JDM 6-speed sources

evolutionmovement · Post by **evolutionmovement** » Tue Sep 13, 2005 3:57 pm

Wondering where I would get one of these and if anyone has an idea of a ballpark figure. Engines are everywhere. There's also the question of final drive, but I'll figure that out later.

Steve

dscoobydoo · Post by **dscoobydoo** » Tue Sep 13, 2005 5:40 pm

do a quick google search.

I have found a few places (some in Canada) and the usual price I have seen is 6500-8000

Hell, for that much money, I would rather paint, engine and do a few other things.

BAC5.2 · Post by **BAC5.2** » Tue Sep 13, 2005 6:24 pm

Version 7 and Version 8 STi's were the only 6-speeds that I know of. The most coveted of which was the Non-DCCD 6-speed from the Version 7.

Expect to spend around $8,000 for a USDM 6-speed and all associated bits. More for 05 stuff since you would need the hubs, wheels, brakes, everything.

You can usually find the stuff for new and good condition used for around 8k.

I'd rather just have a built 5-speed, espically if your intent is straight-line. The 6-speeds have shitty straight-line ratios.

Cheapest swap I have heard of is like 6k. It's usually cheaper if you get an engine/transmission/rear-end/brakes all in one shot. I saw a V5 STi front cut with engine, tranny, rear diff, driveshaft, all brakes, front and rear seats, rear axles and suspension links, dash, and allllll electronics and such for 2 grand on e-bay. If I had the money, I would have bought it and found a donor 93 sedan or something.

mikec · Post by **mikec** » Tue Sep 13, 2005 7:26 pm

Why's the Non-DCCD V7 the most coveted?

evolutionmovement · Post by **evolutionmovement** » Tue Sep 13, 2005 7:28 pm

I usually see front cuts with autos ...

So these are just rediculous all around. I was hoping for a relatively low ratio top gear for mileage, but I guess that's just dreaming and I have no idea how I'd change the final drive if I had to. Guess there's no decent plug and play 'tank' transmission option unless I visit Lawrence and buy a 'my buddy wrecked his STI' used tranny from some shady individual.

Gosh darnit to heck!

Steve

BAC5.2 · Post by **BAC5.2** » Wed Sep 14, 2005 10:46 pm

mikec wrote:Why's the Non-DCCD V7 the most coveted?

No MPT clutch pack to burn up and destroy. The non-DCCD is simply less things to break. The center diff is a sealed unit with gears.

PLUS, STi offers significantly stronger center vicous center diff options.

If you want a low top gear for mileage, good luck. What will end up happening, is you'll have a ratio so low, that in 6th you'll end up having to go ON boost just to maintain speed.

You'd get good gas mileage, until you needed to maintain speed, as you'd start dumping fuel while going on-boost to try to keep up.

Want a sick final drive? Get a GM vehicle. The Caddillac CTS-V has a 6th gear ratio of .53:1.

mikec · Post by **mikec** » Wed Sep 14, 2005 11:51 pm

Makes sense. Thanks for clarifying.

evolutionmovement · Post by **evolutionmovement** » Thu Sep 15, 2005 5:11 am

My current 5th gear isn't bad. I'd just like to be able to keep it or even get a little higher. The car has plenty of cruising power without any turbo at all so I don't imagine I'd be boosting unnecessarily. I suppose AWD will drag it down, but I can't see having the same final drive as being an issue.

Yeah, the GM 6-speeds are stratospherically geared on top. Modern alloy engines, variable valve timing, and cylinder deactivation with the allowable high gearing from a big (naturally high torque) motor makes packaging and serviceability the only possible draw backs to larger multi-cylinders nowadays as they don't make any normal light cars that mate well to small engines anymore. Even the Mini weighs about as much as my wagon and gets worse mileage being a 1.6 since it needs to boost to move it.

Steve

scottzg · Post by **scottzg** » Thu Sep 15, 2005 6:35 am

is there a way to have a rear biased drivetrain and not spend the 8k for a 6 speed?

Oh, and not swap to an open center diff.

Post by **Legacy777** » Thu Sep 15, 2005 7:07 pm

scottzg wrote:is there a way to have a rear biased drivetrain and not spend the 8k for a 6 speed?

Oh, and not swap to an open center diff.

You can weld the center diff and make your car RWD.....otherwise....no.

BAC5.2 · Post by **BAC5.2** » Thu Sep 15, 2005 8:20 pm

scottzg wrote:is there a way to have a rear biased drivetrain and not spend the 8k for a 6 speed?

Oh, and not swap to an open center diff.

The vicous center diff isn't, technically, an open diff. It's a limited slip, working exactly as a vicous rear diff (or front) works. With the center diff, there are a few things going on. To start, you must know how it is configured, and how the transmission works. There are two shafts in the transmission. The main shaft, and a secondary shaft (the output shaft). The mainshaft is what the clutch resides on. First gear, Second gear, and Reverse are machined onto this shaft, they are all one peice. Third and Fourth gears ride on the input shaft but spin freely on needle bearings. Third and fourth gear are actually all one peice, and are pressed onto the output shaft (effectively becoming one peice with the output shaft). The shift collar locks the input shaft side of third and fourth, to the input shaft. In neutral, clutch pedal released, 1st and 2nd gear are both spinning on the input shaft and the output shaft (the mating gears ride on needle bearings on the output shaft). When 1st gear is engaged, the shift fork moves the engaging collar onto the engagement teeth, which locks 1st gear to the output shaft, spinning the output shaft with the power of the engine. When in 1st or 2nd gear, with the clutch out (pedal depressed), and the vehicle not moving, is the only time nothing is moving inside of the transmission. So the output shaft begins turning when the clutch pedal is released. The output shaft has two ends. One is the pinion part of the front diff's ring and pinion. The other end of the output shaft, goes to the center diff. The center diff is a sealed vicious unit. There is a shaft coming out of the center diff, with a gear on it. There is a shaft with a gear on it "idling" next to the center diff, meaning it's riding on bearings and the only power applied to this shaft is from the center diff's output gear. This shaft is splined, and those splines meet with the drive shaft to supply power to the rear end of the car.

So, your in third gear, and everything in the vehicle is properly warmed up. Your cruising along on a slippery road, and you nail it. The front tires attempt to slip upon acceleration (the front wheels being the path of least resistance for torque to exit the vehicle. Note: Some wheel slip is required in both the MPT center diff, and the Vicous center diff. Otherwise, there will be no change in transmission output speed, and nothing for either center diff to equalize). Engine RPM's increase, and the output shaft of the transmission increases in speed as well. Now, the inside of the center diff, I am slightly confused about. But I would imagine that there are plates suspended on bearings with silicone fluid floating between them. As the fluid heats, it expands. There are two sets of plates, one from the output shaft of the transmission, and one set attached to the shaft with the gear on it, that would drive the rear wheels. How it's setup, I'm not completely clear, it could use vanes like a windmill or it could be far more complicated than anything I've said so far. But the basic function is as follows. One side of the center diff (the plates from the tranny output), are spinning faster than the output plates to the rear wheels. The input plates cause thermal expansion of the silicone, and it attempts to force the output plates to spin at the same speed as the input plates. The center diff only sees these forces. Nothing other than the plates/shafts, is designed to move, nothing is designed to actually touch, the only "wear" item is the fluid. So the tolerances are incredibly close. If I knew more about the setup, I'd imagine that I'd be able to get you near exact tolerances to speed, temperature, etc. on what the center diff requires to operate. Realize, also, that there is an incredible amount of torque going through the transmission at any given time, ESPICALLY at lower gears. Remember, there are actually thousands of foot-pounds of torque at the wheels, not the hundreds shown by dyno's (those readings are estimated flywheel readings).

Thanks to all of these wonderful mechanical concoctions, the time for the center diff to lock the plates together, is almost non existant. Since the input side of the center diff is always spinning, and the output side of the center diff is always spinning at a slightly slower speed (or tries to, thanks to drivetrain frictions and the rear wheels essentially "dragging") the center diff is almost always near the verge of locking. In fact, take a quick drive around the neighborhood and then lift the car into the air. I bet when you try to spin one of the wheels, another one at another end of the car will try to spin also. Better yet, jack up a "cold" car and spin one of the front wheels. Fairly easy to spin. Yank the E-Brake (rear wheels only, dontcha-know), and the front wheel suddenly becomes slightly more difficult to spin. Turn on the car, put it in 1st gear and let out the clutch. All 4 wheels (or at least one at each end) should spin. Yet again, try to stop just one of those rear wheels. Even cold, it's difficult. Quickly yank the e-brake as the engine is "idling" in 1st gear, and the car will likely stall. With a clutch type center diff, you always risk burning out the clutch packs in the diff. Clutch packs are like any other friction surface, they wear fastest when they are slipping. Off the show room floor, the first time duty-solenoid-C engages any of the clutches, they are wearing out, and becoming less and less effective as the time goes on. While I will admit, a clutch type center diff IS, in fact, a split second faster acting than a vicous type, a vicous type is far more consistent. I doubt there is any notable performance advantage to either, espically since any Subaru with a clutch type center diff, has a transmission weighing significantly more (The 6-speed in the STi weighs a staggering 80 pounds more than the 5-speed in the WRX).

I realize that this was an INCREDIBLY long post, and if you want the cliff-notes, I'll state it simply. The "lag" of the vicous center differential, is almost non existant. In my own personal experience, I've found that I will immediately spin one front and one rear when I'm driving on an extremely low-grip surface. Furthermore, short of locked, the vicous center differential is the closest you will come to a true power variable unit. As far as I know, Torsen style differentials require load variation in order to function properly, so on ice, for example, the vehicle with a torsen style center diff (a.la. VW), only the front wheels will spin. At least with the vicous (and to it's credit, the MPT Clutch diff), two wheels are always spinning.

Again, sorry about the lengthy post, I hope at least some information was gained about the Subaru Manual Transmission. I could be completely incorrect, and that likelihood is entirely possible, but at least I might have opened eyes to the confusing mess of gears that lies below the shifters in our cars.

Oh, and Subaru offers center differentials through STi that have different tolerances, allowing more power to be shifted between ends of the car. I believe stock in the WRX is 8Kg, and STi offers 12Kg, 16Kg, and 20Kg. What that all refers to, I'm not sure. It may relate to the effort required before the fluid shears, and allows the front wheels to spin free towards oblivion.

If I am wrong, which again is totally possible, please correct me.

A sole final note, both the MPT clutch system and the Vicous clutch system will also direct power forwards to the front wheels if the rear wheels slip. It works both ways. Just incase that was cloudy to anyone. Both center diffs also help greatly on deceleration to maintain traction (as you come barreling into a turn, you slam the brakes, weight shifts forward, front wheels would like to lock, braking force of the front wheels is diverted slightly to the rear wheels, and helps maintain balance and traction). Usually, you won't just lock the front wheels, but all four of them.

Post by **Legacy777** » Thu Sep 15, 2005 9:08 pm

Sounds like you got things pretty correct.

Just a minor clarification. The center diff is composed of the differential and viscous coupling. The viscous coupling is where the fluid & plates are. I've got some techincal data on the viscous coupling and how the fluid reacts, etc. It goes in detail, however my server is acting up. I'll post it when I get things up.

Also, the automatic does not have a center differential, just the rear extension housing with the clutch packs.

Just to add, when I did my swap and drove around in the wet. I was amazed at the grip. There was very little slip if any. The car just took off. So I agree the actual lag is minimal.

The ratings on the center differentials is probably related to the shearing properties of the fluid.

As you mentioned with the turning one wheel and it being easy when the car is "cold". The higher the number, the closer it's going to mimic a true direct connection center diff.

scottzg · Post by **scottzg** » Thu Sep 15, 2005 10:13 pm

thx phil!

I wish i had a picture.

BAC5.2 · Post by **BAC5.2** » Thu Sep 15, 2005 10:49 pm

Thanks Josh!

Sorry I was combining the vicous coupling and the center diff. For further clarity, the "center diff" is the actual gears, while the vicous coupling is simply the means by which power is transferred between the gears. I believe that's correct.

As another note, the stepped center diff (the actual gears) in the WRX (1.1:1 with a 3.5454xxxwhatever rear diff) simply gives mechanical advantage over the power split. While the rear diff x the center diff still equals 3.9:1 (same as the front), the center diff sees the rear wheels as being more difficult to turn. This, effectively, makes the vehicle attempt to transfer more power to the front wheels. Plenty of reasons behind this, the main one being saftey. Look at an F-Body, or just about any modern vehicle, and they all err towards the caution of understeer. In our automotive day, that was less of a concern, and the general public was less inclinded to sue over spilled coffee.

Watch a WRX launch. Any decent launch will give a nice spin to the front wheels prior to take off. Watch a Legacy launch (I've got a good deal of experience with this), and it's not the fronts that are so readily inclinded to bark, but all 4 wheels. On one of my runs, my car squatted and rotated as all 4 wheels spun free of the tarmac for a very short period of time.

Again, I'm not POSITIVE, but I'm pretty sure that's the reasoning behind the 1.1:1 center differential.

I apologize for the Automatic and Center Diff idea. While I think I understand the MPT Clutch pack setup, I'm unfamiliar with the overall powertrain on the 4EAT equipped Subaru's of our generation.

evolutionmovement · Post by **evolutionmovement** » Thu Sep 15, 2005 11:08 pm

Phil, what about the supposedly beefed up 5Mt in the new Legacy?

Steve

Post by **Legacy777** » Thu Sep 15, 2005 11:28 pm

Busdriver · Post by **Busdriver** » Thu Sep 15, 2005 11:51 pm

Thanks, that's awesome...

BAC5.2 · Post by **BAC5.2** » Fri Sep 16, 2005 1:17 am

Steve - I'm not sure.

There have been numerous changes since the WRX first came out.

Pre 2003.5, the gears were standard. A picture of the stock gearset vs. the STi RA gearset can be seen here:

http://www.thawa.net/bac52/Jays%20Trann ... earset.jpg
(stock, obviously, on the right, RA on the left).

Post-2003.5, all WRX's came with RA width/pitch/profiled gears for 3rd and 4th.

In 2004, the transmission case actually changed dimentionally, and was converted from stub-in-axles (the way our transmissions are configured), to stub-on-axle (the stub is inserted into the diff). This maintains today. The STi has had this setup since its US release.

As far as the Legacy/Forester goes, I'm not entirely sure, I haven't seen one apart to be able to tell for sure. I'll have to get back to you on that one. I don't know how beefed up it is, but I would imagine that IF they changed anything, it would be using the RA gearset.

The thing is, is the Legacy really housing a beefed up transmission? Why would Subaru install a beefed up transmission in a car not designed to get beat on? Subaru is losing money on transmission warranty claims in the WRX. If anything, they would put the "beefed up" transmission into the WRX. I doubt there's a "we'll show them" mentality at FHI about the WRX and it's transmission. The fact, is that stock gears are NOT big enough and NOT strong enough to handle even stock power. That's a discussion for another thread, but I assure you it's more failure of machine than man.

It could simply be a myth, and the theory of a beefed up transmission in the Legacy/Forester is due solely to the fact that they aren't expected to perform as well as a WRX. Or it could be truth. I don't know, but I'd bet there are simply not enough people really tweaking out the Legacy or expecting them to be race cars. I mean, you can't piss in a parking lot and miss a WRX. I almost NEVER see LGT's or FXT's or OBXT's or any such vehicle. The only ones I see are driven by old men, or my friend who road races his (with minimal power mods). So it could just simply be a matter of not enough people to fuck them up yet. Get what I'm saying?

evolutionmovement · Post by **evolutionmovement** » Fri Sep 16, 2005 1:58 am

Yeah, but the next WRX is set for the 2.5 and I doubt it will get the 6-speed. The current transmission would be a definite liability, so maybe they're waiting to put the 'beefed up' 5mt from the new Legacy in?

Steve

BAC5.2 · Post by **BAC5.2** » Fri Sep 16, 2005 2:04 am

Could be.

If anything, the beefed up tranny has ALL RA gears (1 through 4), and that would be the only change.

I'll ask around and see if I can come up with anything.

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JDM 6-speed sources

JDM 6-speed sources