this thread is still going??!? wow
This is a discussion on Converting AWD to 2wd RWD w/ pics within the Powertrain forums, part of the Tutorials & DIY category; this thread is still going??!? wow...
this thread is still going??!? wow
Dyno 12/18/04: 201 WHP / 198 WTQ
yeah i know right i have been watching this thread it seems like for almost a year now.
It just looks stock . . .
no, trust me... group projects are best for me... but something like that is more of something i'd like to do myself[i]
Your one of those guys I hated working with in group projects [/B]
I've been working on converting my BG Legacy to RWD. I bought a welded center diff (incedentally from a guy I know who said it was welded by Coastal Dyno :lol: ). I tried to put it in to my car yesterday at work, and if it had fit (WRX center diff versus Legacy 5mt center diff) it would have been a piece of cake.
The following is a fairly thorough tutorial on how to swap the center differential. Exhaust removal will be a bit different on WRX than on non-turbo cars for fairly obvious reasons, but the basics still apply...
Materials you will need:
-10, 12, 14, 17, 19, 21, and 23mm sockets. I used a set of Matco Swivel Impact sockets and managed to get pretty much everything
-17mm and 19mm wrenches (for removing bolts with nuts)
-2 tubes of gasket maker/Tail housing and shift linkage plate gaskets (from Subaru?)
-White lube/White lithium grease
-Gardener's, Mechanix or other tough gloves
-A Vehicle lift or 2 sets of jackstands
-A good jack / a big friend
-Some way to organize bolts and nuts
-A Subaru with the appropriate center differential (don't assume they're all the same, because I will tell you from experience that they are NOT)
-Set of Roll Pin punches or some long thin phillips head screwdrivers and a hammer
-A chisel (for separating transmission housings)
-4 quarts 75w90 Gear oil
-About 5-8 hours depending on how fast you work, how many friends you have helping and how many beer-thirtys come around
-Phillips head screwdriver(s)
-Impact wrench / Cheater bar, hammer, and patience
-Spear and Magic Helmet
THE PROCESS FOR INSTALLATION:
-Jack up/lift the car up
-Remove the front wheels
-Unplug the O2 sensors from the exhaust
-Remove the exhaust by loostening the flange at the head (6 bolts, do it while the engine is cold to avoid removing the studs from the head), the rubber hangers (use lots of white lithium grease aka white lube) and the metal J-hook that is bolted to the transmission (not sure if this part is on WRXs but it is on some other subarus.
-Remove the heat sheild above the exhaust (4 bolts, 2 nuts)
-Mark the location of the forward driveshaft in relation to the rear driveshaft and remove the 12mm bolts that hold them together as well as the carrier bearing. Slide the forward driveshaft out and set it aside.
-Remove the Transmission Mount/Brace by unbolting the 6 (two in front, as pictures, 4 rearward from that) bolts that hold it in place, and the 4 that bolt it to the transmission itself. Don't confuse your bolts or lose this piece!
-If you want to only replace the center differential and not drop the transmission (which I reccomend avoiding if possible for reasons I will get in to later), drain the gear oil out of the trans by removing the 21mm (or is it a 23mm? Can't remember) plug at the front of the unit and remove the bolts for the shift linkage. The linkage is held in place by 2 bolts that anchor in to the frame and 3 or 4 that bolt on to the tail of the transmission, 2 roll pins that connect the shifter arm to the shifter shaft on the transmission (one inside the other), as well as a boot plate (phillips head screws) that is under the center console (the portion around the shifter pops out by itself, you don't have to remove the whole console) and then remove the ever-problematic shift knob ). The rubber boot and shift lever should be able to be pushed through the opening easily.
-Remove the exhaust J-bracket bolts (2) from the right side of the transmission and set aside this assembly.
-Remove the rearward-most section of the transmission by removing the 10 or 12 14mm bolts that sandwich it to the mid housing. You will need some good (Matco) universal sockets for this job, and I reccomend removing the transmission crossbrace and jacking up on the engine a bit to get the tail of the trans to angle down a little. After the bolts are out, you will need to tap on the sides of this housing with a soft head hammer (a dead blow works alright but a nylon covered sledge works better) and carefully crack the two housings apart. If you decide to try and hammer a screwdriver or chisel into the gap, be EXTREMELY careful not to dent the mating surfaces, and work a little bit at a time all the way around. Be very patient at this step because the housings are only soft aluminum and any maring or deformation will cause gear oil to puddle on your driveway. This is by far the most time consuming step of the process.
-Once the tail housing is off, the center diff will kindly greet you with a quick "mushi-mushi". You have to simultaneously pull out the center diff and the output shaft (which resides above and to the right). Be very careful not to drop or lose any shims, rings or whatever falls out during this process.
-Now either replace your old diff with a welded one or weld your old diff using CoastalDyno's write-up of the process. Like removal, you will have to insert the new diff at the same time as the output shaft.
Continued on next thread...
Last edited by mranlet; 06-07-2005 at 02:53 PM.
REASSEMBLY (not as easy as "the reverse of removal"):
-Clean off the mating surfaces of the shift linkage plate, both ends of the tail housing and the mid case housing with a razor to remove old fragments of gasket, being careful not to get any inside the transfer case. Either use new gaskets (available at your local Subaru dealer?) or do what I did and use gasket maker (NOT RTV silicon sealant, you not be able to ever remove it again). Wear gloves while cleaning the surfaces because the housing edges can be sharp and gear oil in a cut = a bad time.
-Squish the tail housing back on to the mid housing. It might take some messing with the output shaft to get all the splines to match up, and if you do this and used gasket maker, be very careful not to ruin your bead.
-Replace the bolts that hold the tail housing to the mid housing, but don't torque them down too much or else you may break the bolts or strip the holes. I tightened them in a counter clockwise fasion skipping every other bolt until they were all arm-power tight (not impacted).
-Repeat the cleaning/gasketing/squishing/bolting process for the shift linkage plate.
-Pass the shift lever and boot back through the transmission tunnel opening and bolt the rear linkage mount back on to the frame.
-Slide the driveshaft back in to the output shaft and align the flange with the rear half of the driveshaft according to your mark, this is to ensure that the driveshaft has stayed balanced. Make sure that the carrier bearing is right side up or else you will have a rumbly ride.
-At this point I would reccomend waiting an hour for the gasket maker to set up and filling the transmission up with gear oil through the dipstick hole. If you used Subaru gaskets, there is no reason to wait, but any gasket maker will require you to follow the instructions on the back of the package, which will say "wait an hour". I used 3 quarts of 75w90 differential oil and haven't had a problem yet (knock on keyboard). The WRX may take a little more or less than 3q, but I found that to be the optimal amount according to my dipstick. To aviod making a horrible mess, use one of those 2-foot long funnels that taper very gradually. They're no more than $5 at an auto parts store or Sears and are well worth the money.
-With the transmission all oiled up, you can either try running the car VERY GINGERLY IN 1ST GEAR (since no exhaust or O2 sensors are hooked up yet) to make sure that all 4 wheels are turning, or (if you don't want to make your computer freak out and burn up valves) simply move the rear wheels by hand and make sure that the front hubs also move. Using a fused center differential basically makes the car act as if it were a 4x4 in 4-wheel mode (front and rear axles locked together). If both axles move together then your center diff is working and it's time to remove the front axles!
REMOVAL OF THE FRONT AXLES:
-Unbolt the lower control arms where they meet the subframe by removing the two large bolts on the rearward bracket and removing the large bolt and nut on the forward bracket, then and disconnect the sway bar endlinks. Swing the spindles out of the way and place a block of wood between the strut and frame to keep them from falling into your face (lower control arms in the face = a really bad time).
-Using a roll pin punch or small screwdriver, gently tap the roll pins out of the axle ends. Save the roll pins just in case you ever have to put the axles back in (the axle ends and stubs on the transmission side also have the holes offset so they should only fit in one way).
-It isn't a bad idea to mark which axle goes to which side, just for the sake of being thorough
-Using a punch and Axle socket, tap the fold on the axle nut back out to round (in oem state the axle nut will look like a regular hex-head nut with a tube along the inside that has been dented to fit a recess in the axle shaft). Remove the axle nuts and pull out the axles fron underneath.
-Now is a good time to mention that, although the design of the front axles does not require you to plug any holes in the transmission (thank you Subaru engineers), you should make an effort to cover the axle stubs that stick out from the transmission to avoid rust and dirt-ification.
-Remove the wood spacers and bolt the Lower Control arm brackets and nut/bolt back on to the frame after applying some lube and anti-seize to the assemblies. Reattach the sway bar endlinks and remount the front wheels.
BACK TO REASSEMBLY:
-Replace the heat sheild and fasten down the 4 bolts and 2 nuts.
-Get 2 bystanders to hold up the exhaust while you replace the hangers, J-bracket and tighten down the nuts on the head flange, ensuring that the gaskets are in place and are in decent condition. Also make sure that your O2 sensors are clipped into place as well.
-Drop the car back on to the ground and do a smokey RWD burnout!
Why not remove the transmission?
Firstly, because you don't really NEED to. It also takes a lot longer, you need a transmission jack or a really big helper, realigning input shaft and clutch splines is a muggerfugger, it can be difficult when there are turbo(s) and intercooler piping in the way, several electrical connections tie it to the motor, and wrestling the starter motor around the steering linkage can get frustrating. If those points aren't enough reason, then good luck!
Hopefully this has been a very helpful Tutorial for anyone bold enough to attempt this project. When I accually obtain the correct differential for my car, I will make this into a website with lots of pics and goodies of the like.
Until then, I have one welded WRX/2.5RS center differential for sale - $250 shipped. (Email me at email@example.com for details)
Here are a few pictures that should help anyone in the project. I had the transmission dropped becasue I was also doing clutch work, but it makes it easier to see everything. The Access Panel on top of the transmission can be removed if you happen to have the transmission out and want to take an impatient peek at your center differential. Thanks to a reusable gasket, it can be replaced without having to clean and re-gasket any mating surfaces.
The front shafts don't have to be removed...
I did this conversion about 12 months ago. I have pics of my centre diff if you want to see how i did it. I just don't know how to post them here.
By the way, does anyone want to part with a set of U.S spec corner markers??
I think everyone would benefit from those pictures.Originally Posted by AJREXWGN
Street Racer Emeritus
'02 2.5L WRX - Retired
I was told by a guy on NASIOC that if you remove the front axles and plan on driving the car you need to take apart the cv joint on the hub side and put that back into the hub. If you dont do that, the wheels bearng will get all forked up. IDK if this is true, just what I was told.
Originally Posted by chrisj From NASIOC
BEFOREOriginally Posted by TypeC
AFTER ready to install-
Arrow showing the removed spline section that used to run the front wheels...
So you just need to change the center differential for driving RWD?
Or are there any other changes need to do...
respectively is there anything to pay attention at?
It's a way hard for me to get through your slang guys
so there has been testing done? before and after RWD? and its only 3whp?
dang i was hopeing for a little more, mybe if you remove the Front Diff too.
well ill let you guys know for sure, my suby goes in tuesday and comes out wednesday with RWD,
05 aspen white STi
that is unless you are making power like shepracing, then you need both and you still have to steer the car to go straight......Originally Posted by afpdl
Another one done the conversion:
But are there any reports about a converted wrx?
I think the rear axle and rear differential will not bear up with the 100% power...