Another one on transmission reliabiltiy

Discussion in 'Traction | Handling | Drivetrain' started by hassan_hamdan, Oct 9, 2017.

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  1. hassan_hamdan

    hassan_hamdan Private

    44
    135i m package
    Hey everyone, so ive been doing alot of digging around the internet the past few days trying to wrap my head around the concept of transmission reliability.
    I am currently running a 09 E82 6AT that is currently stock! I havent done any mods to it yet and I do plan on doing most of the work over the winter. I know the current Zf 6hp21 is rated for 450~ Nm. With that being said if i am planing on building first to 450 whp, then more later on, with the stock transmission hold it. Some have said it depends on how the torqe comes on, others say it will but only for a certain amount of miles before it blows. I am considering that if it is going to cost me anywhere from 4-8 grand to build up an auto transmission, then should I just consider buying one that is dct or even maunal? Basically I dont want to start modding over the winter and come the spring blow my transmission and start being myself up about it.

    Any insight would be greatly appreciated!
     
  2. R.G.

    R.G. Sergeant

    382
    Henderson, NV
    E92 N54, F02 N54
    At 450 a well maintained ZF should not be problematic at all but like anything else there are always duds out there. Swap the fluid/filter out, read up on the CORRECT adaptation procedure (not that pedal throttle adaptation non sense), be easy on it when you can be and it will be reliable.
    DCT swaps are just now coming in to their own but will be a fair chunk of change same with the 4L8. Right now IMO Propulsive re built looks to be the best option with costs factored in. Haven't had to look to far just yet. Been a fair amount above 450 for 20k on my ZF and maxed out stockers for 60k prior to that. (knock on wood)
     
  3. hassan_hamdan

    hassan_hamdan Private

    44
    135i m package
    But what about after 450? like 450 is the first goal, and I know its doable like you said, however what happens after that? The second problem that I have with rebuilding my transmission (EX Level 10) is that being in Canada our peso of a dollar is making the option to rebuild much harder, hence im wondering if I should just change to a differnt platform. Im honestly debating on selling my car and getting the same one with a manual or adding a few grand and getting a n55 with dct, since it would be easier to build that way.
     
  4. R.G.

    R.G. Sergeant

    382
    Henderson, NV
    E92 N54, F02 N54
    N54 comes with a DCT in IS trim as a quick heads up. A lot of variables and assumptions would have to be made on my part to answer that question well. I think many have asked themselves that same Q, myself included. Didn't make sense in the end for me but maybe earlier in the ownership of the car it may have.

    I will say this Hassan, after a certain amount of torque/hp, unless you're planning a straight line build, there are a lot of weaknesses in chassis that need to be addressed to handle it...properly. Just something to keep in mind. GL
     
  5. doublespaces

    doublespaces Administrator

    AZ
    2009 E93 335i
    The 6HP21 is good for 550wtq for a fairly extended use without being abused under typical circumstances. Beyond that you are significantly accelerating the deterioration of the transmission. DCT is not the move you want to make unless money is not really a problem for you. And remember the most expensive part about going to a built DCT is those clutch packs, several thousand dollars and when they wear out that is what you're looking to pay. Again. This is where a Manual transmission shines or a very durable option like the 4L80. But if you want to keep your factory driving mechanics and access to fantastic tuning software like xHP, then the Propulsive option seems to be the best route. Replacement clutch packs are also sold at a reasonable price.
     
  6. hassan_hamdan

    hassan_hamdan Private

    44
    135i m package
    Hmm interesting, and thats the dilema that im currently in, I could either spend that money on building a transmission, or swtiching my car for a newer e82 or e83 manual and then just roll with that. But out of curiousity, how did you get the 550wtq number?
     
  7. doublespaces

    doublespaces Administrator

    AZ
    2009 E93 335i
    Its just the commonly accepted figure after reading about a lot of failures over the years. There are obviously many factors to this, a fresh transmission may be able to handle 750wtq a few times, the clutches are a wear item so their history tells you everything about what they can handle.
     
  8. BOosted 335i

    BOosted 335i Private

    37
    335i
    so when is it good practice to change out the filter.for example.i take care of my car & auto trans.only beat on it here and there.car has 47,000 miles for 2008.at end of warranty(with stealer)i changed trans to Redline atf d4.then 3 yrs later i did it again.mind you this was done with in 18,000 miles of each other.i may put 4-5000 miles a year if im lucky.not driven in winter months.may have been over kill but i dont mind changing the fluids.Now i have a single turbo installed this past June so need to be careful now.
     
  9. hassan_hamdan

    hassan_hamdan Private

    44
    135i m package
    And that wraps up the discussion on the auto, in therory they can handle high torqe, it just depends on the way you drive it, the condition of the discs, and how often you end up replacing them. It sounds like the manufactuers output is really just a number they used for the longevity of the transmission.
     
  10. hassan_hamdan

    hassan_hamdan Private

    44
    135i m package
    Fingers crossed for you.
     
  11. R.G.

    R.G. Sergeant

    382
    Henderson, NV
    E92 N54, F02 N54

    ZF recommends 80-100k
    You're trans should last longer then it should with that fluid schedule. Doing it that frequently should also negate the recommended drive cycle requirements since it is not having to adapt to the fluid wear. 50k without drive cycle, 100k with DC and that trans should be solid at 500-550wtq.
     
  12. hassan_hamdan

    hassan_hamdan Private

    44
    135i m package
    So in theory lets say I get to 530~ wtq, i could still continue to use my transmission as is, as long as im not beating on it constantly, and changing the fluids every 50k or so?
     
  13. R.G.

    R.G. Sergeant

    382
    Henderson, NV
    E92 N54, F02 N54
    That's been my experience and is basically the parroted platform norm. Your transmission will let you know if it is unhappy. Missed shift, random gear disengagement, refuse to upshift, etc. It'll give you ques that it's time to either dial it back a bit or start putting funds aside for replacement. It rarely fails like a light switch, on one day then suddenly dead.

    The one piece of advice I would stress to anyone with a ZF AT. Anytime you change the fluid, mess with trans adaptations, add hardware, whatever, give the transmission some mileage before putting it under heavy stress. 100 miles under 3k rpm, then 50 miles with some 4k shifts, 50 miles with some 5k etc.
     
  14. hassan_hamdan

    hassan_hamdan Private

    44
    135i m package
    So, iv been doing some more diggining and someone recommened upgrading the transmission oil cooler. Not sure if they there is already one from the transmission, and looking at the e90/1addicts posts, there is discussions about it, however becuase photo bucket broke the internet couldnt tell if it comes from the factory and how to go about upgrading/installing one. According to Vader Solutions, the guy is currently running 800whp with the stock transmission and his fittings to create a cooler for it. Im skeptical about that number tbh, but what do you guys think/know about it ?
     
  15. doublespaces

    doublespaces Administrator

    AZ
    2009 E93 335i
    I can sell you a bolt on transmission cooler that is brand new. All you need are the transmission fittings and some 8AN hose. It is a Mishimoto Bar and Plate cooler, no need to zip tie things or any of that stuff, it just bolts on in front of the radiator. If you're interested just PM me.
    [​IMG]
     
  16. hassan_hamdan

    hassan_hamdan Private

    44
    135i m package
    So explain to me first why upgrading the cooler will help. Iv read that it does, but havent found why it actually helps. As well as for the trans fittings is there any place that is recommened for them?
     
  17. doublespaces

    doublespaces Administrator

    AZ
    2009 E93 335i
    There are only two trans fittings. One of them no longer makes them anymore and the other is @omarmarji

    Someone else would need to get into the nitty gritty but heat kills transmissions.
     

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