'94 FWD transmission non conversion swap questions
 

Hi,

I've read a lot of stuff on this forum regarding SVX tranny swaps, but most seems to deal with MT conversions, or FWD to AWD conversions. There are a lot of posts out there dealing with AWD transmission replacements, but not much on FWD swaps, so I have started this post to try and get some expert opinions on issues related to doing a FWD to FWD automatic tranny swap from a non-svx Subaru donor vehicle.

Background on my situation:
I've got a '94 FWD SVX with a blown automatic tranny.

Getting the transmission rebuilt is very expensive, so I am looking to get a good used one. However, as you all know, the used FWD SVX tranny's are rare and go for a premium.

I am not interested in doing a FWD to AWD conversion, nor am I interested in doing an AT to MT conversion. I just want to stick with a FWD 4EAT 4spd automatic.

Here are some questions that would be very helpful to get addressed by you knowledgable folks:

1. First off, I'd like to verify some assumptions based on the research I've done so far:
   • a. Is it true that since 1989, just about all the 4spd automatic transmissions subaru used are basically the same 4eat tranny -- the main difference is the gear ratio in the differential. Of course the FWD and AWD trannys are different because the FWD does not have a built in transfer case and rear output shaft.
   • b. I understand the gear ratio for the FWD is a bit higher -- the FWD is 3.7 instead of the 3.5 used in the AWD SVXs.
   • c. Subaru stopped making FWD cars after 1995, and few were made in 1995.
   
   
2. I have talked to a couple of people who have said that the 4.44 ratio trannys may last longer due to the increased ratio, but the fuel use will increase dramatically. Soooo, I was wondering what ratio you folks would suggest to get the best of both worlds -- better longevity and okay fuel economy? 3.9 possibly?
   
   
3. Is there a particular model, trim and year of non-svx FWD Subaru donor car I should be looking for?
   
   
4. Do I need to be concerned about the TCU with the ratio change?
   
   
5. How do I get the speedometer re-regulated to work with the changed ratio?
   
   
6. Any particular years to avoid? Any that would be better?
   
   
7. What about turbo vs non-turbo trannys? I think there were a few FWD turbo subarus made.
   
   
8. Any worries about stub shafts matching, or TCU issues?
   
   
9. Any concerns about wiring harness issues?
   
   
10. I understand that there was a change in the transmission fluid filter and screen? Does this really make a difference in the longevity of the tranny? If it does, is there a recommended type and a range of years when it was used?
    
    
11. Any reasonably inexpensive upgrades that I can do to help preserve the replacement tranny besides running synthetic fluid and using a tranny cooler? Is there a "shift-kit" that would be a good idea that doesn't cost too much?
    
    
12. I plan to install a transmission cooler when I replace the tranny to help keep it cooler. Any suggestions on location for the cooler?
    
    
13. I am thinking that it might be helpful to post an update with the results of the swap, along with any notes and issues that surfaced during the swap. Do you think I should add those posts to this thread, or start a new thread and have a link in this thread pointing to it?

Thanks for your opinions and thoughts!

Philip

Re: '94 FWD transmission non conversion swap questions
 

I will attempt to answer your questions;


1. yes,yes,yes

2. If you can find a 3.9 FWD go for it.I can't speak for how much of a difference you will see from 3.7 to 3.9 but I can't imagine its huge.

3. Not sure, I know early imprezas had FWD

4. No TCU change is needed, keep the FWD with FWD and you will be fine.

5. No it should be fine. there is a gear mechanism in the transmissions that give speed based on rotation. You do not need worry about that. Although I think higher ratio might put it off a slight bit (I am not 100% but nothing to be worried about).

6. Not that you can, but avoid Phase II 4EATs (not compatible nor come FWD)

7. Not sure of any in the US anyways. I believe the loyales and etc were all 4wd that came turbo.

8.No, you can pull the old stubs if needed and put them in the new trans. IIRC they should all be male and correct spline count.

9. No should all plug and play

10. No but you should change it when you put it in to be sure.

11. All the shift kits do is raise the pressure, I don't think anyone has confirmed that it helps in the long run.

12. Front drivers side wheel well (in front of the tire). If you live in a climate that gets cold you might run into problems with the tempature not reaching the correct operating temp. If so you will have the TC unlock at highway speeds if I recall correctly. I lived in central NC and had a cooler on my FWD. I don't recall running into this problem but it wasn't usually below freezing.

13. You can do either but if you do it here the search will pick up on everything you asked and hopefully provide some feedback from you.

Re: '94 FWD transmission non conversion swap questions
 

I just saw you are from Milwaukie about 35 mins from me. If you have questions, need help etc feel free to reach out. Pulling the FWD trans is easy to an extent.

Re: '94 FWD transmission non conversion swap questions
 

It will have to be a FWD 4EAT out of either a Legacy, or an Impreza, the Loyal, and XT's used a different bell housing and won't bolt up to the EG33.

The Speedo will be off depending on the difference in the circumference of the SVX's wheels compared to the donor cars tires....some early Impreza had 13" tires...

I think there were a few FWD Turbo Legacys, which should have the extra clutch packs, and "Should" be a better transmission...but were probably abused more too....

Re: '94 FWD transmission non conversion swap questions
 

Huck, all turbo legacys were awd. Any fwd transmission is going to be the absolute weakest version of them all. aka, minimum friction discs used. The SVX FWD was 3.70, any legacy or impreza is 3.90. That's the only option out there and they are few and far between.

Re: '94 FWD transmission non conversion swap questions
 

Ok I'm going to ask a very stupid question.
Here goes... What if you used a 4wd tranny and not hooked up the rear wheels?
I suspect it will throw codes. But would it work at all ? Just inquisitive.:confused:

Re: '94 FWD transmission non conversion swap questions
 

It will work, and you can just use the rear housing off the original FWD (After removing the rear Transfer unit)

Re: '94 FWD transmission non conversion swap questions
 

That would get you a weaker 3.54 geared front diff though?

or I suspose you could get any gear ratioed trans you wanted but still weaker because they are designed for both front and rear drive?

Re: '94 FWD transmission non conversion swap questions
 

OK, I waited.
Swapping a FWD Subaru transmission is a very easy swap!
No driveshaft, no rear end.
Just get the lowest mileage or rebuilt FWD Subaru transmission that you can find from a 1990-1995 subaru and be done with it!
IF you use a 4.44 with a FWD tailshaft all you will do is spin the tires!
The Legacy and the Impreza almost weighed the same, but I suppose that the Legacy driver had a lighter foot.
You can get a FWD Subaru trans for about $250 and up, good luck to you Sir.

Re: '94 FWD transmission non conversion swap questions
 

Looking for those 30 / 35 year old tran. can't be too easy to find.

Re: '94 FWD transmission non conversion swap questions
 

Where did you go to school?

Re: '94 FWD transmission non conversion swap questions
 

Fwd and Awd transmissions are identical save for the rear housing and few parts inside.

Re: '94 FWD transmission non conversion swap questions
 

Plus with FWD you would spin tires before burning up the clutches....:D

Re: '94 FWD transmission non conversion swap questions
 

I was under the impression front diff would blow, not the trans.

something about the gear width or something?

Re: '94 FWD transmission non conversion swap questions
 

It's all the same gears. Only difference is tooth counts on the differential. Everything else is 100% identical through the transmission with only having a set of sun gears with no transfer basket to house the clutches in the rear.