[B_Rice]

Originally Posted by Merc for hire

I want to add to this thread also. I too have this second gear grinding issue when shifting from 1st to 2nd gear at 5000+ rpm.
It usually happens within 5 minutes of starting the car and less frequent as the car gets fully warmed up.
I think the clutch disengagement/engagement doesn't match the clutch pedal in real time.
I am experiencing this at the frequency about once a day now.

This gearbox also has problem downshifting to 2nd rapidly due to the reverse gear gate getting in the way.

This car will be returned after lease is over. I am done with BMW manual gearbox, my old E46 manual transmission did not have any of these issues.

You rev your engine that high when the car isn't warmed up?

[Pparana]

Originally Posted by Legal Bill

This is a disappointing read. Does anyone know if there has been a specific redesign for the synchros, and if so, when it went into effect?

FWIW, other manufacturers have encountered this problem. They discovered that the fluid used in the tranny can help. So, while I'm sure it is not an approved fluid for BMWs, something like GM Friction Modified Synchromesh or the "reformulated" Honda tranny fluid may clear this problem right up. Both manufacturers had problems with synchros and both came out with "new" tranny fluids:

http://www.amazon.com/88900399-Synch.../dp/B00BK7M2VW

http://www.amazon.com/Genuine-Honda-.../dp/B001IWL1O8

The friction modified fluids are actually LESS slippery than typical transmission oils. Thus, the synchro can grab sooner and get up to speed faster. I had the second gear grind in my Honda S2000. The different fluid pretty much made it go away.

I use redline MTL oil, the stock oil is very thin. It seemed to help,but needs to warm up as well, and your still not taking any fast downshifts to 2nd. I really do not have many instances where I need to downshift to 2nd fast or from 1st to 2nd fast.

The cdv valve is annoying. I think that is what most people are feeling, as there is a delay in release from when you come off the pedal. It seems as if the main goal is to penalize people who know how to drive a manual.

[ocN55]

Originally Posted by Pparana

I use redline MTL oil, the stock oil is very thin. It seemed to help,but needs to warm up as well, and your still not taking any fast downshifts to 2nd. I really do not have many instances where I need to downshift to 2nd fast or from 1st to 2nd fast.

The cdv valve is annoying. I think that is what most people are feeling, as there is a delay in release from when you come off the pedal. It seems as if the main goal is to penalize people who know how to drive a manual.

Seriously, the CDV valve drives me nuts!! I can feel quite well that there is a delay between what the clutch and my left foot are doing.

[Drpoomanchu]

Same here, after reading this thread it dawned on me but i have always wondered why the engagement felt odd in this car and now it all makes sense. I have gotten used to it but almost seems like im predicting engagment at times and not driving the car subconsciously. I feel like im always thinking about the shiftpoints and disengaging and engaging of the clutch something ive never done with any other manual.

[Drpoomanchu]

Originally Posted by Pparana

I use redline MTL oil, the stock oil is very thin. It seemed to help,but needs to warm up as well, and your still not taking any fast downshifts to 2nd. I really do not have many instances where I need to downshift to 2nd fast or from 1st to 2nd fast.

The cdv valve is annoying. I think that is what most people are feeling, as there is a delay in release from when you come off the pedal. It seems as if the main goal is to penalize people who know how to drive a manual.

This is also known as a Liberal or Socialist CDV...

[BMW335iOn18s]

Also, the fact that the engine/trans mounts are soft is only making the issue worse, adding to the "delayed" or "imprecise" feeling. Theoretically upgrading the mounts should help but I haven't found any aftermarket solutions. I am curious to know whether the M2 has stiffer mounts....it probably does and they would most likely be a nice upgrade for our cars.

[XutvJet]

I've owned my M235 6MT since early February. Shortly after getting the car, I made my own "clutch pedal stop" with a piece of 1/4" high durometer foam and 3M tape. I've been driving manuals since 1993 and found the clutch engagement on the M235 to be off at times, specifically starting in 1st and the 1-2 shift. It's like the engagement point moves around a bit. Basically I could occasionally be a abrupt when leaving in 1st or on the 1-2 shift. I found this annoying and a bit ego shattering considering how long I owned and competitively raced manual transmission cars.

After learning a bit more about how these CDVs work and most importantly, BMW's clutch system design that maintains the engagement in the same overall area as the clutch wears, last week I decided to remove my clutch stop and see if there was a change. To my amazement, it's far easier to modulate the clutch and I'm smooth all the time. Yes, the OEM clutch travel is a bit excessive, but it makes for much easier and consistent modulation. Given this, I do have doubts about the overall effectiveness of the clutch stop and it's operation in relationship to BMW's clutch system design. I can also see how even just a 3/8" thick clutch stop could potentially negatively effect the life of the clutch assembly.

[XutvJet]

Originally Posted by BMW335iOn18s

Also, the fact that the engine/trans mounts are soft is only making the issue worse, adding to the "delayed" or "imprecise" feeling. Theoretically upgrading the mounts should help but I haven't found any aftermarket solutions. I am curious to know whether the M2 has stiffer mounts....it probably does and they would most likely be a nice upgrade for our cars.

I don't find the mounts to be bad at all. Plus there's a negative tradeoff in NVH when going with stiffer mounts. I've learned that racecar parts are best served to remain on racecars.

[BMW335iOn18s]

Originally Posted by XutvJet

I don't find the mounts to be bad at all. Plus there's a negative tradeoff in NVH when going with stiffer mounts. I've learned that racecar parts are best served to remain on racecars.

I agree with you, but I think the M2/3/4 mounts should make a nice upgrade. The stock mounts really are too sloppy. I've learned how to circumvent this with my left foots muscle memory, but I'd still like stiffer mounts. Honestly once the m240i comes out with rev matching it will be a moot point.

[Boneman]

My car goes in Monday. Driven by tech today, experienced grind with every shift above 5000 rpm from first to second. 21000 miles on car

[Liquidpaper]

Originally Posted by Boneman

My car goes in Monday. Driven by tech today, experienced grind with every shift above 5000 rpm from first to second. 21000 miles on car

My car went in today for the exact same thing. I found that you can avoid the grind if, when you throw the clutch in, you wait about .2 of a second before shifting. It's not an excuse for the grinding, but it worked while I was waiting for an appointment.

[Merc for hire]

Yea it happens all the time now for me too. Stupid problem. I will probably bring it in on next oil change.

[Liquidpaper]

Originally Posted by Merc for hire

Yea it happens all the time now for me too. Stupid problem. I will probably bring it in on next oil change.

It didn't exist when I got the car, so I have reason to believe something broke (I'm at 25k miles about, and I think I started noticing this about 6 months ago) rather than its just a design flaw.

[Wheelwright]

It will be "fun" to have clutch and transmission repaired after warranty period expires. In Canada the clutch itself (with the flywheel because it usually needs replacement too) costs $4800 CDN to replace . And the transmission soon follows because the clutch irreparably damages its synchro which manifests itself as grinding sound and sensation. I speculate a dealer or good specialist (they aren't any cheaper, I checked) will charge around $10000 CDN to replace the transmision. So there you have it: for a mere $15000 CDN you can continue "enjoying" your ultimate BMW experience. Because BMW charges Ferrari prices for parts and labour why not buy a used 360 Modena at this point ? Or take an axe to BMW piece of shit (as regards durability) and buy a Corolla for this $15000. At least in this way you won't continue throwing money down the drain with no end in sight.

[DanielGr]

I haven't looked at this - but does the M235i use a dual-mass flywheel? If so, did at any point BMW test run-out and play in the flywheel?

In my previous Renault Sport Megane (you guys don't get in US) - I had similiar issues I would say to what you describe but perhaps a bit worse. I would get issues with shifting into 1st and 2nd, especially on warmer days.

In that case - it turned out the dual-mass flywheel had failed which was causing the clutch to not disengage fully, so when you were in 1st with the clutch pedal fully in, you were still rolling forward a couple of km/h.

The failed DMF caused both the flywheel and pressure plates to have burn marks on them from slippage.

FWIW that gearbox was manufactured by Getrag, which I believe BMW also uses for its manual gearboxes?

[Liquidpaper]

Originally Posted by DanielGr

I haven't looked at this - but does the M235i use a dual-mass flywheel? If so, did at any point BMW test run-out and play in the flywheel?

In my previous Renault Sport Megane (you guys don't get in US) - I had similiar issues I would say to what you describe but perhaps a bit worse. I would get issues with shifting into 1st and 2nd, especially on warmer days.

In that case - it turned out the dual-mass flywheel had failed which was causing the clutch to not disengage fully, so when you were in 1st with the clutch pedal fully in, you were still rolling forward a couple of km/h.

The failed DMF caused both the flywheel and pressure plates to have burn marks on them from slippage.

FWIW that gearbox was manufactured by Getrag, which I believe BMW also uses for its manual gearboxes?

Getrag box for 228i and ZF box for M235i (same box as 1M).

[Wheelwright]

Originally Posted by DanielGr

I haven't looked at this - but does the M235i use a dual-mass flywheel? If so, did at any point BMW test run-out and play in the flywheel?......
The failed DMF caused both the flywheel and pressure plates to have burn marks on them from slippage.

Thanks for your feedback. And yes, M235i uses dualmass flywheel. And no, in my case they didn't test run-out and play in the flywheel. Why would they ? Getting to the bottom of it was never their priority, gouging the customer was. I did keep the flywheel though. Maybe I can still bring it to independent specialist to have run-out and play measured ? (assuming they even perform those tests).

[Merc for hire]

Originally Posted by Liquidpaper

It didn't exist when I got the car, so I have reason to believe something broke (I'm at 25k miles about, and I think I started noticing this about 6 months ago) rather than its just a design flaw.

I have only 8000km, about 5000 miles.

[Merc for hire]

Originally Posted by Wheelwright

It will be "fun" to have clutch and transmission repaired after warranty period expires. In Canada the clutch itself (with the flywheel because it usually needs replacement too) costs $4800 CDN to replace . And the transmission soon follows because the clutch irreparably damages its synchro which manifests itself as grinding sound and sensation. I speculate a dealer or good specialist (they aren't any cheaper, I checked) will charge around $10000 CDN to replace the transmision. So there you have it: for a mere $15000 CDN you can continue "enjoying" your ultimate BMW experience. Because BMW charges Ferrari prices for parts and labour why not buy a used 360 Modena at this point ? Or take an axe to BMW piece of shit (as regards durability) and buy a Corolla for this $15000. At least in this way you won't continue throwing money down the drain with no end in sight.

I agree. This gear grind issue will probably be the biggest reason why I will return this car after 2.5 more years. I can't stand an imperfect manual transmission in a car of this caliber.

I drive a lot in heavily populated part of the city and now I am scared to do a quick 1-2 shift when people are nearby.
I have been embarrassed few times already from grinding my gears loudly when people are watching and followed by pointing and laughing at my "amateur" driving skills.

[Pparana]

Originally Posted by Merc for hire

I agree. This gear grind issue will probably be the biggest reason why I will return this car after 2.5 more years. I can't stand an imperfect manual transmission in a car of this caliber.

I drive a lot in heavily populated part of the city and now I am scared to do a quick 1-2 shift when people are nearby.
I have been embarrassed few times already from grinding my gears loudly when people are watching and followed by pointing and laughing at my "amateur" driving skills.

I would also try changing the fluid to redline mtl. I will be working on modifying the cdv valve next month. I will post the results.

Mine does not grind with the mtl, a slight vibration on a fast 1/2 shift, Almost like I dumped the clutch to fast. I think it is more the cdv or the syncro design. Perhaps the thicker fluid keeps the gears better lubricated. I have zero evidence for any of this.

[Liquidpaper]

Originally Posted by Liquidpaper

My car went in today for the exact same thing. I found that you can avoid the grind if, when you throw the clutch in, you wait about .2 of a second before shifting. It's not an excuse for the grinding, but it worked while I was waiting for an appointment.

Update: They drained the oil and found metal, so they're currently on hold with BMW re: replacing the entire box or just fixing it. Don't really care so long as it gets fixed.

Just as a reminder -- my grinding was so bad that, even under no load, above 4500 rpm it would grind into second every time (even with a fairly slow shift).

My guess is that gearboxes aren't supposed to have loose metal floating around, so this sounds like it just broke, rather than it being a design defect (hopefully).

I'll update again when they let me know what they are going to do.

[Wheelwright]

Originally Posted by Liquidpaper

Update: They drained the oil and found metal, so they're currently on hold with BMW re: replacing the entire box or just fixing it. Don't really care so long as it gets fixed.........My guess is that gearboxes aren't supposed to have loose metal floating around.........

It is likely those metal shavings were produced by damaged synchro(s). According to my research and personal experience most synchros are damaged by clutch not disengaging properly (look-up: clutch dragging), very few gearboxes come from the factory with synchros already damaged or weakened.

Because of that I would strongly push them examine the clutch because if it has a disengagement problem it will keep eating synchros and therefore gearboxes. That's what was happening in my case anyway: I hope you have better luck.