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  #16  
Old 09-05-2014, 04:21 PM
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Re: '94 FWD transmission non conversion swap questions

40:9=4.44
37:9=4.11
39:10=3.90
39:11=3.545
All of the ring gears and all of the pinion gears are the same diameter.
If we are only talking about the strength of the teeth in the front and rear differentials, then the ratio with the fewest number of teeth would have the thickest teeth and there fore the strongest teeth.
In this case the 4.11 should have the strongest ring and pinion teeth.
However the 4.44 has different first and second gear TRANSMISSION ratios that are lower than all other 4EATs by a sizeable amount making that transmission easier on the band and clutches.

So, theoretically a 4.44 trans, using the 3.545 clutch basket, and a 4.11 differential SHOULD be the strongest set up.

The other day when my Claret 4.44 chipped a pinion tooth after years of abuse, I just swapped in another 4.44, reinstalled my ECUTune valve body and called it a day.

A REALLY long day becaust the trans that I bought has water damage issues.
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  #17  
Old 09-05-2014, 04:42 PM
1986nate 1986nate is offline
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Re: '94 FWD transmission non conversion swap questions

Tom, get back in the shop. I'm too lazy to type that all out...
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  #18  
Old 09-05-2014, 04:46 PM
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Re: '94 FWD transmission non conversion swap questions

One thing that I have noticed is that in almost ALL of the differential failures (regardless of ratio)
its the ring gear that breaks a tooth.
I think that the only pinion tooth that broke,
that I have seen
was on my Claret.
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  #19  
Old 09-05-2014, 04:49 PM
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Re: '94 FWD transmission non conversion swap questions

Quote:
Originally Posted by 1986nate View Post
Tom, get back in the shop. I'm too lazy to type that all out...
OK.

THey, you should have hocrest type it out for you.
He's FAST!

Hi Dave!
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  #20  
Old 09-05-2014, 05:27 PM
92 SVX 92 SVX is offline
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Re: '94 FWD transmission non conversion swap questions

lol, ok so one reason the svx fwd diff is better is because of the 37:10 teeth then?
On the fwd models obviously. And thanks I had thought there was more to the 4EAT awd vs fwd
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  #21  
Old 09-05-2014, 06:24 PM
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Re: '94 FWD transmission non conversion swap questions

Quote:
Originally Posted by 92 SVX View Post
lol, ok so one reason the svx fwd diff is better is because of the 37:10 teeth then?
On the fwd models obviously. And thanks I had thought there was more to the 4EAT awd vs fwd
Well the reason the FWDs break is that ALL of the power is going through only ONE differential!
Since the AWDs can have a 50/50 split a 3.7 AWD would be TWICE as strong!
It would be actually stronger than twice as strong as the second diff and the driveshaft sap some of the HP & TQ.
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  #22  
Old 09-05-2014, 08:38 PM
phreich phreich is offline
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Re: '94 FWD transmission non conversion swap questions

Quote:
Originally Posted by huck369 View Post
It will work, and you can just use the rear housing off the original FWD (After removing the rear Transfer unit)
Hi Huck369, et al,

I have found a local 4eat out of an AWD 1993 legacy turbo touring wagon that has 108K miles on it for $250.

Online research seems to indicate that this has a 3.90 differential ratio, which would work on the SVX.

Other responders in this thread indicate that the 4eat trannys built for the turbos have either stronger or more clutch disks in them than the non-turbo 4eat transmissions. However, some responders say that they are all the same. Does anyone know for sure?

Will there be any issues with the turbo AT's torque converter bolting up with the SVX flexplate, or do I need to use a turbo flexplate with that torque converter.

From Huck's post quoted above, I am lead to believe that converting an AWD 4eat to a FWD 4EAT is a simple matter of unbolting the transfer case at the back of the AWD, and bolting on the FWD rear case instead. Huck and others, have you actually done this (or the opposite), and know it's just that simple, or am I likely to need to disassemble the AWD 4eat and replace components at the tail end of the transmission or in the integrated differential in order to put the FWD rear case on it?

A question I have for you folks is; how to determine how much is too much wear on a used 4eat? In my experience with other ATs, there is always some clutch material, and maybe a bit of magnetic sludge in the bottom of most ATs. I understand you just don't want to find lots of either, and certainly no metal bits or fragments. The ATF should also not be dark and smell burnt. What should I expect to see in this 100K 4EAT from the '93 legacy turbo wagon? Are there any special tell-tales that I should look for one way or the other?

Is there any way to determine if the subaru 4eat transmission has been rebuilt by looking at anything on it (unless made obvious by a label or stamping)?

The other local used tranny's are much higher mileage -- 165k and up, that's one of the reasons I am interested in this tranny.

I am thinking of picking up the tranny tomorrow, so your timely advice is welcome.

Thanks,

Philip
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  #23  
Old 09-05-2014, 09:02 PM
1986nate 1986nate is offline
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Re: '94 FWD transmission non conversion swap questions

108k on a 93 turbo trans should be fine. The turbo legacy trans is the same strength in the high clutch, may have slightly less frictions in the lower clutches but I don't recall. Either way, won't be a problem. $250 is a good price. You'll need to swap around the rear housing on the transmission as mentioned and it'll work just fine in your FWD.
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  #24  
Old 09-05-2014, 09:37 PM
Tapani Tapani is offline
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Re: '94 FWD transmission non conversion swap questions

If Your own tranny has failed You may want to try to find another SVX converter. Yours will be full of debri. The turbo legacy converter has a higher stall speed and you may not like it, especially in a fwd car with lower gearing than stock.

Just something to think about. The legacy tc will bolt to the SVX flex plate.

T
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  #25  
Old 09-06-2014, 01:10 AM
phreich phreich is offline
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Re: '94 FWD transmission non conversion swap questions

Quote:
Originally Posted by Tapani View Post
If Your own tranny has failed You may want to try to find another SVX converter. Yours will be full of debri. The turbo legacy converter has a higher stall speed and you may not like it, especially in a fwd car with lower gearing than stock.

Just something to think about. The legacy tc will bolt to the SVX flex plate.

T
Can you tell me what the stall speed RPM of the stock '94 FWD SVX torque converter is vs the '93 Legacy Turbo wagon Torque Converter stall speed RPM? How far apart are they? I tried to look it up on the web, but didn't find the stock stall speed RPM specs.

Thanks!

Philip
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  #26  
Old 09-06-2014, 07:13 AM
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Re: '94 FWD transmission non conversion swap questions

Quote:
Originally Posted by phreich View Post
Can you tell me what the stall speed RPM of the stock '94 FWD SVX torque converter is vs the '93 Legacy Turbo wagon Torque Converter stall speed RPM? How far apart are they? I tried to look it up on the web, but didn't find the stock stall speed RPM specs.

Thanks!

Philip
You can use an SVX torque converter (and input shaft) with any 4EAT transmission.
If you use a 4.44 torque converter with an SVX transmission it will overheat and fail.
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  #27  
Old 09-06-2014, 04:11 PM
phreich phreich is offline
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Re: '94 FWD transmission non conversion swap questions

Quote:
Originally Posted by svxfiles View Post
You can use an SVX torque converter (and input shaft) with any 4EAT transmission.
If you use a 4.44 torque converter with an SVX transmission it will overheat and fail.
Hi Tom,

I understand that the '93 Legacy wagon Turbo tranny has a 3.9 differential -- so it's not a 4.44 TC.

Do you know what the factory TC stall speeds for the '93 turbo legacy wagon, and '94 FWD SVX are? Tapani mentioned the turbo probably has a higher TC stall speed, but it would be helpful to know what the difference actually is. I haven't been able to locate this information online.

I have asked my favorite Subaru Parts person Leah if she can find out this info. If she gets back to me, I'll post the answer here. It was surprised that some Subaru "aficionado" hasn't already posted a chart showing the differences between the various 4eat trannys used on various Subarus. It would be very useful information to have to have some tables showing the various clutch packs, TCs, and differential ratios were used in the various versions of the 4eat trannys, as well as an application guide showing what cars each version of the 4eat tranny were used on. If anyone here knows of such information, maybe you could start a thread and post it either on this forum, or on the www.ultimatesubaru.org/forum which would server a larger audience than just SVXs (and post a link to it on this forum).

Update: Leah called back and said that the '94 FWD SVX TC has a stall of 2350-2750 RPM, the early 90's turbos have a 2800-3200 RPM stall.

Thanks,

Philip

Last edited by phreich; 09-06-2014 at 05:54 PM. Reason: Updated with TC stall rpms
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  #28  
Old 09-06-2014, 05:45 PM
phreich phreich is offline
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Re: '94 FWD transmission non conversion swap questions

Okay, now that we know what the TC stall RPMs are, some further questions come up:

1. I understand that the normal lockup on the TC is done by the TCU -- and so the stall RPM won't effect the lockup from a MPG standpoint on the highway. Is this correct?
2. Given that the turbo TC has a higher stall speed, what will the effect on driveability be?

I would think that the major effect will be when the accelerator pedal is punched hard -- and then the engine RPM would be higher before the non-TCU RPM based manual TC lockup would occur. I would think that this might actually be somewhat beneficial because 3100RPM is probably closer to the maximum hp the 6cyl engine puts out. When downshifting to pass because of accelerator pedal depression, there might be more power at the higher RPM CT lockup which would cause it to accelerate faster when passing?

At lower accelerator pedal depression, the TC would engage, but wouldn't lock up until higher RPMs were reached. Would this feel sluggish, or would the driver just get used to using higher RPMs to "get off the line" when quick acceleration from a stop was wanted?

I look forward to y'all's thoughts and opinions on this.

Philip
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  #29  
Old 09-06-2014, 10:01 PM
Tapani Tapani is offline
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Re: '94 FWD transmission non conversion swap questions

The TC stall speed is adjusted to match the engine characteristics. On most cases the torque multiplication is also increased with a higher stall speed - when the speed difference is great - from stand still.

Further, a higher stall speed greatly increases heat generation - this is not good.

Stall speed is naturally affected by engine torque too.

I had an Outback 4.444 tranny + TC in my low pressure turbo SVX. Stall speed was above 3000 rpm, very frustrating - I lost all the low end grunt in the air - heat to the fluid.

Now with a stock 1996 JDM tranny + TC the stall speed is roughly 2700 rpm, I would still like to lower it to maybe 2400 rpm. Especially in higher gears the TC just churns up heat.

Lower gearing, only FWD and an increased stall speed will all add up - and take the driveabilty in the wrong direction.

Please remember this is just my opinion :-)

Kind regards,

Tapani
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  #30  
Old 09-07-2014, 03:36 PM
phreich phreich is offline
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Re: '94 FWD transmission non conversion swap questions

Does the 4eat have a TCU controlled TC lockup in addition to the TC controlled stall speed lockup, or is the only TC lockup done within the TC itself and based solely upon the TC stall speed?

I thought there was a TCU controlled lockup that would take over once the car got up to 4th gear and cruising speeds.

I found this file with a dyno test of the eg33: http://www.subaru-svx.net/photos/files/SVXtypeR/797.jpg
Given the torque and HP curve listed here, I am wondering what the higher TC stall speed will feel like. It seems it would make it seem more like a sprinter when the accel pedal was punched.

I've never dealt with upping the TC stall speed before, so I am really hoping for some more feedback. Tapani is concerned about this -- but he also went with a 4.44 ratio AWD tranny coming from a 3.5 ratio tranny. I am going from a 3.7 FWD tranny to a 3.9 FWD tranny -- no where near the difference in differential ratio.

I am planning on installing the tranny mid next week, so I hope to get some opinions from y'all on the driveability issues with the 3.9 differential ratio and the higher stall speed TC.

BTW, if there is a TCU controlled TC lockup, what is that based on -- being in 4th gear, or rpm, or what?

Looking forward to your thoughts and experiences with this.

Thanks,

Philip

Last edited by phreich; 09-07-2014 at 03:58 PM. Reason: Added dyno info, and additional question
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