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#1
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Transmission care
Ok, we've got a '92 with 190K on it, and would like to make sure it keeps running. Can you folks tell me the best way to make the tranny last? Should we replace the fluid, or leave it alone? Any other tips? Thanks.
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#2
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Re: Transmission care
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If the oil is dark and smells burnt, look for another box. 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. |
#3
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Re: Transmission care
Replace the fluid but don't bother dropping the pan and changing the filter. It isn't really a filter; it's a wire screen and it doesn't get clogged. It's a waste of a pan gasket and screen. I like to use genuine Subaru transmission/power steering fluid. It's a quality fluid with good additives (subaru coolant is real good too but that's neigher here nor there). Add to it one bottle of lubegard atf protectant. This will make the fluid work better and last longer. Both the red bottle and the platinum which is a silver bottle are good--other brands and products are not equivalent. http://lubegard.com/~/C-113/LUBEGARD...ATF+Protectant
Upgrade/update your TCU with firmware with higher line pressure in 3rd and 4th gear to prevent high clutch and brake band slipping and eventual failure which otherwise plague SVXs. |
#4
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Re: Transmission care
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Tony 1996 Polo Green Subaru SVX LSi, 168,XXX miles, Redline D4 ATF, Redline 75W90 gear oil, K&N HP-4001 Oil Filter, Mobil 1 5W50 FS (3qt) and 5W30 High Mileage (4qt) Oil Blend, Motul RBF600 Brake Fluid, AC Delco A975C Air Filter, NGK BKR6EIX-11 plugs, Centric Rotors, Power Stop Evolution Carbon Fiber Ceramic Brake Pads 2005 Gray Acura RL, 165,XXX miles, Redline D4 ATF with Lubegard Platinum Protectant, Mobil 1 5W20 High Mileage Extended Performance Oil 2009 Red Toyota Venza, 123,XXX, Mobil 1 5W30 High Mileage Oil 1992 Red Ferrari 348 ts, 82,XXX, Redline everything |
#5
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Re: Transmission care
that is correct.
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#6
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Re: Transmission care
Oh well, I guess that filter kit was a waste of money then. At least it wasn't too expensive.....
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Tony 1996 Polo Green Subaru SVX LSi, 168,XXX miles, Redline D4 ATF, Redline 75W90 gear oil, K&N HP-4001 Oil Filter, Mobil 1 5W50 FS (3qt) and 5W30 High Mileage (4qt) Oil Blend, Motul RBF600 Brake Fluid, AC Delco A975C Air Filter, NGK BKR6EIX-11 plugs, Centric Rotors, Power Stop Evolution Carbon Fiber Ceramic Brake Pads 2005 Gray Acura RL, 165,XXX miles, Redline D4 ATF with Lubegard Platinum Protectant, Mobil 1 5W20 High Mileage Extended Performance Oil 2009 Red Toyota Venza, 123,XXX, Mobil 1 5W30 High Mileage Oil 1992 Red Ferrari 348 ts, 82,XXX, Redline everything |
#7
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Re: Transmission care
You guys can pamper your autos all you like, I can't wait for mine to let go, but sadly, it seems to have been well taken care of.
STI 6 speed FTW!!! |
#8
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Re: Transmission care
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http://www.subaru-svx.net/forum/show...+filter+screen There are probably others that replaced the box due to this happening. Quote:
This combined with the high torque that the band and high clutch have to transmit, causes the slipping. The line pressure can be increased, to add clutch pressure, by increasing the resistance of the dropping resistor. The resistance is 12 ohms increasing this to 25 ohms, by using two dropping resistors connected in series, will raise the pressure by about 30%. Increasing the pressure excessively will cause C and B solenoid binding, and hard changes. The high torque is instantly reduced by 30% by shifting back to 3rd gear, this changes the overall ratio from 2.4:1 to 3.5 :1, the ATF output is increased by the same amount, and the heat produced by the torque converter is also reduced. It is the excessively high US ratio that has caused so much trouble. This is why fitting on trans that has a lower final drive ratio, like a Legacy 4.11:1 or an Outback 4.44:1, reduces the load on the box by about 17%/26%, results in a longer lasting, better preforming SVX. 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. |
#9
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Re: Transmission care
Na, there's no way a screen can get clogged. Aside from it being a very large surface area of a not very fine mesh I've never seen a clogged screen and I've rebuilt a lot of blown 4EAT transmisisons. I've had maybe half a dozen full of chunks of frictions that have fallen apart and maybe 4 full of chunks of bearings but I have never seen a clogged one. Even most blown 4EATs have clean screens.
The pump actually pumps a very large volume of fluid even at low RPMs. It incorporates a hydraulic feedback mechanism controling the volume of the vane pump so that the volume per rotation is higher at low rpms and lower at high rpms so that the actual volume pumped is equalized across the RPM spectrum. The sole reason for low line pressure at light cruise is the programming of the TCU. The stock programming has a very high solenoid a duty ratio under light cruise which bleeds of a whole lot of line pressure; there is no lack of fluid flow volume preventing a higher line pressure. That is easily accomplished by adjusting the main line pressure maps for each gear. Reprogramming the TCU with more line pressure in light cruise in 3rd and 4th gear or any gear's main map for that matter doesn't cause hard shifts or transfer clutch binding either. There are seperate maps and routines dictating the line pressure during gear changes and turns. |
#10
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Re: Transmission care
[QUOTE[QUOTE]]
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http://www.subaru-svx.net/forum/showthread.php?t=53883 This was the cause of the problem. Quote:
Quote:
It can be accomplished a lot cheaper, by reducing the dropping resistor's resistance. Quote:
As I have said, the main problem with the std SVX trans is the excessively high final drive ratio. 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. |
#11
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Re: Transmission care
Ugh, kind of a pain dealing with these line by line quotes....so I won't use them
so anyway....You're saying that someone had a loss of line pressure....changed his screen...and got his line pressure again? I find this hard to believe. If that is the case please say so directly. A picture where someone says he thought his filter was dirty doesn't do much for me. no, the pump's output is controlled by a cam which changes the volume of the vane pump per rotation. The regulation of line pressure performed in the valve body you are describing is beside the point. The one and only point of any consequence is there is plenty of pump output to have much higher line pressure at light cruise and the only reason it isn't higher is because the tcu is bleeding it off. If you really want to argue that tampering with the electrical connections is a better method of controling line pressure than setting the data right in the TCU firmware I'll just have to aggree to dissagree with you right now and not waste any more time. |
#12
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Re: Transmission care
Oh no, another tranny debate. I am a pretty damn good engineer and these threads make my head spin. Of course, I am not an automotive engineer but an electrical/optical engineer so trannies are not my specialty.
I'm surprised no one mentioned bypassing the radiator with a higher flow oil cooler. I bought, but have not yet installed, a 10,000 GVW flex-a-lite cooler which has a pretty small footprint and a low flow resistance. I agree with Mike on Lubegard. I have had great luck with the stuff and the folks at BITOG rave about it. It is an ester based additive which should help reduce operating temperatures. It is like water wetter for your tranny. Although I like Lubegard, I personally opted for Redline with no additives over Subaru ATF with Lubegard but I think that is a great option too. From what I have gleened from the many threads on the subject, increasing the dropping resistor would help the line pressure a little but Mike's TCU map changes would help it a lot at those critical low RPM, low throttle conditions. If stupid little crap like valve cover gaskets and O2 sensors ever stop going, I may be able to get the wife to agree to letting me buy Mike's TCU upgrade or valve bodies or both. Maybe a group buy by 1996 owners for the TCU upgrade would help spread out the cost of Mike mapping stuff out for our newer TCUs. (hint...hint to 1996 owners)
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Tony 1996 Polo Green Subaru SVX LSi, 168,XXX miles, Redline D4 ATF, Redline 75W90 gear oil, K&N HP-4001 Oil Filter, Mobil 1 5W50 FS (3qt) and 5W30 High Mileage (4qt) Oil Blend, Motul RBF600 Brake Fluid, AC Delco A975C Air Filter, NGK BKR6EIX-11 plugs, Centric Rotors, Power Stop Evolution Carbon Fiber Ceramic Brake Pads 2005 Gray Acura RL, 165,XXX miles, Redline D4 ATF with Lubegard Platinum Protectant, Mobil 1 5W20 High Mileage Extended Performance Oil 2009 Red Toyota Venza, 123,XXX, Mobil 1 5W30 High Mileage Oil 1992 Red Ferrari 348 ts, 82,XXX, Redline everything |
#13
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Re: Transmission care
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Michael, why did Subaru program the original TCU for such light line pressure in light cruise? |
#14
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Re: Transmission care
Subaru used the same solenoid a map for all 4 gears. They probably used the same solenoid a map in all their other model cars and for every year since they first released the 4eat. It was probably generated by a perfectly reasonable formula that calculated the minimal line pressure necessary to hold the rated carrying capacity of the transmission. It obviously works fine in 1st and 2nd gear which use larger clutch packs and it obviously works fine in other model cars which aren't as heavy as the SVX and have a higher gear ratio than the SVX.
The reason solenoid A and the maps and routines controling it are included in the system to begin with is to minimize the pressure the pump has to pump against. Pumping against pressure requires power so minimizing the pressure increases efficiency. Increasing line pressure 15% during light cruise might be enough to stop slipping if all the seals in the transmission and the high clutch are still very good. Maybe a 40% increase would do it. It's not practical start low and see where transmissions stop burning up. Putting it close to max pressure in the main map is an easy way to definitively fix the problem and the amount of power it takes to spin the pump against the higher pressure really isn't significant--especially compared to the power loss from erroring on the other side where the high clutch still slips. |
#15
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Re: Transmission care
I would much prefer an flashable OEM ECU to a TCU upgrade on my 1996. Let the autos die!
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