[jaximointhecut]

Hello all,

Whenever I accelerate quickly and shift from 1-2, there is 50/75% chance that once I try to put the car into second gear, there is an awful grinding noise which is followed by the car staying in neutral.

I've told the dealership about this and taken it in for service, only to be told that there is nothing wrong with the car. Before going in, I mentioned that the research I did online resulted in bad synchros or a transmission that was going out soon.

I have CPO up until August of next year, and I plan on keeping this car for a long time. As a performance car, I expect it to be able to handle shifting from 1-2 while pushing the car. After all, that's the whole point of this car right? To go fast?

Any input would be appreciated. Dealing with this dealership over in New Orleans is exhausting. I need this problem to be addressed before my warranty expires.

[overcoil]

Phone video or dash cam video.

Have complaint documented on service form.

U sure your depressing in clutch all the way.

And 1-2 shift should not be rushed as no shift should. Rush meaning slammed quick from slot to slot

[jaximointhecut]

Originally Posted by ScottSinger

Phone video or dash cam video.

Have complaint documented on service form.

U sure your depressing in clutch all the way.

And 1-2 shift should not be rushed as no shift should. Rush meaning slammed quick from slot to slot

Yes, definitely depressing the clutch all the way. I'm OCD with my driving position to make sure that I'm able to depress the clutch every time. I'll have my girlfriend record a video of it for documentation. It sounds identical to this video online:

A new transmission is over 6k

[overcoil]

is your warranty up in august 2019 or is it august 2020 ?

[jb-slow]

Drain the trans, drive it until it won't anymore, refill the trans and have it towed in, new trans under warranty. It's already in your service history, just grenade it.

[XutvJet]

Unfortunately the 1-2 syncros are failing is a somewhat common issue with any 2012+ BMW using the ZF 6MT (M cars, M235, most F series 3s and 4s).

A refurbished M235 6MT is $3,200-3,600 from BMW plus you might as well replace the dual mass flywheel and clutch while you're at it. You're likely looking at $6K USD all in. This should all be covered under the CPO warranty. Surely there's another BMW dealer in your neck of the woods to work with. You need to be annoying about this and take them on a drive and show them how it grinds. You may also need to contact BMW US and start a document trail as the issue will only get worse as time goes on. Hopefully you don't have any power mods as that will give them reason to deny warranty coverage.

If you bought used, the prior owner probably did it in by driving it hard before the fluid was fully warmed. These 6MTs use a pretty robust fluid for hard driving, but it's critical that you give the tranny 10-15 minute warm up before hitting the gears hard as the fluid takes a bit of time to warm up. I avoid hammering a 1-2 shift often as the 1-2 syncro is the weak link and there's really no point to slamming the gears aggressively unless you were drag racing for a lower elapsed time.

[jaximointhecut]

Originally Posted by ScottSinger

is your warranty up in august 2019 or is it august 2020 ?

My warranty is up August of 2020. I leave the city at the end of summer, so I want this dealership to pay for whatever is needed for the car. AC isn't blowing properly and passenger tail light has water inside.

[jaximointhecut]

Originally Posted by XutvJet

Unfortunately the 1-2 syncros are failing is a somewhat common issue with any 2012+ BMW using the ZF 6MT (M cars, M235, most F series 3s and 4s).

A refurbished M235 6MT is $3,200-3,600 from BMW plus you might as well replace the dual mass flywheel and clutch while you're at it. You're likely looking at $6K USD all in. This should all be covered under the CPO warranty. Surely there's another BMW dealer in your neck of the woods to work with. You need to be annoying about this and take them on a drive and show them how it grinds. You may also need to contact BMW US and start a document trail as the issue will only get worse as time goes on. Hopefully you don't have any power mods as that will give them reason to deny warranty coverage.

If you bought used, the prior owner probably did it in by driving it hard before the fluid was fully warmed. These 6MTs use a pretty robust fluid for hard driving, but it's critical that you give the tranny 10-15 minute warm up before hitting the gears hard as the fluid takes a bit of time to warm up. I avoid hammering a 1-2 shift often as the 1-2 syncro is the weak link and there's really no point to slamming the gears aggressively unless you were drag racing for a lower elapsed time.

Very helpful, this is exactly what I needed. Thank you.

[Dylan86]

Haven't had a grind yet except for my own mishap (not paying attention).

The 1-2 shift is not like any other when under power. There's a LOT of movement in the driveline from coming off-power, engaging/disengaging the clutch, and getting back into power. You have to time it "just right" in order to get a fast/smooth shift on a 0-60 attempt to avoid the synchro's from grinding.

I noticed a difference immediately with the driveline movement when I installed uprated Diff bushings. It took about 50-75% of the movement between shift away, causing the gearbox to perform much smoother than before, most notably from 1-2nd.

Consider all of the harsh drivetrain movement going on underneath, and consider that the gearbox is simply "cradled" inside of the aluminum case, with bearings, and given room to move around or "flex" when needed.

[overcoil]

Originally Posted by Dylan86

Haven't had a grind yet except for my own mishap (not paying attention).

The 1-2 shift is not like any other when under power. There's a LOT of movement in the driveline from coming off-power, engaging/disengaging the clutch, and getting back into power. You have to time it "just right" in order to get a fast/smooth shift on a 0-60 attempt to avoid the synchro's from grinding.

I noticed a difference immediately with the driveline movement when I installed uprated Diff bushings. It took about 50-75% of the movement between shift away, causing the gearbox to perform much smoother than before, most notably from 1-2nd.

Consider all of the harsh drivetrain movement going on underneath, and consider that the gearbox is simply "cradled" inside of the aluminum case, with bearings, and given room to move around or "flex" when needed.

At the point in the vid where he talks about shifting the 300SL u may find interesting.

[Dylan86]

Originally Posted by ScottSinger

At the point in the vid where he talks about shifting the 300SL u may find interesting.

Ah yes, must drive similar to the Eaton Fuller's I've driven in some heavy trucks, you time the shift similar to how he's saying, kind of like 1-break-2 and it sucks the gear selector right into place when done correctly. I can actually shift like this in a synchronized gearbox, but it's not good for them long term lol