[ae4007]

I have a 13' N55 6 speed, and recently my second gear has been grinding really bad when you downshift and upshift into it at RPM's higher than 4k. I took it to the dealership and they said I need a new transmission. Luckily I have CPO and it's being covered.

This is my second BMW transmission I have problems with. My previous car was an E60 545i 6 speed as well, and third gear would grind really bad.

Is this a common problem on BMW manual transmissions? Anyone else have this problem?

[donkey]

How many miles were you at when it started grinding?

I have heard of this problem before but so far my transmission is as smooth as butter.

[Bbb34]

Originally Posted by ae4007

Is this a common problem on BMW manual transmissions? Anyone else have this problem?

More info in these two threads.

http://f30.bimmerpost.com/forums/sho....php?t=1308545

http://f30.bimmerpost.com/forums/sho....php?t=1028795

[floydarogers]

Originally Posted by ae4007

...Is this a common problem on BMW manual transmissions? Anyone else have this problem?

It's very common, especially for 2nd, for the synchros to wear and eventually giving some problems. But usually not so bad that the transmission needs rebuilding (or replacing).

Look, clutches wear out. Synchros are clutches; they wear out. Frankly, your driving style or technique probably has something to do with it, too. Do you rev-match? You didn't say, but if you don't you need to learn to do so. Notice that some newer BMWs do it for you (except in Sport mode!) ...

[Carbon.F30]

Originally Posted by ae4007

I have a 13' N55 6 speed, and recently my second gear has been grinding really bad when you downshift and upshift into it at RPM's higher than 4k. I took it to the dealership and they said I need a new transmission. Luckily I have CPO and it's being covered.

This is my second BMW transmission I have problems with. My previous car was an E60 545i 6 speed as well, and third gear would grind really bad.

Is this a common problem on BMW manual transmissions? Anyone else have this problem?

I had the exact same problem when I purchased my F30 335i. The gear would grind every time I went into second, although I had the clutch to the floor, and quite commonly it also happen going into first and third. This was an issue when I test drove the car and so they agreed to replace the transmission (which was under both warranty and CPO anyway).

Anyway, seems like it is a relatively common issue, and I don't think it's just with BMW. A friend of mine has a 2015 VW GTI and he also had the same issue. Turns out for him the synchro was bad. It's a similar issue with the manual gearbox.

I might be a little off topic here and I'm not sure if it is true, but I hear if you have spacers, or are considering putting them on, those can also cause issues with the x-drive/transmission? Can someone clarify that? I think my car might have spacers (the rear wheels sit flush with the body, rather than being tucked into the wheel wells), but this is only with my summer tires. My winters still sit tucked into the wheel well. If the car does have spacers then I don't want to be back in the shop after CPO expires with the same issue.

[lkstaack]

I purchased my 2014 335i 6-speed used with 31k miles. My SA couldn't pull up service records on it, but my parts guy could (don't know why). Parts said that my car had a new transmission installed at 25k miles. I wish I knew why.

I also found that my steering wheel was replaced at 11K miles and replaced again along with horns at 15k miles. I wish I knew why.

[ae4007]

Originally Posted by drive335

How many miles were you at when it started grinding?

I have heard of this problem before but so far my transmission is as smooth as butter.

I noticed is somewhere around 48k miles but it happened so rare I thought it was just me messing up. It didn't start doing everytime until now 10k miles later

[ae4007]

Originally Posted by floydarogers

It's very common, especially for 2nd, for the synchros to wear and eventually giving some problems. But usually not so bad that the transmission needs rebuilding (or replacing).

Look, clutches wear out. Synchros are clutches; they wear out. Frankly, your driving style or technique probably has something to do with it, too. Do you rev-match? You didn't say, but if you don't you need to learn to do so. Notice that some newer BMWs do it for you (except in Sport mode!) ...

All my cars have been manual except one and I have driven them all for over 100k miles and only the E60 and F30 gave me problems so I don't think it is my technique. I don't drive my cars hard on the daily, I do some spirited driving maybe 2-3 times a month. I do know how to rev match but I didn't think it would be necessary for normal driving. Maybe it is just my bad luck. Glad I have that CPO warranty though.

[ae4007]

Originally Posted by nrajput

I had the exact same problem when I purchased my F30 335i. The gear would grind every time I went into second, although I had the clutch to the floor, and quite commonly it also happen going into first and third. This was an issue when I test drove the car and so they agreed to replace the transmission (which was under both warranty and CPO anyway).

Anyway, seems like it is a relatively common issue, and I don't think it's just with BMW. A friend of mine has a 2015 VW GTI and he also had the same issue. Turns out for him the synchro was bad. It's a similar issue with the manual gearbox.

I might be a little off topic here and I'm not sure if it is true, but I hear if you have spacers, or are considering putting them on, those can also cause issues with the x-drive/transmission? Can someone clarify that? I think my car might have spacers (the rear wheels sit flush with the body, rather than being tucked into the wheel wells), but this is only with my summer tires. My winters still sit tucked into the wheel well. If the car does have spacers then I don't want to be back in the shop after CPO expires with the same issue.

I heard the same rumor about spacers on AWD or X-drive cars. My car is RWD so not sure if it still affects it. Either way I don't run spacers.

[donkey]

Originally Posted by ae4007

All my cars have been manual except one and I have driven them all for over 100k miles and only the E60 and F30 gave me problems so I don't think it is my technique. I don't drive my cars hard on the daily, I do some spirited driving maybe 2-3 times a month. I do know how to rev match but I didn't think it would be necessary for normal driving. Maybe it is just my bad luck. Glad I have that CPO warranty though.

That's probably the issue - the synchros on these cars don't seem to be as strong and if you're forcing them to do all the work on every downshift I'd imagine they would wear out faster and cause the grinding you experienced.

Rev-matching and heel-toe is half the fun of driving a manual anyway

[STR8-6IX]

synchro issue, you dont need a new transmission for that.

it probably failed because of your driving style.

[Trooper99]

Is this a common problem?

[lkstaack]

Originally Posted by drive335

you're forcing them to do all the work on every downshift

That's what they are designed to do. Double-clutching is a thing of the past.

[donkey]

Originally Posted by lkstaack

That's what they are designed to do. Double-clutching is a thing of the past.

There's a difference between double-clutching and rev-matching.

Also, if that's what they were designed to do, why did they add rev-matching for the LCI/340i?

[lkstaack]

Originally Posted by drive335

There's a difference between double-clutching and rev-matching.

Also, if that's what they were designed to do, why did they add rev-matching for the LCI/340i?

Whatever. You don't have to do either with a proper BMW transmission.

[donkey]

Originally Posted by lkstaack

Whatever. You don't have to do either with a proper BMW transmission.

Way to avoid the question. Again if it wasn't important BMW (and many other manufacturers) wouldn't have added auto rev-matching.

Remember this thread? Why would you want that feature if it's useless?
http://f30.bimmerpost.com/forums/sho...4#post21249604

Yes you can get away with not rev matching by letting the clutch out like a granny and making the synchros do it. No that's not the only or best way to do it.

If you're good at rev matching you don't even have to think about it

[AudiA4]

Originally Posted by lkstaack

That's what they are designed to do. Double-clutching is a thing of the past.

THIS!!! ^^^ A thousand times this.

Rev matching is not necessary on modern transmissions. It's like arguing you should rewind your DVD.

[donkey]

Originally Posted by AudiA4

THIS!!! ^^^ A thousand times this.

Rev matching is not necessary on modern transmissions. It's like arguing you should rewind your DVD.

Then why did BMW add auto rev-matching for the LCI?

Didn't your transmission also have the 1-2 grind and need to be replaced?

[AudiA4]

Originally Posted by drive335

Then why did BMW add rev-matching?

Didn't your transmission also have the 1-2 grind and need to be replaced?

Yes, but from the previous owner. I noticed it driving it home from purchase.

The synchros are a known weakness in the F30 transmission. I drove 3 manuals before my purchase, and 2 of them had bad synchros.

Every car I've ever driven has been a manual, and never have the synchros been a problem.

p.s. They added rev matching for the SAME reason people learn to do it heel-and-toe...so as not to upset the chassis mid-corner during performance driving (or even casual driving), NOT in order to save wear on synchros.

[donkey]

Originally Posted by AudiA4

Yes, but from the previous owner. I noticed it driving it home from purchase.

The synchros are a known weakness in the F30 transmission. I drove 3 manuals before my purchase, and 2 of them had bad synchros.

Every car I've ever driven has been a manual, and never have the synchros been a problem.

p.s. They added rev matching for the SAME reason people learn to do it heel-and-toe...so as not to upset the chassis mid-corner during performance driving (or even casual driving), NOT in order to save wear on synchros.

I can agree with that - that the primary purpose of the rev-match feature was not to save wear on the synchros but to prevent the chassis from getting upset and to prevent drivetrain shock when downshifting, even in a straight line.

Yes you can use the synchros to downshift by letting the clutch out slower. But a rev match will be faster if done properly and allows you to get back on the gas quicker (since you're not on the clutch).

If the synchros are a known weak point for F30's - I would even go as far to say that it MIGHT be possible that using them more would make any potential flaws noticeable sooner. Or any drivetrain shock from an incorrect downshift without rev matching (i.e. the clutch was dumped too soon causing a shock) could mess them up more than a synchro that doesn't have these issues.

That last part is just a guess - but there's no denying that rev matching in general can be useful for these cars.

[AudiA4]

Originally Posted by STR8-6IX

synchro issue, you dont need a new transmission for that.

it probably failed because of your driving style.

According to BMW you do. BMW will not let the dealer open up the transmission case. If any part is bad, it's a complete transmission swap and the dealer sends the bad transmission back to BMW (presumably for them to study and/or rebuild).

[floydarogers]

Originally Posted by AudiA4

...
The synchros are a known weakness in the F30 transmission. I drove 3 manuals before my purchase, and 2 of them had bad synchros.
...

Every MT BMW I've ever had, from the 78 E21 & E12 to my E34 and E46, have had 2nd gear synchros that eventually get stiff. The 1->2 and 2->3 (and back down) gearshifts are the most used shifts. Often, the engine speed differences between them are the most, too. Both contribute to more wear.