[SteweC]

First time posting here. I made an account because of how much this is bothering me, lol.

[Service appointment is already booked, but a few days out from now]

So I've had my M2 for about a month and a half, and I have put 800 miles on it.

At 490 miles, I had an issue come up while driving that I thought was driver error. I was slowing down for a red light, shifted from 3rd to 2nd gear, and when I let the clutch out in 2nd gear the car chirped the tires, braked hard, and threw me forward. This happened around 20mph while letting the clutch out.

I spent a decent amount of time wondering if my mind was playing tricks on me, and if I was going much slower than 20mph. I figured either I was completely wrong about my speed, or I didn't shift "all the way into" 2nd gear.

It did not happen again until today, and this time, I know it wasn't driver error because I repeated it 3 times.

I was driving down a slight hill approaching a red light, shifted from 3rd to 2nd, was letting the clutch out, tires locked for a second, and the car threw me forward. This time, I immediately put the clutch in, shifted to neutral, put it back in 2nd gear, and it did the same thing, and I did it a third time.

This all felt pretty violent, and I'm concerned this could happen while I'm in traffic.

Has anyone had this issue with the MT?

What could possibly even be causing this issue?

Lastly, the car did not give me a forward collision warning or anything like that, and I had gear assistant on, and I felt the rev match successfully take place each time.

Thank you.

[NewToM]

All I can do is confirm I have not experienced anything like you are describing. Hope it all gets sorted.

[Dave07997S]

I haven't had this issue but I have to be honest with you it almost sounds like driver error. What speed did you downshift from third to second? If the rear tires locked up for a second the ABS could have gone off and that's why the brakes hit hard.

[SteweC]

Originally Posted by Dave07997S

I haven't had this issue but I have to be honest with you it almost sounds like driver error. What speed did you downshift from third to second? If the rear tires locked up for a second the ABS could have gone off and that's why the brakes hit hard.

Around 20mph

[1stM]

Try turning off Rev Matching.

[Dave07997S]

Originally Posted by SteweC

Around 20mph

It sounds like if there is a problem, it is probably with an ABS sensor. I would try turning off rev match as well as 1stM suggested.

[SteweC]

Originally Posted by Dave07997S

It sounds like if there is a problem, it is probably with an ABS sensor. I would try turning off rev match as well as 1stM suggested.

Appreciate that.

If you don't mind, next time you're in your 6MT, let me know if you can move your shifter in 2nd gear and it will stick where you move it to. Hard to explain, but I have a ton of play in 2nd gear while it's still in gear, and it will stay there. I can't do that in any other gear.

[SteweC]

Originally Posted by 1stM

Try turning off Rev Matching.

I'll try, but it has only happened twice in 800 miles.

Idek if I could diagnose it as a rev match issues if it doesn't happen for another 400 haha.

[islandfalconer]

Sounds a little like what happened with my transmission. A faulty shifter position sensor. The car misbehaves. It tried to revmatch, or gets very confused. I almost hit a car in front of me. In the end they replaced the entire transmission. But it died very much sound like how my issue started

[SteweC]

Originally Posted by islandfalconer

Sounds a little like what happened with my transmission. A faulty shifter position sensor. The car misbehaves. It tried to revmatch, or gets very confused. I almost hit a car in front of me. In the end they replaced the entire transmission. But it died very much sound like how my issue started

Oh wow, do you have the manual transmission?

Any chance you would be willing to upload any proof of replacement? I have a feeling they're going to brush this issue off at the service center.

Did you experience exactly what I was experiencing in 2nd gear? The car would jerk forward really hard?

Edit - I know that might have sounded weird, what I meant is any type of documentation that discusses the replacement. It's not like I don't believe you lol.

Thank you btw.

[Bret]

I’m definitely curious to find out what the root cause of this is. I don’t see how turning off rev matching would help unless the problem can be readily duplicated in which case turning off rev matching would let you know if it was related to it being on or not. I think the biggest obstacle is going to be duplicating the issue for the service technician. Things like this can be a pain because they’ll want to assume that you don’t know how to drive a manual transmission car.

[SteweC]

Originally Posted by Bret

I’m definitely curious to find out what the root cause of this is. I don’t see how turning off rev matching would help unless the problem can be readily duplicated in which case turning off rev matching would let you know if it was related to it being on or not. I think the biggest obstacle is going to be duplicating the issue for the service technician. Things like this can be a pain because they’ll want to assume that you don’t know how to drive a manual transmission car.

That would be a pretty bad argument coming from them. Even if you were absolutely horrible at driving manual, nothing like that should happen. It's also not possible to replicate, so if it was driver error, you really should be able to replicate that driver error.

Abuse can't even be a reason either in my opinion. I've been following break-in, but even if I dumped the clutch at every green light for 800 miles, the car should still be fine.

I took my drivers license test in a manual transmission lol. I'm 28 now. The instructor 11 years ago said she hasn't seen someone do that in years.

[clutchdj]

Originally Posted by SteweC

That would be a pretty bad argument coming from them. Even if you were absolutely horrible at driving manual, nothing like that should happen. It's also not possible to replicate, so if it was driver error, you really should be able to replicate that driver error.

Abuse can't even be a reason either in my opinion. I've been following break-in, but even if I dumped the clutch at every green light for 800 miles, the car should still be fine.

I took my drivers license test in a manual transmission lol. I'm 28 now. The instructor 11 years ago said she hasn't seen someone do that in years.

turn rev matching off and heel toe downshift. if you can't duplicate the problem, maybe the auto rev match is part of the problem.

[robopp]

Originally Posted by SteweC

Oh wow, do you have the manual transmission?

Any chance you would be willing to upload any proof of replacement? I have a feeling they're going to brush this issue off at the service center.

Did you experience exactly what I was experiencing in 2nd gear? The car would jerk forward really hard?

Edit - I know that might have sounded weird, what I meant is any type of documentation that discusses the replacement. It's not like I don't believe you lol.

Thank you btw.

Your issue is that the dealer will either need to find a code or reproduce the issue. Without one or both of these things they can’t do anything. Try to figure out what causes the issue to happen, or take a video of it happening. You and the dealer are on the same side vs BMW.

[Cgdigisco]

So I’ve had an issue when downshifting into second gear, where the car doesn’t rematch. When I left off the clutch the RPMS cause the car to lurch forward, and it can happen without warning.

I haven't been able to recreate it, but I can confirm I’ve dealt with something similar.

If I have to guess, it’s shifting into second gear when you are going too slow (you not direct at you specifically).

[SteweC]

Originally Posted by Cgdigisco

So I’ve had an issue when downshifting into second gear, where the car doesn’t rematch. When I left off the clutch the RPMS cause the car to lurch forward, and it can happen without warning.

I haven't been able to recreate it, but I can confirm I’ve dealt with something similar.

If I have to guess, it’s shifting into second gear when you are going too slow (you not direct at you specifically).

I have considered this, but the problem is that it's too violent to simply be a lack of rev matching in my mind.

If you downshift without a rev match, that wouldn't lock the tires up for a second.

Are you saying that you've experienced something similar in terms of chirping the tires and throwing you forward?

[Cgdigisco]

Originally Posted by SteweC

I have considered this, but the problem is that it's too violent to simply be a lack of rev matching in my mind.

If you downshift without a rev match, that wouldn't lock the tires up for a second.

Are you saying that you've experienced something similar in terms of chirping the tires and throwing you forward?

Ah I see, no I haven’t experienced that. Just an issue a few times downshifting into second gear.

[KC87ZB]

Actually this can happen, in your situation it should not.

If you shift down multiple gears at once and drop the clutch, the engine braking can cause the rear wheels to lock. On the M2 I'm not sure you could break traction but fundamentally this is possible and I have done it - again, not in the M2.

ABS will not prevent rear wheels from locking up unless you are applying the brakes, and this sounds like a clutch/transmission issue not a braking issue.

I do hear what you are saying but I would have to agree that first impressions are this is driver error, although I am going to buy into you know what you are doing.

Without revmatch on I don't know if even dumping the clutch on a 3-2 downshift would chirp the tires at 20 mph - not sure I want to try.

Faulty sensor of some kind, shift position, throttle position, parking brake, .. I would be curious if your parking brake is engaging for a moment.

This is a weird one - maybe ghosts.

EDIT: I wonder if , going downhill, the car is activating the emergency braking

[kyrix1st]

First time driving a manual?

There's very little that can go wrong with 6MT other than due to a mechanical defect(s) from the factory or an issue with auto rev match function. This sounds like you are either 1) letting the clutch out too slowly with the rev match off or 2) too fast with the rev match on. In either case, your downshift rpm is likely not where it should be by the time you release the clutch, hence the tire chirping from trying to match the difference in rotation of the drivetrain.

If you are an experienced AND good MT driver, I would bet on the latter since these cars come with CDV, which does mess up one's clutch release timing.

EDIT: This time I actually read the OP. I think you are letting the clutch out too slowly, because downhill will make the drivetrain rotate faster than it would on a flat surface, requiring higher rpm than that of when you initiated a downshift. That may explain why the car lurches forward every time you downshift in downhill conditions.

[Del33]

6MT driver here and I do not experience anything like what OP is going through. 2nd gear doing 20mph is right around 2k rpms. Even if you downshifted to 2nd going 30mph, that still leaves you with a few thousand rpms more to go before I would think that the rear wheels would lock up. Even when guys misshift, they don't usually lock the wheels and just rev really high and bend valves. It really doesn't make much sense what the OP is experiencing but I'm curious to hear what they find. If it was a sensor issue with the auto rev match system, I would think that the engine just wouldn't rev match,, not lock up the rear wheels. But I'm no BMW tech. Keep us posted on your findings OP.

[Dave07997S]

Originally Posted by SteweC

Appreciate that.

If you don't mind, next time you're in your 6MT, let me know if you can move your shifter in 2nd gear and it will stick where you move it to. Hard to explain, but I have a ton of play in 2nd gear while it's still in gear, and it will stay there. I can't do that in any other gear.

I tried it today, I couldn't replicate it.

[islandfalconer]

Originally Posted by SteweC

Oh wow, do you have the manual transmission?

Any chance you would be willing to upload any proof of replacement? I have a feeling they're going to brush this issue off at the service center.

Did you experience exactly what I was experiencing in 2nd gear? The car would jerk forward really hard?

Edit - I know that might have sounded weird, what I meant is any type of documentation that discusses the replacement. It's not like I don't believe you lol.

Thank you btw.

I think I have the Warranty Invoice. But yes it is a Six Speed, and it jerked and I almost ran in to a car. It definitely sounds the same as mine. It hit worse and than it was in every even gear 2/4/6