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-   -   change from AWD to FWD (https://www.subaru-svx.net/forum/showthread.php?t=38803)

nick_kas 05-03-2007 04:17 PM

change from AWD to FWD
 
I was wondering if you could switch and awd svx to a fwd. I want to do this so it will be more reliable and get better gas millage. I found a trany on craigslist for 100 bucks. let me know your opinion. thanks

svxistentialist 05-03-2007 04:50 PM

Nick

It can be done because anything is possible.

Something being possible, however, is no guarantee that this is advisable.

IMHO what you have in mind here is too big a job to undertake to gain the stated objectives.

If you put a FWD tranny in as you are contemplating, this tranny will need a FWD transmission computer, aka TCU. The one currently in your car will expect signals that control the AWD functions. A FWD TCU will not expect to see or handle these signals.

Assuming you installed the FWD box, and that it was good, you need to strip out the rear propshaft driving the back axle. You will still be left with the centre unused diff, and the two axles, or half shafts as we call them over here. Ideally, to gain the lower weight of the FWD car, you need to strip these out as well.

This is way too much trouble to go to in order to gain what you are looking for.

Huck might have very good ideas on how much trouble this change you want is going to be.

I would not do it to my car to gain a few mpg.

Joe:)

Hocrest 05-03-2007 04:58 PM

I've done it, and like Joe has mentioned the AWD TCU doesn't shift properly when hooked up to a FWD trans. We tried a FWD TCU out of a Legacy and that didn't work right either, so you'll have to get one out of a FWD SVX.

The one thing not mentioned is that you'll need to come up with stub axles to replace the rear axles. These can be found in any FWD Leg, Imp or SVX.

It only stayed in until we sourced an AWD trans to go back in, so we never did get the right TCU. As for mileage, this was in the racer so gas mileage was not really a concern and was never measured.

nick_kas 05-03-2007 11:13 PM

i was thinking about putting a manual fwd transmission. So i dont think you need the computer and everything. I was just wondering if that would be possible.

svxistentialist 05-04-2007 01:50 AM

Quote:

Originally Posted by nick_kas
i was thinking about putting a manual fwd transmission. So i dont think you need the computer and everything. I was just wondering if that would be possible.

See Dave's post above. You will need a TCU to match the transmission and with the correct wiring and signals that the transmission needs.

They are not really simple devices. 4EAT transmissions are computer controlled. You need the correct computer.

Joe

huck369 05-04-2007 05:03 AM

Quote:

Originally Posted by nick_kas
i was thinking about putting a manual fwd transmission. So i dont think you need the computer and everything. I was just wondering if that would be possible.

Yes it is possiable, and easier than putting a AWD manual in.

As for the rear stubs, just dissasemble the outer stubs off the rear axles to put in the hubs, then remove the driveshaft, and rear diff.

Installing a manual is a bit of work, but less if you're just doing a FWD manual(write up in my sig)

svxfiles 05-04-2007 06:42 AM

Back when Subaru made both fwd and awd cars, the fwd's weighed 90#s less, and got 2 mpg better.
They also had smaller tires, and handled like crap compared to the awd's.
I'm keeping mine AWD!

lhopp77 05-04-2007 07:31 AM

Partially Correct
 
(removed double posting)

Lee

lhopp77 05-04-2007 07:37 AM

Partially Correct
 
Quote:

Originally Posted by svxfiles
Back when Subaru made both fwd and awd cars, the fwd's weighed 90#s less, and got 2 mpg better.
They also had smaller tires, and handled like crap compared to the awd's.
I'm keeping mine AWD!

Partially correct. They had the same size tires and handled fine. Just not quite as good as the AWD. They were quicker because the gear ratio was a little lower, but of course there was a little more torque steer. I would actually think the weight difference was greater than #90. It was lighter tranny (no rear transfer), only rear axles stubs instead of full axle shafts, no rear differential, no driveshaft assembly and no rear subframe for rear differential mounting. The front axle shafts were heavier (read stronger) than on the AWD.

What you are proposing is a valid option if costs are a consideration and AWD traction is not needed. I actually preferred driving my 94 FWD over my 92 AWDs except in bad weather. I think if you check FWD owners, they well tell you they are quite happy with their cars. For all around driving I do prefer my 96 AWD. (My 94 would outrun 2 of my 92s both off the line and top end and it had significantly more miles than either of them. Also, one of the 92s had a K&N cone filter (not recommended) and a stebro exhaust and still lost.--on the track of course :) )

Lee

svxfiles 05-04-2007 08:22 AM

Quote:

Originally Posted by lhopp77
Partially correct. They had the same size tires and handled fine. Just not quite as good as the AWD. They were quicker because the gear ratio was a little lower, but of course there was a little more torque steer. I would actually think the weight difference was greater than #90. It was lighter tranny (no rear transfer), only rear axles stubs instead of full axle shafts, no rear differential and no rear subframe for rear differential mounting. The front axle shafts were heavier (read stronger) than on the AWD.

What you are proposing is a valid option if costs are a consideration and AWD traction is not needed.

Lee

Partially correct.:p
The tires were smaller.
The Certificate of Origin stated a #90 lesser weight.
They cost about $1000 less, when new, and their resale value was around $1200 less after one year, at that time.
So no one bought them.
BTW, I sold new Subarus from 1983-2004.

JaySVX 05-04-2007 11:23 AM

Crazy yet potentially plausable idea, and would make things a WHOLE lot easier. Take your awd, and ask if anyone wants to trade their fwd with you. No rebuilding your car, and chances are, they'll be quite eger to take you up on the proposition.

It's Just Eric 05-04-2007 12:06 PM

Coming from a guy who has had a fwd svx, and bought TWO awd svxi with bad trannys...the fwd is jus...missing that subaru charm. Sure, having gobs of torque steer might be fun for scaring your little sister, but everytime yu need to pull out in traffic you'll feel like an ass. Ever seen a guy chirp second in a civic? Youll look almost like that.
As far as swapping for reliability...you can swap out damn near any trans and have it more reliable. Or hell, you can even just install a trans cooler and stop driving it like your in the next installment of the fast and the ficticious (Which, youd have an even harder time doing if you swapped to fwd in the first place)
And for gas mileage...there's theese aesome tire valve caps thatll get ya to 45 mpg :rolleyes: But more seriously...the money and time invesed into a fwd conversion could easilly be spent on a fresh synthetic oil change, new air filter, a few extra pounds of air in the tires, and some genral matinence stuff like o2 sensors and whatnot.

huck369 05-04-2007 12:34 PM

Quote:

Originally Posted by It's Just Eric
Coming from a guy who has had a fwd svx, and bought TWO awd svxi with bad trannys...the fwd is jus...missing that subaru charm. Sure, having gobs of torque steer might be fun for scaring your little sister, but everytime yu need to pull out in traffic you'll feel like an ass. Ever seen a guy chirp second in a civic? Youll look almost like that.
As far as swapping for reliability...you can swap out damn near any trans and have it more reliable. Or hell, you can even just install a trans cooler and stop driving it like your in the next installment of the fast and the ficticious (Which, youd have an even harder time doing if you swapped to fwd in the first place)
And for gas mileage...there's theese aesome tire valve caps thatll get ya to 45 mpg :rolleyes: But more seriously...the money and time invesed into a fwd conversion could easilly be spent on a fresh synthetic oil change, new air filter, a few extra pounds of air in the tires, and some genral matinence stuff like o2 sensors and whatnot.

I figure he has a bad tranny, and looking at options...

We had a 1990 AWD Legacy that toasted the tranny, and I couldn't find a AWD tranny (in my budget:rolleyes: ) but found a FWD tranny for $200, put it in, and never had any trouble out of it, (shifted perfect) still using the AWD TCU....I didn't even remove the rear diff, just left the driveshaft out (wish I had kept the 4.11 rear diff now...)

lhopp77 05-04-2007 12:34 PM

Wrong
 
Quote:

Originally Posted by svxfiles
Partially correct.:p
The tires were smaller.
The Certificate of Origin stated a #90 lesser weight.
They cost about $1000 less, when new, and their resale value was around $1200 less after one year, at that time.
So no one bought them.
BTW, I sold new Subarus from 1983-2004.

No matter that you sold Subies---the tires were NOT smaller. All 97 models had smaller tires, but prior to that all were the same. I did not argue about what the documents stated for the weight difference---I said I "thought" it would be more because of all the items I listed. :)

Find me a single 94 with stock wheels and tires that are smaller. :p Remember---I owned one. In fact it was the lowest level model ever produced--the LE. (It is still in the family.) On it I could have added the lack of ABS brakes as another weight subtraction. (The ABS pump and toner wheels.)

Lee

Delfonso 05-04-2007 07:35 PM

AWD TCU compatibility
 
So there seems to be a disagreement about whether or not an AWD TCU will work with a FWD transmission. My TCU needed replacing in my 94 FWD and for a quick fix I found the TCU out of a 92 AWD. Afterwards, my car is showing symptoms of a misadjusted TPS, such as no power mode. I'm gonna get a voltage meter on it today, but (question) there's no difference in the TPS between years (92/94) or transmissions (AWD/FWD) is there? I'm running the ECU out of the same 92 AWD as well.


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