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DIY: Auto To Manual Swap

349K views 420 replies 128 participants last post by  gc_soobs9 
#1 · (Edited by Moderator)
IMPORTANT, IF YOU DO NOT HAVE THE ABILITY OR UNDERSTANDING TO REMOVE AN ENGINE AND A TRANSMISSION, YOU WILL NOT BE HELPED BY THIS INFORMATION, THIS INFORMATION REGARDS PROBLEMS THAT WILL BE ENCOUNTERED DURING AN AUTO-TO-MANUAL SWAP

THE FOLLOWING WILL/MAY BE LOST DURING A CONVERSION

CRUISE CONTROL
ABS (believed to be solved by retaining the TCU and using a resistor to give the TCU the illusion of being in neutral, this doesn't solve cruise control) read more here Legacy Central -- Transmission Conversion and here '98 RS 4EAT to 2000 RS 5MT w/ LSD - NASIOC

CREDIT! I received a large amount of technical and mechanical help From SleepySubieSleepySubie on my project, All credit goes to him, I provided the garage and the budget for this learning experience. CREDIT!


This covers an RS Transmission swap, more specifically a 98 RS Auto to a 2000 RS Manual,

Step 1: Parts collection (the following is specific to my situation, specifics may vary without notice)

Manual Transmission (including mounts)
Matching Shifter Linkage (includes bushings/nuts bolts ect.)
Matching Shifter (Ensure that you have ALL bushings and screws)
Matching Flywheel and Clutch/Pressure Plate
Matching Clutch (master and slave) and Pedals NEED CONFIRMATION, on brake pedal engage switch
Matching Manual Starter
Manual Driveshaft
Manual Rear differential (be sure to match gear ratios, consider this a great time to upgrade to LSD)
Manual ECU Not Required but fuel maps are different between the two. (Same year/trim as your vehicle RS gets RS, L gets L, WRX gets WRX)
your model/trim shifter trim and shift knob (Auto shifter trim offers enough clearance for proper shifting with a short shifter without modification)

We used the 98 RS Automatic CV Axels for both front and rear, if you check with any retailer of rebuilt or OEM replacement parts they tend to use the same part number for both auto and manual variants, which could show either that these parts are the same or that these retailers don't care, I'm going with the first as the 2000 rs axels appeared identical to the 98's (in the rear, the fronts had the ABS ring on the axel vs on the hub no spline additions or extras aside from that) they will, however, charge extra for one or the other left or right on the LSD rear axels, but we couldn't order either to be sure since none of the retailers had any in stock or capable of being ordered.

!!!! If you collect a transmission from a year/model that is not of your own, such as in my case where I purchased a 2000 RS transmission for my 98, you MAY need to keep your speed sensor as the connector varies.

Step 2. Mechanical breakdown (Simple as dirt because this is covered in other DIY's in the forum)

remove the engine, trans, drive shaft, and rear differential.

you will have to remove the shifter trim and separate the automatic shifter from its arbitrary linkage, there will be a few bolts most likely stuck to some degree which you will need to separate from the transmission, if you wish to sell it, you're gonna want to leave that sucker intact. now, what you do with the shifter itself is up to you! As long as you leave the little clips with wires leading away from the shifter alone you will be fine.

Continue to split the Transmission from the engine if you didn't during your original removal process.

At this point, you can check the speed sensor on your transmission, if the replacement transmission has the same sensor you can keep it, if not, simply remove the old one from your automatic and put it in the manual trans.

If your automatic transmission is 98 or older, and your replacement transmission is 99 or newer you will notice that the transmission has 6 bolt locations while your motor has 4.

This will cause no imminent threat to your project! it will cost you another 10-15 dollars. We had to tap a new hole into the starter and purchase a larger bolt to bolt the second end of the starter down, this also requires you to expand the hole on the 2000 MT5 Starter. This secures your starter properly and taping the whole larger doesn't hinder your future USDM WRX swap.

Obviously, you will need to remove the torque converter and flex plate from your engine. and proceed to replace it with your matching clutch, pressure plate, and flywheel. You can now reattach your engine and transmission and put them back into the car. (If you haven't done this before, I suggest installing the starter after the engine/trans are securely in place, less to get caught on)

You will want to install the shifter linkage before you insert the drive shaft as it's going to get in your way, kartboy bushings are great to do now rather than later. and since you're playing with it, go ahead and install the shifter. (leave the trim off till you're done)

Proceed to install the new rear differential and drive shaft, and reinsert the old axles (for the front, you may want to purchase new pins for the inner connection between the axles and transmission)

Step 3: Some assembly required

Now you're going to need to take apart the lower portion of your dash on the driver's side, and gain access to your ECU this will be under the passenger's feet, covered by a metal kick plate.

Start by replacing the ECU (the same years/trims will clip right in)

Next, we will go over to the Pedal box

the pedals you should have purchased need to match your clutch cylinder, from my findings on the 98 (I haven't had the privilege to search other auto or mt5 vehicles other than my own and the donor car)

You will notice the TCU dangling there or bolted onto the Auto brake pedal, this has to be removed, but according to what I've read this controls your ABS system, removing it kills automatic ABS, one simple solution is to get a fully manual wiring harness, manual abs unit, and controller. but that isn't so practical (unless you're doing a WRX swap in which case you really don't need to be reading this) regardless there is information about this problem at the top of the page to refer to, as information is found I'll add it to the DIY

If I am assuming correctly, the manual brake pedal and auto brake pedal are the same, or I'm wrong and the 98 was wired for both pre and post-brake pedal boxes either way you should get lucky and the connectors match or you have both in there, the clutch side, on the other hand, you won't be so lucky, you don't have a clutch switch. there are two options here. you will run a 12 gauge wire directly from the ignition to the starter (yes the starter on the transmission) OR you will run a wire from the ignition to the clip on the clutch pedal (standard spade connectors fit snugly) and run a corresponding one out, all depends on how much you trust yourself to start the car in neutral or with the clutch depressed.

Now for some more wire housekeeping, now if you return to your shifter area you will notice your funny little shifter wiring, ** due to me having lost the pictures I'll be blunt and explain till I get the visuals up** here you have 4 wires on one clip and two on the other, the 2 others light up an indicator to help you figure out what mode you are in when it's dark, it's useless. The other 4 have a great purpose, 2 control a locking motor to keep you from exiting park while the car is off and the other two dictate that it IS indeed in park, (this allows two things, ONE it allows you to take your key out, and two, it turns the fuel pump on, which is kinda important!), the simple man's way of doing it would simply be to take the two that activates the switch (easily known as the ones that DON'T go to the locking motor) and splice them together and retain the clip and plug it into the shifter harness and toss the shifter.

Finally, we return to the engine bay, the following you will have to find wiring pinouts on your own, I will post the RS ones when I post the pictures

you will need the reverse lights, there is also the neutral position switch (I haven't looked it up but we believe its for cruise control which you cannot use anymore), both send a signal, so one goes to ground, and one goes to the reverse light pin. The best way to do this is to locate the Auto wires per those pins and splice them into the transmission sensor wires as you wouldn't want someone hitting you because your reverse lights weren't on. and that's it for wiring!

In a way, you could almost say that you're done! But for obvious reasons, you will want to check and double-check that all of your exterior lights are working as they should. Between now and when you turn the car on, please ensure you have emptied out and refilled both your differential and transmission with new fluid, and unless you're crazy and lifted the engine with the radiator you're going to need to refill that as well.

And as per any DIY ESPECIALLY THIS KIND

I AM NOT RESPONSIBLE FOR ANYTHING YOU BREAK/SHORT/DESTROY DURING THIS PROCESS, OR ANY FAILURE OF THE VEHICLE DURING NORMAL OPERATION, NOR AM I LIABLE FOR YOUR VEHICLE IF ANY BREAKING SYSTEM FAILS AND/OR CAUSES AN ACCIDENT THAT LEADS TO YOUR INSURANCE COMPANY REFUSING TO PAY DUE TO UNANNOTATED MODIFICATION OF YOUR BREAKING SYSTEM

** I TYPED THIS ALL IN ONE SITTING I'M PROOFREADING IT AS WE SPEAK Images will be uploaded soon for now, here's a video of sleepysubie starting my car with no exhaust *

Impreza 2.5 RS No headers - YouTube
 
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#324 ·
I got it done for $1000 - I bought a wrecked RS and stripped it, then mounted everything up.

I guess $1200 if you count fluids all around and bushings.

Then again, I sold the auto tranny, other motor, and other misc. parts over the course of a year or two and probably made money on the conversion. If you have the room, and come across a wrecked RS, it's worth the hassle in my opinion.

Same goes with everyone having issues with the pinout. If you swap the main harness you end up with a fully functioning car - no 2000RPM idle, no weird stuttering or the ECU being put into limp mode - it all just works.

But to each their own. I appreciate people doing the hard work of trudging through the electrical gremlins to respond back to people here. We need this kind of community to enable new owners.

-TC
 
#322 ·
I spent roughly $500 on the swap itself, but I also got the trans, axles, shifter bushings, pedals, and diff for free. I would say it could cost up to $2,000 for everything at the most if you can't find any deals. Try to find any cars that might be wrecked or parting out and get it as a bundle, you'll save a ton of money
 
#325 · (Edited)
Now for some more wire housekeeping, now if you return to your shifter area you will notice your funny little shifter wiring, ** due to me have lost the pictures I'll be blunt and explain till I get the visuals up** here you have 4 wires on one clip and two on the other, the 2 others light up an indicator to help you figure out what mode you are in, when its dark, its useless. the other 4 have a great purpose, 2 control a locking motor to keep you from exiting park wile the car is off and the other two dictate that it IS indeed in park, (this allows two things, ONE it allows you to take your key out, and two, it turns the fuel pump on, which is kinda important!), the simple mans way of doing it would simply be to take the two that activate the switch (easily known as the ones that DON'T go to the locking motor) and splice them together and retain the clip and plug it into the shifter harness and toss the shifter.
1)Can you list the colors of the wires you're refering to?
2)what do you mean "retain the clip and plug it into the shifter harness and toss the shifter? and how do you know which two activate the switch?
4)to trick the computer to thinking the key is out, the wires to splice/connect together are blue+black or black+black? Ive read both in this thread.
5)does splicing these wires from question 4 allow the starter to start the vehicle? I dont need the clutch switch hooked up
6)still clueless about how to get reverse lights to work? wire colors/location to splice would help.
7)can I swap over the auto VSS into the MT or do I need to use the MT VSS? would the auto harness plug right into the MT VSS?
 
#326 ·
Can someone please help me, i'm a little lost with all the information on the VSS issue.
i currently have a 02RS 5MT in my 99RS. i keep getting CEL 0500 , anyone have pictures or links of the rewiring of the sensor to the automatic harness, i see some are saying i have to get a VSS that matches my cluster, any info would be appreciated
 
#327 · (Edited)
racerx7, I havent dont it myself (still working on it) but from what Ive read you just unscrew the vss from the auto trans and screww it right into the manual trans. I believe it should plug right into the harness but like I said, havent got that far on my swap yet.

still have a few questions...
1)for NSS, ive heard many conflicting and contradicting statements. can I just bridge pin 11 and 12 from the grey plug on the harness that goes to the tranny inhibitor pig tail? or do I run wires straight from 11 & 12 to the actual physical NSS on the manual trans? I dont care about utilizing the clutch safety switch to start the car so if I can make it easier by not using that I will.

2)also read something about wiring to pin 82 on ecu and then to ground...this is so confusing because nobody explains it very clearly.

my car just needs to drive to the shop to get the motor swap. I dont need anything to work correctly...just to work.
 
#328 ·
Cost for my swap: roughly $750 (which is more than I paid for my forester shell :( )+a good EJ25 short block. A buddy of mine had a 2.5RS parts car that I took the pedal set, trans that was popping out of fifth on the freeway, shifter assembly driveshaft (which was brand new from Subaru), and limited slip rear end from for $450. Then I traded a good EJ25 short block to a dude that was building a dune buggy. In turn he gave me a complete/intact ECU main harness from an 01 forester with all brain boxes (ECU, cruise, ABS, etc). Then roughtly $300 for a clutch, fluids, shifter bushings, a new stake nut, washer, and gaskets (to fix the pop out issue).

TL/DR: find a parts car and harvest everything you can is my humble opinion.
 
#329 · (Edited)
quick question...when installing the tranny into the block, how many of you closed up the gap between bellhousing and block using the mounting bolts? Ive read that some insert the shaft and wiggle the tranny until its flush with the block and ive read some close up the last 1/2" or so using the mounting bolts. We had to use bolts to get it the last little bit and I'm nervous I might have damaged the pilot bearing, but I really dont want to take the tranny back out.

EDIT: so I finished my swap today and everything works fine. there is a slight high pitched humming noise coming from under the car though that gets louder on acceleration. not sure if something is vibrating on the heatshield or not. I do have alot of the bushings upgraded to poly.

NOTES FOR THE SWAP:
1)wrx pedals do NOT fit in a 2.5 RS. it was easy to get the pedals in there and seated but when I lined up the mounting holes for the brake booster, the master cylinder studs that go through the firewall were no where close to lining up and when I'd stick those through the firewall the brake booster holes wouldnt line up. took a helleva lot of cutting and drilling to modify them to work on my 2000 RS. for an RS, get RS manual pedals.
2)my wiring job is only temperary because I will be doing a wrx motor swap soon so it is the minimum you need. all I did for the wiring is cut pin 11 & 12 (2 big white wires) off the brown harness plug going TO the tranny, and twisted them together. then I cut and twisted together the blue and black wires going to the white, 4 wire plug that goes to the auto shifter in the center console. thats it. boom. I did not hook up reverse lights or vss (speed). I have an old jdm sti 5spd that I swapped in and from what it looked like the VSS was not interchangable with my auto trannys vss...I could be wrong but it doesnt matter. I will have a whole manual harness anyway.
3)I didnt have to make a studd for the starter. I just bought an 02' wrx manual starter and it fit right in.
4)if you bleed the clutch line for hours and you still dont get any back pressure in the pedal...your slave is most likely bad. ask me how I know.
5)I highly suggest a tranny jack.
6)aslo when you push the clutch fork back to engage the throw out bearing to the pressure plate, there is SUPPOSE to be a snap to let you know it engaged. mine did not but it still engaged when I pushed on it. I was freaking out for a while thinking it wasnt engaging and I was going to have to removed the tranny but when I felt the clutch fork on my buddys wrx it felt the same so I left it and its fine. the clutch fork will feel really loose and sloppy which is what I believe that external spring is for.
 
#330 ·
Greetings everyone, I'm pretty new to this forum but have been active in the Suby life for around 12 years, mostly the GD chassis, but I finally joined the GC life last week with a 00 RS sedan auto. Long before purchase I have been doing TONS of reading regarding a 5 speed swap into the RS. I may be getting my hands on the drivetrain out of a friends 00 OBS. I'd have the car as a donor so I could pull just about anything I needed from it.

My question revolves around the electrical side of the swap between these cars. I haven't found any really data on if I can just pull the dash harness, Cruise controller, and ABS controller and retain the auto RS ECU or not. Can I use those OBS parts in the RS and just repin my auto RS ECU? Or should I try and find a 5 speed ECU? After the swap is complete I want everything to function properly.

If I have somehow completely missed a place discussing using 2 MY2000's for the swap please point me in the right direction.
 
#333 ·
My question revolves around the electrical side of the swap between these cars. I haven't found any really data on if I can just pull the dash harness, Cruise controller, and ABS controller and retain the auto RS ECU or not. Can I use those OBS parts in the RS and just repin my auto RS ECU? Or should I try and find a 5 speed ECU? After the swap is complete I want everything to function properly.
Depending on how comfortable you are with wiring, the "easiest" way would be to pull the OBS parts and the wire harness and do a 1-for-1 install into the RS. This would lead to fewer gremlins in the end.
 
#335 · (Edited)
2000RS Auto to 2002WRX Manual



Have you found a solution to the high rev?

Condition: Just completed mechanically a 2000 RS with 2002 WRX transmission and diff. went in easy.

Issue: High rev always! 2K at start up. after highway driving and warm, 3700 RPM!!!!! I just ordered a Manual ECU to hopefully lower the RPMs. Full disclosure, i have an EXEDY clutch kit that may be a light weight clutch. double bad for the Auto ECU i think.

Issue: wiring for Spedometer, Reverse and Neutral are all different. Any ideas about splicing in the harnesses? I have a complete 1998 JDM WRX harness & ECU and the rest of the 2002 WRX USDM harness and ECU. the reason i have not installed it is because i still have a 2.5RS block.

Any ideas or does anyone think i made the right move by just ordering the manual ECU?

Thanks!
 
#337 ·
Can you use an auto abs harness with a manual abs pump? Young gent got me a manual pump for $20 and looks like it bolts up and plugs into my 1996 Impreza harness. The Sti motor and wiring I have are sans abs, cruise and ac. But my Impreza has all those things and from what I can see they're all separate harnesses. Cruise I could care less about but ac and abs are an absolute must for me. Ac is a straight swap as the Sti wiring still has ac plugs. Abs seems to be the odd man out. Some info on this would be awesome.

Two questions for the peanut gallery here, what is the vacuum stuff that mounts to the forward side of the passenger strut tower? And what is the two hardlines that are mounted to same said shock tower? They look the same or similar on both cars. What are those?

Thx
 
#338 ·
I did my manual swap this year and when smooth, got the reverse lights to work, as well as the car turning on without pressing the cluch, and since you have to disable the traction control unit you will have no abs and your speedo won't work , but I figure it out, it only takes two wires and you will have full speedometer form your cluster and from your data link, if anyone need help I can guide you with pics so you won't get stuck on the swap.. I did not post any pics here but I did on my Instagram at zroboost_gc8 thanks
 
#341 ·
Jeff-ery---I am using the auto harness, I got my speed line to work for a while but now is reading 20 miles over so I have to re track the. Wiring..the car stars like it was auto and I don't have the neutral safety switch installed, car starts without pressing the clutch tha way I don't put to much stress on the crank..
 
#342 ·
I'm going to finally be 5mt swapping my GC next month. I have a 2000 sedan.

Does anyone know if I'll run into issues trying to use a 2000 coupes main harness and ecu for the swap? The cruise and abs modules will be swapped over from the coupe harness as well. I don't see any reason I can't but I don't know where power to the rear doors comes from within the harness. Also wasn't sure if there might be some other hidden issue I haven't thought of.
 
#348 ·
Looking to do auto to manual swap need to know what transmission i can use i looked on a few forums and read a few builds I know I either need to take the rear diff. With the tranny I got it from or match my 4.11 diff. So with that said I just need to confirm what year and generations of subaru manual transmission I can swap in auto subaru impreza 2.5rs gc8
I think subaru forester xt would fit with the matching diff. Of 4.11
But I seen a out back transmission and pedal assembly same year as my car from the junkyard
Thank you for the advice sick of driving a auto ?

Sent from my SM-G930V using Tapatalk
 
#349 ·
01-02 outback (probably any foresters/outback as they have higher ride height but idk) you can use the trans and diff, need impreza drive shaft since wheel base is longer on other models. But the cross member is way lower set. o accomadate increased ride height, they lowered the cross member/front sub frame so you will need actual impreza trans cross member. I found this out when my outback trans shift linkage was wedged against the drive shaft. You will also need the rear shifter bushing that bolts the the body behind shifter housing. I just cut mine and welded it higher up and it works fine. Look up pics of the bushing and you will see the difference. Pretty simple
 
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