Lineartronic® CVT????

[timmy318]

Well. I'm going to be building the 818 off of a '07 WRX. I like an automatic for everyday use but I like the capabilities of the manual. Pretty much what I'm trying to get at is would it be at all possible to use the Lineartronic® CVT that Subaru has. Paddle shifting is just something I have grown to like in other cars and I'm wondering if it could be transferred to this one. I know that they only have it available for the non-turbo models. The reason being is that they couldn't handle the power (I think). Are there any other transmission out there that would work like this one or are there any mods that could be done to strengthen this trans? If not then I guess manual it is!

[PhyrraM]

On such a light car I think many might be suprised on how well the regular old 4EAT can work. Add a manual controller (IIRC it's been posted that they are available) to add 'paddle' shift functions. Pre '96 it was available in native 2WD also.

I think that too short of a first gear is going to be an issue on virtually all 818 builds...manual or automatic, 4-5-or 6 speed. That would put a point in the CVTs court because 'first' gear can be set to any ratio.

As far as the lineartronic CVT, you would have to find out how it derives AWD and see if it's feasable to convert to 2WD. Because it's newer, with more electronics involved, I can see Subaru changing it traditionally simple AWD system for it.

[Rasmus]

I would love to use the CVT without the paddles in the 818. Just four buttons. Reverse, Neutral, Forward, and Race. For 'Race' the CVT would try to keep the motor at peak HP (say 6200 rpm) all the time. You could tune the motor to have an extremely peaky hp curve at that single RPM. Tuned runners. Turbo two sizes too big, because you don't care about lag a low rpms. You only have two rpms. 750 (Idle) and 6200.

[BipDBo]

Belts suck. I wouldn't buy an econo-commuter with a belt transmission, much less put it in anything meant for performance.

You can't mod a CVT to make it stronger. It is limited by the friction coefficient between the pads on the side of the belt and the surface of the pulley. Over time, those pads wear out and the surface of the pulley gets worn down, lowering the friction coefficient, causing slippage and a very expensive failure. A CVT is a ticking bomb, and it ticks faster the harder you push it. Subaru was incredibly foolish to try it, especially on AWD. When the wheels don't slip, the belt will.

[timmy318]

So is there actually a transmission that could possibly be used for this?

[PhyrraM]

......You can't mod a CVT to make it stronger. It is limited by the friction coefficient between the pads on the side of the belt and the surface of the pulley. .......

There are whole aftermarket industries that revolve around just that. Upgraded brake pads and clutches are all just in our heads and we've been drinking the Kool-Aid?


Edit: Not advocating (or de-advocating) a CVT (as I've never driven one), just saying that they most certainly can be made stronger if/when the aftermarket embraces them.

[skullandbones]

I have to admit, I'm a new fan of paddle shifters. Trying to get a little more practise on my wife's Camero but it's hard to get her out of the driver's seat!

I think it would be an efficient way of by passing mechanical or cable components on the build. That would be one more bucket item off the list. WEK.

[Rasmus]

Belts suck. I wouldn't buy an econo-commuter with a belt transmission

I wouldn't call the Legacy an Economy Car.


Subaru's new CVT runs a chain, not a belt like they're old unreliable CVT's from the 1989-1994 Justy. Yes the chain and cones will wear out eventually. But a clutch and flywheel also wear out eventually.

I can see you've already made up your mind about this technology and are enjoying a tall frosty glass of Hate-o-raid. Forum posts and posturing won't change your mind. Your build is your build. Don't put a CVT in it.

[timmy318]

Trying to get a little more practise on my wife's Camero but it's hard to get her out of the driver's seat!

Lol. I know the feeling. It's hard to get my dad out of the Hot-Rod we just finished building

[BipDBo]

I wouldn't call the Legacy an Economy Car.


Subaru's new CVT runs a chain, not a belt like they're old unreliable CVT's from the 1989-1994 Justy. Yes the chain and cones will wear out eventually. But a clutch and flywheel also wear out eventually.

I can see you've already made up your mind about this technology and are enjoying a tall frosty glass of Hate-o-raid. Forum posts and posturing won't change your mind. Your build is your build. Don't put a CVT in it.

Although what you show looks like a chain, it is actually a belt. It is actually built with a chain core, with angled contact patches on the side. If you coated the whole thing in "V" shaped rubber, you may call it a chain-reinforced belt. Some manufacturers actually advertise it as a chain but they are in error. A chain will mesh with cogs. A belt uses static friction against a smooth pulley surface. You can doose a chain and cog with oil and it will not slip any more easily than without the oil. That's because it relies on force perpindicular to the surface contact patch rather than static friction force parallel to the contact patch. No one has ever made a chain driven CVT and never will. That is because cogs have a finite number of teeth, from which you cannot derive infinately variable ratios.

The technology has, and will continue to advance. Auto companies have spent an enormous amout of research on materials science to optimize the static friction coefficient and the durability of the surface contact materials. This is chiefly why they are so expensive to repair. The materials science may well be close t dimenishing returns by now. It will always be limited, however to its basic design reliance on friction. Meshing gears will by nature, always be cheaper, more durable and more reliable than components relying on friction.

[Etos]

On such a light car I think many might be suprised on how well the regular old 4EAT can work. Add a manual controller (IIRC it's been posted that they are available) to add 'paddle' shift functions. Pre '96 it was available in native 2WD also.

I think the main problem is fit and finish. It's just as long as a 6MT and I don't think many even know how to make it 2wd or if it's even possible. Personally I just don't like automatics but it's not an issue of what I do and do not like. It is a big, heavy trans that will be difficult to implement into the 818.

[Mechie3]

CVT's suck so bad that Formula 1 banned them becuase the regular transmission couldn't keep up.

http://www.youtube.com/watch?v=6A9V2O5D8mc


(My Fmod uses a CVT too)

[timmy318]

Well, if the Lineartronic® CVT causes problems due to the hp in the wrx, I guess I can just unmount the turbo.... Kinda sucks but it's a price I'm willing to pay for having this trans or another similar trans in the car

[PhyrraM]

I think the main problem is fit and finish. It's just as long as a 6MT and I don't think many even know how to make it 2wd or if it's even possible. Personally I just don't like automatics but it's not an issue of what I do and do not like. It is a big, heavy trans that will be difficult to implement into the 818.

The 2WD version is shorter than the 5-speed manual.

I, personally, would use the 5 speed manual. However, considering the weight of the 818, it's effect on first gear, and a possible builders wish for a type of automatic, I see no reason to knock the 4eat off the list. It will be heavier than a 5 speed (but lighter than a 6-speed), but I doubt fitment will be an issue.


EDIT:
Bottom: 2WD 5speed manual.
Second: 2WD 4EAT automatic.
Third: AWD 5speed manual.
Top: AWD 4EAT automatic. (Uses same driveshaft as the 6-speed manual, basically same length as the 6-speed)

[skullandbones]

Just guessing but is the 5 speed man on the bottom, the 6 speed man second from the top? So what's on top and third from the top? Also, do you have a salvage yard or do you just collect trannys? Thanks, WEK.

[Etos]

Now correct me if I'm wrong here, but weren't the 2WD versions non EAT? That would require a custom shifter wouldn't it? Also I didn't consider the 2WD version purely cause of how hard they are to come by in decent condition. Those are ooooold suckers(early 90s, that about 20 years now).

I'd be curious if you can measure the 5 speed without the backend and compare that as well? Also would you happen to know if you can even turn a 4EAT into a 2WD? Surely ANYTHING is possible, I mean within reasonable means. Basically would it be easier/cheaper to get a 2WD trans, take it to andrewtech and have them beef it up vs converting the 4EAT into 2WD?

Skullnbones:

Bottom is the 2wd trans. Top is an automatic(not sure which one), 2nd is a 5 speed, 3rd is another automatic(again don't know which one).

[PhyrraM]

Just guessing but is the 5 speed man on the bottom, the 6 speed man second from the top? So what's on top and third from the top? Also, do you have a salvage yard or do you just collect trannys? Thanks, WEK.

Found the pic on the internets.

Bottom: 2WD 5speed manual.
Second: 2WD 4EAT automatic.
Third: AWD 5speed manual.
Top: AWD 4EAT automatic. (Uses same driveshaft as the 6-speed manual, basically same length as the 6-speed)

[PhyrraM]

Yes, the 2wd versions are all pre-'96 in North America. They can be sourced newer in most overseas markets. Most parts are the same as the corrosponding AWD version, so there are not problems with rebuilds or service.

As long as the auto is from a Legacy or an Impreza (basically-bolted to an EJ series motor) it is electronically controlled and only needs a cable shifter and the control circuits. IIRC, one for line pressure and 2 for the shifts (AWD has another one for the AWD clutch).

Something I just now thought of.....The SVX had a 3.54 final drive ratio in both 2WD auto and AWD auto. Possibly a much better choice for a car as light as the 818. First gear won't go by nearly fast. That I can recall, no other Subaru (Auto or manual) has had a final drive lower than 3.9

[Rasmus]

Bottom: ...
Second: ...
Third: ...
Top: ...

What bizarre ordering is that. I read that 4 times through, then my brain started hurting. Help a man out.

[timmy318]

Something I just now thought of.....The SVX had a 3.54 final drive ratio in both 2WD auto and AWD auto. Possibly a much better choice for a car as light as the 818. First gear won't go by nearly fast. That I can recall, no other Subaru (Auto or manual) has had a final drive lower than 3.9

So a SVX trans would work?????

[PhyrraM]

What bizarre ordering is that. I read that 4 times through, then my brain started hurting. Help a man out.

It's still in order, just reversed from the picture. Bottom to top..I was typing as I was scrolling up to reference the pic.

[skullandbones]

Found the pic on the internets.

Bottom: 2WD 5speed manual.
Second: 2WD 4EAT automatic.
Third: AWD 5speed manual.
Top: AWD 4EAT automatic. (Uses same driveshaft as the 6-speed manual, basically same length as the 6-speed)

I got it. Oh no, there must be something wrong with me: I understood it!!! Thanks, WEK.

[PhyrraM]

So a SVX trans would work?????

Nobody knows until the actual kit comes out. I'm *guessing* that it will physically fit after a proper crossmember/trans mount is fabricated/modified. The mount is different than the 5-speed that FFR will officially support. The shift linkage and cable will also be on the builder.

As far as electrically? Your gonna have to be comfortable figuring a few things out. Using an early pre-'96 donor would be easiest because that's what the SVX was. However, I'm sure it can be done with later WRX electronics - you just have to make the appropriate modifiactions. Sitting down for a few days with all the proper wiring diagrams should eventually sort out the differences.

Worst case..I'm 85% sure that the 3.54 SVX final drive can be swapped into a newer WRX automatic transmission.

[timmy318]

Thanks for the help! Would've never of figured this out on my own :P

[BipDBo]

CVT's suck so bad that Formula 1 banned them becuase the regular transmission couldn't keep up.

http://www.youtube.com/watch?v=6A9V2O5D8mc


(My Fmod uses a CVT too)

CVTs do perform well when they are working right. They keep the engine at optimal rpm, and do not loose time shifting. Performance-wise, they are theoretically ideal transmissions. I just don't trust them, and I certainly wouldn't push any more power through them than what came on the factory floor. There are two reasons why they worked for Formula 1: First, that is a high rpm, low torque application. Secondly, they can be rebuilt after each race. It's one thing to engineer a machine to make it through a 500 mile race. It's another to get that machine to go over 100,000 miles under various conditions.

Perhaps I'm being too cautious with them, though. The alternative, the conventional torque converter automatic has been around for a very long time, but has still yet to be "tried and true." It's insanely complicated and is often the weak link in a vehicle, causing many more problems than the engine. The best option, IMO, is a manual. It's simple and reliable. When the clutch wears out, it's cheap and simple to replace. I also have high hopes for dual clutch automatic transmissions.

The 818 is lighter than the donor car, so that would help the problem. A CVT would probably be an excellent application for a high mpg 818 build.

[Rasmus]

The 818 is lighter than the donor car, so that would help the problem.

I thought the same. Taking a CVT designed to push around an AWD 1550 kg car, with 200hp and giving it RWD (FWD) duty in a 818 kg car with 330 hp should ease the strain.

[Etos]

A crazy idea to what would quite an awesome setup would be taking the BRZ engine, giving it a little tune and sticking the impreza CVT trans to it and tuning that too. That certainly would be quite a nice ride and blow the BRZ right out of the water

[Rasmus]

Photos of the 2012 CVT "belt":






Arguments about 'Belt vs Chain' aside, It looks beefy.

[Rasmus]

I also found a February 2012 news report from Subaru about a beefed up CVT going in the 2014 Outback turbo-diesel. Selected quote from the article:

Intriguingly, Senior said the arrival of a high-torque Lineartronic in Outback indicated its potential suitability for high-performance models such as the next generation WRX and STi due in 2014.

“If you’re able to put that sort of torque through a CVT it then opens up the possibilities of it being in our more performance variants. I think that’s the future direction for us.”

[timmy318]

Awesome!

[BrandonDrums]

Just FYI, there are some incredible and relatively affordable torque converter upgrades for the 4EAT that blow my mind.

http://www.youtube.com/watch?v=k2TX_g5MzwY

For drag-racing at least, having an AT and being able to brake boost at launch makes a scooby an absolute rocketship.

05-09 Legacy GT's have shifters on the steering wheel. the first few years were more like buttons, then they went to paddles. There are after market kits available too I think. Subaru actually did a really good job of the manual shifting logic. The shift is very quick and feels quite un-lame for a simulated automated clutch on a slushbox.

I had an outback wagon as a loner from the dealer for a few days back when I first got my WRX in 06. It lacked a sport mode that the legacy GT has for the shifting but it did have a manual shift mode on the gear leaver that worked really well in my opinion. The shifts on the GT are even quicker from what I understand.

For someone unable to drive a manual or who just wants an auto, if you could drop the 4 speed from a Leggy GT with the paddles you could have a heck of a whole lot of fun.

[timmy318]

Just FYI, there are some incredible and relatively affordable torque converter upgrades for the 4EAT that blow my mind.

http://www.youtube.com/watch?v=k2TX_g5MzwY

For drag-racing at least, having an AT and being able to brake boost at launch makes a scooby an absolute rocketship.

05-09 Legacy GT's have shifters on the steering wheel. the first few years were more like buttons, then they went to paddles. There are after market kits available too I think. Subaru actually did a really good job of the manual shifting logic. The shift is very quick and feels quite un-lame for a simulated automated clutch on a slushbox.

I had an outback wagon as a loner from the dealer for a few days back when I first got my WRX in 06. It lacked a sport mode that the legacy GT has for the shifting but it did have a manual shift mode on the gear leaver that worked really well in my opinion. The shifts on the GT are even quicker from what I understand.

For someone unable to drive a manual or who just wants an auto, if you could drop the 4 speed from a Leggy GT with the paddles you could have a heck of a whole lot of fun.

Great! Thanks for the info!!!!

[SccrMan13]

Having never driven a cvt does it feel direct like a manual transmission or is there a disconnected feel like with most autos? Also when is subaru bringing out a dual clutch.

[305mouse]

I drove a Nissan rental once that had a CVT. It was nice, but different. There are no shifts, you don't feel anything. I also got 37 mpg doing 80 mph from Rochester, NY to Columbus, OH on one tank of gas.

[Rasmus]

Having never driven a cvt does it feel direct like a manual transmission or is there a disconnected feel like with most autos?

I admit it doesn't feel as direct as a manual. There's no rowing or clutching. Plus jerk is missing. By "Jerk" I mean the change in acceleration. Velocity is a change in position. Acceleration is a change in velocity. Jerk is a change in acceleration. How does a CVT car feel when it accelerates? Best I can describe it as is taking off in a jet engined plane. There's a force pushing you back into your seat and it never lets up. Just like a jet. There's no abrupt double jerk as you change out of one gear to the next gear. There's no subtle jerk as your engine moves up and down it's HP curve across it's RPM range. Smooth, consistent, acceleration at peak HP.

With the lack of a tactile reminder from the missing changes in acceleration (e.i. missing jerks) many car guys hate the feel of it. You don't "feel" like you're going any faster. It doesn't 'feel' fast. But then you look down at your speedometer and realize you're doing over 95mph. How did that happen so quick?

[Nelff]

you know, I think that I could get used to that...

[Oppenheimer]

Although what you show looks like a chain, it is actually a belt. It is actually built with a chain core, with angled contact patches on the side. If you coated the whole thing in "V" shaped rubber, you may call it a chain-reinforced belt. Some manufacturers actually advertise it as a chain but they are in error. A chain will mesh with cogs. A belt uses static friction against a smooth pulley surface. You can doose a chain and cog with oil and it will not slip any more easily than without the oil. That's because it relies on force perpindicular to the surface contact patch rather than static friction force parallel to the contact patch. No one has ever made a chain driven CVT and never will. That is because cogs have a finite number of teeth, from which you cannot derive infinately variable ratios.

The technology has, and will continue to advance. Auto companies have spent an enormous amout of research on materials science to optimize the static friction coefficient and the durability of the surface contact materials. This is chiefly why they are so expensive to repair. The materials science may well be close t dimenishing returns by now. It will always be limited, however to its basic design reliance on friction. Meshing gears will by nature, always be cheaper, more durable and more reliable than components relying on friction.

I get what you are saying about the technical definition of a 'chain'. Its kinda like what everyone calls a 'coil spring' is really a helical spring (a coil spring is a flat coil like in a clock or watch).

So the thing inside a modern CVT is a metal belt, even though by appearance most would want to call it a chain. I can see how a manufacturer that was trying to get across to the average consumer that the thing inside their CVT is not made out of rubber would want to avoid using the term 'belt' and would prefer to use the term 'chain', which most potential buyers would understand immediately to be made of metal, and strong, even if its not technically accurate use of terminology.

So if a chain is only a chain because it engages a toothed sprocket (whereas a belt interfaces to an angled pully), what is a cogged rubber belt that interfaces with a cogged pully? Is that still technically called a belt?

[Xusia]

So if a chain is only a chain because it engages a toothed sprocket

Chiming in support of Oppenheimer here, that is not the definition of a chain. The proper definition is:

A connected flexible series of metal links used for fastening or securing objects and pulling or supporting loads.

By that definition, what's in the Subaru CVT IS indeed a chain. It may be a rubber coated chain, but it is a chain nonetheless.

[Rasmus]

So the above is a chain, and

this is a belt. Got it.

Jokes aside. I only care if it can reliably transfer torque between the primary and secondary pulleys.

[PhyrraM]

I think the fact that Subaru is even putting it behind the diesel speaks volumes about where the tech is, and where they think it can go.

Will there be teething issues? Certainly. Will they eventually be straigtened out? Certainly.

Will they ever belong in a race car? Certainly. The advantage of optimizing a (race) motor to operate in a very small RPM range will eventually overweight any current issues with torque capacity or reliability.

Will I ever want on in a sports car? Dunno yet. I'm sure the tech won't 'get there' soon enough for MY 818.