S65/S85 throttle actuators.

Discussion in 'E90 Saloon / E92 Coupe / E93 Convertible M3 (2008-2013)' started by alpina527, Jan 24, 2014.

  1. 24 Jan 2014 at 9:10 PM #1
    alpina527

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    As many of you know, the S65 is an extremely reliable engine but still with one major flaw. The throttle actuators wear out relatively quickly. Having two of these on every car poses the question as to whether to replace them both when one fails or just do the one and hope for the best. The only answer is to buy a new one from BMW at Circa £700 plus fitting. The story is the same on the S85 V10

    This is the first signs of a failed actuator.

    [​IMG]

    I've been looking into this project for a few months now and I've finally get there. Finding a spare S65 throttle actuator wasn't easy because of the BMW policy of keeping the old units replaced under warranty. I wanted to find what's happening and make something better.

    BMW dealers sometimes call it an electrical failure of the actuator but it's usually nothing to do with the electrics. They are very well sealed and look well made.

    The plastic moulded gears in the unit are made to a price, not longevity.

    Here are the parts laid out after dis assembly.

    [​IMG]

    The white compound gear in the middle of the picture is driven by the hard steel gear of the dc motor. Attached to the white gear is a 13 tooth reduction gear that drives the black output shaft with a lever on the other end of it's shaft which opens the bodies. The motor is driven against a hefty spring which keeps the throttle steady at any given throttle opening through the gear train.

    [​IMG]

    Here's the reduction gear. There is heavy wear on the teeth which is difficult to see in the photo.

    [​IMG]

    Any wear that happens on this reduction gear gets transferred to the plastic output gear. Again it's difficult to see but on close inspection you can see how thin the teeth are in the normal driving speed portion of the gear.

    [​IMG]

    The main white gear that runs on the steel motor gear shows no signs at all of any wear. This is mainly down to good engineering practice of using a plastic gear on a steel gear. This eliminates most of the wear and runs clean with no dust.

    However, the small reduction gear is part of the same moulding and runs on the plastic output shaft also made of plastic. Not a disaster, but plastic on plastic is a bit of a no no. This small gear not only takes a lot of torque through it when opening the throttles but also has to maintain speed by gently reciprocating backwards and forwards on the same teeth to do this.

    So, basically there's nothing wrong with the large white gear in itself. The problem stems from the attached reduction gear and the output gear which is moulded to the output shaft.

    I'm under warranty and have just started getting the dreaded idrive warning. If I take it to the dealers they will only replace the one actuator (still with the plastic moulded gears) . That means I will be back soon for the other one.

    Having spoken to various applications engineers, most of them favour making the gears out of Brass and Delrin 150 plastic.

    This is my brass and Delrin 150 reduction gear. Much stronger than the original and hopefully it will see me out.

    [​IMG]

    [​IMG]

    [​IMG]

    This is the oem output gear and shaft. The gear width is 10mm so by carefully offsetting the gears I've managed to get this width up to 11.3mm for some extra strength.

    [​IMG]

    This is my replacement gear viewed from both sides.

    [​IMG]

    Comparison between new and old with the shaft fitted.

    [​IMG]

    Finally assembled.

    [​IMG]

    Now I just need a spare morning to upgrade and fit both my actuators.:peace:
     
    Last edited: Feb 2, 2014
    rivarama likes this.
  2. 24 Jan 2014 at 9:15 PM #2
    Neil McRae

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    top job mate, delrin is good stuff and will give a lot of longevity, are you worried about wear from the brass to delrin though?
     
  3. 24 Jan 2014 at 9:32 PM #3
    Ash m3

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    Excellent post :thumbsup: are you planing on selling them :confused:
     
  4. 24 Jan 2014 at 9:35 PM #4
    alpina527

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    No, apparently it's more than up to the job of the surface finish is good enough. I've polished the teeth so it should be much better than the plastic. It's certainly stronger that's for sure.

    The reduction gear doesn't carry out the same kind of function as it would in a regular gearbox. Once you are cruising, it's hardly moving. Hard to explain, but the applications engineers recommended the combo with manufacturing and longevity in mind. It would be better in hard steel but It's overkill

    Well I did make a few spares, so pm if you need any
     
    Last edited: Jan 24, 2014
  5. 24 Jan 2014 at 10:11 PM #5
    Chezlar

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    Fair play. Impressive
     
  6. 24 Jan 2014 at 10:25 PM #6
    Z4M

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    You missed a bit. :D
     
  7. 24 Jan 2014 at 10:31 PM #7
    Toffeeman

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    Wow Ian, that is a fantastic build. That setup looks like it will outlast the car.

    I look forward to seeing how you get on with them on a daily basis.
     
  8. 24 Jan 2014 at 10:35 PM #8
    alpina527

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    Cheers. I like to make things to a quality not a price. They run very smoothly.

    It's taken far more work than I envisaged.

    I'm looking forward to fitting them.
     
  9. 24 Jan 2014 at 10:38 PM #9
    Schuey

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    Well done mate.

    Some clever people on this forum that could teach BMW a trick or two :thumbsup:
     
  10. 25 Jan 2014 at 12:04 AM #10
    Arkenphel

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    Bloody awesome work, Ian!

    I'm interested and would like a set please! What sort of work is involved in fitting these? Can my local Indy do it?

    Seeing as I'm gonna be keeping my M3 for a quite a few years more, this would be an excellent idea, seeing as my current set of actuators have another 20k miles left in them, based on how long the first set lasted.
     
  11. 25 Jan 2014 at 8:45 AM #11
    tonyjacko

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    Gents how long can you expect the standard actuators to last on average, mine is still under warranty but it's good to know for the future?

    Cheers Tony
     
  12. 25 Jan 2014 at 9:17 AM #12
    Arkenphel

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    Mine went about 40k miles in. Seems to last about that long, though some people have had failure with much, much less mileage.
     
  13. 25 Jan 2014 at 9:50 AM #13
    Snowman

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    Top Job Ian, Will be keen to know how they run/operate on a daily basis.
     
  14. 25 Jan 2014 at 9:55 AM #14
    daz05

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    Great post Alpina. Many have been scratching their heads on this, you get a unit last week and this happens. :)
     
  15. 25 Jan 2014 at 10:19 AM #15
    Mattys

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    Hats off to you Ian, thats a amazing job. :thumbsup::thumbsup::thumbsup:

    In a geeky way they look quite sexy in black and brass. Sad I know, but I do love a nice piece of engineering.

    Why BMW / Siemens haven't updated the units yet is frustrating and quite sad really. I now there is a cost element, but it gets my back up that they knowingly keep making something that has a high failure rate.

    Anyone planning on keeping a S65/S85 running for a while would be smart to invest in a few of these just in case.

    Keep us updated on how you get on mate!
     
  16. 25 Jan 2014 at 10:36 AM #16
    RAWM3EVO

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    Ian,

    Great job !

    you say you started getting issue ... did it throw a code?.. if so what was it?
     
  17. 25 Jan 2014 at 12:53 PM #17
    alpina527

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    The idrive faults shown in the first post indicate what's coming.

    The actuators self test by going through a full opening of the throttles. Any resistance and they will throw a code which puts you into limp mode. It can disappear next day though.

    At the moment my car drives fine but the idrive fault list will be back soon.
     
  18. 25 Jan 2014 at 2:40 PM #18
    mpy32

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    Great job Ian
    I have
    DSC failure ! Drive moderately
    DBC failure ! Drive moderately
    FTM system error !
    start assistance inactive !
    45000mls
    New Actuators ??

    Not used the car since last Sunday went to go out this afternoon and won't Start just turns over
    Got BMW monthly warranty thankfully
     
    Last edited: Jan 25, 2014
  19. 25 Jan 2014 at 2:55 PM #19
    chrisc

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    Great work Ian :thumbsup:
     
  20. 25 Jan 2014 at 3:24 PM #20
    Isher

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    Top job Ian, really well done :thumbsup:
     

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