DCT Mechatronics starting to fail?

[Matthew_M3]

Hi forum members,

Posting this to get some feedback from others to see if they have had this issue and/or if they solved it.

Key bits of information:

99k miles
Full trans service completed at 65k miles
Currently running AlpineMSS GTS DCT tune

A few weeks ago, I notice my car was shifting oddly when cold, specifically from gears 2 into 3. Once the car got warm, there were no issues. A few days later, I was leaving my complex, making a U-turn in 1st, and halfway round the car lurched, jumped into 2nd gear, and gave me a transmission malfunction. I only had access to the even # gears. Reset the car and malfunction went away, car worked as normal. Booked an appointment with MRF to have him investigate. Trans fluid was not low on fluid at and Adaptations were reset. In the days after, the car still has the issue, doesn’t feel as sever as before, but I had some “hiccuping” in the teams when warm, at speed. Unfortunately I haven’t paid close enough attention at the times it happened to document the specifcs (what gear, speed, etc

Malek @ MRF has advised that I remove the GTS DCT tune and see if the issue persists afterwards, so that is my next course of action. Will post my findings afterwards. If it doesn’t rectify, then a trans replacement might be down the road.

Just wanted to see if anyone had similar issues and what they found it to be

Thanks,

Matt

[mikerunt]

When my mechatronics failed I lost full power mid turn 9 at Big Willow. No other warning signs- just completely lost all “go”.

[Starboy]

Welcome to the club ... of mechatronics failures

Symptoms are similar- been driving normally, and a few more aggressive shifts would trigger the transmission error code, and odd/even # of gears would be gone. In my case I lost reverse too.

Either you'd have to swap for a new/used transmission or at least replace the mechatronics.


Some evidence I've found:

Mechatronic Problem
If you read the codes, you may get fault codes related to the valve body also known as the BMW mechatronic. BMW ZF mechatronic are notorious for problems with 2 to 1 st gear downshift or shift flare during the upshift. These harsh upshifts and downshifts are often due to a TTC clutch failure, overheating, damaged solenoid, worn solenoid springs and other problems with the mechatronic unit.
If you checked everything above but are still having problems with your BMW transmission the cause most likely is the mechatronic unit. If you are looking to save money, you can consider replacing only the solenoids in the mechatronics unit/valve body. If you decide to replace the solenoids yourself, remember to change the foam strip that goes between the solenoid terminals and connectors.


https://www.youcanic.com/bmw-transmission-problems/



Indy shop said its the Mechatronic Unit. Which comes to a total of 8k parts and labor haha ooph.

So from my research, it seems best just to replace the whole transmission right? because I've read where people in the same spot as me, replace the Mechatronic, and still the problem persisted.



https://www.m3post.com/forums/showthread.php?t=1957220

[Honda]

Alot of people who had GTS DCT tune complained about this failure...

[Helmsman]

Originally Posted by mikerunt

When my mechatronics failed I lost full power mid turn 9 at Big Willow. No other warning signs- just completely lost all “go”.

Originally Posted by Starboy

Welcome to the club ... of mechatronics failures

Symptoms are similar- been driving normally, and a few more aggressive shifts would trigger the transmission error code, and odd/even # of gears would be gone. In my case I lost reverse too.

Either you'd have to swap for a new/used transmission or at least replace the mechatronics.


Some evidence I've found:

Mechatronic Problem
If you read the codes, you may get fault codes related to the valve body also known as the BMW mechatronic. BMW ZF mechatronic are notorious for problems with 2 to 1 st gear downshift or shift flare during the upshift. These harsh upshifts and downshifts are often due to a TTC clutch failure, overheating, damaged solenoid, worn solenoid springs and other problems with the mechatronic unit.
If you checked everything above but are still having problems with your BMW transmission the cause most likely is the mechatronic unit. If you are looking to save money, you can consider replacing only the solenoids in the mechatronics unit/valve body. If you decide to replace the solenoids yourself, remember to change the foam strip that goes between the solenoid terminals and connectors.


https://www.youcanic.com/bmw-transmission-problems/



Indy shop said its the Mechatronic Unit. Which comes to a total of 8k parts and labor haha ooph.

So from my research, it seems best just to replace the whole transmission right? because I've read where people in the same spot as me, replace the Mechatronic, and still the problem persisted.



https://www.m3post.com/forums/showthread.php?t=1957220

You guys had a DCT tune?

[bipp]

Originally Posted by Helmsman

You guys had a DCT tune?

I had some "GTS" tune the shop put on. Not sure if it was the OEM DCT tune or an "aftermarket" one.

Starboy - hesitantly, I want to say it should not cost $8k - not sure if this is USD or RMB (looking at your location). Even at a fairly expensive local shop (because of labor rates in my area lol) I paid around $7k for my fix (add $2400 + tax for the used DCT I got). For me, the math did not make sense to try and repair my transmission rather than to just replace it with an used unit based on labor costs.



These were the codes I had at the time my mechatronics failed (5A62 and 5A63, for any future people searching):

[Starboy]

Originally Posted by Helmsman

You guys had a DCT tune?

I haven't had any tune on it, completely stock, never tracked (but was aggressively driven in the mountain roads frequently, for at least 10k miles in the last two years)

Guess the combination of extensive manual mode usage & defect in the mechatronics will shorten the DCT lifespan

[Starboy]

Originally Posted by bipp

I had some "GTS" tune the shop put on. Not sure if it was the OEM DCT tune or an "aftermarket" one.

Starboy - hesitantly, I want to say it should not cost $8k - not sure if this is USD or RMB (looking at your location). Even at a fairly expensive local shop (because of labor rates in my area lol) I paid around $7k for my fix (add $2400 + tax for the used DCT I got). For me, the math did not make sense to try and repair my transmission rather than to just replace it with an used unit based on labor costs.



These were the codes I had at the time my mechatronics failed (5A62 and 5A63, for any future people searching):

Oh sorry the $8k was from Saint_M3 when he mentioned he's got a quote from his local indy shop for the Mechatronic unit, presumably in the Washington area back in 2022.


Asked my dealership for parts and they gave me crazy numbers like:
$6.8k for a new mechatronic unit
$22k for a new DCT trans
$0.6k for labor (lol)


But if I go for a used transmission (including mechatronic) it'll cost $2k with labor, so it really doesn't make sense to repair, should just go for a used one.



For records, I lost rod 5/7, error code: 5A6D

[mikerunt]

Originally Posted by Helmsman

You guys had a DCT tune?

I did yes

[Helmsman]

Originally Posted by mikerunt

I did yes

Thanks. Have you reason to believe that the tune have contributed to the issues?

[mikerunt]

Originally Posted by Helmsman

Thanks. Have you reason to believe that the tune have contributed to the issues?

To be honest - no idea. My car did sit for a little before I took ownership so I’m chalking it up to dried seals…not really sure.

I will say I have yet to put any tune on my trans since replacing the mechatronics and so far have had zero issues.

[bipp]

Originally Posted by mikerunt

To be honest - no idea. My car did sit for a little before I took ownership so I’m chalking it up to dried seals…not really sure.

I will say I have yet to put any tune on my trans since replacing the mechatronics and so far have had zero issues.

Same here. Took the car to Laguna this past weekend and had no problems thrashing it both days on the OEM tune. I will note that I did have the bimmerworld banjo installed for a bit more fluid. previously, everything was stock. I don't run Hoosiers / aero like mikerunt's car, and mine went kaput when running on endurance 200s at Thunderhill. Maybe it was a temp issue since it was 100+ out, but doubtful that it was a fluid pressure issue. I did not get laggy shifts like other people did when their unit before it went out.

edit: if you flash with the Euro DCT tune, I doubt we can blame the tune. if you flash with the OEM GTS tune - well, the DCT itself is the same unit, albeit the GTS has more fluid and possibly better cooling. with coolers and the overfill banjo or an aftermarket pan, I don't see why the car can't run the OEM GTS tune. I plan on going for the Euro DCT tune in the future.

[Matthew_M3]

Appreciate the response and dialogue here so far.

AFAIK, there are DCT differences between the regular and GTS cars in terms of their internals. I was told by Malek that the internals on the GTS DCTs are beefed up to accommodate the increased aggression of the gearshifts.

I’m assuming that, even though the software works on our cars, it does increase the amount of strain on internals of the transmission.

I’m still waiting on a response from Alex to get it reprogrammed to stock so I can test further. So far the car is running mostly fine, still a bit touchy when cold though.

[Redd]

9+ yrs, 92k kms on Alpine GTS tune and zero issues. I do change my DCT fluid every 20k kms / 2 years tho. Mechatronic valves/solenoids are extremely small and can get clogged by dirt. Having fresh clean fluid is important to keep them happy and healthy.

Afaik the GTS DCT is internally and externally the same as non-GTS M3. Only the tune and banjo fill bolt are different.

[Helmsman]

Originally Posted by Redd

9+ yrs, 92k kms on Alpine GTS tune and zero issues. I do change my DCT fluid every 20k kms / 2 years tho. Mechatronic valves/solenoids are extremely small and can get clogged by dirt. Having fresh clean fluid is important to keep them happy and healthy.

Afaik the GTS DCT is internally and externally the same as non-GTS M3. Only the tune and banjo fill bolt are different.

Ordered Alex tune incl DCT (finally, after you talked me in to it.... After I had the DCT sorted I don't have much more to wish for but probably load the tune for the fun of it. Doubt I leave it on for ever tho, too many tuned-DCT-issue threads flying around...