99 rs 4eat

azn2nr · Post by **azn2nr** » Mon Sep 27, 2004 7:18 pm

if i just swap the trans out of a 99rs and put the rear diff in form the rs too does the front diff come with the trans or is it a seprate part?

also when swaping a motor in that was a 5mt and putting it with 4eat i know it will bolt up but will there be any other problems i will face hooking it up?

lastly what all is involved in a rwd conversion? ive seen ppl talking about it on nabisco but no details. anyone here know

BAC5.2 · Post by **BAC5.2** » Mon Sep 27, 2004 8:07 pm

The front diff is contained in the tranny, as is the center diff.

A motor from a 5MT will bolt right up to a 4EAT, and as long as you have the correct ECU, wiring, and TCU, everything will work just fine.

I've never heard of RWD being accomplished on a 4EAT, and I don't think it can really be done.

http://www.ninosautoaccessories.com/pro ... cts_id=152

That's the RWD conversion kit, and it's the easiest I've ever seen.

Post by **Legacy777** » Tue Sep 28, 2004 2:16 am

Any idea how the RWD conversion works and what is replaced without removing the tranny?

vrg3 · Post by **vrg3** » Tue Sep 28, 2004 2:26 am

I believe the 5MT RWD conversion kit basically replaces the rear differential with a gear arrangement that just sends power straight from the transmission's output shaft to the rear propshaft.

Couldn't you convert a 4EAT to RWD by disconnecting the solenoid that regulates MPT clutch lockup (thereby leaving the clutch fully locked up) and then removing the front axles? You'd want to seal up the openings in the front differential somehow (maybe you could just cut off the axles just past the stubs and let then spin around doing nothing). Wouldn't that work?

BAC5.2 · Post by **BAC5.2** » Tue Sep 28, 2004 3:31 am

Vikash - I suppose that would work, but I've never seen anyone do it, and I have my reliability questions about doing something like that.

WRXdan · Post by **WRXdan** » Tue Sep 28, 2004 3:42 am

vrg3 wrote:I believe the 5MT RWD conversion kit basically replaces the rear differential with a gear arrangement that just sends power straight from the transmission's output shaft to the rear propshaft.

Couldn't you convert a 4EAT to RWD by disconnecting the solenoid that regulates MPT clutch lockup (thereby leaving the clutch fully locked up) and then removing the front axles? You'd want to seal up the openings in the front differential somehow (maybe you could just cut off the axles just past the stubs and let then spin around doing nothing). Wouldn't that work?

I might try a RWD converstion on one of my 4EATs. I think I will try to weld up te transfer clutch. The hard part is what to do with that front diff. The front diff drives the speedo, and the trans brake locks the front shaft. I would love to just remove the whole front diff and save on rotation weight. But I need a speedo. Maybe convert to a total electronic speed??

THAWA · Post by **THAWA** » Tue Sep 28, 2004 5:24 am

BAC5.2 wrote:Vikash - I suppose that would work, but I've never seen anyone do it, and I have my reliability questions about doing something like that.

why, cause it's an auto?

vrg3 · Post by **vrg3** » Tue Sep 28, 2004 6:04 am

THAWA - Probably cuz he's worried about pushing the MPT clutch too hard.

Phil - I don't think you'd need to worry about pushing the MPT clutch too hard. Clutches wear the least when they're not slipping, right?

Dan - You can make yourself a VSS by just epoxying little magnets to the driveshaft and putting a reed switch near it. Maybe you could then retrofit a speedometer from a later Subaru after they switched to having the VSS bolt to the transmission?

BAC5.2 · Post by **BAC5.2** » Tue Sep 28, 2004 6:12 am

Good point Vikash, that's where my durability concerns came from, but as anyone who has toasted a clutch will know, once it starts to slip, there's nothing that'll save you.

I'd just be worried about replacement down the line, that's all. With a converted 5MT, there isn't a center diff clutch to wear out, just a more accessable, and more durable clutch to replace (you can get an Exedy Hyper-Single for 900 bucks and never have to worry about that half of the car again).

Mmm, RWD WOULD be fun, but I just couldn't bring myself to convert a Subaru to RWD. Not unless I had a spare one that I didn't care much about.

Why couldn't you use the ABS sensors to calculate speed? Isn't that how some cars calculate speed?

vrg3 · Post by **vrg3** » Tue Sep 28, 2004 6:17 am

You might be able to use the ABS sensors, but it would actually be easier to do what I described. The ABS speed sensors are variable reluctance types, which aren't trivial to interface with. And their frequencies are a lot higher than the stock VSS, I think.

Post by **Legacy777** » Tue Sep 28, 2004 2:51 pm

vrg3 wrote:I believe the 5MT RWD conversion kit basically replaces the rear differential with a gear arrangement that just sends power straight from the transmission's output shaft to the rear propshaft.

You're talking about the rear diff in the car? or the center diff in the trans? I'm still not getting how this kit works without opening up the trans.

vrg3 · Post by **vrg3** » Tue Sep 28, 2004 3:57 pm

Sorry, yeah, I mistyped. It replaces the center differential with a gear arrangement that just sends power straight from the transmission's output shaft to the rear propshaft.

azn2nr · Post by **azn2nr** » Tue Sep 28, 2004 5:42 pm

would a standalone take care of the ecu problem?

and im stupid but what is a tcu?

BAC5.2 · Post by **BAC5.2** » Tue Sep 28, 2004 5:55 pm

Would a standalone ECU take care of what problem?

TCU = Transmission Control Unit, IIRC

Post by **Legacy777** » Tue Sep 28, 2004 6:47 pm

vrg3 wrote:Sorry, yeah, I mistyped. It replaces the center differential with a gear arrangement that just sends power straight from the transmission's output shaft to the rear propshaft.

yeah but from the link posted above, it says "This kit allows the user to easily and simply convert his or her car to RWD without removing the transmission from the vehicle."

Are we talking about the same kit? Can the center diff be taken out without dropping the trans?

vrg3 · Post by **vrg3** » Tue Sep 28, 2004 6:52 pm

Yes, the center diff can be removed with the transmission in place. Morgie replaced his once and took really useful pictures:

http://public.fotki.com/morgie/morgie/l ... nter-diff/

azn2nr · Post by **azn2nr** » Wed Sep 29, 2004 12:54 am

BAC5.2 wrote:Would a standalone ECU take care of what problem?

TCU = Transmission Control Unit, IIRC

you said in your first post that you would need the corect ecu. and tcu.

so would you need the tcu from the at trany and the ecu from the motor. or both ecu and tcu form the automatic car?

my object here is i want to put a ver 4 sti motor in my car but dont want the hassle of converting it to hydro mt. since my car is an auto and rs automatics are readily availible with the rear ends i just want to swap the trans first. or the motor first wichever is easiest to do. the motor im looking at has a ecu with it but stis never ( or so it is said) came in auto form. so my problem is which electornics go with wich parts to make this work.

BAC5.2 · Post by **BAC5.2** » Wed Sep 29, 2004 1:07 am

If you swapped an engine, you will need an ECU to handle it. Your stock Turbo Legacy ECU won't be able to control an Ej20T. So yes, you will need some ECU to be able to control the EJ20T. You'll also need something that will control the tranny. Swapping to a 5mt isn't going to be much more of a pain in the ass than swapping an EJ20T and wiring it all up.

azn2nr · Post by **azn2nr** » Wed Sep 29, 2004 1:24 am

ok now im confused.

if i just swap the engin into my car now and keep the stock trans all i would need is an ecu that can "handle" the motor no mater if the motor had a mt of an at on i before? correct.

and if after i did the motor swap and my trans goes to hell (again) i can swap my at out for an at out of a rs with no problem as long as i have the tcu to control the tranny? right.

correct me if im wrong but thats how im understanding it right now.

Post by **Legacy777** » Wed Sep 29, 2004 1:49 am

hmmm so you just have to remove the rear tailshaft.

I still think it would take longer then they say on that site.

vrg3 · Post by **vrg3** » Wed Sep 29, 2004 2:31 am

Jason - You may have a hard time using a 99 RS TCU without an ECU from the same era... from what I understand there's some communication between the ECU and TCU in newer cars.

azn2nr · Post by **azn2nr** » Wed Sep 29, 2004 6:33 am

well the ecu would be from the same era being from a ver 4 sti. just if they will work together is my delima.

in the end im shooting for a jdm ver 4 sti hooked to a 4eat out of an rs. that way i get the performance i want and still be able to upgrade the body when this one gets toasted.

BAC5.2 · Post by **BAC5.2** » Wed Sep 29, 2004 7:39 am

I think it'd be easier to swap the 5MT over than to try and figure out the wiring between the ECU and the TCU.

Where are you getting a V4 STi motor? That's pretty old, so I hope you aren't paying a ton. $2500 or so and you can get a V7 motor.

I've seen V6 front cuts go for $3500 on e-bay, and that comes with EVERYTHING you need. I almost want to buy a GM6 and a JDM STi front cut and swap it all up RHD and all

azn2nr · Post by **azn2nr** » Wed Sep 29, 2004 9:43 am

theres a local guy that gets them. 2500 wont get you a v7. my neighbor got a 95 wrx motor for that much and thats just the motor. he also has a v5 in his garage with the trans. i just need the hydro equiptment and pedals and rear end to put it in. the only problem with that is that its obd2 suposedly and wireing would be a bich. ver 4 isnt that old though just MY96.

someone on nabisco said that the jdm motors are actualy obd1 up till ver7 in wich case ill get that because that was my target in the first palce.

converting to manual would be easier with an entire front clip as in the car just cut in half because most of the parts should be there except for the rear end.

i still think that somehow keeping it auto and just changing the motor and trans would be easier i just need to figure out how. if not ill just go manual. thers got to be a last resort somewhere

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99 rs 4eat

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