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Old 10-09-2000, 06:00 AM   #1
CRZ_MSL
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Join Date: Jun 2000
Exclamation Preventing Subaru Auto-Trans Failure

It seems that someone(?) thinks that Subaru slushboxes are not as beefy as they could be.

If anyone knws about the shortcomings of Subaru auto-transmissions, and how to rectify them, it is SVX owners.

The 4EAT is a Nissan designed transmission used in cars such as the 300ZX, Infiniti Q45/ Nissan President, Sylvia /240SX, Maximia, and IIRC the Mazda 929.

It was/is also the automatic transmission of choice for Subaru.

The primary reason for automatic transmission failure is heat. The stock SVX transmission cooler is a single tube, easily clogged (there is even a procedure the dealer is supposed to do to unclog it) and not up to the task of cooling abused transmission fluid.

There are three things you can do to address the problem (in addition to regular fluid changes):
1) Transmission cooler. Cost: < $125

2) Clutch pack upgrade. You can upgrade the solenoid clutch pack for increased flow. Some argue that this is actually better for your transmission than just an aftermarket cooler. Level-10 provides these, and I think Kinetic Concepts has/will have one available. Cost: $800(?)

3) Complete transmission upgrade. Send your transmission to Level-10 boot camp and it will come back to you with upgraded torque converter, clutch plates, clutch packs, a special sauce in place of the normal fluid, and the ability to take 150% over stock horsepower. These guys do auto-transmissions for racing in Saudi Arabia. And for $3500 they will do yours.


Currently I have a 10"x12" stacked plate transmission cooler installed in my car. I have a temperatue gauge in the lower gauge pod hooked up to it. The gauge reads temps as low as 133 on a cool night, and as high as 205 on a hot day with the AC running in stop-start traffic. On even the hottest days with the AC on in free-flow traffic I don't see temperatures above 195. I wonder how hot things were getting with the stock cooler.
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Old 10-09-2000, 06:59 AM   #2
Overtime
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Post

Interesting stuff...

I believe the Probe/MX-6 use the same 4EAT, but don't quote me on that.

Interesting, though, to hear that the Impreza got what seems to be a strengthened tranny compared to the SVX-at least, it doesn't seem to experience any of the problems the SVX is having.

Anyone know some of the differences between the two?
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Old 10-09-2000, 11:33 AM   #3
webkris
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I sold WRX to buy
Dodge Neon Rally Car

Lightbulb

I documented installing a trans-oil cooler. I'm glad it's there - I beat on my car http://karguyzine.tripod.com
- Kris
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Old 10-09-2000, 01:34 PM   #4
MPREZYA
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How similar is our 4eat to the 300zx. I ask as HKS has a tranny controller that improves line pressure on the 300zx auto's. Any info on this will help.
Rich
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Old 10-09-2000, 04:12 PM   #5
cvalle-sd
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Lightbulb

The two biggest differences I can think of are power input 165/149hp and competition fo r cooling resources - I think the radiators for the Impreza/SVX are identically(Similarly?) sized, but the svx has a tiny frontal area, as opposed to the Impreza's basically open-air setup, especially with the scoop and vents open (ha ha I said frontal), and has a huge hot engine. The stock tranny cooler is really an appendage of the engine cooler. I'd bet that under extreme conditions, you'd get heat soak back into the tranny.

aka "Alfaru"

ps - I'd love to see an SVX with Imp-style hood vents/ducting to the radiator
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Old 10-10-2000, 06:43 AM   #6
suby2nr
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About 1990 manufacturers were changing from asbestos to other materials in the cluth plates. Some of these materials give off more fibers into the trans fluid causing trans coolers to clog and shift valves to stick leading to trans failure. Subaru began a program, they don't like to call them recall's, to install an inline filter and back flush the cooler on legacy and SVX. By about '93 they claim the problem was repaired in production and say a filter retrofit is not needed although since '99 the transmissions have a external filter on the trans. Sometimes subaru won't release a cooler kit without a serial number from a covered vehicle (90-92). The 93-94 legacy turbo has a factory installed filter if you need a filter. A filter is not a bad idea along with an external cooler instead of the one in the radiator. Pull off the return line to the trans, aim it towards a large pan and start the engine to check cooler flow if your using the stock cooler.
Ed @ ISR www.autocaresubaru.com
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Old 10-10-2000, 06:06 PM   #7
Daios
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So getting a cooler for our auto trannys would be the way to go or at least the first step? Is that cooler from Pepboys really all that good? As compared to other aftermarket AT coolers. I think i might go and get one so I feel safer knowing my tranny oil is cooler. Oh and where would I get a temp gauge to find out what the temp is in the tranny? Is it easy to install?

-Daios
MY00 BRP SeDan
"Go Auto Tranny!"
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Old 10-10-2000, 06:16 PM   #8
cvalle-sd
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Thumbs up

The ones you can get from Pep boys are pretty good - other makes might be more sturdy, but in my SVX, I had the tranny cooler between the AC and the radiator, so it wasn't really an issue.
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Old 10-11-2000, 05:06 AM   #9
redwagon
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While I agree with you that heat is the root of all evil, you can still attack that at the cause by increasing shift pressure. The fluid gets hot from pumping, churning in the torque converter and conducted heat from the engine. BUT, most of the heat is inshifting, and the damage done in the trans is done to the plates and bands. You can increase plate life by decreasing the time the clutch packs take to engage by increasing line pressure. I don't know if kits are available for Subaru models, but they should be. You might have to look to Japan.
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Old 10-11-2000, 07:30 PM   #10
Kevin Thomas
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1989 1989 XT6

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Redwagon,

You may not have to look as far a Japan at all. *Hint, Hint* Keep your fingers crossed. Something new may be springing up very soon. I'll be sure to post it once it's completed on my car.

On a side note, at WOT, isn't your car at full line pressure? If this is the case, than how could you wear our your plates and everything else any quicker if you have full line pressure at WOT?

[This message has been edited by Kevin Thomas (edited October 12, 2000).]
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