335i - DCT maintenance

[shotta287]

Old man's 335i cab DCT (N54) is coming up to around 85k.
Would it be a good idea to give the box a service? I know that it is sealed for life according to BMW. Is this something that a main dealer would even do if you asked them to?

[aeropilot]

As you say, BMW say its sealed for life, so how exactly will you 'give it a service' and as you say, as there is no service schedule for it, BMW won't do it.......and there aren't any service parts available for anyone else to do it......

You've already answered your own question.

[shotta287]

By service I mean transmission oil/fluid change. Similar to the VAG DSG procedures.

I know some of the BMW ZF auto boxes are also sealed for life but I have read of some people carrying out aforementioned fluid changes.

[aeropilot]

shotta287 said:

By service I mean transmission oil/fluid change.

I know BMW North America instruct dealers to refuse this even if a customer asks, don't know about UK, but I suspect likely the same.
Its not a simple procedure by all accounts, as there is no oil level check or dipstick, and overfilling causes the gearbox to 'drown' in oil, overheat and fail. There is a BMW service procedure for it though.
I've seen posts on BMW boards from indie's and owners that have trashed their DCT boxes from DIYing, as air can be easily induced into the system, and you can't can't all of the trans fluid anyway, only about 50%.

If the dealer does says yes, be prepared for a big bill.

[SebringMan]

I'd ask Driver Transmissions in Birmingham; they'd know what to do.

[aeropilot]

SebringMan said:

I'd ask Driver Transmissions in Birmingham; they'd know what to do.

I wouldn't, as from reading up, the car has to be connected to the BMW diagnostics kit during the refilling and trans sequencing process which is why DCT's have been trashed by Indie's and owners attempting the job themselves.

Not my money though, but as an ex-DCT owner, I'd leave well alone

[Wills2]

If it's not broken then don't bother trying to fix it.

[shotta287]

I know Driver Transmissions pretty well actually but will leave the 'service'.

Out of interest, is the DCT on the 335i the same as the E9x M3? I'd imagine it is but given a softer tune..

[Wills2]

Yes I believe it is but different software, the current F80 shares the F10 M5 DCT. (all are Getrag units)

I've done over 150,000 miles with MDCT, currently have done 70,000 miles in my F80 M3 it's a pretty robust box a few "ghosts in the machine" but overall very happy with them.

Edited by Wills2 on Thursday 29th March 19:22

[shotta287]

It is a brilliant gearbox, suits the N54 engine well imo. Pretty rare too considering most were the ZF autos or manuals.

Haven't experienced the newer M models but from what I've heard and read, no complaints.

[bigdom]

Find someone who specialises with Getrag gearboxes and ask them the question. BMW sealed for life is bks.

Whilst it’s not ZF, who in Germany recommend a service every 60k (and have service centres dotted all over the country), and VW every 40k on a DSG box, even in the U.K. Having rebuilt gearboxes in the past, I’d personally seek another perspective if keeping the car for a while.

[Wills2]

bigdom said:

Find someone who specialises with Getrag gearboxes and ask them the question. BMW sealed for life is bks.

Whilst it’s not ZF, who in Germany recommend a service every 60k (and have service centres dotted all over the country), and VW every 40k on a DSG box, even in the U.K. Having rebuilt gearboxes in the past, I’d personally seek another perspective if keeping the car for a while.

How many Getrag DCT boxes have failed, they have been around for 10+ years? Please show us the stats, the "bks" comes from Getrag themselves do you have a quote from them?

ZF and the BorgWarner DSG have nothing to do with the Getrag DCT, different companies, different gear boxes made to different specs.

How many miles have you done with DCT and what was your experience?

Edited by Wills2 on Thursday 29th March 22:19

[Huskyman]

Funnily enough BMW list the fluid, the filters and the sump pan for the DCT here
http://www.realoem.com/bmw/enUS/showparts?id=DX72-...
And
http://www.realoem.com/bmw/enUS/showparts?id=DX72-...

I for one cannot believe that a transmission fluid doesn’t degrade over time, and they do change it.

Edited to add and a bit off topic I almost lost a gearbox on my e90 due to this lifetime fill nonsense.

Edited by Huskyman on Friday 30th March 10:10

[shotta287]

Did some more reading and searching and I think BMW will only do a DCT flush if they've worked on the transmission for a repair etc.
Otherwise no chance of them doing it if you simply ask them.
Gearbox specialists such as Driver Transmissions would be able to do it but still a risk.

[anonymous-user]

I done a bit of reading & from what I could understand they aren't designed to be serviced. You can buy the parts for them and push comes to shove you can open, drain and refill but it'll only change 50% or so of the fluid. I guess you could do a load of fluid changes one after the other but it'll cost a fortune and you'll probably still not manage to change all the fluid.

The ZF boxes on the other hand are designed to be serviced by ZF, it's just BMW who say they're sealed for life.

[Smokey32]

The fluid is 40quid a litre and it takes 11 litres. LIke said if it aint broke don't fix it. I had mine topped up, because it was leaking, with new pan and screws, etc.

[bmwmike]

The fluid is bound to degrade over time especially in a transmission. Metal particles and condensation at least. Perhaps there is a magnet for catching debris.

The question is really over what time frame it becomes a problem and if the manufacturer of the box says it's sealed for life.. what do they mean by life.

I'd trust the box manufacturer over BMW any day.

[Sardonicus]

If its a wet clutch gearbox then these shed material which will contaminate the oil and ultimately clog pump strainers/filters this combined with heat cycles will degrade the oil over time and mileage , over what period who knows? example.. VAG DSG boxes for example with wet clutches are 40k miles oil and filter service make of that what you will