not in gear! The Serv Mgr said "muscle it" but that doesn't help because it feels in but not. The Barton helped but did not cure. Just today, at the end of my long driveway I shift 2-1 and it "popped" into gear, but I let out the clutch and grind!!! MF'er!!!

Apparently there was a huge change to the clutch at some time. My friends 16 had the "baby elephant" clutch but my 20 is a normal clutch. I sometimes wonder....

I would like to hear if any one else experiences this.

Yes, this happens occasionally also - where you think it's in gear, but it is not. About 1% of the time, like you've said.

I'm thinking it is the synchronizer.

 

[2ndAmend]

Second:

Stop 1-6! You are probably grinding because of the huge rpm change. 1st is useless past 3500 because even the 305’s break loose, Do a moderate throttle in 1st then get it into 2nd and hit it. Then go to 4th or 5th which is appropriate for 50. You won’t get your best ET’s this way. but it will be MUCH gentler on your baby!

 

[lithdoc]

Second:

Stop 1-6! You are probably grinding because of the huge rpm change. 1st is useless past 3500 because even the 305’s break loose, Do a moderate throttle in 1st then get it into 2nd and hit it. Then go to 4th or 5th which is appropriate for 50. You won’t get your best ET’s this way. but it will be MUCH gentler on your baby!

Did it for 35k miles on the '17 without an issue... I don't think I'm doing anything unacceptable, but something is off with just 4.5k miles on this one.

 

[WhiteTiger21]

most likely synchronizers, i' have replace 2 transmissions and recetly my third tr6060 has gone... best of luck thou, warranty should indeed cover it.

 

[Challey Cat]

I'm having a new issue with my 2020 M6.

The car was built in 11/20, currently has 4600 miles.

Recently a gear grinding noise happens when trying to shift 1->6 or 2->6 at higher RPMs, usually after accelerating and RPMs being at above ~3k. When shifting at lower RPMs, I'm able to shift to 6th without noise.

Before I go to the dealership (whose competence is not great) I'd like to have a better idea what the problem is what I need to ask them to fix.

Please advise.

Thank you!

If your 17 did it without issue. Did you do that 1-6 trick from brand new or after it had some miles on it? I've had a few tremecs and they all did the almost in first gear thing 1% of the time. That caan be remedied by choosing any other gear first then first gear again. If you cycle a couple of other gears on your way to 6th without releasing the clutch that should help the problem if not solve it since when driving it like that you're obviously not in a hurry after your first gear blast. If you take a service rep for a "dupliucate the problem " drive, they might schoff at you and maybe even accuse you of abusive behavior and threaten to not cover it. It's great that your 17 didn't grind but that's not how the car was intended to be driven. I do it too sometimes but run the pattern on my way to a higher gear with no issue.

 

[lithdoc]

If your 17 did it without issue. Did you do that 1-6 trick from brand new or after it had some miles on it? I've had a few tremecs and they all did the almost in first gear thing 1% of the time. That caan be remedied by choosing any other gear first then first gear again. If you cycle a couple of other gears on your way to 6th without releasing the clutch that should help the problem if not solve it since when driving it like that you're obviously not in a hurry after your first gear blast. If you take a service rep for a "dupliucate the problem " drive, they might schoff at you and maybe even accuse you of abusive behavior and threaten to not cover it. It's great that your 17 didn't grind but that's not how the car was intended to be driven. I do it too sometimes but run the pattern on my way to a higher gear with no issue.

I've driven both the '17 and '20 the same. Was careful during break in, and then drove it normally. I mostly cruise in 6th, do mostly city driving, and 1-4 and 1-6 speed shifting is something I've always done, just depends on the speed I get to in 1st. C6 Corvette with TR-6060 had mandatory 1-4 speed shifting for better MPG, so again, I don't think my behavior is something abusive or something that the car should no be able to handle. If I was aggressively downshifting and redlining, that'd be a different story.

 

[Slidd]

I've done 1-3-6 but never directly 1-6. Just seems bizarre.

So how does it shift going through the gears as normal?

Definitely do not tell the dealer you do this or I bet any chance of warranty will go out the window, in the OM pretty sure it says not to skip gears.



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[Spoolin]

I think the problem here is going from 1st to 6th gear after a high rpm hit in 1st. I don't think the synchro's have enough time to slow the trans down to hit that high of a gear from 1st to 6th. To be honest, it's really a bad idea to do this type of shifting. It's always best to shift through each gear so the synchro's can work properly.

 

[lithdoc]

Well, sounds like the synchronizer is gone early. Now time to go make the warranty claim.

The amount of issues I've had with my '20 vs. zero with the '17 makes me think it's not just my "reckless driving."

 

[Challey Cat]

Well, sounds like the synchronizer is gone early. Now time to go make the warranty claim.

The amount of issues I've had with my '20 vs. zero with the '17 makes me think it's not just my "reckless driving."

Wasn't accusing you of wreckless or abusive driving. I do the same thing occasionally. Was just giving you a heads up of how a service writer might interpret the issue you're having.

 

[Rockster]

Did it for 35k miles on the '17 without an issue... I don't think I'm doing anything unacceptable, but something is off with just 4.5k miles on this one.

What 2ndAmend said.

I will add that you got away doing this with a 2017 is no guarantee you can get away with this with a newer model car/transmission. The transmission internals could have changed.

If you want to skip shift I think you need to dial it back from 1st to 6th and use some intermediate gears.

 

[Jimmy N.]

Did it for 35k miles on the '17 without an issue... I don't think I'm doing anything unacceptable, but something is off with just 4.5k miles on this one.

Well, sounds like the synchronizer is gone early. Now time to go make the warranty claim.

If you can make those 1st to 6th shifts without using the clutch, then it's not unacceptable. But if you need to use the clutch to make it happen, the synchros are taking a real beating.

There's nothing inherently wrong with skipping gears, but you need to know how to shift correctly first.

 

[TropiCat]

For my 2019 manual on page 226 it talks about skip shifting 1-4, so the manual does talk about it for 1-4 at least.

1–4 Skip Shift In Auto Drive Mode, Default, or Street Drive Modes, there are times when you must shift the transmission directly from first gear to fourth gear instead of from first gear to second gear. This is to help you get the best possible fuel economy from your vehicle. This occurs when the engine coolant (antifreeze) is higher than 106°F (41°C), vehicle speed is greater than 19 mph (30 km/h) but less than 21 mph(34km/h),and the transmission is in first gear, and the accelerator is at ¼ throttle or less. NOTE: The1-4Skip Shift feature is disabled when selecting Track, Sport, or Custom Drive Modes. Refer to “SRT Drive Modes” in the “Multimedia” section for further descriptions of these modes. After you shift the transmission to fourth gear, you can press the clutch in and shift to another forward gear.