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#1
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Increase torque split in auto??
Just a quick idea... would one be able to fit a resistor inline to increase the torque split but not induce binding?? I understand its a signal not a voltage reading but what do ya think??
Tom |
#2
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You're going to get binding if you try to put in too much torque without enough slip.
__________________
-Jason (8/23/07-Present) 1995 Subaru SVX LSi (197k) Polo Green (#1102) 03/95 Mods: DDM Tuning 4500k 35w Low Beam HID, 100w H3 Bulbs, Extra Ground Cables, 15 minute $12.96 mod, svxfiles designed transmission mount (), sporting a "new" tail light bar, silver BBS rims, custom power steering cooler (one that doesn't dump ATF constantly), new negative lead cable, no more third or fourth gear (1977-Present) 1977 Chevrolet Corvette (81k) Silver (12/01/2011-Present) 2005 Subaru Outback 2.5i Limited 5MT (97k) I have a bad feeling about this. -Obi Wan Kenobi |
#3
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No... removing power from the solenoid causes it to go to 0% duty, which fully engages the clutch, causing 50/50 split.
Full signal (not power... signal) causes the solenoid to go to 95% duty (there is no 100%) and thus give you 100/0. This is when you put in the FWD fuse. What Tom is suggesting is a way to make the car start off with something other than 90/10 (if that is indeed what the base split is; I intend to dig deeper about that). For instance, starting with 70/30. To answer your question... since it is a signal, I'd think you'd need a way to create your own signal instead by creating a circuit designed specifically to translate the signal based upon a ramp. So that you still get 50/50 when need be, but that any signal which goes past a certain duty level is sent as the duty level for your specified rating instead. I understand the concept at hand, but don't look it me when it comes to designing the actual circuit. I don't know anything about that sort of thing. Someone with more experience will have to chime in and tell you what would be required. Of course we'd also have to know exactly how Solenoid C and the TCU operate together before messing with it... |
#4
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When I can be absolutely sure in this regard, I will comment further. Thanks, Trevor.
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Trevor, New Zealand. As a child, on cold mornings I gladly stood in cowpats to warm my bare feet, but I detest bull$hit! |
#5
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95% duty cycle of Solenoid C results in the clutch being 100% disengaged. Though I don't know what that means, perhaps you do.
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#6
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Couldn't a variable pulse wave generator make this happen?
If so, I think I can lay hands on one in an industrial relay form.
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[SIGPIC]http://www.subaru-svx.net/forum/image.php?type=sigpic&userid=5569&dateline=1207440 507[/SIGPIC] Naught but by the grace of God "42" Current Stable By Age:'89 Subaru XT6 Silver "Audrey" as in Hepburn '96 SVX LSi #767Brilliant Red "Lil Red" Now on the front burner. Looking for a totalled, but running parts car. |
#7
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Therefore if a 95% duty cycle of Solenoid C results in the clutch being 100% disengaged, the solenoid is open and there is low pressure delivered to the clutch when it is open and pressure would close the clutch. However this must be absolutely confirmed before any suggestions can be examined. I hope Tom has hands on knowledge of the mechanics involved. P.S. If the above is correct, Tom's idea of a resistor would appear feasible and worthy of experiment.
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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! Last edited by Trevor; 12-05-2007 at 09:28 PM. Reason: P.S. Added |
#8
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So the idea is to have the car operating at a standard torque split with more rear bias than it does now, right? Obviously we can't exceed 50:50, but more rear than I have now would be awesome. After the first few winter days in the SVX, I can say that it definitely doesn't swing the tail as easily as the Foresters when I step on it in a turn. It also doesn't do donuts as tightly.
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Chris 92 Ebony Mica LS-L "A Rolling Restoration": 223,250 KM - Sleeping 2007 STi 6MT, Stance GR+ coilovers, PWR Rad, JDM hood badge, svxfiles 6000K HIDs, JDM Clear Corners, $15/15 min mod, $20/20 min mod, Energy Swaybar Bushings, Hella Supertones horns, Gold STi BBS rims, Group A lightweight crank pulley, A/C system removed, Custom header-back exhaust, Hybrid carbon/metal rear sway bar, restored headlights with CCFL halos 2008 Subaru Legacy Spec B - Diamond Grey Metallic - Sold 2020 Ram 1500 Longhorn - Red Pearl |
#9
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I don't think a resistor will do the trick. The solenoid will still pulse open and closed at the same rate.
I think you need a circuit like this to generate your own duty cycle. Then you need a switch to select whether the transmission uses the TCU's duty cycle or the one from your circuit. http://www.doctronics.co.uk/555.htm#more%20astables You could replace R1 and R2 with a single potentiometer which you would turn to vary the duty cycle. (Please check this with an electronics expert before you try it out. I've repeatedly proved in my memory dump thread that I don't know much about electronics.) The ultimate solution is to reprogram the TCU. But there is a lot of reverse-engineering to be done before that becomes possible.
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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; 12-06-2007 at 01:51 AM. |
#10
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Danny 1994 Silver SVX in hybernation, awaiting for the monsterous awakening (Lebanon) 1967 Mercedes-Benz 250SL Euro Specs, Hard/Softtop, White/Red. Under Complete Restoration 2013 Mercedes-Benz SL350 Euro Specs, White/Red. Mint... Another step into SL Collection. |
#11
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Most certainly it is a crude approach and reliable calibration of any control arrangement would be unlikely. There are other ways of reducing the on time, but the low impedance of the solenoid increases the difficulty. In all of this, the prospect of increased clutch wear will have to be taken into account.
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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! |
#12
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Sorry to confuse you Danny. Let me explain. What I am proposing is a knob that the driver can turn to vary the torque split. Something like the DCCD (Driver Controlled Centre Differential) on some STi models.
The TCU controls the torque split using a duty cycle. It pulses the solenoid on and off. A 95% duty cycle, for example, means that the power is on 95% of the time and off for 5% of the time. That is why I am saying a resistor might not work - the power will still be on 95% of the time but at a reduced voltage. The circuit I posted is a duty cycle generator. The duty cycle is selected by the two resistors R1 and R2. Replacing them with a potentiometer would allow the driver to vary the duty cycle by turning the knob. A two pole switch would be fitted to connect the solenoid either to the TCU or to the duty cycle generator. My final point was an alternative solution. That the TCU program could be modded to produce a different duty cycle. For example, to change the function of the manual button such that it changes the torque split rather than its current function of locking out first gear. This will become possible once somebody reverse-engineers the program in the TCU. It's on my website waiting for anybody who wants to look at it. I need to finish looking at the ECU before I start on the TCU.
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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 |
#13
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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 |
#14
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as a mechanical engineer that has worked with plenty of electrical engineers over the years, that is my understanding of solenoids too (i.e., they're either all the way open, or all the way closed). -Bill
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Retired NASA Rocket Scientist Most famous NASA "Child" - OSIRIS-REx delivered samples from asteroid BENNU to Earth in Sept. 2023 Center Network Member #989 '92 Fully caged, 5 speed, waiting for its fully built EG33 '92 "Test Mule", 4:44 Auto, JDM 4:44 Rear Diff with Mech LSD, Tuned headers, Full one-off suspension '92(?) Laguna, 6 spd and other stuff (still at OT's place) My Locker |
#15
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Jdm
Did I not read somewhere here that the JDM transmission and TCU provided an initial 35-65 torque split? If so what makes them different?
Who needs throttle steering? |
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