High RPM 1st to 2nd gear grind

[Rupes]

Why is this happening? Been driving a stick for almost 20 years. I occasionally grind going into second under spirited driving. I can't seem to duplicate it, but it happens every so often. Thoughts?

[smmmurf]

Assuming the clutch is fully pushed in when you hear the grind, the issue is the synchronizers cannot keep up with the speed at which the car is being asked to go into gear.

Both scenarios have the same practical solution, apply less/slower force as you move the car from Neutral-Left (the position in between the 1-2 gates) to the 2nd gear position. Allow the synchro to do its work. When ready, the gear falls into place with light effort.

There is a difference between quick and smooth and quick and rough shifting. It is very difficult to communicate the difference between the two over the Internet.

Note, grinding gets worse as synchros wear/age. Eventually, the transmission will grind at lower and lower RPM's holding shift speed/technique constant.

Either way, the solution to stop it from grinding is still the same from a driving perspective (slower shifts and/or lower RPM). Mechanical remedies include changing transmission fluid (should be done every ~30K according to BMW) and/or replacing the synchro (requires transmission coming out).

[jphughan]

Performing a 1>2 shift at high RPM on this car creates significant resistance from the synchros. You need to be gentle on that shift, wait while the shifter stops briefly about halfway into the gate until the synchro resistance drops, and then the shifter will nicely slide into 2nd. Do NOT attempt to overcome that resistance by simply pulling harder.

[Yoddha]

Originally Posted by jphughan

Performing a 1>2 shift at high RPM on this car creates significant resistance from the synchros. You need to be gentle on that shift, wait while the shifter stops briefly about halfway into the gate until the synchro resistance drops, and then the shifter will nicely slide into 2nd. Do NOT attempt to overcome that resistance by simply pulling harder.

I'm having the same trouble, could you please clarify your explanation. Cheers

[GVIFlyer]

Good information. The last two M3s I've had were equipped with the DCT, the one before it a SMG. In the manuals I've owned, to include my current Honda S2000, I've always pulled power shifts when straight line racing. I had no idea that this wasn't a good idea in the M3.

[jphughan]

Originally Posted by M__3__R__A__G__E

I'm having the same trouble, could you please clarify your explanation. Cheers

What part needs to be clarified? Just don't try to force the shifter into gear by adding more force, instead wait until it simply slides into gear. If you still grind, the damage has probably already been done.

[jphughan]

Originally Posted by GVFlyer

Good information. The last two M3s I've had were equipped with the DCT, the one before it a SMG. In the manuals I've owned, to include my current Honda S2000, I've always pulled power shifts when straight line racing. I had no idea that this wasn't a good idea in the M3.

Arguably it's not a good idea on any car. It just seems that the gear ratios on this car plus the engine's wide rev range make it especially difficult and therefore especially damaging if you try to do it anyway. Neither the M3's manual transmission nor overall driveline is built for drag racing, so expect some hefty repair bills if you regularly try to use it that way. If you want a drag racer, buy a muscle car.

And there's no need to power shift on 1>2 anyway. The engine will still be in its power band when you engage 2nd without the need for you to keep your foot on the throttle during the shift.

[SenorFunkyPants]

Its worth noting that even if you had no syncromesh left at all you should still be able to shift without grinding the gear teeth....as long as you get the timing right.

[Candide13]

Originally Posted by GVFlyer

Good information. The last two M3s I've had were equipped with the DCT, the one before it a SMG. In the manuals I've owned, to include my current Honda S2000, I've always pulled power shifts when straight line racing. I had no idea that this wasn't a good idea in the M3.

Sounds like about the worst thing you could do to the M. Seriously though, I think the M-engineers spend zero effort on the 1-2 shift, which is irrelevant for track racing. My personal advice is to get into 2nd early and smoothly and take it from there, much more rewarding with this kind of car.

[marksae]

I recently switched tranny fluid from OEM to Royal Purple. My 1-2 shift at redline is much improved! I never try to force the shifter into gear. With the OEM fluid, sometimes it would feel like 2nd gear is blocked when shifting at redline. With Royal Purple, I can now at least feel confident that the shifter will go into 2nd gear each time. It still goes into with a lot of resistance though. It definitely ain't no S2000!

[italyix]

1-> 2 gear grind at high RPM = syncros toasted. Here is what I did:

1. Complain to dealership (if under warranty) of said problem, they will schedule a test drive with foreman
2. Foreman will drive your car (with you inside) and assess if said grind occurs as well as assessing if gears are hard to engage
3. If step 2 is validated, you get a new transmission

That's what happened to me

[Rupes]

Originally Posted by italyix

1-> 2 gear grind at high RPM = syncros toasted. Here is what I did:

1. Complain to dealership (if under warranty) of said problem, they will schedule a test drive with foreman
2. Foreman will drive your car (with you inside) and assess if said grind occurs as well as assessing if gears are hard to engage
3. If step 2 is validated, you get a new transmission

That's what happened to me

Did this happen consistently? I get mine about once out of 10 or 20 fast shifts.

[bimdo]

Originally Posted by italyix

1-> 2 gear grind at high RPM = syncros toasted. Here is what I did:

1. Complain to dealership (if under warranty) of said problem, they will schedule a test drive with foreman
2. Foreman will drive your car (with you inside) and assess if said grind occurs as well as assessing if gears are hard to engage
3. If step 2 is validated, you get a new transmission

That's what happened to me

i went through a similar process,and also got a new trans under warranty with surprisingly little resistance from bmw.it was difficult on pretty much every 1-2 shift.

[s85e90]

Although these cars aren't the smoothest at high RPM shifting (specifically the 1-2 shift) if it's happening more often it's probaly the syncros

[s85e90]

Originally Posted by marksae

I recently switched tranny fluid from OEM to Royal Purple. My 1-2 shift at redline is much improved! I never try to force the shifter into gear. With the OEM fluid, sometimes it would feel like 2nd gear is blocked when shifting at redline. With Royal Purple, I can now at least feel confident that the shifter will go into 2nd gear each time. It still goes into with a lot of resistance though. It definitely ain't no S2000!

The Royal Purple makes it shift like butter!

[italyix]

Originally Posted by Rupes

Did this happen consistently? I get mine about once out of 10 or 20 fast shifts.

Consistently. I would have had to wait a few seconds in order not to grind and the shift was hard to engage as well.

[V1.47fan]

Originally Posted by Candide13

Sounds like about the worst thing you could do to the M. Seriously though, I think the M-engineers spend zero effort on the 1-2 shift, which is irrelevant for track racing. My personal advice is to get into 2nd early and smoothly and take it from there, much more rewarding with this kind of car.

Makes sense, lol shift early on a high revving engine with no low end torque. Much more rewarding to shift like a Grandma.

[Goat Rodeo]

I had a 2011 E92 M3 6MT that I drove for 25K miles. I never had an issue with a grind 1-2 and I shifted at or near redline often.

My 2013 is doing this often.. really nasty grind on 1-2 w/ high revs, and not even near redline.. and actually pops forcefully out of 2nd gear, leaving me feeling like an idiot as the car falls flat on its face!

Will take it in and see what the dealer says.

[Yoddha]

Originally Posted by s85e90

The Royal Purple makes it shift like butter!

Will using a different transmission fluid (or any fluid for that matter that isn't OEM) void your warranty?

[Wizegi///M3]

This same exact thing was happening to me and BMW replaced my transmission. I bought my M3 used, so no idea how the previous owner was shifting. Car had 18k on the ODO when it was replaced.

Been perfect every since.

[chris719]

It happens because BMW has gone cheap on the 6MT on the E46 M3, Z4M, and E9x M3. All three shift poorly into 2nd. Now, if you look at the marketing material for the F8x they have claim to have upgraded the synchros for "improved shift comfort" and "precision". Too bad you cant retrofit a 1M gearbox, that gearbox is the same as in the new M3 supposedly.

[MikeD]

Originally Posted by M__3__R__A__G__E

Will using a different transmission fluid (or any fluid for that matter that isn't OEM) void your warranty?

They can use any reason to void your warranty.

You're looking for MT fluids with proper friction additives. I think most high performance MT fluids have them, including OEM. The final issue is how long the fluid would last? the high performance ones may last longer. Ultimately it's really changing the fluid at 30k intervals that really matter, not the fluid.