How Subaru AWD Works
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- čas přidán 10. 12. 2023
- Here’s how Subaru’s symmetrical AWD system works!
Subaru has been known for their AWD systems for decades. It is a full time AWD system that drives all four wheels of the vehicle. There are a few variants, including having a center differential based on a viscous coupling, a multi-plate clutch pack, a planetary gearset with a clutch lockup and a limited slip differential. In this video, we teardown the center differential with a planetary gearset from a 5 speed automatic transmission out of a 2005 Subaru Outback.
Power is sent from the boxer engine to the 5 speed automatic transmission, which changes gear ratios. At the tail end, a center differential splits power between the sun gear going to the rear tail shaft, and the planet carrier, which goes through a countershaft to the front differential. Through gearing, different torque splits can be applied to each axle.
The front differential is located within the transmission bell housing, below the input shaft. This means the front has equal length axles, and combined with the symmetrically oriented boxer engine, lends to Subaru’s “symmetrical” AWD moniker. This layout limits torque steer, however it puts the heavy engine weight ahead of the front axles, unlike a longitudally mounted RWD based AWD system where the front differential is beside the oil pan, underneath the engine.
Overall the Subaru AWD system and the 5 speed automatic seems to be a very robust system, with this transmission showing very little wear after 300,000km and 17 years of use. From a maintenance perspective, this transmission does away with an external transfer case, prop shaft and differential, instead choosing to have all those functions well integrated into the transmission assembly.
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Meanwhile in an alternative universe a dentist is giving a lecture with a wrench.
😂🔧
For 300km that trans is in pretty damn good condition. But yeah you should also do a tear down of the cvt. Subarus have some pretty solid ones and I’d love to see a rip down of one.
I'd love to see one too!
It sucks to think that cvts are usually weaker than a standard geared transmission.
@@vipervidsgamingplus5723 i mean logically speaking, one can clearly see how a belt driven pulley is weaker than gear on gear and clutches
Seems to be a good CVT Transmission, my dad has a 2019 Outback.
Except the very homosexual „fake shifting“ its very good
@@shakalpb1164 yeah thats one thing i dislike with all companies that are using cvt’s. The fake shift mimicking. Just let it be a cvt, everyone already knows it is so let it hold the high revs and push power
From someone who’s driven Subarus all their life and now drives a Mitsubishi Triton for Work , let me tell you I have taken Subarus traction and control on the road, especially in wet weather for granted!!!!! These new two wheel drives, front wheel drive or rear wheel drive, on a hill slight bit of rain, and you just slide everywhere. Subarus control is unprecedented, taking into account the small increase in fuel consumption, and lack of being able to switch between two wheel and four wheel. They’re amazing
Nice
An incredible piece of engineering! Kudos to you for your understanding of how it works & your excellent explanation
Thanks. It took me a few days but I studied it a bit and tried to understand it. I love appreciating these wonders of manufacturing and engineering.
I love you too
@@speedkar99 how did you study it?
@@18890426 Other youtube videos.
I've been into Subarus for 20+ years, and this is the best teardown of a Subaru transmission I've ever seen. Would love to see an STI transmission, or at least the front diff.
Glad you enjoyed it
It’s amazing the amount of engineering that must go into designing transmissions like these! Just the tear down with all those clutches makes my head spin!
The base design is by nissan. Alot of the parts interchange into the older nissan pathfinder transmission.
I agree. Manufacturing and engineering! Then everything gets taken for granted.
Subaru engineering on their drivetrain system is top of line. What their cars are capable of is simply incredible. Another well made Japanese based product
Agreed. Quite the feat here
Just wish they put the same effort into their motors :(
You probably didn't own a SVX 😅
Yeah sure…that EJ sure had a lot of thought put into maximizing reliability and durability…NOT!
Garbaggio, hot steamy piles of it. Literally. 😊
Came for the info, stayed for the insane sound of the impact wrench edited together quickly.
Glad you enjoyed it. It's very tedious to edit
I love your videos! Are you working on a Subaru one? 👀
Soon enough! @@nairb2
Aging Wheels has some great impact/drill edits too.
Subaru AT VTD system is pretty ingenious. I recall when I owned my Impreza I could feel torque shifting between the front and rear axle when I was driving on a snowy frozen lake. Cool stuff.
That's cool! From what I understand the torque split isn't that different between the front and rear wheels, probably 40/60. Interesting that you could even feel that much.
@@speedkar99It's actually 45F/55R. Just like in a WRX. That's actually a Torsen center diff.
You should try Acuras SH-AWD, that system really transfers power between the wheels.
got big balls eh to drive on a frozen lake
@@BMW_Z4idiot thanks sir! Got an old video on my channel of it
Watching this begs the question: Who thought this all up and made it work? Fascinating. Thank you.
I'm sure the engineers started with something much simpler and then just kept adding onto it.
@speedkar99 same as computers. Those are on the different level of complexity, but you can still understand the basic architecture and how stuff works.
Mr Subaru.
Dang, great video explaining this complicated Subaru AWD Engine; what a beauty, so that's why they're so good on rough terrain, and durable and expensive
It sure is a touch setup. I like it
@@speedkar99 Really Well designed, the only that I don't like, is the price, but I guess it's worth it. This is for Wagons/SUVs right, not cars/hatchbacks?
@@saultube44Afaik they suvs are just lifted crossover wagon versions of their sedans?
@@angelolagussa1312 AFAUK, until you know, your speculations are of no relevance to me
@@saultube44dunno if it’s exactly the same but all Subarus have this AWD system.
I like how you respond to every comment. ❤
Love from South Denver Subaru Club
Thanks. I try to at least
Seriously complicated technology and your knowledge is amazing too. Keep up the streams, I really look forward to them. Cheers from UK..
Thanks. I'm sure it started alot simpler and they just kept adding onto it.
Thank you for this explanation of the basic automatic transmission. You made it very easy to understand. Best of CZcams 100%
You are welcome!
Pumped for the Subaru content! Let's GOOOOOO!
No problem. I got an H6 Engine teardown and a differential video from this Outback coming soon.
You are expert in your clear and perfect explanation of the planetary gears, hydraulic and solenoid works. Thank you.
This video is fantastic! Thanks man! Nice pace, no awkward pauses or silent streaks, very well explained and very entertaining.
Glad you enjoyed it!
That valve body thing looks a-maze-ing inside!
It sure is amusing!
Thank you for taking the time & making a video full of knowledge for everyone curious out there :)
You Sir, are magnificent, And your videos are about as in-depth as it possibly gets.
thank you soo much for giving me the knowledge of the automotive world.
You are welcome! The best way to learn is to take something apart.
A lot of thought went into the engineering and design of this transmission. A lot. Makes me appreciate the amount of planning and execution to make all this happen in one unit. Integrating the front differential with the transmission makes perfect sense and saves space too.
The next time I see a Subaru on the road. I will go out of my way to smile and wave at the owner because quite frankly they absolutely deserve it.
Thanks
Just came here because I was getting torque converter codes on my '13 Crosstrek and wanted to understand the whole transmission system better before I took it in. Thanks so much for your breakdown and explanation. This video was amazingly helpful to get a little education and I feel I will definitely be to better understand what the service mechanic tells me about the issue I'm having.
You are welcome. Hope you solve the issue.
You are the best teacher and no equal to you.
Thanks
"This is basically an exploded view" 😂😂😂
💥💥
The valve body is (literally) an analog mechanical computer.
Yep! Except it's electronically controlled with solenoids.
Controlled by a (literaly) digital computer. @@speedkar99
Thank you for making this! I have been looking for a demonstration of these things for the longest time ever!
You are welcome
G’day Sir! I salute you for your teardown explanation.. I am
Into old Toyotas but man this is really interesting stuff and your explanation is crystal clear! Subaru’s awd is really an engineering marvel!
Amazing, how engineering mind comes to these ideas/designs, then even more amazing is how the production is quickly designed to make the parts in volumes from the drawings to the tooling and most amazing is how in a few years a completely new model gearboxes are out and all starts almost from the scratch. But one thing I am sure is you can never put it back together again (11:41).
Very nice presentation (as always) and showing how we take things for granted. When the average person buys the car, get the keys and starts the engine the last thing on his/her mind is the complexity of parts that allows us to drive it the way it is designed for.
Your videos will always change the way we look at the car machinery after watching them. There is an old Chinese proverb from 500 BC (maybe philosopher Confucius?): “I hear I forget, I see I remember, I do I understand.” Well your videos are the bridge between see and do. Not only we see it but almost like as we did it ourselves. But not only that, many times you through into your videos some facts from statistics or experiences you will not find in manuals especially when you talk about good or bad things in design or manufacturing.
So thanks for doing these videos and sharing with everyone. I hope you get enough financial support to continue doing what you are doing but even more for your wife and brother. I hope they will never run out of money for their new clothes and underwear. And toothbrush.
Well said! I agree 100%
I am very thankful for your feedback. I'm glad that people can benefit, just as I do when I learn as I tear things down. I didn't learn any of this in engineering school.
I hope you gonna lay your hands on subaru Lineatronic CVT some time in the future. Its almost 14 yrs old now and should hit junkyards soon.
I wish it was that easy. Even if they were there at this age, junkyard transmissions are like $300 after core plus I gotta pull it.
Impressive description throughout the tear down. You have a gift for teaching!
Glad you could learn something new! Thanks
Just stumbled upon this video , absolutely fascinating ! I don’t even own a Subaru and I rewatched it twice 😂
Thanks..glad you appreciate and can learn something new!
So cool to actually see all the parts. I love it!
Me too
Awesome teardown and explanation 👌
Thanks!
I’ve owned Subaru outback for years I think they’re the best car ever thank you for this video not that I am that capable but I often wondered how it all worked with the gearbox thank you very much indeed you’re a clever man😊
You are welcome. I learn by taking things apart just like this.
_Now to get it back together ready for a 7am start tomorrow!_
Loved it! Thanks for going to all that trouble. Hope it pays off for you.
You are welcome! I hope so, as long as people learn something new!
That one tiny little parking pall is a good reason not to rely on it alone to park your car (yes I know it locks the gearset as well). A parking brake should be set in N and then take your foot off the brake to let the car lurch and rest on the parking brake before finishing the shift into P. Remember to set the parking brake tighter and harder on hills so the car won’t roll forward slowly while the brake is set. You might have to tighten it to hold the car before shifting to P. It also prevents stress on the gearbox by not having the weight of the car resting on the transmission while in P. Of course, this is especially true when parking on a hill. Don’t forget to turn your wheels toward the curb on a hill. If it is a manual car put the gearbox in 1 for parking if the back of the car is pointed down hill or R if the front of the car is pointed down hill. Still make sure the car is resting on the parking brake alone before you put the lever in R or 1.
I am guilty of not practising what I preach with the parking brake.
did he just say ez clap, didnt know you were chill like that
Yeah boy! I'm not that professional around the home lol
Thank you for making this video!
You are welcome
Que paso guey.
Another extremely thorough and easy to digest video.
Big fan bro. 💪🏼
Appreciate it!
Transmissions are crazy sophisticated to me....let alone AWD systems.
As always,LOVE this video Brotha!!! Along with your detailed explanation and showings of everything!!! Great video!!! : >)
Thanks!!
Great video! Awesome to see the inside of the valve body. First time seeing the combination planetary gearset + clutch for me. I am more familiar with the 4EAT which IIRC are full-time FWD with a clutch pack that can send some power to the rear (or fully lock like a transfer case).
It sure was interesting to dive in and see how it works! This is such old technology but I can learn alot.
There really isn't much difference between the 4EAT and 5EAT VTD system other than the added planetary gearset for the rear bias.
@@niuhuskieguy True! But with a VTD gearset, the car can never enter a 'FWD-only' mode, correct?
@@avsti Correct. If the clutch packs aren't active, the system will be like a basic all time 4x4 with centre diff. Much closer to the manual transmissions than the 4EAT.
4:32 yup easy clap is the last thing I expected on this channel💀
LOL I say that all the time at home
Wow, you are incredibly fast !
You're an excellent teacher !
Thanks
Excellent video, thanks for sharing.
You are welcome
This guy is brilliant.
Thanks !
You are welcome
Not often you see a Subaru 5EAT taken apart. I wished they ran a 4.111FD instead. I also wished Subaru put the VTD center diff as standar across the model line up. It's a much better AWD system. Your average non-car person wouldn't know the difference between the multiplate transfer clutch VS this VTD center diff. Awesome video!
Thanks. These don't fail too much that's why they aren't apart
That was awesome!
Great vid!
If I ever have the misfortune to use the wealth of information, I'll def come back!
The best itip I got out of this was the extended socket to avoid the mess when removing the oil drain plug.
Thank you!
You are welcome
*uses broken bricks to hold transmission shafts
Genius, man. 🍻
I didn't want to build a V-block just for this quick demonstration
AMAIZING video!!, thank you so much.
You are so welcome!
Interesting concept. Thanks for sharing...
You are welcome.
Excellent explanation!
Thanks
Great vid, clutches & steels, bands wrap around drums and carriers
This one had no bands and drums
Incredible video and explanation, had 6 Subarus manual and autos now. Love my 5spd AT behind the flat 6, incredible engineering. If you have a Subaru I highly recommend finding a local Subie specialist to work on it rather than many other general mechanics.
They seem easy enough to work on by anyone, except all these rusty fasteners.
As it says in a Haynes manual, reassembly is the reverse of the disassembly procedure 👍🏻🇬🇧
With some persuasion yes
Amazing engineering. Thanks for this video and your explanation. Now I must clean up the wall behind me from everything that went WAY over my head. 🤣😂
I'm glad you learned something, as I did too!
The STI drivetrain is very strong and it’s a stock trans and all that. I’m throwing over 600 ft lbs at it and it’s holding well.
Nice!
1:39 i thought it was funny how you quickly ended your sentence to note how cool it looks. i feel the same way lol
I find the variety of differential and transfer case types to be extremely interesting.
Plated diffs with electromechanical control, or electrohidraulic, or electromagnetic, or gerotor pump, geared lsd's, center diffs for transverse engines, torque vectoring diffs with or without spider gears and planetary gearsets
This VTD subaru is one of their finest, at first it was viscous, later it switched to electro hydraulic.
Lexus GS has a similar system before 2007, with planetary open diff with plates, after 2007 they switched to a torsen C fully mechanical diff
The trick to cutting with a cordless grinder is to use the thinnest cutoff wheel you can find. 1/16” or 1/32” works well. But no matter what they are power hungry.
Yeah that's why I'm sticking with the corded grinder. The cordless one is for filing my toe nails 🤣
Just so you know: an open diff is a constant 50/50 torque split. People often confuse that. An lsd or in this case the clutch pack allows the torque to go to the wheels that have the most traction.
Therefore, when the diff is locked, it’s not a 50/50 split but a xx/xx split, meaning it changes dynamically. If both front tires are on ice and both rear are on asphalt, 90 something percent of the torque will go to the rear with the diff locked.
I understand your point. I sometimes get confused between torque and RPM.
Also this diff is technically 45/55 seeing the difference in the size of the sun gears driving the output shafts.
@@speedkar99 yes but when its locked, that ratio goes out the window a bit depending on where traction is available
5:09
That's what I like to hear, thanks man!
Haha
Good editing
Thanks
Love your videos of pulling these things apart! If you ever get your hands on a subaru dual-range 5 speed manual, I'd love to see a vid on that!
Hell yes. I tried the low range on my Impreza just once and didnt see any point in it. The gear reduction isnt significant in any way useful. I've now driven in winter conditions for a few months and it's "awd" does what it should. Its a hawkeye and that has mechanical 4wd. The 2.0R is plenty for winter time unless you really need to be ken block which you dont really have to or can handle.
That would be cool, I never knew they had low gearing.
Very good, thanks
You are welcome
"...so you can make it to your local takeover and show the VQ boys how it's done."
Always enjoy catching the shade tossed in with the lesson, good stuff @speedkar99
Ah glad you caught that one!
The most beautiful parts of Subarus are hidden in the dark where nobody can see them.
Subaru: Ugly on the outside, beautiful on the inside.
I agree. They are very unique vehicles mechanically and I appreciate them being different as an engineer.
my subaru has a manual transmission, its very fun in the snow
Awesome
Thanks a lot brother 👑
Welcome
That IS a nice, thick, beefy shaft!
😋
Thanks for your effort . Mrs has a 2012 Outback 3.6r with that trans . I am a retired auto tech but did most of my work on Fords . I you pull the plug on the pan you get 4 qts out of it . I have been changing just 4 qts every 20000 miles . Trying to make the car go as far as possible . Those clutch packs look good for the mileage that unit had .
Yep it sure looks clean.
Keep doing fluid changes and it should last a while
Cool vid. Man
Very well done... ty for this.
Thanks
awesome video.
Thanks
Outstanding
Thanks
very nice as usual thanks
You are welcome
Amazing explanation... subie is unique
Appreciate you, man.
Thanks
it works great!
I am a bit technical. But not even close enough to fully understand how all this system of levers, gears, clutches... works. Still, I drive a Forester. So thank you so much for the video!
You are welcome
5EAT with the VTD system. It's actually a WRX AWD system with no adjustment. That clutch pack in the rear by the *Torsen* center diff is actually to alter the torque split from 45F/55R to about 50/50. Even if it wears out completely, you still have 45F/55R.
Yes it's 45/55.
however, I don't understand how this is a torsen differential I don't see any worm gears
The 2015+ WRX CVT uses this style center diff, not the 5spd nor split case WRX 6spd manual. The VTD center diff is actually a Planetary Gear differential. A Torsen would apply friction to limit slip. The VTD clutch pack limits the slip.
Amazing how complicated that system is. We definitely don't think about that when buying a car
Agreed! So many parts to make it work.
Interesting video
Thanks
Pff, the engineering that went into this. Thanks for tear down.
You are welcome!
Brilliant! Godbless you
Thanks
I have a 2001 Outback LL Bean with the H6 engine. My understanding is that the transmission logic is as follows:
* In first and second gear, the differential clutch is actuated hydraulically and there is a 50/50 torque split. Always.
* In third and fourth gear, the computer releases the clutch such that 90% of the torque goes to the front axle and about 10% goes to the rear, simply to reduce drag/increase fuel mileage.
* In third and fourth, the system monitors front and rear axle speeds, and if the front axle spins faster than the rear, then the clutch is progressively engaged until speeds are equalized. It can operate the opposite way to reduce rear axle speed as well.
* Both axles use limited slip differentials to control side to side wheel speeds.
The VDC cars work totally differently, and have no limited slip differentials, they use torque vectoring in order to provide stability control and the center differential is totally different. They can also give 50/50 torque splits in higher gears. This system is similar to the system in the STI's.
At least that is my understanding....YMMV.
Thanks for your input, it makes sense at higher gears and thus higher speeds, the front wheels are mostly powered, similar to other crossover type vehicles
please do a subaru cvt. great video
I sure will...if I can find one.
I can easily follow along & understand how an ice engine works & what all the parts are doing. I understand how a clutch & fluid torque converter work. The fluid torque converter itself is pretty genius. In how how they were able to use fluid & centrifugal force. To move the weight of an entire car with no actual mechanical shaft connection from the engine to the transmission drive shaft. But when in it comes to transmissions with all the gears, parts, valves,etc.. It boggles my mind trying to folliw along & fully grasp how all those parts work together & exactly what's going on inside.
I understand where you come from, it's because it's hard to visualize gearsets moving and clutches activating.
@@speedkar99 Plus trying to visualize how all the fluid travels around in the worm tray & trying to visualize what's happening in the valve body....I think the fluid changes directions and travels in different paths in the worm tray depending upon what gear it's in & how fast different shafts are spinning.
But it's still mind boggling & I don't understand how someone can fully grasp everything that's going on inside......🆚 something like a jet turbine that's pretty easy to fully grasp how it all works.
12:15 I don’t think those are “sun” gears with “step-down planet gears” around the input and output shafts, that you might see with a ring gear. To me those look like they are functioning as differential side gears, going around together with both shafts until there is a difference in speed. Which is also why there are so many!!
Automatic Transmissions are full of magic and mischief. I prefer manual transmissions, and Subaru makes an amazing one. Just replace the throw out bearing when it makes any noise or be ready to buy a new transmission.
The older automatics were reliable. Can't say much about the newer CVTs
Worth to mention that in the selеctor position 1 the central dif remains locked on the low speed. In the past quite often the fail of the solenoid C caused the fail of RWD part, so Subaru became FWD only. We even installed a switch to toggle between FWD and AWD back in the days :)
Awesome! My brother installed a toggle on his Infiniti G37
That particular planetary centre diff (on the 5EAT) has a 40/60 F/R split when the clutch is open.
Isn't it 45/55? 2005 Outback
@@speedkar99 Could be me misremembering! Just knew it wasn't a 50/50.
Awesome video! Can you put it all back together???😅
Only thing I love about my wrx sti is yes the awd and the awesome transmission. 👍🏼.. only
Saying that coz I had a spun rod and yeah mucho dinero..
Great 👍 info. Does the WRX have a separate reservoir for the center differential apart from the front differential and transmission?
I had Legacy between 2002-2015 270K km with not a sinlge issue except a radiator upper plastic tube died after 220K .
It was 2.0L 125hp 4AT AWD car, a pure please to drive...
They sure can be reliable cars once the headgaskets have been taken care of.
Awesome video, must be a lot of fun making these.
If one ever comes your way, could you open up an Acura SH-AWD system. They use magnetic clutch packs, and a torque vectoring system which sends different amounts of power to the front or rear along with side to side. It’s a lot more advanced than Subaru AWD and probably a lot less complicated. Be cool to see!
Have a great day!
I really really want to find an SH AWD setup to tear apart!
@@speedkar99 Well if my 2011 MDX dies on me I’ll donate it to the channel. It only has 108,000 miles so that might be a while haha.
By the way, I have a ton of confidence in the MDX V6 3.7 L V-Tech after watching your J series tear down, old design but solid engineering and manufacturing. It burns a bit of oil but I stay on top of it.
Happy wrenching!
Definitely superior manufacturing! Well done Subaru…..other brands start taking notes
It sure is solid