We Blew Up BOTH our Subarus Transmissions

**Transmission Troubles: A Tale of Two Subaru RX's**

I was driving my Subaru RX with a 5-speed transmission when I noticed something strange happening. The car would stutter and hesitate, as if it were struggling to keep up with the demands being placed on it. At first, I thought maybe I just needed to adjust to the new gearing, but as the problem persisted, I began to suspect that there might be a more serious issue at hand.

**The Problem: Overpowered Transmission**

Upon closer inspection, I discovered that my transmission was not designed to handle the increased horsepower generated by my engine modifications. The gears were small and thin, unable to withstand the stress being put on them. In fact, when you downshifted from fourth to third gear too quickly, it would chip a tooth - and repeat this process over 180,000 miles, eventually leading to a domino effect that would bring the transmission crashing down.

**The Failure Point: Gear Size and Design**

I think it's fair to say that the failure point of this transmission was the actual gear itself. The dimensions and size of the gears were not engineered to handle the amount of horsepower being applied. This is especially surprising, considering that even with small gears, a four-wheel drive system like the STI 6-speed would be able to put more power through the wheels.

**Comparing to Other Transmissions**

To get a better understanding of why my transmission was struggling, I decided to compare it to other high-performance transmissions. Upon opening up my car's transmission and examining its inner workings, I discovered that the gear set was incredibly stout and beefy - much more robust than what I had initially expected.

**Confronting the Reality: Poor Design and Manufacturing**

However, as I continued to examine the transmission, I realized that it was still a poor design for handling 400 horsepower. It seemed that the engineers had not anticipated this level of power being applied to the car, leading to a situation where the transmission was unable to cope.

**The Verdict: A Poor Design Flaw**

After conducting further research and analysis, it became clear that the Subaru RX's 5-speed transmission was indeed a poor design for handling high horsepower. As such, our advice would be to avoid pushing your engine modifications too hard on this particular car - or be prepared to deal with the consequences.

**The Way Forward: Rebuilding or Replacement**

We have two RX's now without functioning transmissions. Should we rebuild them with stock 5-speeds, replace them with STI 6-speeds, or perhaps even install a sequential transmission? The choice is yours! Let us know in the comments below what you think.

**Conclusion**

Well, that was a lot of fun - and a whole lot of learning! We managed to break stuff (transmissions, anyone?), but at least we found out who wasn't responsible for the mess. Thanks for watching, everyone!

WEBVTTKind: captionsLanguage: enwe threw $330,000 in this WRX upgrading everything from the tires to the turbos a couple weeks ago I took this car to the Canyons where the transmission mysteriously exploded and then Justin while driving ladx had the exact same failure look man it's not my fault all right I wasn't even doing anything mhm within 2 weeks two different drivers two failures but the same model of transmission now we know I'm not the problem because I'm a professional race car driver but Justin on the other hand he's a big strong board maybe he broke the transmission with his strength or maybe could subie be to blame for such a weakness in their transmission get your pitchforks ready Vape Lords today we're cracking these Transmissions open to see how they work look at their failure points and diagnose what went wrong we're going to figure this out solve the mystery so this doesn't happen to you welcome to Donut yeah this has to pop off all right while Justin and the boys are pulling the Transmissions out of the wrx's in front of me I have a transmission from a 350Z the reason I have this is because we're going to use it as an explainer to see how these things work and particularly this one works really really well it's a proven platform if anything is different from this to the WRX we'll know if it's our fault or if it's sub's fault that not mine let's do a little Deep dive in inside a spinning ball of engineering Marvel all right now that we have our transmission pretty much disassembled at least from the case we get to see the inside of it and see how this thing works there are a couple of main components here I'm going to walk through each one so we can see how you get transmission of power from your engine to the rear wheels all this hard work is making me thirsty good thing today's video is sponsored by by air up air up is a great and unique way to meet your daily water intake simply fill up your air up bottle with plain old water pop on your favorite scent pod pull up to activate and boom your plain water is now loaded with delicious flavor or should I say scented flavor it's just regular H2O no chemicals no sweeteners or artificial nonsense and when you don't want any flavor all you got to do is push the scent pot down to deactivate it's that easy with the holidays around the corner there's no better time to give family friends or loved one a gift with taste arir up is perfect for people who love water which hopefully is all of you because water is good for you so click the link below save up to 30% with aups holiday bundles but you're going to want to click fast because this offer ends December 26th for those of you who shop after Christmas just click the link below thank you rir up first things first you have your input shaft now this input shaft is what's Driven directly off the flywheel and the clutch on the engine side and on the back end here we have our output shaft our input shaft and our output shaft when the car is in neutral rotate independently of each other well we want to get transmission of power from the engine to the rear wheels we need to make some sort of connection and to do that you have a counter shaft now the counter shaft is the link between those two shafts and the way that you make that connection is with these shift Forks now these shift Forks are directly tied to the gear selector inside the car I want to shift into first gear I shift into first the shift Fork engages this gear set right here that gear set interacts with a gear on the counter shaft that counter shaft then interacts with this output shaft and now the input shaft spins the output shaft push the clutch in pretty clever way getting power to the rear wheels when you need to manage torque at various speeds now one clever bit of engineering that allows you to shift from one gear to the next without grinding it are these synchronizers so these are little gear sets that kind of have a little bit of play with them and they're angled like this which allows this shift Fork to be able to slide into a new gear set while that gear is spinning at a different speed pretty cool now obviously you have a bunch of moving parts inside a transmission so that leads to a bunch of failure points a lot of the failure points are usually in the shift Forks themselves or in the gear so those are the things that are obviously moving the most and getting the most use and one of the things that makes a transmission robust is the gear set itself the material of the gear as well as the actual mass and size of the gear so as you can see first is the largest gear it has the most teeth it has the largest diameter fourth on the other hand has the smallest diameter however it's a lot wider it also has very thick teeth now in the case of Nissan for example this could be considered an overbuilt transmission you can put a whole bunch more power to it because the engineers built it way Bey Beyond its means of failure now apparently on the Subaru third gear in particular is a small baby little massless gear set if old Jeremiah Burton was a bon man I would say third gear in the Subaru transmission totally disconnected from the input shaft which will prove that I had nothing to do with it all right so I was out driving a nice Canyon Road going at a reasonable speed I was probably around 6,500 RPM when I shifted from third to 4th uh it went made a l a very loud noise and then wouldn't go into third if I could have done anything different I wish that I wasn't the one driving when it broke we pulled this transmission out of a freaking junkyard who knows who else beat the crap out of this thing I just happened to be the one got stuck with the mess I plead not guilty I had nothing to do with it I was just driving when it popped we had a track day film with the new WRX versus highx right I just wanted to go out to the track day I'd already done a couple of laps not very fast we're just going around the carousel I'm in third I didn't even go to Second that's how slow I was going on purpose and then I go to shift in the fourth fell out of third you hear a big pop and then it goes in the fourth o there went that guess what just happened what could you have done to prevent it not drove that day I am not guilty yes I broke the Ascender fine this could have been anyone as well I was just unlucky this is not my fault I plead not guilty I'm done not spilling all over the floor buddy oh oh that's not looking too good for Jeremiah not my fault here we go yeah who small yeah small skinny I mean that's kind of the running theme with the subers is that as long as you don't go crazy with the turbo and everything they're fully fine super reliable yeah well that's the thing it's like the WX is just hey this is an Impreza with Boost the STI is the one you should be doing all this stuff to in the first place cuz it's made for that extra power but people can't afford it okay look the only argument I can see you coming up with down there in those comments is the fact that we didn't have to upgrade the 350Z Transmissions between turbo and V8 swap but here's the thing that's rear wheel drive they're built completely different for different stress levels these all drive transmissions have to fit in a small package naturally the things are a little bit smaller and they go through a bit more stress plus this car was meant to be driving in loose dirt slight rally kind of thing and it's a smaller engine less power going through I don't know what you want me to say but as soon as we open that transmission you're going to see they're completely different this is transmission out of High car what a colossal mess if only you saw the amount of metal that came out of it yeah hold on oh look at that are these teeth from a gear I think oh yeah they are that's exactly what that is so for the record low Rex did not not have this much compared just so you know hydrate oh that looks pretty good yeah nothing here no nothing in here looking pretty good we need to dive deeper into the belly of the Beast tree if you guys could only smell this oh that's a weird smell it's weird it's like a smelling oh dude oh dude Oo we got some milky goo you can see the big chunks of metal coming right here yeah so I did continue to drive this car after I bow thir tier and I did not yeah I did because I hate tow truck drivers okay one thing that we haven't really talked about is pretty common in the Subaru forms for you to come across people who have had third gear failures in the 5-speed transmission yeah around a certain horsepower number sure without further Ado let's take a look at the inside of our 5-speed sub transmission see what went wrong let's hanging up on something oh I remember that kid oo well there seems to be a problem right there uh our culprit as predicted third gear the actual teeth on the gear itself really are just chewed up on both the input shaft and the counter shaft that's really really bad yeah third gear is not looking great uh now one of the things while these sleeves are not engaged with the uh with the gears themselves they should freely spin on this shaft well that's fraking well those metal fragments got inside there and prevent it from rotating freely you think that happened cuz you kept driving on it well I think what happened is these gears are not to be able to handle 400 plus horsep just take a quick look at our 350Z transmission here these things are incredibly uh Stout they're beefy the teeth themselves are really thick and the gears themselves are wide and thick these are so small so say you do a rough second to Third and you chip a tooth okay that's not great but it's still going to be still run so you downshift real hard from fourth to third chip another tooth you do that over 180 ,000 miles and eventually domino effect domino effect yeah now I think it's fair to say that failure point of this is the actual gear itself the the dimensions and size mass all of that of this gear set is not engineered to be able to take the amount of horsepower being applied you have to remember this transmission even with these small gears is made to put Power to four wheels whereas this is just two wheels so why is this so much more robust than this is if it has to do more work I don't know ask the engineers cuz it's not our fault I think probably it's a packaging design they have to fit smaller gear set in a smaller uh case in bell housing also it could just be manufacturing because it's cheaper there's a lot of factors here that could play in why they chose to make smaller gears for this but it doesn't really make up for the fact that it can't handle 180 plus more horsepower than stock with all that being said this was a design flaw when you put that much horsepower to a car they didn't design it for that so I don't know if it's a flaw but we've looked at High car transmission it's my turn now let's see if low car has a similar issue all these I think we're going to open this thing up and it's going to be the exact same story maybe even a little bit less bad so far so good all right we're looking good so far let's keep going okay so we're looking at fifth gear right here everything seems to be okay uh-oh M as bad as yours that's correct we need to go further we need to get into the belly of the bees hold on stop stop stop all right I'm not seeing anywhere near as much metal my gears are still somewhat inct oh God that is a lot of metal holy crap it's all hiding okay so on the input shaft the gears are pretty much dude they're like worn down worn completely down but you still have some teeth uh on the connecting shaft that's cuz I I went straight into neutral and didn't touch it again and I parked it within 100 yards so should have done that too I don't think you slowing down saved it I think you were driving it less hard when it blew that's true and it just blew the teeth off of this gear right so this probably was already breaking this was probably already breaking over time and it just this is completely sheared off and if you have no teeth on one gear it's not going to interact with the other one okay so we have two third gear failures High car much worse but it also made a lot more horsepower that is true so when it does go it and you drive a lot harder than I do uh so third gear failure we're chalking it up to a poor design in terms of being able to handle 400 horsepower Our advice would be if you're going to put put engine modifications on your Subaru RX uh and you have this transmission don't don't or just realize that this is going to be your life or save up while you just hammer on this one and then when it pops it pops we have two wrx's that are now not functioning because we don't have Transmissions that works should we uh replace these guys with some uh STI 6-speeds should we just rebuild them with the stock 5-speed should we put a sequential in one of them let us know in the comments below Justin this is a lot of fun yeah we learned a whole bunch and we broke stuff and we found out we weren't the the ones who did bad innocent boys thank you guys so much for watching this everything El at donut bye have a good onewe threw $330,000 in this WRX upgrading everything from the tires to the turbos a couple weeks ago I took this car to the Canyons where the transmission mysteriously exploded and then Justin while driving ladx had the exact same failure look man it's not my fault all right I wasn't even doing anything mhm within 2 weeks two different drivers two failures but the same model of transmission now we know I'm not the problem because I'm a professional race car driver but Justin on the other hand he's a big strong board maybe he broke the transmission with his strength or maybe could subie be to blame for such a weakness in their transmission get your pitchforks ready Vape Lords today we're cracking these Transmissions open to see how they work look at their failure points and diagnose what went wrong we're going to figure this out solve the mystery so this doesn't happen to you welcome to Donut yeah this has to pop off all right while Justin and the boys are pulling the Transmissions out of the wrx's in front of me I have a transmission from a 350Z the reason I have this is because we're going to use it as an explainer to see how these things work and particularly this one works really really well it's a proven platform if anything is different from this to the WRX we'll know if it's our fault or if it's sub's fault that not mine let's do a little Deep dive in inside a spinning ball of engineering Marvel all right now that we have our transmission pretty much disassembled at least from the case we get to see the inside of it and see how this thing works there are a couple of main components here I'm going to walk through each one so we can see how you get transmission of power from your engine to the rear wheels all this hard work is making me thirsty good thing today's video is sponsored by by air up air up is a great and unique way to meet your daily water intake simply fill up your air up bottle with plain old water pop on your favorite scent pod pull up to activate and boom your plain water is now loaded with delicious flavor or should I say scented flavor it's just regular H2O no chemicals no sweeteners or artificial nonsense and when you don't want any flavor all you got to do is push the scent pot down to deactivate it's that easy with the holidays around the corner there's no better time to give family friends or loved one a gift with taste arir up is perfect for people who love water which hopefully is all of you because water is good for you so click the link below save up to 30% with aups holiday bundles but you're going to want to click fast because this offer ends December 26th for those of you who shop after Christmas just click the link below thank you rir up first things first you have your input shaft now this input shaft is what's Driven directly off the flywheel and the clutch on the engine side and on the back end here we have our output shaft our input shaft and our output shaft when the car is in neutral rotate independently of each other well we want to get transmission of power from the engine to the rear wheels we need to make some sort of connection and to do that you have a counter shaft now the counter shaft is the link between those two shafts and the way that you make that connection is with these shift Forks now these shift Forks are directly tied to the gear selector inside the car I want to shift into first gear I shift into first the shift Fork engages this gear set right here that gear set interacts with a gear on the counter shaft that counter shaft then interacts with this output shaft and now the input shaft spins the output shaft push the clutch in pretty clever way getting power to the rear wheels when you need to manage torque at various speeds now one clever bit of engineering that allows you to shift from one gear to the next without grinding it are these synchronizers so these are little gear sets that kind of have a little bit of play with them and they're angled like this which allows this shift Fork to be able to slide into a new gear set while that gear is spinning at a different speed pretty cool now obviously you have a bunch of moving parts inside a transmission so that leads to a bunch of failure points a lot of the failure points are usually in the shift Forks themselves or in the gear so those are the things that are obviously moving the most and getting the most use and one of the things that makes a transmission robust is the gear set itself the material of the gear as well as the actual mass and size of the gear so as you can see first is the largest gear it has the most teeth it has the largest diameter fourth on the other hand has the smallest diameter however it's a lot wider it also has very thick teeth now in the case of Nissan for example this could be considered an overbuilt transmission you can put a whole bunch more power to it because the engineers built it way Bey Beyond its means of failure now apparently on the Subaru third gear in particular is a small baby little massless gear set if old Jeremiah Burton was a bon man I would say third gear in the Subaru transmission totally disconnected from the input shaft which will prove that I had nothing to do with it all right so I was out driving a nice Canyon Road going at a reasonable speed I was probably around 6,500 RPM when I shifted from third to 4th uh it went made a l a very loud noise and then wouldn't go into third if I could have done anything different I wish that I wasn't the one driving when it broke we pulled this transmission out of a freaking junkyard who knows who else beat the crap out of this thing I just happened to be the one got stuck with the mess I plead not guilty I had nothing to do with it I was just driving when it popped we had a track day film with the new WRX versus highx right I just wanted to go out to the track day I'd already done a couple of laps not very fast we're just going around the carousel I'm in third I didn't even go to Second that's how slow I was going on purpose and then I go to shift in the fourth fell out of third you hear a big pop and then it goes in the fourth o there went that guess what just happened what could you have done to prevent it not drove that day I am not guilty yes I broke the Ascender fine this could have been anyone as well I was just unlucky this is not my fault I plead not guilty I'm done not spilling all over the floor buddy oh oh that's not looking too good for Jeremiah not my fault here we go yeah who small yeah small skinny I mean that's kind of the running theme with the subers is that as long as you don't go crazy with the turbo and everything they're fully fine super reliable yeah well that's the thing it's like the WX is just hey this is an Impreza with Boost the STI is the one you should be doing all this stuff to in the first place cuz it's made for that extra power but people can't afford it okay look the only argument I can see you coming up with down there in those comments is the fact that we didn't have to upgrade the 350Z Transmissions between turbo and V8 swap but here's the thing that's rear wheel drive they're built completely different for different stress levels these all drive transmissions have to fit in a small package naturally the things are a little bit smaller and they go through a bit more stress plus this car was meant to be driving in loose dirt slight rally kind of thing and it's a smaller engine less power going through I don't know what you want me to say but as soon as we open that transmission you're going to see they're completely different this is transmission out of High car what a colossal mess if only you saw the amount of metal that came out of it yeah hold on oh look at that are these teeth from a gear I think oh yeah they are that's exactly what that is so for the record low Rex did not not have this much compared just so you know hydrate oh that looks pretty good yeah nothing here no nothing in here looking pretty good we need to dive deeper into the belly of the Beast tree if you guys could only smell this oh that's a weird smell it's weird it's like a smelling oh dude oh dude Oo we got some milky goo you can see the big chunks of metal coming right here yeah so I did continue to drive this car after I bow thir tier and I did not yeah I did because I hate tow truck drivers okay one thing that we haven't really talked about is pretty common in the Subaru forms for you to come across people who have had third gear failures in the 5-speed transmission yeah around a certain horsepower number sure without further Ado let's take a look at the inside of our 5-speed sub transmission see what went wrong let's hanging up on something oh I remember that kid oo well there seems to be a problem right there uh our culprit as predicted third gear the actual teeth on the gear itself really are just chewed up on both the input shaft and the counter shaft that's really really bad yeah third gear is not looking great uh now one of the things while these sleeves are not engaged with the uh with the gears themselves they should freely spin on this shaft well that's fraking well those metal fragments got inside there and prevent it from rotating freely you think that happened cuz you kept driving on it well I think what happened is these gears are not to be able to handle 400 plus horsep just take a quick look at our 350Z transmission here these things are incredibly uh Stout they're beefy the teeth themselves are really thick and the gears themselves are wide and thick these are so small so say you do a rough second to Third and you chip a tooth okay that's not great but it's still going to be still run so you downshift real hard from fourth to third chip another tooth you do that over 180 ,000 miles and eventually domino effect domino effect yeah now I think it's fair to say that failure point of this is the actual gear itself the the dimensions and size mass all of that of this gear set is not engineered to be able to take the amount of horsepower being applied you have to remember this transmission even with these small gears is made to put Power to four wheels whereas this is just two wheels so why is this so much more robust than this is if it has to do more work I don't know ask the engineers cuz it's not our fault I think probably it's a packaging design they have to fit smaller gear set in a smaller uh case in bell housing also it could just be manufacturing because it's cheaper there's a lot of factors here that could play in why they chose to make smaller gears for this but it doesn't really make up for the fact that it can't handle 180 plus more horsepower than stock with all that being said this was a design flaw when you put that much horsepower to a car they didn't design it for that so I don't know if it's a flaw but we've looked at High car transmission it's my turn now let's see if low car has a similar issue all these I think we're going to open this thing up and it's going to be the exact same story maybe even a little bit less bad so far so good all right we're looking good so far let's keep going okay so we're looking at fifth gear right here everything seems to be okay uh-oh M as bad as yours that's correct we need to go further we need to get into the belly of the bees hold on stop stop stop all right I'm not seeing anywhere near as much metal my gears are still somewhat inct oh God that is a lot of metal holy crap it's all hiding okay so on the input shaft the gears are pretty much dude they're like worn down worn completely down but you still have some teeth uh on the connecting shaft that's cuz I I went straight into neutral and didn't touch it again and I parked it within 100 yards so should have done that too I don't think you slowing down saved it I think you were driving it less hard when it blew that's true and it just blew the teeth off of this gear right so this probably was already breaking this was probably already breaking over time and it just this is completely sheared off and if you have no teeth on one gear it's not going to interact with the other one okay so we have two third gear failures High car much worse but it also made a lot more horsepower that is true so when it does go it and you drive a lot harder than I do uh so third gear failure we're chalking it up to a poor design in terms of being able to handle 400 horsepower Our advice would be if you're going to put put engine modifications on your Subaru RX uh and you have this transmission don't don't or just realize that this is going to be your life or save up while you just hammer on this one and then when it pops it pops we have two wrx's that are now not functioning because we don't have Transmissions that works should we uh replace these guys with some uh STI 6-speeds should we just rebuild them with the stock 5-speed should we put a sequential in one of them let us know in the comments below Justin this is a lot of fun yeah we learned a whole bunch and we broke stuff and we found out we weren't the the ones who did bad innocent boys thank you guys so much for watching this everything El at donut bye have a good one