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#676
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I can see the duty cycle using the actual select monitor... if there is anything I can help with in this regard let me know... As for the AWD split. In US models the lower the duty cycle to the sol. C the closer one is to a 50/50 torque split. the higher the duty cycle, the less power is transfered to the rear wheels. That is why when the FWD fuse is installed, it provide a 12v constant to the sol C which allows the transfer clutches to lay laxed... Let me know if this is confusing
Tom |
#677
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I bought an old oscilloscope recently, which is probably the best tool for the job. But I suppose there is a chance that my old analog "AVO" meter might actually read a voltage proportional to the duty cycle. In any case, I have no need to measure the duty cycles electrically. I have figured out how the TCU generates them and can read them from the memory through the select monitor interface.
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Subaru ECU and TCU Website 1992 Alcyone SVX Version L 1992 Alcyone SVX Version L 1994 Alcyone SVX S40-II 2004 Subaru Legacy 2.5 SE Sports Tourer 1996 Subaru Legacy 2.2 GX Wagon 1988 Subaru Justy J12 SL-II |
#678
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Next time you get the select monitor out to play with it, I'd be interested to know the answer. It doesn't have to be those exact splits, just a range of values, split versus duty to plot on a graph and join up the dots.
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Subaru ECU and TCU Website 1992 Alcyone SVX Version L 1992 Alcyone SVX Version L 1994 Alcyone SVX S40-II 2004 Subaru Legacy 2.5 SE Sports Tourer 1996 Subaru Legacy 2.2 GX Wagon 1988 Subaru Justy J12 SL-II |
#679
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I will test it out when i take this stock trannied 96 out for a test drive later on...
Tom Quote:
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#680
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In the past I have always used “FWD” as meaning Four Wheel Drive, which in this instance has lead to what amounts to an error. Please read as follows:- When the normally closed solenoid is energised via a high duty cycle the valve will open and control pressure will be bled off. Reduced pressure will result in the clutch opening and therefore no Four Wheel Drive, i.e. only Front Wheel Drive. Again sorry for the confusion. Trevor.
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Trevor, New Zealand. As a child, on cold mornings I gladly stood in cowpats to warm my bare feet, but I detest bull$hit! |
#681
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I know that math isn't always the order of the day, but I did some anyway, assuming that the TCU uses a linear plot for torque split. So here's the math...
We'll take the SolC duty cycle and call it 'x'. 'x' can go from 5 to 95. For simplicity's sake, we'll have 'y' represent the rear torque split, which can go from 50 to 0. So when x=5, y=50. And when x=95, y=0. Assuming this is a linear plot, that gives us the equation y = (5/9)x - (25/9) Now, if we then assume x=65, which is about what my car registers on SolC during normal driving, this gives us a result of y=33.3. So the torque split would be 67/33, approximately. If you then think about how the JDM VTD box advertises a torque split of 35/65, it starts to sound rather interesting. Anyway, that's just some math. Whether it means anything or not is up to the hands-on mechanical guys. |
#682
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I know this is kinda off topic but the VTD gearboxes are mechanically VERY different from our own... Just lets keep it to the transfer clutch boxes we all have to deal with, those lucky VTD suckers can suck eggs
Tom |
#683
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also good to remember, the TCu is not going to allow either a 50/50 split nor a 100/0 split under normal driving. Binding is no good and FWD gives you nothing on a positive side. I will go out and do some testing now to see what we find.
Tom |
#684
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ok Here is what we have...
At idle in Park or Neutral: 95% Idle in D or R: 70% Coasting in D: 70% 1/4 throttle accel: 55% 1/2 throttle accel: 35% 3/4 throttle accel: 33% but quickly begins to rise up to 35 and further up as you accelerate. Full throttle accel: 5-15% and quicklu rises to 35% and further up as you accelerate. Now as you do your match remember 0% is 50/50 and 100% is Front Wheel Drive only Now, unfortunately it is a real select monitor so I cannot see more than one parameter at a time. I wish I could see this and plot it in relation to throttle position to get a more accurate description but what I thought were throttle percentages are gonna have to be good enough for now Tom |
#685
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The Duty cycle sent to Solenoid C, varies with the inputs like. Gear position, throttle opening, road speed, and 'out of limits' wheel speed difference. The condition giving the highest pressure applied to the clutch, would be, full throttle, no speed, 1st gear, or wheel spin. The least pressure would be light throttle, high speed, 4th gear. As I said before the PWM sent to the clutch is different for the two types of AWD, Transfer and VTD, they are opposite signals. So when You read the US Transfer signal, and Phil reads the VTD signal, they are opposite. Harvey.
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One Arm Bloke. Tell it like it is! 95 Lsi. Bordeaux Pearl, Aust. RHD.149,000Kls Subaru BBS wheels. 97 Liberty GX Auto sedan. 320,000Kls. 04 Liberty 30R Auto Premium. 92.000kls. |
#686
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If it is a linear relationship I have a doubt about your maths. Or maybe mine. It's late (here) and one or both of us is wrong. Your x coefficient "5/9" is positive therefore your graph will slope upwards. But I think it should slope downwards, from (0,50) to (95,0). So the coefficient should be negative. By my reckoning the equation would be y=(-5/9)x + (475/9). Your x=65 would give y=17, therefore 83:17 torque split. Or, if the known points are actually (0,50) and (100,0) [which makes more sense, 100% duty = FWD] it becomes easier y=(-1/2)x + 50. Then x=65 gives y=18, therefore 82:18 torque split.
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Subaru ECU and TCU Website 1992 Alcyone SVX Version L 1992 Alcyone SVX Version L 1994 Alcyone SVX S40-II 2004 Subaru Legacy 2.5 SE Sports Tourer 1996 Subaru Legacy 2.2 GX Wagon 1988 Subaru Justy J12 SL-II Last edited by b3lha; 04-15-2008 at 05:27 PM. |
#687
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Wan, the % of Duty cycle sent to the clutch, and the actual torque split may not be in line. The % of PW is exact, the actual grip of the clutch is not. So we just have to use the % and assume that the clutch follows suit. The 36/64 of the VTD is a mechanical variation, the PW signal can only move it from there to 50/50. Harvey.
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One Arm Bloke. Tell it like it is! 95 Lsi. Bordeaux Pearl, Aust. RHD.149,000Kls Subaru BBS wheels. 97 Liberty GX Auto sedan. 320,000Kls. 04 Liberty 30R Auto Premium. 92.000kls. |
#688
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Subaru ECU and TCU Website 1992 Alcyone SVX Version L 1992 Alcyone SVX Version L 1994 Alcyone SVX S40-II 2004 Subaru Legacy 2.5 SE Sports Tourer 1996 Subaru Legacy 2.2 GX Wagon 1988 Subaru Justy J12 SL-II |
#689
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Harvey.
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One Arm Bloke. Tell it like it is! 95 Lsi. Bordeaux Pearl, Aust. RHD.149,000Kls Subaru BBS wheels. 97 Liberty GX Auto sedan. 320,000Kls. 04 Liberty 30R Auto Premium. 92.000kls. |
#690
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In theory, 0% will result in a 50:50 and 100% will result in 100:0, even if the TCU does not normally use those values.
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Subaru ECU and TCU Website 1992 Alcyone SVX Version L 1992 Alcyone SVX Version L 1994 Alcyone SVX S40-II 2004 Subaru Legacy 2.5 SE Sports Tourer 1996 Subaru Legacy 2.2 GX Wagon 1988 Subaru Justy J12 SL-II |
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