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

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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.

153 Comments

  • matt says:

    I have a 2012 Legacy GT with 6MT. In the past 6months i have been experiencing an intermittent “light graunch” (not a grind or a pop) coming from my clutch/trans area which occurs only on clutch release and only in 1st and 1st to 2nd. Car drives perfect and shifts perfect but there is this annoying intermittent sound. Clutch appears to have plenty of meat on it with 68,000 miles (replaced prior to my purchase with stage 1 clutch) when it was inspected during an oil change from the inspection panel. I did a trans fluid change in December with the SOA high performance trans fluid and sound went away for about 4-5 days but then crept back. Was thinking about switching to Redline 75W90NS fluid but was wondering if you had any thoughts on what it could be or where I should start. Any help you can offer would be appreciated. Thanks.

    • Martin Hand Martin Hand says:

      Fluid types will not correct something like that, sounds to me as if there is some type of mechanical failure. The noise going away from fluid change is most likely coincidental. To depict between the clutch or transmission failure I would have to see the vehicle for myself.

  • Joseph says:

    Hello Sir, I hope I can get some help here. I’ve read through all the threads and can’t find one with similar symptoms. I just purchased an 03 outback limited edition 5 MT. The transmission makes a constant ticking sound in every gear. The best way to describe it is that it reminds me of when kids use to place a card on the forks of their bicycles to make noise rolling around in the spokes. The fast I go the faster the noise. There is also a slight wobble to the shifter when I have my hand resting on it. Fairly certain it’s a bearing tick. Any wisdom would be appreciated.

  • Sam says:

    I launched my 09 wrx at 5,500 rpms and something broke internally. Car still moves forwards and backwards and shifts into every gear just fine. There is however a heavy clunking from the trans area when the car rolls. Any thoughts?

  • Anth says:

    I have an 05 Outback manual trans, my wife was on her way to work when it would no longer climb a gentle hill. Acted like the clutch was shot, engine would rev and it wouldn’t go anywhere. Could hear a grinding noise as well. Towed it to a shop, on the lift it looked more like a transmission problem. Front wheels would spin and rear didn’t or vice versa. Mechanic took it down from the lift and tried to drive it, and it was back to driving normally. The car seems to drive normally still. There was no obvious indication of a problem before this happened. I was thinking perhaps this could be a bad viscous coupler. Any thoughts?

    • Martin Hand Martin Hand says:

      Sounds like your on the right track, you can remove and inspect the viscous coupler without removing the transmission.

      • Anth says:

        Hi, thanks. I got the viscous coupler out. I don’t know of any test to see if indeed it was the problem. I’ll no doubt replace it though. One more question though, when I took a look in the bottom of the transfer case I noticed some loose pieces of metal. The pieces were not shavings but broken pieces of metal. I couldn’t figure out how to send you the picture. The snap ring looks intact on. I’m hoping that the metal pieces came out of the vc, but then again some of this makes me feel like a caveman at a rocket science seminar. I appreciate the expertise.

      • Anth says:

        I replaced the viscous coupler and put it back together. After about a week I was riding along and it acted like the clutch was slipping. I pulled the transmission out and the clutch doesn’t look bad to me. On the inside of the clutch disc there is a little wear. There are grooves on the pressure plate springs where the throw out bearing makes contact. I bought a new clutch kit and when comparing the two, the new one isn’t any thicker. The old clutch isn’t worn down hardly at all. No grooves in the pressure plate. No scorch marks on the flywheel. I’m stumped. Can anything else cause the slippage? I didn’t smell that burnt clutch smell either when it slipped.

  • Mason says:

    Is there a way to test the VC on my 99 Impreza Wagon (5MT) by spinning a wheel or wheels while elevated a certain way?? Or some kind of test? I’ve been all over the Internet and CANNOT find an answer.

  • Dean Cameron says:

    Hi i have a liberty 2001 RX 2.5 5spd dual range box with stubs. 1st gear synchro probs and diff probs. Bought a good legacy box non stub…but it has no speedo drive in right hand case like the liberty box. In theory i should be able to split both cases and transfer the speedo drive into the legacy box. Ive successfully modified both sets of shafts to make a set that has non stub end suit legacy box and ABS ring cv joint suits. Your thoughts and experience would be appreciated. Thankyou

  • Eric Joseph says:

    got a 2000 subaru impreza my manual transmission is dropping oil between the gearbox and engine want to know what I need to get it fix

  • Michael says:

    Hello, I have a 2000 outback that had a 1st gear that sounded straight cut when I traded another vehicle for it in december. I started getting noise in all gears, thought it was the TOB, then I lost 1st gear. It shift through all other gears and makes no noise now, but 1st gear is gone. I can physically shift into 1st, but it doesn’t do anything. No sounds, no movement. I have 9 day to get this figured out and repaired then I need to drive from Chicago to Seattle. What is needed part wise and work wise to repair this? Any idea on what happened?

    • Martin Hand Martin Hand says:

      Your going to need to remove the transmission and dis-assemble it. This is the only way to find out whats wrong and whats needed. There are just too many possibilities.

  • Neil Clark says:

    Hi There!

    A while ago I smashed second gear, and had the gearbox replaced with a rebuilt one with straight cuts. A short while after the retaining clip on the back of the centre diff popped out, causing all sorts of pain, noise and horrible grinding.

    The collar bearing on the centre diff was completely gone plus the other bearings on the countershaft felt a little bit ordinary.

    I swapped the centre diff and countershaft (bearings and all) from my broken gearbox in to this one. When removing the broken diff it refused to come out: I think because the bearing had collapsed and gotten hot enough to fuse itself in somehow. On installing the replacement diff, I had to gently tap it in with a mallet to seat it properly as it was still tight.

    The car now drives fine and the original noises are gone. Except now I have a slight rattling/grinding noise only on overrun (can only hear it in 5th, because you know, straight cuts 🙂 ) at about 3000-4000 rpm. But it only happens when in gear and the clutch fully engaged. If I slowly engage the clutch, so there is load on the transmission but there is still pressure on the clutch pressure plate, the noise doesn’t seem to reappear until the clutch is fully engaged.

    From what I’ve read this could be clutch noise due to the aftermarket clutch, although I don’t have a lightened flywheel which is usually also associated with this. I have the stock flywheel (it was machined when the clutch replaced) Exedy HD organic clutch, and Group N mounts all round for that extra NVH!

    Hopefully I’ve been descriptive enough, for maybe some idea of what it could be?

    One thing that I am concerned it might be caused by is the shim on rear end of the countershaft; what would happen if the wrong size shim is installed? I used the shim from the broken gearbox so the shim ‘followed’ the good bearings across.

    Thanks for reading my short essay!

    • Martin Hand Martin Hand says:

      Get the car in the air and have someone run through the gears while your listening under the car. Use a stethoscope and try to pin point where the noise is coming from. As long as you put everything back correctly in the transmission you should be fine, I wouldn’t worry about the shim. I usually never have to re-shim the bearings. The bearings are all the same size, it’s shimmed to the differences in the case and gears.

  • Melvin Johnston says:

    I am thinking of importing a 2000 Subaru Forester ST/B from Japan with a 2.0L turbo engine-250 HP. Only thing that I am having trouble deciding is whether to get a 5 speed manual or 4 speed automatic. Your opinion would be greatly appreciated as you have worked on both and know which transmission would be more reliable. I’m assuming that the manual would be cheaper to work on but not sure how much trouble viscous coupling would be. How trouble-free is the automatic? Looks like more to go wrong. Also wondering which transmission would work the best with the turbo. One last question-how much difference in mileage would there be between the 5 speed manual and 4 speed automatic? Thanks so much for your help and expertise. It is appreciated!

  • Venustus says:

    My Subaru Forester started whining 3 weeks ago. It whines at speeds below 69km/hr, when I accelerate and goes silent when I put the leg off the gas pedal. When changed gear box oil I noticed some iron filings. After changing the oil the noise did not go away. Kindly assist, could it be one of the bearings collapsed?

  • nick mancini says:

    2011 legacy 2.5l 6 speed can the viscous coupler be installed in the car or transmission has to be removed …

  • Jim says:

    Hi

    I am will be using a Subaru engine and gearbox as a mid mount chassis setup in a space frame buggy I am building. In doing this I will not be needing the tail shaft out the rear of the gearbox any more. So I was hoping you might know someone who may have already done something similar in the past. As I will be needing a blocking plate and a method of gear changing setup.
    Can you point me to anyone that may be able to help me please.

    I am based in Australia but I am prepared to get the goods and build this car no matter what. I have already purchased engine and box and full billet steel crank rods and forged Pistons to build a high HP engine. So I am not trying to waste your time or any one else’s.

    Thanks again Jim

  • Steven says:

    Ok here’s the deal:
    2000 Outback. 5sp manual.
    255,000. Good reliable car. We live way up in the California Sierras between Tahoe and Yosemite. When it snows; boy does it snow(!) …four years ago it was 624 inches for the season. It easily comes down at the rate of a foot per hour for 3-6 hours at a time. We laugh when the Midwest complains about a 15 inch snowfall.
    And this Outback (and our 3 other Subis too – all bought used) plows right thru it w/o a problem.
    We run a little ski lodge near a big ski resort and often must drag out our Bay Area guests from drifts when one of their chains comes off. It’s funny to see our little 96 Impreza (wABS) dragging their big SUV that can’t function where Subarus have no trouble.
    After 250,000 our stick shift transmission is suffering the failure of the “viscous connector”. Is there any place to get this $500 part any cheaper?
    I’m afraid a used part will have a much too short life. But my gosh…$500(?!)
    Any advice? Plus: is the failure of the VC unavoidable? Did I do anything that caused it to fail?
    Or is it inevitable ?
    Thx so much!
    PS: why does my 2001 Putback automatic turn 500 rpm slower at 75mph that my 2000 5sp manual? I always thought automatics turned slower than automatics. What’s going on?
    Thx!

    • Charley says:

      “It’s funny to see our little 96 Impreza (wABS) DRAGGING THEIR BIG SUV that can’t function where Subarus…” (emphasis added)

      “Did I do anything that caused it to fail?” Yes. You answered your own question. I laugh when someone complains when they break their own car.

  • Cain says:

    Hey Martin, I have an 95 Impreza L that I bought for $800. The transmission shifter is very loose, and you can’t tell what gear you’re in when shifting. What do you think? I want to tear the whole thing apart and rebuild it from scratch, and this article is giving the confidence to do that. But if its something simple, I will approach it from that angle also. Thanks for the article and your time man.

    • Martin Hand Martin Hand says:

      There is a bushing underneath the car that the shifter pivots in, I would bet that’s worn out. I have seen this many times. The transmission will not cause the shifter to be loose.

    • Jonathan says:

      This is pretty common I think, my WRX and LGT both had this issue, there is a shifter yoke, wouldn’t call it a bushing, and the rod inside of it gets loose. very cheap part and even if you wont do it yourself, shops only charge half an hour of labor to fix it.

  • I think that I have this problem(bearings and viscous coupler) with my 2009 Forester manual transmission(88,000 miles). Do you know where I might get it repaired in MO?

    Thanks,

  • Carl says:

    I have a Liberty (legacy) 5 spd manual trans that is making clonking noise when turning (only after approx 20min driving). I have concluded from lots of internet research it is the Viscous Coupler. Pulled tranny out and removed the transfer case and removed the VC. It is very obvious the the bearing the VC rides in is extremely bad (sloppy and noisy). The VC appears to be good except some discolouring right on the end (bearing side).
    So wondering could my problem just be the bad bearing rather than the actual VC. Is there a way of testing the VC?

    • Martin Hand Martin Hand says:

      The bearing would just be noisy, since your in there I would replace the friction and steel plates and the solenoid assembly just to be safe. Replace the drum if it is grooved from the clutch discs.

  • Michael Ballard says:

    I am so glad I found your site and this article. I’m in North Carolina and want to do this work myself but it’s been hard finding out good information about what is needed. I have done plenty of work on cars but never transmission repair. I bought a 2001 forester manual transmission and it’s making a grinding noise under load in all forward gears. shifts fine, but sounds like it’s full of gravel! The research I’ve done has me leaning toward bearings but I’ve been hesitant to tear into it. Any help or insight you can provide would be outstanding!! One question, the images you posted that say viscous coupler look like what I’ve seen called the center diff. is that the same part? At this point I’m thinking the next best step is to just get starting tearing it down to check the bearings. your thoughts would be greatly appreciated.

  • Adam Ashmore says:

    To abtone that can help
    Iam a owner of a 2000 subaru outback limited 5 speed and iam looking for a vicous coupler and not finding any plaxes to purchase one..i would like to findone that is a little more upgraded than the oem replacment.
    I had tbe xluch replacedWith a stage two racing cluch ( i live in Maine and wanted sometbing for the tough terrain. )
    If you know of a web site that could help me please email it to me..

    Tbank you for your time
    Sincerely
    Adam. A

    • Martin Hand Martin Hand says:

      I purchase all parts directly from Subaru. Find a local Subaru dealer in your area. I also get good used hard parts from a few different transmission whorehouses in the area, you could look for a place like that where you live maybe?

  • matt friedlander says:

    Should the viscouse couple spin freely once you have this apart? Can you turn it by hand? My trasmission whines as my speed increases but is not rpm dependent. Trying to figure out if its a bad bearing or the coupler.

    • Martin Hand Martin Hand says:

      Sounds to me like the transmission needs bearings. I have never heard a viscous coupler make a noise like your explaining, it only works when turning corners.

      • Rudy Del says:

        I had the whine at high speeds only not high rpms, Subaru replaced two gear reduction bearings and two other transmission bearings saying the viscous coupling was good. $900 later and after one week, going from garage to driveway I hear a loud clunking noise. Towed it back to subaru and now they say new tires on front and worn tires on back caused the viscous coupling failure. Mismatched tires ? really? Please add your comments. Many thanks.

        • Martin Hand Martin Hand says:

          That just doesn’t sound correct. I cant even replace Subaru MT transmission bearings for that cheap and our labor rate is less than half of the dealer rate. No shop should perform a repair on your AWD transmission then let it go out the door with mismatched/un-even tires. How are you supposed to know this, that’s why you take it to them.

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