E36 SMG - Knowledge

Discussion in 'E36 / E30 FAQ' started by daandaman, Jul 10, 2012.

  1. 10 Jul 2012 at 11:36 AM #1
    daandaman

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    I'd like to gather all the knowledge about the SMG 1 (e36 evo) system.

    Currently, I'm getting quite knowledgeable about this system, and I've repaired allready 2 faults, without buying new components.

    I see creating this thread as a start to group the information and people with know-how.


    :cool:
     
  2. 10 Jul 2012 at 5:24 PM #2
    daandaman

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    Note 1:

    So far I've discovered that the side to side moving cylinder on the actuator, can be dismantled.
    In the cast aluminium housing you find a lathe'd aluminium cilinder, outside thread, normal/clockwise. It has a very thin O-ring around it.
    Inside the cylinder there is the piston which holds a metal rod that actually pushes the gear selector shaft sideways (rotates it).
    This piston consists of an aluminium piston with a Nylon (PolyAmide) glide bearing that is sliced to remove. On this piston there is an extending 'shaft', around which a black, hard (dont know if it is supposed to be thát hard) pressure seal fits.
    On top of that pressure seal, still around the extending 'shaft' of the piston, there is a button (like the one on your jeans) like ring. The 'shaft' is punched so it fits tightly on the pressure seal, actually squashing/preloading it a bit.

    What i've done to try and counteract a leak that originated from this cylinder assembly, leaking into the actuator, dripping out of it again on the main joint of the 2 cast parts, is dismantled this cylinder, fitted 3 layers of PTFE (teflon) tape around the thread. Also I noticed that button-like cap around the aluminium 'shaft' was not so press fitted anymore (I could turn the button-cap around for a 90 degrees L&R), so I used a centerpunch and a hammer to expand the 'shaft' again, automatically pressing the button-cap down again, and preventing it from turning around.

    Because the aluminium cylinder fits inside the cast actuator housing, leaks from the O-ring aswell as from the pressure seal (obviously) drip into the housing.

    Note; My car had difficulties switching to third and fifth, not back. This indicates that the extending motion of the cylinder assembly (actuating the selector shaft that direction) had problems.

    Untill now, It seems i've fixed the problem. Will have to observe in a few months if the leaking has completely stopped.


    This part is not individually acquirable. Only the 1600 euro actuator as an assembly is buyable.
     
  3. 10 Jul 2012 at 5:33 PM #3
    daandaman

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    Your Motor:
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    Note 2;

    The pump motor is an Siemens item. Not individually aqcuirable.

    It is screwed into the hydraulic unit by 2 simple allen bolts.
    Due to the extreme heat generated by the exhaust and the motor itself, the rotor (the actually rotating part of the motor, containing the spooled wires) gets really hot.

    On my particular motor, the rotor insulation (plastic parts) had melted away, causing the spooled wires to short.

    Note; motor (pump) relay did not burn!

    The motor did not work anymore, causing me stranded. Easy to diagnose, the motor didn't prime anymore when opening the door, nor when using the override thingy in the fusebox, nor when using GT1 to activate the pump.

    I disassembled the motor very carefully, you have to bend some metal tabs with quite some force.
    I used a screwdriver with 4mm thickness, cut of the actual screwdriver head, and made a 2 mm long cut in the end of the rod, half deep, aproxx 2mm from the end. This made the screwdriver into a very rigid 'hook' type apparatus. This helped me to open up the tabs that seal the motor.

    There was a lot of molten/burned stuff inside it.

    I brought the rotor to a motor winding company, they rewound it with fibreglass paper insulation, and rebalanced it. My carbon brushes were still good. They are of the curved type.

    I've read that occasionally also the carbon brush holders (made from a thermoplast) can melt.
    There is a land/range rover that has an abs pump unit, containing the same engine, but with a different end plate (that screws to the pump body). Using the number on your motor, you might track down one of these ABS pumps for parts.

    The bearings are of the self centering glide type, should need no maintenance.
     
  4. 10 Jul 2012 at 5:41 PM #4
    daandaman

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    Your Motor:
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    Note 3;

    Having a breakdown of the SMG 1 can mean you are stranded with the car, and depending of the fault you might find yourself:
    *unable to drive
    *unable to be pushed/pulled on a trailer
    *unable to start the engine (having no steering assistance/brake booster)

    If your car did select neutral, but won't start because of a lack of hydraulic pressure (failed pump), then after (obviously) using the override-thingy in the small pump fuse box (that won't work with a failed pump)

    *you'll have to close an electric circuit. The SMG 1 equipped cars have, next to the large fusebox, an extra set of relays. Depending on the build year, there can be 1 big relay preventing the car from being started or 2 small ones, where the bottom one (nearest to the nose of the car) can be the culprit, according to TIS. In my car it was actually the TOP one!!

    With a little piece of wire, and 2 not-so-wide crimp on spades, you can make your own EWS&SMG relay override tool.

    Find out which relay of the ones next to the big fusebox is operating this engine start prevention, make and test your override cable, and keep it in your toolbox!!!!

    invaluable tip!! DO IT!!
     
  5. 10 Jul 2012 at 5:47 PM #5
    daandaman

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    Note 4;

    To work/diagnose the SMG1 system, and to prevent huge dealership bills,
    you ideally need GT1 (group tester one) on a cheap old laptop that MUST HAVE a hardware COM1 port (rs232).
    You will also need a TRUE "ADS to COM" adapter. Search for 'Gert' or 'rv8flyboy' and 'ADS interface'. It is the one I use, and so is confirmed to work.

    Other software and hardware might work, but you'll have to check this yourself.

    Personally I bring this dedicated old laptop with its cable and a 12v-220v adapter with me, so that IF (or more WHEN) there is an error, I can do CPR on the car, which might get me home. Road assistance won't, only when bringing me on a flatbed.
     
  6. 10 Jul 2012 at 5:50 PM #6
    daandaman

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    Note 5;

    I can confirm that a lightweight flywheel with sprung hub clutch kit actually does work on the SMG1. Although the flywheel part numbers of a smg/non smg M3 do not match, a normal LTW flywheel for an e36 M3 fits.

    You will need the aformentioned software to get the car back to life after this transplant; you'll need to bleed the system (must be disconnected when changing parts) and to relearn (adapt) the charasteristics of the system.

    No downsides apart from a little roughness (expectable) and it drives awesome.
     
  7. 10 Jul 2012 at 6:03 PM #7
    jamie123

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    are you talking about the short that cancels the diff lock? if so there is a tool in the relay box that lets you do this.
    also you dont need a true ads interface to access the bleed function in dis,i bled mine without one,before getting gerts cable.
     
    Last edited: Jul 10, 2012
  8. 10 Jul 2012 at 6:07 PM #8
    daandaman

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    no, the relay that prevents the starter motor to turn, starting the engine. Needed to get PAS and brake booster for the tow. This relay won't switch when the pump is dead.

    It is actually not a diff lock that gets cancelled, it is the pump relay that gets forced to switch (or overrides the relay, dunno for sure) so the clutch gets pushed in. Hence why you are not allowed to drive for a long time with this override placed.
     
  9. 10 Jul 2012 at 6:09 PM #9
    jamie123

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    ah that makes sense,it explains why tis says not to leave in for long.:thumbsup:
     
  10. 24 Jul 2012 at 8:49 PM #10
    daandaman

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    Having my complete setup (hydro unit, actuator, hoses, resevoir, sensor, new pentosin) in perfect running condition, just a sliiiight weep (1 drop from both actuator cylinders every 1000km, perfectly acceptable for a hydraulic machine) I am still experiencing a problem.

    I am coming to think of it that this SMG 1 is not tested in hot climates for extended periodes of heavy driving. Being quite a flawless design, the pump fails are due to heat management, as are the fault I am experiencing now from time to time.

    It is now quite warm in the netherlands, and only then, and before when it was warm, I'm having this fault. In the cool or cold periods there is no problem.

    What happens is that the car, after a hard drive and then being parked for some time, gives an error. When I then start the bleeding sequence, I can actually HEAR the air move trough the lines. Drives like a dream afterwards.

    The car also gets slow in it's shifting when driving around with a hot engine at slow pace, for instance after driving hard and then entering an urban area or traffic jam. You can really hear the gas bubbles pass small orifices as it is making tiny screamy sounds when it is shifting at stand-still.

    Also, the biggest problem is from 2nd to 3rd gear, and I didn't check yet, I believe that motion is done by pressure trough the line closest to the manifolds.

    The fluid being new (so no water/moisture in the system) and the entire condition top notch, I'm expecting that maybe the lower two lines that pass the heat shield of the exhaust manifolds, get too hot.

    Pentosin chf11 is rated untill 'and above' 130degrees C. Which is offcourse nothing compared to the blistering temperatures just behind the heat shields.

    Also the pumps melting when driving hard at slow paces, gives me the tought that the system is just lacking at one point; heat management.


    I'd like to start a bit of a discussion about this topic. For me; I'm really considering relocating the hydro unit to the boot floor (where the spare wheel would be) and running new PTFE (teflon) with stainless steel woven outter lines. This way the unit will only get as hot as the 12V motor and hydraulic fluid gets. The actuator part actually stays cooler than the gearbox, which doesnt get over 70 degrees anyways.

    This 'air' (or gasseous pentosin) problem is all that is left in my system being absolutely mint.

    Any ideas or comments?:)
     
    Last edited: Jul 24, 2012
  11. 24 Jul 2012 at 8:59 PM #11
    jamie123

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    hmm intersting i think from what i have read the e46 smg can suffer from too much heat as well,why would bleeding the system resolve this? perhaps you are drawing in air from somewhere?
     
  12. 24 Jul 2012 at 9:45 PM #12
    daandaman

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    No, impossible, the air cant get in as there are no leaks, it would spray out at 80 bar. and the (remaining) pressure prevents this too. Bleeding gets the vapour out, or at least whatever gas there is inside. Think ive got to measurre the temperature in a cooking pan at which it starts to boil and compare that with some IR temp gauge readings on the hydro lines near the manifolds or so.


    I think the elevated pressure prevents the fluid from boiling but then when switched off the pressure drops whilst temperature remains high. Explanes too why the next day i never have issues, only when i had issues directly after parking and waiting.
     
    Last edited: Jul 24, 2012
  13. 24 Jul 2012 at 9:47 PM #13
    jamie123

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    with that i mind would you say that bleeding the system every now and again is worth while?
     
    Last edited: Jul 24, 2012
  14. 24 Jul 2012 at 11:42 PM #14
    daandaman

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    No, in this case it just fixes the problem at the moment that it occurs. But this shouldnt happen at all!
     
  15. 1 Sep 2012 at 5:13 AM #15
    daandaman

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    Who has a spare pump(hydro unit) for r&d purpose? Allready bought a 2nd hand actuatorr but itss gettingg expensive now! Think im onthe path to aa reliable smg1 systtem but needto test
     
  16. 1 Sep 2012 at 8:08 AM #16
    jamie123

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    i have but it depends what your planing to do to it and id want to be part of the r&d
     
  17. 2 Sep 2012 at 4:53 PM #17
    daandaman

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    great!

    I want to disassemble it and find out what are wear-parts and if they can/must be replaced and where to find/make those.

    Also I want to get better knowledge about how the two [3/3] (hydro technic term) fluid switches exactly work, as they work different then how described in TIS.

    Finally I want to make a set to be able to relocate this unit to the spare wheel well, so the fluid pipes can be routed without passing by the exhaust. This would save the fluid from being over heated, and the pump(motor) from getting engine room heat.

    And sure! whatever you can help with would be nice.

    I wanted to make an open discussion about the SMG1 here anyways. What do you know about the system alreadY?
     
  18. 11 Nov 2012 at 8:01 PM #18
    steviet

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    A 3/3 valve is a valve with three selectable positions (i.e. extend/lock/retract if its controlling a cylinder) and 3 ports, normally a pressure in, return to tank, and a dead head. Hard to explain with words... I would try getting some heatshielding in and if its a self contained hydraulic system, try and find an alternative hydraulic fluid.... Something with a better heat rating... I work with hydraulics in my work, so might be able to shed some light on some basic stuff, though Ive no experience with this particular system/ unit...
     
  19. 11 Nov 2012 at 8:29 PM #19
    daandaman

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    Hi steviet. What I meant with finding out how the 3/3 valves work is how the sachs system operates the 3 way selectable valves. They are not conventional style valves like you'd find in a hydraulic installation (industrial).

    The fluid advised by bmw is already really highly rated stuff so that won't help much. And the system is already shielded from factory :)
     
  20. 11 Nov 2012 at 9:44 PM #20
    steviet

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    Have you got pictures of the valves? At the end of the day, they're there to operate the cylinders (for the shift action I presume), so must be moved by something, be it solenoids, manually selected pilot pressure or something else. Also, there must be some sort of feedback to tell the valve to move back to its lock position once the cylinder has achieved the required stroke for the selection..... Or am I barking up the wrong tree?
     

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