For all the haters...

[BAC5.2]

Everyone dogging on owners of WRX trannys shifting them poorly causing breakage.

It's not the drivers fault.

After seeing the internals of a Suby tranny, and talking to a VERY intelligent Suby Tech, it's no fault but the trannies.

And it's not why you think.

The gears simply CANNOT handle the power. They are WAY to narrow and WAY to soft to put up with the abuse. In all reality, the gears themselves look Cast.

Myth 1: The tranny breaks because of bad shifting.

False: Synchro's are there for a reason. If you shift with the clutch, you will hurt the synchro's more than the gears.

Myth 2: The case flexes.

FALSE!: This is a big one. The case does NOT flex. I used to think this was the problem. False. Not the problem. First of all, the myth goes that the case flexes and pulls the gears slightly apart, thus putting lots of stress on the gearbox.

In reality, the gear shafts are stacked (not side by side, but stacked). So any "opening" of the case, would not allow the shafts to pull apart.

Also, the bearings have alignment pins that must meet up with the tranny or the case will NOT close. The odds that the case would flex open, spread the gears, then MAGICALLY close back on the alignment pins, is a ridiculously outrageous claim. Doesn't happen.

Also, there is a HUGE girdle in the middle of the tranny. The tranny is BRACED. Think of it like a steel shank in a really good quality hiking boot. The tranny would have to torque out HUGE bolts, and somehow pivot around or on the girdle to seperate.

Also, the bellhousing of the tranny is one peice. The housing is bolted and pinned to the case. If the case opened, the housing would crack.

AND, the transmission is bolted to a horizontally opposed engine. If it did happen to open, it would likely damage the block too.

To top it off and kill this myth: The case is aluminum. If it flexed, it would not flex back. It would crack or shatter.

Simple fact of the matter, the gears are to weak. Straight up, weak.

You want to go 0-60 in 5.4 seconds, you are going to break something, and it will probably be a gear. They are weak.

Want pics for proof?

When the drain plug was pulled, FULL TEETH dropped from the tranny:



The case was FILLED with metal shavings. You can actually see (not in picture) where the teeth actually SHOT out and pinged off of the case. The gear teeth, quite literally, shot peened the case.



And the proof of the pudding, what USED to be 2nd gear:



To solve it all, the following went in place of the stock, crappy gearset. MRT straight cut, synchro'd gears. The strongest, synchro'd box you can build. About the most expensive synchro'd box you can build, too.




Oh, and for those propaganda-ist's who claim the STi RA gearset is bulletproof, they are wrong.

RA on left, stock on right (look at the tooth size). Also look at the smooth portion where teeth used to be....



And there we have it. The proof. The case isn't at fault, the driver isn't at fault, it's the gears and the gears alone.

[vrg3]

Huh. That's good to know it's not the case flexing.

If you're aware of this weakness in the transmission, you should be able to make the tranny last, though, right? You just need to not shock the gears with a lot of instantaneous torque. Right?

[BAC5.2]

It's not just that though. The clutch should absorb that scary amount of shock. Turbo lag helps prevent instantaneous forward acceleration shock, but in terms of downshifting, the clutch will eat the shock... or at least it SHOULD.

Of the, probably 20 tranny's he's seen 2nd gear was broken on easy driving rather than WOT runs.

He has even seen people shear the gears SMOOTH (like that RA set) MID GEAR. Just rolling into boost and BAM chunks of gear taken out.

The tranny needs to be revised.

Subaru claims this performance of 5.4 seconds 0-60, no way in HELL you are going to acheive that without launching the car. That's PRIME time to kill the tranny.

[-K-]

The Driver still does matter. Why can some break a tranny every month and some never do? I doesn't take away from tranny being weak.

Any thoughts on the 6MT by your gear man? I wouldn't mind DCCD while I'm at it.

[BAC5.2]

Synchro's make up for most driver error when it comes to the actual SHIFTING of the gears. Faulty shifting rarely causes problems, unless you totally ham-fist the shift in which case, you suck and should be shot in the face.

When a tooth is fully engaged, it's no longer a driver controlled circumstance. Hard shifting isn't hard on gears (by hard, I mean fast) as much as it's hard on synchro's. If you shift within the speed and ability of the synchro's, then you are not going to do much damage, if any at all.

If you shift HARD (as in actually hard), it's STILL not going to be horrible for the gears, as the shaft speeds are still matched by the synchros. The only real significant shocks would come from a TOTAL hack driver, and it would be almost impossible to shift this poorly on such a regular basis to destroy the tranny.

Stage4 guys actually shear teeth off of the gears MID gear rolling into boost. It's the gears that's 99.9% at fault.

The 6-speed is just beefy. It's complicated too. The 6MT has a LOT of shit going on in there, but it works. The gears are pretty sizeable and they can take the power. The ratios are way to short though. TXS (I think it was TXS) was 8hp shy of 500awhp and ran an 11.9, getting into 6th gear at the track. To much shifting.

The DCCD is cool, as it's the only Subaru manual transmission that uses a clutch style center diff instead of a vicous coupling. Very neat, and was making me wonder about converting an Automatic transmission to DCCD by simply having a knob to control voltage to the Duty C Solenoid.

I will see if I can get some pictures of the STi 6-speed internals when I am at the Subaru Training Center next.

[evolutionmovement]

So cryo-treating would help as I suspected. How much, who knows? But I wonder if combined with stouter gears that the longevity would go way up. This is much better than case flex as this is a more surmountable problem. Are there drop in gear sets that are tougher, but not straight-cut or prohibitively expensive? I wonder if just the first three gears could be replaced with stronger components.

Steve

[THAWA]

damn, that's some poor driving if i ever saw any.

[BAC5.2]

Steve - Not worth it to cryo-treat the stock gears. They will be only marginally stronger. Seriously, they look cast. They are NARROW and weak. Just a bad design is all.

Good gears are already prohibitively expensive.

The RA gearset is a drop in gearset, that's quiet, strong, and nice. But they DO break and replacing a set of RA gears ends up costing MORE than a straight cut box.

The gearset I posted a picture of above is an MRT straight cut, synchro'd 1st through 4th with a stock 5th. Drop right in. Parts only: nearly 4 grand. Strongest synchro'd box you can build though.

You can get a full on dogbox for around $4500. A dogbox (Like a TurboXS one) is pretty nice, as they have helical cut gears but no synchro's. I didn't get to drive it, so I don't know exactly how it felt, but it was quieter than my car, lol... except when shifting "CLUNK"

Case flex is a myth.

Stouter gears would be OK I suppose, but you'd be shifting so much, your revs would be so high, it wouldn't be worth it IMO. Stick with LONGER gears if getting anything. You have more time on-boost with slightly longer gears and they help improve spool time.

This is going to be a PIMP gearset. I cannot WAIT to get a ride in this thing. It'll howl like a friggin monkey.

I'm already saving my pennies for a dog box. Knowing that noise, I could deal with that every day. Sounded SO horrible when shifting (you could just dead shift. The owner of the car drove it 2 hours from the shop to his house in DC without the clutch (blown clutch after leaving dealership). Just crashed it into gear. When the box was torn down (TXS redesign of gears, free replacement) the damn thing looked like it had never even been driven on, but man, that was sweet. You could shift SO fucking fast, it was blistering. He had a built front, center, and rear diff too, that thing was a traction MONSTER.... until you just get sideways from all the power.

[professor]

Good info. I've only been around the Subaru boards for about 6 months now, but I've never heard so much bitchin' about transmissions and clutches with any other marque.

There must be something to it.

There is no question that the feel of my clutch and gearbox is the worst I've ever had on a modern car. It could only dream of being a Mazda, BMW, Honda, etc.

But do you really want a dog box on a street car ???

[vrg3]

Wait -- these gears strip in the middle of a gear?! That doesn't make any sense. The torque right when the clutch is engaged after a shift should be much higher than the engine could hope to make on its own. That's why a lot of cars chirp the tires on shifts even if they could never hope to cause wheelspin while already in gear.

I don't believe it. I don't believe damage happened entirely mid-gear. It had to have started at a shift. Or rather, right after a shift, as the clutch was engaged. The teeth could continue to work even after being shorn a little, and then fail catastrophically a couple of seconds later.

The clutch can't absorb enough torque to make engaging a gear as easy on the transmission as even the engine's maximum torque. If it did, it would be slipping all over the place and would generally suck.

I'm not saying there isn't a problem; I'm just having a hard time accepting that one couldn't avoid the damage if one wanted to. Every RS-T owner since 1998 has found that unless handled with a lot of mechanical sympathy, the teeth on 2nd would snap like saltines. But many were able to make it work.

Too bad Subaru kept pretty much the same design for the WRX transmission.

[BAC5.2]

The dog box in that Stage5+ I was in seemed OK, just a bit noisy and clunky.

In all reality, it didn't sound much louder than my car. It was helical cut, so it was a bit quieter.

The only thing I would be concerned about is the no synchro's and the need to double clutch everything. I would not rule out a dog box though. At the very least, a box built like above for my friends stage+ WRX.

[BAC5.2]

I know, personally, of 2 people who have rolled into 2nd gear (easily) rolled onto boost, and BAM tranny grenades. Both were stage 4's I think. Could have been prior damage, and like you said, just failed totally while they happend to spool up.

99% do break at the shift, but it does happen that they shear the teeth mid-gear. I wasn't saying that they ALL break in the middle of a gear.

Subaru trannys just have gears that are as strong as a toothpick.

Just like you think the TD05 should have been standard, Vikash, I think the RA gearset should have been standard. But even those break, as you can see there.

I, personally, would LOVE to have a built tranny. I've recently become fascinated with transmissions. I might have to buy an MRT gearset in the near future and rebuild my transmission at school.

[Brat4by4]

Phil, you need to think about what you are trying to do. What would you fix about your tranny? Well, I for one, know the synchros suck and the gears are just a roulette shot away from possibly breaking... possibly the input shaft if launched too hard. Fix the problems that need addressed and don't fix what ain't broke. Those dog boxes and synchroless transmissions are for more competitive type situations where somehow taking a 1/50th of a second will make you that much faster (in theory).

Don't remember what idea I showed you at first. Having the first 3 gears straight cut and synchroed would be an awesome tranny. No thrust loads in the banshee gears and normal noiseless cruising in the top gears. 1-3 straight cut with maybe 4-5 Sti gears (whichever ones have more width and aren't shorter than Danny Devito) would be a nice compromise for a street car. Now if you plan on doing something different with your car, that's another story.

But... if I could get a sequential transmission that I could shift like a motorcycle, no clutch just slight off-throttle, that would be pimp

[Legacy777]

There will be some case flexing going on. I don't care how much bracing you have, it will not be 100% rigid. Especially considering it's aluminum. I'm not saying case flexing is the cause of all these gear failures. But what I am saying, you will have some torsional flexing of the case under certain circumstances.

With that being the case, I want to bring in the fact that some people have issues with shifting, try different fluids, etc, etc. All these inconsistencies between WRX owners and other subaru owners who have MT's would lead me to believe Subaru has some QC issues with how their transmissions are put together. With that being the case, if you have on transmission with tighter tolerances vs. one with slopper tolerances....the one with sloppier tolerances is going to be more prone to failure.

[BAC5.2]

If I go straight cut, I will get 1 through 4, and they will probably be synchro'd. I just like the idea of being able to SLAM the gears without any worry of breaking anything with a dog box.

There really aren't any wider 5th gears. Even the RA gearset uses the stock 5th gear.

If you want to be able to slam gears without a clutch, get a dog box. You can flat shift it without a clutch if you really try, and it'll take it all day long.

[BAC5.2]

Josh, the VERY MINIMAL torsional flexing of the transmission would have no effect on gear durability at all. Gear mesh wouldn't change without all of the bearing alignment pins becoming misaligned, and then the case wouldn't shut and you would definately have problems.

If you saw the inside of a suby transmission, you'd realize that the only flexing that would go on, would be the transmission and the engine rocking in it's mounts. I think people are underestimating the sheer beefiness of the case. It's really not a weak transmission, it's a weak gearset. Look at the case I posted with the straight cut gears in it. That's a LOT of aluminum, it's a stiff case.

The minimal, if any, flexing that would occur would never be enough to do any kind of damage or effect any kind of driving.

Just about every built transmission running behind the block of 5 and 600 wheel horsepower Subaru's all utilize the STOCK case, right? The TurboXS dogbox uses the stock case. It's not a flimsy case, and the amount of bracing is incredible. The TXS dogbox is a wicked strong tranny too. Probably the strongest available on the market.

Subaru is weird. Bulletproof case (until a gearset blows up inside it), but glass gears.

[dscoobydoo]

I somehow don't see myself spending more for a tranny than I did for my turbo car.

Seems I will be on the lookout and getting a spare 5mt.

[tris91ricer]

I agree with dscooby, considering I bought mine for only $200.
Trannys are expensive though. think of the tolerances and engineering that go into them --that's math at its finest!

[BAC5.2]

BUILT trannies are expensive ($4500 to $5500 for a gearset. DIFFs are expensive though). Regular trannies are cheap if you get them used. The local yard here sells trannys for $75.

I was thinking about buying an RS tranny for $275, and getting it built. But I dunno. I don't think I'll go the 4.11 route, it's already ridiculous that I cruise at 80mph at 3100RPM.

[Legacy777]

BAC,

What sort of thickness is the bracing in the transmission. How thick is the outer transmission shell?

[BAC5.2]

Josh, I didn't think to grab a tape measure, as I didn't really think about case flex when I was looking at it, and the tech didn't elaborate on the myth until last night (not at his shop).

You can sort of see in the picture I posted the thickness of the case, and the bearing girdle.

The case looked to be about as wide as the gear itself. It's got a lot of beef.

[BAC5.2]

Shot of an opened box. TurboXS dog box in a stock WRX case.

[evolutionmovement]

So can the tech get his hands and eyes on the inside of a new GT case? I heard that they've been beefed, but have no idea how. Could just be marketing hype, but what if it's gear sets?

Steve

[dzx]

After reading this post, i'm not too worried about the strength of the gears in my car. 12.4 @ 5000ft is pretty damn good.

http://forums.nasioc.com/forums/showthread.php?t=679938