Transmission Ideas?

[skullandbones]

For those with a little less experience with the WRX gearbox idiosyncrosies, here is an interesting website. Here again, the recommendations suggest that changing gearsets solves a lot of problems.

http://www.turbomagazine.com/feature...set/index.html

Thanks, WEK.

[skullandbones]

For those with a little less experience with the WRX gearbox idiosyncrosies, here is an interesting website. Here again, the recommendations suggest that changing gearsets solves a lot of problems.

http://www.turbomagazine.com/feature...set/index.html

Thanks, WEK.

[jimgood]

Just for the sake of reeling this debate by a few back into the focus of the thread, could you mention one of those "solutions" that you have seen on NASIOC? I'm sure there are as many as there are vendors but are there some that are budget friendly that would still do the job for a modified engine? Thanks, WEK.

One reason I don't want to participate in the NASIOC forum at this time is that I really don't have the time to cover that much ground in the time I have available for surfing and researching. I probably will go there more after things begin to solidify and I have specifics that relate to the project/build. If a vendor is pfishing to get more business let them bring their discussion to this forum. Easier for all of us! Thanks, WEK.

Neither do I have the time...nor the inclination. As someone that is concerned about the strength of the transmission, it is incumbent upon you to do that research. Please input "wrx stronger gears input shaft" into Google and be enlightened.

As to which is best...you'll never get a straight answer to that question on the internet unless you can find the one of the few people that has actually tried more than one gearset behind the same engine output levels where one broke and the other didn't (yet). And that rather small population is probably at NASIOC. Phil of Element Tuning has been poking around this forum and he might be numbered among them.

[skullandbones]

Well Jimgood you are probably right about me having to "break down" and go to NASIOC for a lot of the available info. I followed your advice and looked up the key words you suggested. I spoke to a technician in Colorado about the WRX trans. He referred me to NASIOC, too! However, he was very willing to discuss the issues with the stock trans. His company "Flatiron Performance" has transitioned to a Subaru service center so they don't build the performance upgrades like they used to. He suggested a shop that specialized in that task. They are asking $2188 for a JDM RA gear set but then you have to have it built by a reputable company to install or there is no guarantee. I also saw a complete trans built for $3150 and core charge with the same gear set. That technician also suggested that you should pay attention to the rally drivers as they are the ones who really "work" the WRX the most. So I think the link I provided does reflect some weaknesses of the stock trans that racers have figured out from experience. I also saw a poll on NASIOC that favored (heavily) the above gear sets for modified applications.

It seems to me that people would be willing to discuss this sort of conversation about the stock or variants of the WRX. It's, at least, as interesting as going to school on theoretical physics issues and has some practical value in that it can give some people (who don't know) a better focus on how they will spend their available budget dollars for this project. I would probably go for an upgraded OEM donor like a Legacy at this point, instead of spending $3000+ on a performance trans. But that is because I would not be pushing the envelope like a lot of guys and would vote for a stock or only moderately modified engine. Hey, thanks for your insight. WEK.

[Xusia]

The above illustrates why my plan is to not go beyond stock STI power levels. To go much beyond that starts to get really expensive; both to get the power, and beef up other components...

[RossLH]

As to which is best...you'll never get a straight answer to that question on the internet unless you can find the one of the few people that has actually tried more than one gearset behind the same engine output levels where one broke and the other didn't (yet). And that rather small population is probably at NASIOC.

I have an unfortunate amount of experience breaking gearsets at multiple stages of power. Never did get PPG's, eventually just sucked it up and got a 6-speed. Ran the car into a pole before I got a chance to break the 6-speed. However, 6-speed talk really isn't helpful here.

Bottom line is if you break a stock set, chances are the same driving style at the same power is going to break a budget build just as fast, because as I said before the main issue isn't addressed, and is hardly band-aided.

[Rasmus]

I'd think the limiting factor in the 818 and bone stock 5 speed trans is going to be the tires. Even with a LSD (which I'm sure many of you will swap in) you won't be able to break the transmission before the tires let go. Sure there will be a few bone headed pedal dumpers who pop tranny after tranny by hammering the gear shift, dumping the clutch, and fat fingering the syncros. The rest of us will shift smooth because it doesn't upset the car.

But until you try to launch with warmed up 345/35ZR18 Hoosier A6's and a long *** 3.27:1 final drive (2005-2007 Legacy GT Auto FD) you'll be fine.

But let me just throw this out there. Subaru is rumored to be considering their CVT for upcoming WRX's. Light car with high hp = fast. CVT = Peak HP all the time = faster. No shifting = smooth = even faster

[Oppenheimer]

Exactly. The tires will be the fuse that lets go to protect the trans. Not the most reliable or predictable fuse, but for most (inside the bounds you describe above) it will 'blow' well safe of trans issues.

[BrandonDrums]

I'd think the limiting factor in the 818 and bone stock 5 speed trans is going to be the tires. Even with a LSD (which I'm sure many of you will swap in) you won't be able to break the transmission before the tires let go. Sure there will be a few bone headed pedal dumpers who pop tranny after tranny by hammering the gear shift, dumping the clutch, and fat fingering the syncros. The rest of us will shift smooth because it doesn't upset the car.

But until you try to launch with warmed up 345/35ZR18 Hoosier A6's and a long *** 3.27:1 final drive (2005-2007 Legacy GT Auto FD) you'll be fine.

But let me just throw this out there. Subaru is rumored to be considering their CVT for upcoming WRX's. Light car with high hp = fast. CVT = Peak HP all the time = faster. No shifting = smooth = even faster

Rumored but I doubt that will take place. Another reason why subaru had lowered the power output of their engines is because their CVT can't handle as much torque as the old AT tranny. A CVT would be kinda cool in a WRX but I imagine they'll use the 6mt or develop a automated single or dual clutch transmission for it if they were going to try something new.

The newest rumor is just as the WRX name has been split from the Impreza, Subaru is considering splitting the name STI name from the WRX. In this scenario, the WRX will be what the STI is today, the flagship Subaru AWD rally monster priced at 35-40k and perhaps marketed like the EVO with multiple trims and transmission options. Then the STI will be it's own car that is much higher performance and also much higher-end priced and built to compete with cars like the M3, Lexus ISF or the Audi S/RS4.

Here's essentially what started that rumor http://www.autoblog.com/2012/02/28/b...wrx-this-week/

The other half of that rumor is STI will still be split from the WRX name as just a in-house tuner badge like it is in Japan. Subaru has promised 4 new models by 2016, somewhere I read that 3 of those 4 new models would be performance cars. BRZ, new non-impreza WRX and the STI being it's own car delivers all 3 new performance models technically speaking leaving just the hybrid to being on board.

http://www.autoblog.com/2011/07/07/s...odels-by-2016/

However, this report makes me thing the WRX and WRX-STI are here to stay just on a new platform as they are today. The 5mt could live on in the WRX due to this, I was hoping the 6mt would be standard in the wrx and the STI version would have a DCCD option or something.
http://www.autoblog.com/2011/12/08/n...four-thats-up/

All rumors and speculation though so we shall see! As for the 818, I am a little worried that I'll be more attracted to a smaller, lighter and more powerful WRX/STI over the 818. It could up being a monster if it's light enough...I mean look at this Motor Trend rendering for the new WRX if they brought back the coupe...

Next-Subaru-WRX-Illustration.jpg

The kicker would be if Subaru did offer a DCCD, if it was the size of the 5mt, 2wd convertible and offered as a crate unit, I might drop that in the 818 instead lol.

[riptide motorsport]

Will you guys please stop speaking japanese!!! I'm soooo confused

[Xusia]

That's a LOT of ifs...

[305mouse]

Subaru has a new car coming out this fall. It's called a KX or something.

[PhyrraM]

VX Crosstourer. It's an Impreza wagon derivative.

[Etos]

I think you all need to take a step or 2 back. 300hp in a heavy 3400 pound AWD is pretty good power even with the 24% AWD transmission lose(prox 75 ponies lost to the wheels). Now take that same 300hp in half that weight and make it 2WD reducing the transmission lose.

Do you guys really REALLY feel you need more then that? Cmon, take that step back and realize exactly how crazy you all sound arm chair mechanicing what tranny you'll need for a power level that would actually turn a car from fun to work just keeping it together both driving and mechanically.

You want a solid transmission for upto 400hp, get an 06+ WRX trans and replace the front diff. There's no need to go crazy with PPGs and etc. Getting 400hp is seriously no different then getting 700hp out of a corvette in PTWR. Anymore then that and it's just plain retarded and more for E-Peen awards.

I bet you guys the most FUN iteration of this car will be a much lower powered version. I personally am going destroked from 2.5 to 2.34, long rod and super high compression with about 8-10psi boost from a tiny turbo. Instant power everywhere, 9k RPM rev limit, most likely a specb transmission to keep up with the revs. Aiming for 250-300hp to the wheels which will be underpowered for what the engine can really handle but anymore and it becomes work, not FUN.

[Xusia]

Etos, while I agree with you (my power goal is the same, though I'll prob be taking a less expensive route), I also believe "to each, his own." If 300hp isn't enough for others, that's fine and doesn't impact me in any way. They should feel supported to build it any way they want (no matter how crazy that may seem to others)...

[Rasmus]

9k RPM rev limit

Stock crankshaft can't do that. Not because they'll break but the oiling passages are drilled funny on the OEM cranks and stop oiling the bearings due to inertia. Even if you run a high pressure/high volume oil pump.

Scat (and a few others) makes an aftermarket Subaru crank that doesen't suffer this issue.

[RossLH]

Do you guys really REALLY feel you need more then that?

I don't need 400+whp 818 more than any of us need an 818 in the first place. No matter how you look at it, its nothing more than a toy. You play with your toy the way you want to, and I'll be busy scaring the ever loving crap out of myself in mine.

[Nuul]

I'll be busy scaring the ever loving crap out of myself in mine.

Yup, and anyone foolish enough to sit in my passenger seat.

[Etos]

Stock crankshaft can't do that. Not because they'll break but the oiling passages are drilled funny on the OEM cranks and stop oiling the bearings due to inertia. Even if you run a high pressure/high volume oil pump.

Scat (and a few others) makes an aftermarket Subaru crank that doesen't suffer this issue.

You did read the destroked part right? Plus the factory cranks are good with the right mods which plenty of people do. Not new to subarus(owned one since 05) and by this august will have a 500hp destroked, bored out, fully built block with sleeves, cams, +1 valves, springs, retainers, ported, twinscroll, EFR turbo. Will be one hell of a track car.

The people who know the most about destroked/stroked subaru engines or subaru engines period is Dom from MPS and Micah from 3MI. No one knows more about subaru engines then these guys.

[Etos]

Etos, while I agree with you (my power goal is the same, though I'll prob be taking a less expensive route), I also believe "to each, his own." If 300hp isn't enough for others, that's fine and doesn't impact me in any way. They should feel supported to build it any way they want (no matter how crazy that may seem to others)...

I understand. I also bet 90% of the people arguing about this whole weight vs stress vs whatever will NOT be getting a 400hp 818. The other 10% will realize how over the top such a car will be once they get seat time in it. I understand the alure to having that kind of PTWR. I also have a 570hp turboed S2000, selling it this spring cause it's just not a fun car. Sure the straight line roll through the gears is crazy but it gets old fast. I'd rather have a 300hp 818 with the build I'm doing then this 570hp s2000 which is part of the reason I'm selling it to afford an 818.

[Rasmus]

You did read the destroked part right?

I did.

[RossLH]

The people who know the most about destroked/stroked subaru engines or subaru engines period is Dom from MPS and Micah from 3MI. No one knows more about subaru engines then these guys.

Right on. Micah is a great guy (not to mention a genius when it comes to building Subaru engines), he doesn't know it yet but he'll be building my engine when the time comes.

[Rasmus]

Micah = 3MI Racing = Homemade WRX(from NASIOC), correct?

[PhyrraM]

Micah = 3MI Racing = Homemade WRX(from NASIOC), correct?

Correct.

[Thorne]

Right on. Micah is a great guy (not to mention a genius when it comes to building Subaru engines), he doesn't know it yet but he'll be building my engine when the time comes.

The other thing to consider is that your 818 is going to have a open diff :\.


I wish i could come up with a better trans solution because i really wanted to build one of these but alass I'm selling my donor

[RossLH]

It most certainly will not, especially not with the power I'm looking to make. PPG makes a torsen front diff that'll go real nicely with the dogbox I plan on having built.

....and so what if my transmission will cost damn near as much as the kit itself?

[metalmaker12]

02 wrx suspension (spindles, control arms, etc)with whit line bushings :check
06 sti brembo brakes: check
06 sti steering rack:check
02 wrx tranny with front LSD: check
All other needed components from 02 wrx: check
06 wrx motor with new timing belt and tune up:check
Cobb access port: check

The $&@&$&$&$& kit ...................hopefully soon

[Thorne]

02 wrx suspension (spindles, control arms, etc)with whit line bushings :check
06 sti brembo brakes: check
06 sti steering rack:check
02 wrx tranny with front LSD: check
All other needed components from 02 wrx: check
06 wrx motor with new timing belt and tune up:check
Cobb access port: check

The $&@&$&$&$& kit ...................hopefully soon

What front LSD are you talking about? the 02 transmission is made of glass and it does not have a front LSD by default.

[StatGSR]

you can still purchase and install them dude....... you seem to getting all worked up about this open diff non issue....

[Thorne]

you can still purchase and install them dude....... you seem to getting all worked up about this open diff non issue....

I'm aware you can install them. I'm more curios which one there looking at.

[fritts]

I haven't seen a conversion bell housing for it but what about a Porsche Boxster/Caymen 6 sp. Not an incredibly long transmission but is fairly large in size.

[StatGSR]

^ im pretty sure that transmission is backwards....

[fritts]

whoops..... not a Porsche guy

[PhyrraM]

Unless the Porsche engine turns backwards, the (midengined) Boxster and Cayman should have trannies with very similar layout to the Subaru ones (once converted to 2WD).

[Evan78]

Here's an EJ motor bolted to what I assume is a Boxster transmission from Precision Chassis Works.

Click link for large images and more details.

[StatGSR]

Unless the Porsche engine turns backwards, the (midengined) Boxster and Cayman should have trannies with very similar layout to the Subaru ones (once converted to 2WD).

oops, i was thinking they were RRs

[bugeye_fever]

Well most of them are, lol. No worries. I'm curious to see how the Subie front ring and pinion will hold up at high power levels. Probably a non issue, but i think we've beat the gearset dead horse long enough. Now i've never heard of any failures, but this is the one part of the trans that will see double the stress than it did in a wrx no matter what the power level of the donor was.

[wjfawb0]

I'll never run a car on a track, because I don't want to afford wadding it up and walking away from it. Taking curves on public roads too quickly can be bad news as well. About the only thing I can regularly enjoy in a toy street car is the acceleration. I think that's what I liked least about my STIs. The turbo lag made them less exciting as street cars compared to a roots supercharged cobra mustang. Once the 818 is released with details I'll be investigating what it would take to build one with a broad torque curve and reliable transmission with a limited slip diff. Turning over both rear wheels will be more important to me than how many Gs it can achieve in a corner.

[Exidous]

Edit: Ugh disregard. Old post.

A few facts, without getting into the variables of turbo spool....

1) The engine makes the same amount to torque regardless of what car it is in.
2) The gear ratios are the same regardless of installation.

1 + 2 = 3

3) The torque applied to the gearset will be the same regardless of WRX or 818 installation.

This is drastically oversimplified. Put a subie with 350wtq on a lift and bang through the gears. I'd bet they don't break. Now put the subie on the ground and do the same. Weight matters. Going from 3400lbs to 1800lbs and awd to rwd will reduce stress on the transmission.

Force=mass*accel

The force on the trans gears is directly related to the mass of the vehicle.

[Evan78]

Edit: Ugh disregard. Old post.


This is drastically oversimplified. Put a subie with 350wtq on a lift and bang through the gears. I'd bet they don't break. Now put the subie on the ground and do the same. Weight matters. Going from 3400lbs to 1800lbs and awd to rwd will reduce stress on the transmission.

Force=mass*accel

The force on the trans gears is directly related to the mass of the vehicle.

Are we supposed to disregard because you don't believe what you said or just because the post is old?