To those of you concerned about 5EAT durability

So I was fiddling in my CarTest software tonight starting to build the simulation models for the 2.5i just for curiosity's sake and I tracked down the gear ratios for the 4EAT. 1st: 2.785 2nd: 1.545 3rd: 1.000 4th: 0.694 Got them off of Joe Spitz's site: [url]http://www.cars101.com/subaru/legacy/legacy2005.html[/url] and also verified that these are the same ratios for the WRX 4EAT, and pretty much every older Subaru as well. Then I started scratching my head. Wait a minute, this ratio set looks VERY familiar. Where have I seen this before? Brought up a recent FWD 4AT Nissan Maxima, and an older 300ZX auto model in the software and sure enough they are the EXACT same ratios as the Sube 4EAT except the final drives! So that brings me to my question. Where does the 4EAT come from? Is this a Nissan derived automatic transmission? LOL, answered my own question. [url]http://www.google.com/search?sourceid=navclient&ie=UTF-8&oe=UTF-8&q=Subaru+4EAT+nissan[/url] Yep, it is. Wow....ya learn something new everyday! So now on to the 5EAT 1st: 3.540 2nd: 2.264 3rd: 1.471 4th: 1.000 5th: 0.834 Guess what ratios the Infinti FX45 with a 4.5L 315hp/329 lb-ft of torque V8 is using? [url]http://www.nissannews.com/infiniti/2004vehicles/fx45/specs.shtml[/url] Yep, same EXACT ratios excluding final drive. There are also some Google hits on "5EAT Nissan Subaru" [url]http://www.google.com/search?hl=en&lr=&ie=UTF-8&q=5EAT+Subaru+Nissan[/url] It "looks like" to me that the Subaru tranny's are in fact Nissan derived. I guess this might not be new to those familiar with Subarus, but it's certainly a new discovery for me. I'm pretty familiar with newer Nissans and Nissan is known to make some pretty darn rugged automatic transmissions. The FX45 also has the same drivetrain configuration, so if that sucker is cranking out the power that it is, I have no doubt that the 5EAT in the Subaru could handle a fair amount of excess power as well. The FX35, Q45, M45, and 350Z all use the same exact 5AT gear set as well. Probably about the same trannys in all of those. I checked the Titan/Armada line (5.6L V8 with 390 lb-ft) and 1st, 2nd, and 3rd gears are slightly shorter, but 4th and 5th are the same. So that one might be a bit different and heavier duty. But damn, if the 5EAT is pretty much the same exact tranny as whats in the Infiniti FX45 (315hp/329tq) then the Legacy 2.5GT should be able to handle at least that much power if not more and still be pretty reliable. I was leary about the automatic and had questions about durability with basic mods, but this pretty much lays any of those fears to rest. Nissan is a company that I trust when it comes to building automatics that can handle some abuse without just folding. I also know that some of the quickest WRX's are 4EATs as well and now I know how they can stand up to that sort of power. Auto powah baby! hehe :lol: Steve

good find stevtec :D i think ur on v6p.net too if ur using the same name 8)

good write up steve. good news for those who are planning to put major mods on their car.

I hope the mt subaru's aren't nissan derived--the g35 has apparently had loads of problems with those...

I assume that the AT is the same in every country, but I have noticed that Oz is the only country to offer a transmission cooler for use when towing. Wouldn't this just be overkill if your theory is correct?

Just depends on what bits are on the inside as well and do they have the same strength. As Paul (aka apexjapan) has pointed out before, they ran a old spec B4 4EAT in Japan for AVO which handled the power but after a few lightning runs became very hot and was slipping off the line. This is where the transmission cooler comes in BUT is it really worth the big risk ????

SteVTEC - excellent find. I assume this will dispell any distrust with the 5EAT's. I am very impressed at the transmission, and the fact that is is derived from a good source too makes it a sweeter deal. Mods - this is an excellent thread, this sould be made a sticky, either here or under both 2.5i and 2.5 GT Tech. Thanks for this info. - Mike

[quote name='scubie02']I hope the mt subaru's aren't nissan derived--the g35 has apparently had loads of problems with those...[/quote] Did a quick ratio comparison of the 5MT vs some Nissan longitudinal 5MT's and the ratios are well off. I'm pretty sure the 5MT is a Subaru in-house design. I haven't been on here very much, but from what I understand the Legacy 2.5GT's 5MT is the "reinforced" one to solve the case flex and other issues from the WRX. So I wouldn't be too concerned on that. 6MT STi vs 6MT 350z/G35 are well off as well. Yeah, a lot of Nissan's newer manual trannys aren't the greatest.

[quote name='agctr']Just depends on what bits are on the inside as well and do they have the same strength. As Paul (aka apexjapan) has pointed out before, they ran a old spec B4 4EAT in Japan for AVO which handled the power but after a few lightning runs became very hot and was slipping off the line. This is where the transmission cooler comes in BUT is it really worth the big risk ????[/quote] This is true, and a good question. I've also done a fair amount of research on GM automatics. On their popular 4T65-E transverse 4AT ([url]http://www.gm.com/automotive/gmpowertrain/transmissions/hydra/apps/4t65.htm[/url]) there's no less than 5 different sub-codes. For example, there's a regular duty 4T65-E for the Grand Prix (225 lb-ft), and a heavy duty one for the Grand Prix GTP (280 lb-ft). I forget which sub-code is which, though. So yes, there could be heavy-duty spec and regular spec trannys. To those of you not familiar with Nissan, though, they were near bankruptcy throughout much of the 90's and developed a sort of one-size fits all strategy in a way. Pretty much all of their 4AT's use the same exact ratio set across all transmissions. And I've "heard" that even the older 4-cylinder Altimas (1st/2nd gen, 2.4L) used the same exact manual transmission as the Maxima (3.0L). A tranny like that would be overbuilt for just a 2.4L, but the rationale could be that volumes aren't high enough in the first place to justify spending even more development money just to build and produce a lower cost version. This is theory and speculation, but Nissan may very well be using pretty much the same tranny across their lineup. And from a Subaru perspective, they would most likely just take what Nissan can provide them with OTS (off the shelf) and not significantly re-engineer it. If there's enough interest, I'll fire up an email to the Maxima.org "unofficial" discount parts guy and see what he can find out about the different automatics Nissan is using, and if he can find anything out about the Subaru stuff. He doesn't mind doing a little research for folks on forums since they bring him a TON of business. :) A forum friendly Sube parts person might be a good resource also. Steve

Nice find Steve. I did recall reading somewhere (I think NASIOC) a few years back when someone was mentioning the 4EAT and Nissan connection. But wasn't the 5EAT design also influenced by Prodrive? I wonder if they just touched the Sportshift part of the tranny. As for the 5MT, yes it's an in-house Subaru design dating all the way back to a 1.8L engine design. It's been modified and tweaked over the years. Ken

Subaru, who used to be a part of the Nissan group until GM bought their stake in 1999, used JATCO (Nissan/Mitsubishi) transmissions for many years as well as many parts from Nissan's keiretsu suppliers. In fact, they still do, check the windows of the Legacy- it's made by Carlex, the U.S division of Central Glass, a centerpiece of Nissan's keiretsu. Reading an Australian site, it quoted the transmission of the new Liberty as being built "in-house." Although it might be built by Subaru themselves, that does not discount the possibility that they are building it under license from Nissan, and the basic designs are probably the same. I've heard the automanual function in the Legacy is much better than most of the Nissan cars (when I drove the GT, it held the gears really well- I heard the G35 doesn't) and I doubt Prodrive would lend their name to Nissan's half-baked automanual system, so the system in there might have been designed by Prodrive and manufactured in-house by FHI.

cool! thanks for the info. I sent a message to the Nissan parts guy I know so he might be able to shed some light on the topic. If it is in fact built under license by Subaru then that would pretty much make it their design I guess and not Nissan's. If it was an off the shelf Nissan tranny I'd feel better because I know they can take some punishment. If it's an 'in-house but licensed' design I wonder what they would have done to it? hmmmmmm....

For any one with questions as to Subaru's Auto Tranny building ability: Forester XT stock 4EAT - 295HP, 346 Torque (at the wheels) [url]http://www.subaruforester.com/viewtopic.php?t=4306&highlight=[/url]

I would think that the basic mechanicals and such are identical to the Nissan's tranny, but the automanual system is Prodrive's Sportshift, designed for use with this transmission. [quote name='SteVTEC']cool! thanks for the info. I sent a message to the Nissan parts guy I know so he might be able to shed some light on the topic. If it is in fact built under license by Subaru then that would pretty much make it their design I guess and not Nissan's. If it was an off the shelf Nissan tranny I'd feel better because I know they can take some punishment. If it's an 'in-house but licensed' design I wonder what they would have done to it? hmmmmmm....[/quote]

Would be interested to find out what the links are if any between the two companies as they do sound very similar in gearbox was. I wonder if they have done any other sharing. Could we see an STi GTR in the future.....? Its nice to dream though!

SteVTEC, it looks like you found some interesting information, and I'm sure that there is a link. However, the fact still stands that the stock transmission has started to overheat during testing by reviewers/reporters. Also, if it were that bulletproof, then the JDM version would not have the need to have 260PS vs. 280PS in the manual. This is not to say that the auto is junk, but just proceed with caution. This research you are looking in to will be very helpfull for getting to the bottom of this.

DAVEB is the Nissan parts guru at Maxima.org that I mentioned (he works at a dealership). Here's my PM to him and his reply below. [quote name='DAVEB'][quote name='SteVTEC']Hi Dave! I have a puzzle for you. :) I noticed that the gear ratios in the Subaru 4EAT (auto) (WRX, others) match the Nissan 300ZX auto, Pathfinder, and Infiniti J30 exactly, excluding final drive. I also noticed that the 5EAT ratios on the new 2005 Legacy 2.5GT also match the Nissan 350z, G35, FX35/45 automatic ratios also. That's no coincidence, so I guess Nissan supplies Subaru with their automatics? :eek: Detailed post here: [url]http://www.legacysti.com/viewtopic.php?t=1763[/url] I'm considering a Legacy for a future purchase, but an auto, but still might want to mod a little. I'm trying to figure out what exactly this Subaru automatic is and how much power it might be able to safely handle. My last automatic car was a Honda, so I'm still very leary of automatics :shiner: although our Highlander has been perfect so far. The 5AT in the FX45 handles 300+ lb-ft of torque. Do you think the Subaru has the same EXACT automatic transmission? Does Nissan make regular and heavy duty versions of their transmission models like GM does? (ie my example in that post is the GM 4T65-E and the different sub-codes - like the Grand Prix GT 225tq has the regular duty 4T65-E but the S/C'ed GTP with 280tq gets an "HD" version). So could the 350z/G35 have a "regular" duty tranny and then say the FX45 have a heavy duty version? Or are they all the same thing? Do you know anything about the trannys that Nissan supplies to Sube at all? Are they right off the shelf trannys with no internal mods, or are they modified to Sube's specifications. Lots of questions. :D Thanks for any help, Steve :)[/quote] Hi Steve! I must admit I had already wondered about the seemingly universal use of the 5AT across Nissan's line. As far as hard research goes, I don't really have many options, the Nissan parts catalog is going to list a diff trans part # for each application, even tho they look the "same". [b][color=red]What I did find, was that a lot of the hard parts in a 350Z trans are the same as the Titan/Armada! Anything having to do with callibration (valvebodies, etc), is different.[/color][/b] [color=blue][b]As far as the Subaru angle goes, the identical ratios are a huge indicator that it may be the same basic trans- most of the Japanese car makers have historically used the same vendors and sold each other components.[/b][/color] [b]In the mid 80s I was a tech in a Subaru garage, the Sub used a FWD Jatco auto trans that was basically the same as the RWD Nissan A/T- I used to order Nissan parts to put in Subarus cause they were easier to find! I'll try to find out who actually makes the Nissan 5AT, if it's Jatco, you can be sure they are selling their technology to anyone who will buy it![/b] [color=green][b]If it is the same basic design, a trans that can handle a 5.6 V8 in a 5600# Armada towing a 7500# trailer can probably handle a pretty hot Subie![/b][/color][/quote] veeeeeeerrryyy interesting! :)

The Subaru 4EAT and 5EAT also incorporate the center differential into the transmission case -- it's a big long unit. I doubt Nissan has this same setup, since AWD is not nearly as ubiquitous throughout their model line. So perhaps the gearset and ratios are the same, but the overall system is likely very unique to Subaru. Craig

[quote name='PPower']SteVTEC, it looks like you found some interesting information, and I'm sure that there is a link. However, the fact still stands that the stock transmission has started to overheat during testing by reviewers/reporters. Also, if it were that bulletproof, then the JDM version would not have the need to have 260PS vs. 280PS in the manual. This is not to say that the auto is junk, but just proceed with caution. This research you are looking in to will be very helpfull for getting to the bottom of this.[/quote] Yes, I read of both of those little tid bits early on on this forum, which is why I have been very leary about the automatic, and also why I decided to start doing some digging. Especially since I'd rather get the automatic for my own reasons. The points above though first with the tranny overheating and locking out the manumatic modes, I have the following questions. Was this a full production car or a press fleet test mule? Was the tranny "actually" overheating or was it just an overly protective safe-mode? Was a tranny temp guage hooked up? lol What were the conditions of the test? From what I remember it was a road course where people were really beating the crap out of the cars? What were the weather conditions that day? Any cool down between different drivers? Indeed, on a road course with lots of WOT and shifting almost ANY automatic could overheat regardless of how good it is. So the fact that it was overheating on a press outing may or may not really mean anything based on those questions. As for the 260PS automatic vs 280PS manual rating. Why were the ratings changed? Was it due to the tranny truly not being able to handle the load, or was the engine ratings simply changed for marketing or reasons? There are lots of examples of that out there. Did the auto version still really have 280PS based on dyno tests, or was the engine really de-tuned? If they both had 280PS for real, they might have simply rated the automatic version lower at 260PS to reflect the lower level of performance. Did just the peak HP/PS rating change? What about torque? A 350HP LS1 V8 still has 350HP in the 305HP Camaro version. It was simply under-rated in the Camaro for marketing reasons to separate it from the Corvette even though it still really had around 350HP. So yes, those facts are "[i]the facts[/i]", but their true meaning is a big mystery to me and open to very wide interpretations as you can see here. What the true answer is is the unknown, and that's what I'm trying to figure out. Hopefully DAVEB over at Maxima.org can help shed some more light on the subject. :) Steve

[quote name='c_hunter']The Subaru 4EAT and 5EAT also incorporate the center differential into the transmission case -- it's a big long unit. I doubt Nissan has this same setup, since AWD is not nearly as ubiquitous throughout their model line. So perhaps the gearset and ratios are the same, but the overall system is likely very unique to Subaru. Craig[/quote] This is true. The G35x AWD is using a Skyline ATTESA AWD setup. In the diagram below it looks like the system on the right. [img]http://www.subaru-global.com/about/awd/imgs/01/02/illust_01.gif[/img] Hmmm...the NissanNews.com used to have a diagram of this. Time to Google. Ah, here we go. Better pic of the Nissan ATTESA system. :D [img]http://autozine.kyul.net/technical_school/traction/tech_pic_traction_skyline.jpg[/img] Not sure what the exact layout is on the Pathfinder and Armada, but I don't see the ATTESA buzz words so it's probably different. bleh...brain overload. :lol: Well, if it's using 350z/Titan "guts" I still think it should be a pretty darn sturdy tranny. I'll try to keep digging some more later.

Subaru have almost always had a lower power level in there auto models, most of the time is becuase in the auto version they will use smaller turbo(s) and less aggressive cam etc. to make the low rev response of the auto box car better. The box can handle more then factory power. My car was auto and my auto could handle the power my car made altho it did blow on me (hmmm.. maybe not a good example). anyways some of the 4EAT's had factory power rating of 190kw and they were fine with increased power out puts.

freaking awesome, I shall tell my GF to mod away

Prodrive? I thought they were made from JATCO???? Please look: Here you go, from [url="http://www.jatco.co.jp/E_JATCO/SHOHIN/AT_E.HTM"]http://www.jatco.co.jp/E_JATCO/SHOHIN/AT_E.HTM[/url] : [img]http://www.jatco.co.jp/E_JATCO/SHOHIN/ZU/P26.jpg[/img][img]http://www.jatco.co.jp/E_JATCO/SHOHIN/PIC_AT/pic_08.gif[/img][color=#006600]●[/color] [size=-1][color=#000000]Wide gear ratio[/color][/size][color=#006600]●[/color] [size=-1][color=#000000]High torque capacity[/color][/size][color=#006600]●[/color] [size=-1][color=#000000]Top class, ultra-light design[/color][/size][color=#006600]●[/color] [size=-1][color=#000000]Main vehicles equipped with this AT: [b]NISSAN[/b] PRESIDENT, CIMA, FUGA, SKYLINE, ELGRAND, FAIRLADY Z and other vehicles Edit: Btw if you check out JATCO's Main Customers on their website, FHI is one of them.[/color][/size]

[quote name='fzanetti']Prodrive? I thought they were made from JATCO???? Please look: Here you go, from [url="http://www.jatco.co.jp/E_JATCO/SHOHIN/AT_E.HTM"]http://www.jatco.co.jp/E_JATCO/SHOHIN/AT_E.HTM[/url] : [img]http://www.jatco.co.jp/E_JATCO/SHOHIN/ZU/P26.jpg[/img][img]http://www.jatco.co.jp/E_JATCO/SHOHIN/PIC_AT/pic_08.gif[/img][color=#006600]●[/color] [size=-1][color=#000000]Wide gear ratio[/color][/size][color=#006600]●[/color] [size=-1][color=#000000]High torque capacity[/color][/size][color=#006600]●[/color] [size=-1][color=#000000]Top class, ultra-light design[/color][/size][color=#006600]●[/color] [size=-1][color=#000000]Main vehicles equipped with this AT: [b]NISSAN[/b] PRESIDENT, CIMA, FUGA, SKYLINE, ELGRAND, FAIRLADY Z and other vehicles Edit: Btw if you check out JATCO's Main Customers on their website, FHI is one of them.[/color][/size][/QUOTE]Again, that would fit fine in a rear wheel drive subaru.. [url]http://www.legacygt.com/forums/showpost.php?p=222299&postcount=19[/url]