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  #16  
Old 09-14-2004, 07:14 AM
Targa-Hunter
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Just wanted to reply about the greeting of green flashing lights. I DO NOT have any flashing lights when I start or drive the car. If there are no flashing lights, what does this mean?

Curt
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  #17  
Old 09-14-2004, 11:29 AM
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Earthworm Earthworm is offline
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TCU is bolted to the ECU under the dash at the steering column.

If the power light doesn't flash then either there's no electrical problems with the tranny (likely) or the TCU has completely failed (unlikely).
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  #18  
Old 09-14-2004, 11:48 AM
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I would like to ask what is the differential ratio of the SVXs. I understand that the Legacy transmission is a better transmission. Given if this is true. is there a problem with the differential ratio of the Legacy matching that of the SVX? What is the ratio of an automatic of the Legacy?

Thanks in advance.

Curt
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  #19  
Old 09-14-2004, 02:11 PM
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A quick search of the forums will tell you the SVX uses 3.545 diffs. If you put in a Legacy tranny you will need the matching rear diff. The only exception to this rule is the 2002/2003 WRX 5 spd's with 3.90 front, 1.1 center and 3.545 rear diffs.
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  #20  
Old 09-14-2004, 05:43 PM
RojoRocket RojoRocket is offline
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And, I have in fact read to the contrary here on this board, that the SVX trans was built to handle the extra weight and HP/torque of the car, with more clutch-plates, and is superior to the Legacy trans in this application.

I wonder out loud though if the 3.0 Liter Legacy OutBack trans might be beefier than "lesser" Legacy boxes, and a superior as well as suitable substitute????

Glenn
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  #21  
Old 09-15-2004, 01:30 AM
gl1674 gl1674 is offline
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Quote:
wonder out loud though if the 3.0 Liter Legacy OutBack trans might be beefier than "lesser" Legacy boxes
You don't want that tranny.

First it requires a different TCU and probably a new wiring harness to go between the tranny and TCU. Second that different TCU will not talk to ECU the same way, you might end up swapping ECU and engine as well.

Second, the tranny is programmed very differently - go drive a 3.0 Outback and you'll understand. It tries to "assist" when braking - it downshifts proactively and tries to engage engine braking messing up any smooth deceleration you are trying to do. I just hate that. Power mode does not seem to exist. Downshifting for acceleration just takes forever. IMHO the 3.0 Outback tranny is just messed up.
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  #22  
Old 09-15-2004, 11:46 PM
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I bet the shift solenoids operate the same way. Only two of those wires are important anyway. I'd do it. ...but I'm a dirty boy. Bad thought! Out! Out!

Also, I bet it wouldn't be terribly difficult to interface the newer TCU. It's not a job for anybody, but a reasonably competent electrician shouldn't have any trouble faking it. Because of the annoying characteristics of the newer transmission, I would opt for adapting the old TCU. I really think this would probably be quite easy to do. I'm pretty sure the newer transmission has a few more sensors and perhaps another solenoid, but I'm also pretty sure they're superfluous. It doesn't have any extra gears does it?
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  #23  
Old 09-16-2004, 12:19 AM
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It's still the same planetary gearset. One change the old TCU might not like is the replacement of the brake band with a clutch - the timing of engagement/disengagement might be different. It will work, but might not shift smoothly.

Another change is a new sensor in the tranny on the output shaft of torque converter. With this sensor the TCU can see the difference between torque converter slippage and clutch slippage. This enables learning function in the new TCU - it can adapt to the clutch wear. The old one will obviously work without this new sensor, but who knows how the calibration of accumulator springs and throttle body passages has changed - they now should have some room for TCU control of shift timing.
It will shift, but you might not like the sensations.

Re connecting the new TCM to the old ECU - it might be a bit more challenging, apparently they communicate a sophisticated stuff (like atomspheric pressure) between themselves. Here we go reverse engineering serial protocols and programming single chip controllers.
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  #24  
Old 09-16-2004, 02:14 AM
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Some of us don't like how the transmission shifts anyway.

A buddy and I did an engine swap that required a different ECU. Fortunately, it was a fairly primitive unit. We just added more sensors in addition to the ones used by the instrument cluster and whatever else. A resistor was added to the tachometer, the oil pressure sender needed to be swapped, a few wires on the harness needed to be shorted, one needed power, and the fuel pump needed a special wire added to it. Stupid things, really. We didn't care if it used the cold-start routine; it runs better with the normal routine anyway. Don't need that wire. Snip! Just faking signals that we don't need. Butt-simple. Runs like a champ and started on the first turn of the key. ...okay, maybe not the first turn. Apparently the ECU's ground wire does not ground to the ECU's case, which also needs to be grounded. But that fixed itself when the ECU fell behind the transmission bell-housing during the second turn of the key.

Anyway, my point is that most of the stuff the TCU expects to see can be faked, especially if nobody cares if the transmission holds third gear when the engine is cold or similar behavior - although even that signal can be faked with ease. I'm sure I'm not going to notice a difference in how the transmission shifts at 2500 feet above sea level. Snip!

I want to see somebody do this and beat the snot out of the newer transmission to see if it can take it. I'm curious to know what it takes to break the new slush-boxes. They've got that shift-tronc brain too, yes? Oooh! Oooh! Break it! Break it!
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