Subaru Manual Transmission Repair

Subaru manual transmissions are pretty well built and have minimal problems. When failure occurs there are usually just a couple of things that fail. The most common problem is bearing failure causing the transmission to be noisy and if it’s excessive your trans will sound as if someone has put rocks in it. The other failure that is common is the viscous coupler. In Subaru MT transmissions the viscous coupler acts like a limited slip differential, but instead of allowing slip from the left and right tires the viscous coupler allows slippage of the front to rear wheels. This is for turning only because the front and rear tires while turn at a different rate in turns. The viscous coupler will also slip if the vehicle is under a heavy load going straight and when this occurs the power will be mainly transferred to the front wheels. Most of the time viscous coupler failure is on a WRX model, where the snap ring breaks out of the viscous coupler case. When this occurs there is no power transferred to the rear wheels.

These transmissions are pretty simple to repair, so if you would like to perform your own repair I will give you some tips to help you along the repair procedure. If after reading this you decide that the equipment needed and/or this seems like a little too much…

MDH Motors Specializes in Subaru MT Transmission Repair

Contact us today for an estimate!

Do it yourself Subaru MT Transmission Repair

Do it yourself required tools

  • Shop press
  • Split bearing puller (large and medium size)
  • Press fittings Tip: use different size exhaust pipe and old bearing races.
  • 55mm 6 point socket (mid or deep)
  • 44mm 6 point thin walled socket ( shallow OR deep)
  • Air Tools (1/2” Impact Gun)

First off, separate the transfer case unit from the main transmission case. After that is done, the biggest part that makes this easy is how you split the case and dis-assemble the transmission. The left side of the case will hold you input shaft, counter shaft, differential and shift forks and the other side is just part of the case. Just remove two of the four bolts holding the counter shaft main bearing from the side of the case your removing (at rear of case where transfer case unit was). Always mark the shim that is behind this bearing. It may not seem necessary, but upon re-assemble you can easily mix up how this goes and the holes won’t align correctly.

Now that this is done the rest is pretty self-explanatory, remove your shafts and press on and off the bearings that need replaced. I always recommend replacing all ball bearings and seals. There are some small flat bearings and round bushing type bearings that are OK to re-use. Use your split bearing puller and array of exhaust tubing to remove and press new bearings to the shafts. I use an assortment of 1’ to 3 ½’ exhaust tubing in ½’ increments for the job and also have some roll cage tubing that is more heavy duty for pressing some stubborn bearings. Another good tip for substituting your press fittings is to keep the bearing races. They can become very handy for certain needs, especially if you have a welder. You can then weld and fabricate special press fittings exclusively for certain jobs such as this.

When you get to the differential, do not move or adjust the carrier bearing adjusters. Replace the seals from the inside of the case, and if you want to replace the large O-rings in the differential carrier bearing preload adjusters just mark them. The service manual will tell you to use special tools such as dial indicator to adjust backlash. I have been working on these transmissions for over 10 years and have never had a problem doing it this way when replacing the differential carrier bearings. Another thing to look for that I see sometimes is these bearing races sometime have a tendency to spin in the case. Especially if the bearing is worn, causing drag. To resolve this problem just take a pointed punch (I use a spring loaded one) and ping around the case where the race fits. This will cause the race to fit tight again, cool huh. No need to replace the transmission case.

Hope this was helpful

This post was written by: Martin Hand


If you find this information helpful please consider a donation. These articles, questions and comments are very time consuming so even a small donation gives me motivation to keep educating automotive owners. Donations will allow us to continue open questioning/comments, automotive education and repair tutorials in the future as the business grows. All proceeds go to the expansion and maintenance Thank You

Martin Hand

About Martin Hand

ASE Certified L1 Advanced Mastertech. Martin Hand has over 15 years experience in Asian and European Import Auto Repair. Specializing in electrical diagnosis, engine performance, AT/MT transmission repair/rebuild. Martin is also pursuing a degree in Computers Science & Information Systems starting at Portland Community College while he plans to transfer to OIT. Certified in Java application level programming, experienced with other languages such as PHP, Ruby, JavaScript and Swift. Martin has future plans of automotive diagnostic software development.


  • Brandon Romero says:

    Kind of an old post but worth a shot. I’ve just about finished the rebuild for my 5 speed. Everything all pressed onto the shafts and lined up. Only problem I have is finding a way to secure the drive pinion shaft assembly to torque down the larger nut (191ftlbs). I was able to use an impact to remove it no problem. Maybe just use the impact to install it as well?

  • Marshal Johnson says:

    I have an 09 wrx and second hear while accelerating makes a whining noise and just today shifting into 3rd and 5th felt weird. Instead of how it feels when you shift into a gear normally and you feel it fully go into gear like my other gears do it almost feels like it’s going partially into gear? What are my options?

    • Martin Hand Martin Hand says:

      Start by checking the shifter linkage. There is a u-joint on the linkage that wears out causing shifting problems. If everything externally is okay then you have to start by removing the transmission, take it apart and inspect for worn parts.

  • Clint says:

    Still waiting to see if anyone has info on why my 98 imprezza gearbox makes no noise but I cannot get it to go into 3rd gear it feels like something is jammed behind the shifter every other gear changes smoothly I have been told that it could be the thrust bearing fork others say dismantle the gearbox but as I said no noises from internals any help or hints would be greatly appreciated thanks in advance cheers????

  • Clint says:

    My 98 imprezza refusing to go into 3rd no previous noises or issues any help would be appreciated cheers Clint…

  • Clint says:

    My 98 imprezza drives well no noise but for some reason is not getting into 3rd gear everything else is fine has anyone had this happen no grinding no noise just won’t go into 3 any help would be appreciated cheers.

  • dalton says:

    hi i just rebuilt my 06 wrx trans and when i got done i noticed there was a small stainless straight pin laying on the ground… 🙁 and i have no idea what it goes to, Im worrying i need to split the case back open but im not sure ;-; plz help

    • Martin Hand Martin Hand says:

      It is probably the pin that holds the bearing race in place, there are two of them one for main shaft and one for the secondary shaft. Your going to have to take it back apart or the race could spin in the case and one of them also hold reverse idler in place so you could end up with no reverse or some other type of transmission failure.

  • saleh says:

    Hi, I have problem with manual gear of Subaru station 1990 1800cc 4wd, if you have parts of this gear some where in Israel or how can I have parts by shipping post

  • Derrick Welfare says:

    Awesome page!

    I am having a torque issue with my 2000 MT transmission Outback 2.5L H4. The transmission shifts through all the gears and accelerates fine, just when I’m in mid shit and go to accelorate there’s always a bang. It seems as if the more torque i put on the transmission the more it will bang. If I burn the clutch no banging noise. If I keep it in first and let on and of the gas the bang will continue until i pres the clutch in. I was thinking it is a transmission mount cause it’s not the driveline, I already tried that. Can you help? I dont want to keep throwing parts on it snd not fixing the main issue. Thank you.

    • Martin Hand Martin Hand says:

      You really need two people, get the car in the air so one person can run the vehicle to duplicate the noise while the technician looks + listens for the noise underneath.

  • Fred H says:

    Hi had a rear vearing fail in a 5spd. I have another trans that had had a prob/ little reverse ball bearing got hot & caused lock nut to come loose-must have really heated up!
    The viscous coupler should turn with resistance on the bench? If not its bad or should it be tight and not rotate at all by hand
    (Using the output gear to turn inside while holding the center dif assembly)

    • Martin Hand Martin Hand says:

      Should be hard to turn if turns easy clutches are slipping. Usually if the center differential snap ring is in place and it wasn’t binding on turns before then it will be okay. When they fail they heat up and pop out the snap ring retaining the clutches, it will smell very bad also.

  • Sam says:

    I am looking at a 2005 Outback XT with a 5 speed that will not go into 1st, but the other gears are fine. The seller thinks it is a linkage problem, but I think it is a bad 1st gear synchro.
    I am curious what your think it could be, and if there is any trouble shooting I could do.

  • Greg says:

    I have a 2010 Forester manual with only 100K on the clock. It jumps out of 3rd gear and makes an awful grinding sound. Has done this for quite a while.

    • Martin Hand Martin Hand says:

      Bad third gear synchro +/or gear or the shift fork is worn or all three could have failed. A worn shift fork will not fully engage the hub into the synchro gear which grinds out the synchro and gear.

  • tom says:


  • Ryan says:

    Hello Im running into a strange problem with my 2002 wrx 5mt transmission when I go to back up in my car my car gets locked out of all gears besides 5th and reverse but I cannot use those gears but if I put it where neutral should be I can drive forward and its in first gear. have you ever cam across this problem before? I would like to get your input as to what you think is going on. thank you.

    • Martin Hand Martin Hand says:

      Sounds like there is something wrong with the shift linkage. Start by checking the external linkage first. There is a u-joint and bushing that can fail causing all sorts of shifting problems. If that is okay then you will have to remove and take apart the transmission to find out whats going on.

      • Ryan says:

        Hello and thank you for the fast reply but I decided to dig into the transmission and I took off the center differential housing and noticed I could put it into first or second and still move the 5th and reverse gear shift rail in and out of gear it 3&4 gear I cannot per how the interlock system work have you ever came across this issue before?

        • Martin Hand Martin Hand says:

          You may have sheared off a roll pin holding the shift fork to the shaft. You will still need to remove and disassemble transmission to inspect the other parts. Once you split the case you can leave all the parts in the other case half and inspect the operation of it from there.

  • Ben Anderson says:

    So I have a 2007 Subaru Impreza wrx 5 speed manual transmission. It has a very odd problem. When I’m driving and shift into third gear and let the clutch it it sounds like there are rocks in the transmission. Third gear is still there and engages perfectly but sounds like hell. All other gears work as they should. Any input?

  • David Bardwell says:

    Are there any resources such as images or guides for replacing the output shaft bearings? Mechanics said mine is gone, Dealership says 1400-2000 to replace, but I’m inclines to believe a local trans shop might be able to do it if I can explain what’s shot and how to access it.

    If you’re wondering what’s drawn this conclusion, it started when I thought a CV Axle had started to fail (clanking when turning, rumble when under load) – Had a friend throw it up on a lift and threw it in gear, sound comes from the rear output.

    (I’m in New Brunswick, Canada. Subaru’s got a great market share here but crap for non-dealer mechanics)

    • Martin Hand Martin Hand says:

      Yes Mitchell on Demand or AllData or you can order a factory service manual

      • Peter Brown says:

        Say for the factory repair/service manuals do we go through the car dealers or is there a site designated for these things? Thank you for your time & effort. I’ve tried AllData and Mitchell but just curious as to the content being of a more useful purpose.

        • Peter Brown says:

          My problem I have recently encountered is with a 1995 Subaru LEGACY OUTBACK wagon AWD. When it came to me reverse gear was not engaging so I then replaced the unit with a used transmission and it worked great. (My first transmission to open up) … only thing is after 20 minutes of driving and/or shifting into 4th gear it felt and sounded like the axles were banging and clanging around. So instead of taking the transmission back I took the one I had and changed out the front differential. Swapped out this part from original unit that came with the car. I wonder is the a repair caused by smacking the tension pins out? Any thoughts.

          • Martin Hand Martin Hand says:

            I’m not sure what your asking. If your referring to the roll pins for the cv axles then I highly doubt any damage was caused by tapping them out from the cv axles.

        • Peter Brown says:

          My problem I have recently encountered is with a 1995 Subaru LEGACY OUTBACK wagon AWD. When it came to me reverse gear was not engaging so I then replaced the unit with a used transmission and it worked great. (My first transmission to open up) … only thing is after 20 minutes of driving and/or shifting into 4th gear it felt and sounded like the axles were banging and clanging around. So instead of taking the transmission back I took the one I had and changed out the front differential. Swapped out this part from original unit that came with the car. I wonder is the a repair caused by smacking the tension pins out? Any thoughts.

          • Martin Hand Martin Hand says:

            Good job swapping out the front differential. I highly doubt the damage was caused by knocking out tension pins, I assume your talking about the cv axle roll pins? The transmission probably already had a bad differential as long as there was oil in it.

        • Martin Hand Martin Hand says:

          Alldata and Mitchell data is actually copied from factory service information. They just do things like enhance the wire diagrams for easier reading and change the content layout. Everything is quoted from the manufacturer, I think they add stuff and probably leave stuff out though. I don’t know about obtaining a factory service manual, you can try contacting the dealership. I just use AllData, Mitchell and AITN automatic transmission manuals.

  • James D says:

    I have a 2012 Subaru Legacy 2.5i with 6MT.
    I hear whine coming from the drive-line in my car. The noise is independent of engine RPM; gear, neutral, or clutch in/out. The noise does not seem to change in cornering. Possibly bearing (transmission, differential, transfer case, driveshaft) of viscous coupler?

    Dealer said it appeared to come from transmission and would not repair, only replace.

  • Lindsay says:

    I’ll take a stab at this.
    My ’02 Impreza RS has had an issues with the transmission.
    While getting ready for work one early morning, it sat with the engine running while I scraped the frost of the windows. As it was idling, the engine cut out with a sound to that of stalling.
    I get back in and try to restart it, but as I did, the car jerked forward as if it was in gear, but was not.
    After some inspection and guesses, the third and fourth gear seem to be immobile.
    Only when the clutch pedal pressed down does it not stall out, as I release the clutch pedal slowly, the engine begins to stutter as if it’s about to stall.
    Any ideas on what thre transmission may have an issue with?

    • Martin Hand Martin Hand says:

      Yes I have seen this before, the gears are probably seized on the main shaft of the transmission. Not sure why this happens but the transmission will need removed disassembled and repaired.

      • Lindsay says:

        Yeah, we’ve done the hard part of taking it out. It’s been opened up and is exposed for us to make any repair needed. Also, a small note, a small bit of yellow-ish white plastic came out while the transmission fluid was being drained. It looked as if it was snapped off from where ever it came from. i’ll look more into it this coming weekend.
        Many thanks for the reply Martin!

  • I have a 2003 Subaru Outback wagon with a 2.5 L and 5speed manual transmission. My problem seems to be with the transmission in that after highway driving for 20-30 minutes I will notice front wheel clunking noises at low speeds when steering. You can actually see the wheel jump during rotation while observing outside the vehicle while someone else drives. I replaced the power steering pump, the CV joint (complete unit both sides). And front wheel bearings with ball joints with no difference. Any ideas or suggestions as to what might be wrong?

    • Martin Hand Martin Hand says:

      Sounds like you’re explaining a tire related problem try rotating the tires front to rear and see if this makes any difference

      • artbruce says:

        Viscouse coupler is shot (internal silicon is compromised from overheating) and needs replaced.
        Quote “This is for turning only because the front and rear tires while turn at a different rate in turns”. Hence the clunking noise as the viscouse coupler is not acting as a slip diff any more and the shorter arc your rear wheels are making in a turn are causing the binding at the front wheels.

  • Andrew says:

    Hi Martin/MDH:
    Ive got a 2010 outback with 6spd mt and 115k. the center diff (viscous coupler) is binding badly after hwy driving for >=30 min. The dealer quoted me $3k plus for the repair, which is nearly half of the car’s kbb value!
    i would like replace the center diff myself, im quite mechanically inclined and have done head gaskets, but would still like some sort of hardcopy visual reference…like parts diagram with torque specs….any idea where i could find such? or do you have pictures of the guts to a ty765 gearbox?

    also, besides uneven tire wear, what could cause the viscous coupler to fail prematurely?

    Great site! lots of helpful info! Keep it up!

    Spring Valley, MN

    • Martin Hand Martin Hand says:

      Call your local Subaru dealer and have them email you diagram this is how you’ll have to order your parts anyways. Also can try a transmission manual like ATSG

      • Andrew says:

        score! thru the forum i managed to download pdf of MY2010 Legacy factory service manual for free!!
        From reading thru said manual, it gives 4 main steps to replace center differential:
        1. remove the entire transmission from vehicle
        2. remove transfer case from transmission
        3. remove extension case from transfer case
        4. remove transfer driven gear to expose center differential

        This leaves me with 2 questions:
        – are steps 1 & 2 necessary? ….can i just remove the extension case housing and transfer driven gear to replace the center diff?
        – what, if any, other items should be replaced while i’m in there besides center diff bearing?
        (subaru dealer recommended needle bearings, snap rings and remeasuring for shim washers)

        Thanks for your earlier response…i made a donation in return. 🙂

    • dave says:

      The tire size is the main cause of the viscous coupler to fail early. Check out ste viscous couplers if you need to get it replaced

  • Kody says:

    Ive got an 01 legacy gt wagon with a 2.5 and a manual trans. recently my car has begun leaking transmission fluid in extremely high quantities (over .5 quarts per day) and the transmission has begun to pop and knock/grind after about 2000-2500 rpm under light load (in any gear) was wondering if there is any known potential cause or if I’ve more than likely grenaded the tranny… thanks for your time!

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