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#1
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Swapped Tranny issues
So we've narrowed down exactly what the race car (and Marlettpat's) tranny are doing. They both have Impreza 1.8 FWDers in 'em at the moment. It seems that at full throttle it shifts into second then doesn't go anywhere until you take your foot off the gas. Both are doing it in 1st (redline autoshift) or D. We are running the SVX torque convertor, Pat the Impreza. Both have the SVX awd TCU in 'em. We're thinking that a TCU swap is in order but don't wanna go to something we can't leave in 1st and have it redline shift for us. Any ideas on a TCU or other issues that might be causing it. Both shift better than any awd Subie tranny I've been in provided you're not at full throttle.
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British vehicles are my last ditch attempt to keep the nasty Italian thoughts in my mind at bay. So far its working. |
#2
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Cosmic rays? Lack of adequate sacrificial offerings at the 4HEAT altar?
Seriously, your trans is acting like the Powerglide in my parent's Camaro - let up on the gas to bump the engine vacuum up and make the trans shift earlier. Have you changed the ATF? Any chance that this version of the 4HEAT has a different fluid capacity? Since both 4HEATs are FWD versions, I'm wondering if there is something going on regarding the signal going from the TCU (from an AWD-equipped SVX) to the trans telling it to shift. What does the TCU do when the car is in "limp home" mode? Have you tried putting the FWD fuse in and seeing if it still behaves in the same way? -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 |
#3
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Fluid is right about mid level in ours. We did change the sludge when we dropped the pan. I highly recommend it for most of the higher mileage subarus. This lowely FWD with 80k on the odo had about a 1/2 inch of thick crud down there. Rest of the fluid was fine though. Didn't even think about the FWD fuse. I'll have Pat give it a shot. Limp mode I think drives it in 3rd only or something like that. We're getting plenty of power. Just that bogging which on an autox course is tough to pinpoint when you're doing everything else.
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British vehicles are my last ditch attempt to keep the nasty Italian thoughts in my mind at bay. So far its working. |
#4
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No shift speed signal.
I think it needs the FWD TCU. In the AWD box, it uses the rear speed sensor to provide the shift speeds. As the FWD box only has the front speed sensor, it needs the FWD TCU to signal the changes.
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. |
#5
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British vehicles are my last ditch attempt to keep the nasty Italian thoughts in my mind at bay. So far its working. |
#6
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The FWD TCU uses the front speed sensor to do the changes. Give it a go, either FWD TCU will do the job. Harvey.
__________________
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. |
#7
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British vehicles are my last ditch attempt to keep the nasty Italian thoughts in my mind at bay. So far its working. |
#8
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Ben,
Harvey had this comment in SVXHunter's 5 speed, "my brakes are locking up" thread: "The only electrical connection is from the ABS to the TCU, that causes it to change to 3rd gear. Dont think it would be a problem." Maybe Harvey can shed some light on this comment as it might relate to the issue at hand? -Bill
__________________
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 |
#9
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Shifting
Hi Ben, If you have the owners manual take a look. It says if you put the transmission in first gear it will stay in first gear. If you put it in second gear it will shift between first and second. If you put it in third it will shift between first, second and third dependent on were you have the accelerator. If you have the manual mode engaged. In third gear it will shift between second and third. If in second gear it will stay in second, even starting in second. As pointed out before, selecting first, it stays in first. What year is the Loyale transmission from? Maybe that has something to do with it. Take care, BOBB
P/S How is Yogi? "B" |
#10
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Yeah Bobb, 1st keeps it in 1st until it hits redline then it shifts to 2nd until speed slows enough to go back to 1st. Some Subies just hit a rev limiter (which is what we don't want). We want it to shift only when necessary. It's a 93 Impreza tranny.
ABS??? There isn't any ABS on our car
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British vehicles are my last ditch attempt to keep the nasty Italian thoughts in my mind at bay. So far its working. |
#11
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Quote:
Ben, My point exactly...in removing the ABS have you eliminated a signal that the TCU is expecting? There might be a wire floating around now that needs a resistor hooked up to it to "fool" the TCU - thus my comment about Harvey enlightening us. -Bill
__________________
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 |
#12
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I am pretty sure that all 4eat will change at peak rpms to save the engine. That change point is probable different for the different engines. I remember saying a long time ago, that the shift pattern in the TCU of the smaller engines may have a better shift timing than the SVX. Because they don't have as much power to waste, the TCU would do a faster, harder change to maintain velocity. Harvey.
__________________
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. |
#13
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Harvey,
There you go! So, it would appear that the focus shifts (pun indended) back to the TCU being used (and the speed sensor input). -Bill
__________________
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 |
#14
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That makes more sense. Pat's car still has ABS and his is doing it as well. Bill BTW, I had to stay home so I'm not in DC. We'll hook up at some point. Sorry, I completely forgot!
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British vehicles are my last ditch attempt to keep the nasty Italian thoughts in my mind at bay. So far its working. |
#15
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I do not believe you can swap a tcu from any other model subaru without changing the wiring. You would need to change all the pins on the pinout to match with those in the new tcu. I tried to swap the tcu from the car i got my trans out of in my FWD and it would never leave 1st gear. So i left the svx tcu in the car.
Tom |
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