Full build forced induction

[spitfire481]

Originally Posted by flat4-86

Is this transmission honestly that fragile? I never had this issue with or worry with my 04 STI . This is becoming a big concern now with the power levels in trying to hit. I'm just a bit confused because 3 tuning companies I spoke with personally said the transmission would be fine at the power I'm trying to attain. One of those companies was FBM to name one. Are they hoping I yardsale my transmission to get more money out of me? This is getting serious now because there aren't many if any options or there for the transmission in this car to hold the power

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It's hit or miss around or under 400whp it seems. If you were to hold 3rd or 4th gear in your hand you would wonder how it could even hold that for one good pass. The internals are tiny. Especially side by side with guts from a v160. There is a gearset out and another in development, but the lack of warranty has me going another direction for the power I'll be making

[flat4-86]

Makes sense why power wouldn't affect the synchros. I'm a clean no miss shifter. I KNOW how to properly drive and not abuse a car

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[spitfire481]

Going down a track and shifting hard at 8500rpm will beat up the syncros. making 350+ hp but taking 2 seconds between each shift during high rpm pulls to help save the synchros seems wrong. We have replaced two transmissions on NA track cars that crunch going into 3rd and 4th. If you plan on babying your car around, sure the stock trans may last forever. If you plan on taking advantage of the power and abusing your car, it's going to fail at some point

[Spartarus]

Originally Posted by spitfire481

Going down a track and shifting hard at 8500rpm will beat up the syncros. making 350+ hp but taking 2 seconds between each shift during high rpm pulls to help save the synchros seems wrong. We have replaced two transmissions on NA track cars that crunch going into 3rd and 4th. If you plan on babying your car around, sure the stock trans may last forever. If you plan on taking advantage of the power and abusing your car, it's going to fail at some point

Originally Posted by spitfire481

Going down a track and shifting hard at 8500rpm will beat up the syncros. making 350+ hp but taking 2 seconds between each shift during high rpm pulls to help save the synchros seems wrong. We have replaced two transmissions on NA track cars that crunch going into 3rd and 4th. If you plan on babying your car around, sure the stock trans may last forever. If you plan on taking advantage of the power and abusing your car, it's going to fail at some point

You raise a good point. Increased RPM will increase synchro wear.

That said, I hardly take 2 seconds between each shift. Just ensuring the clutch is all the way in by the time you're going into the next gear should be adequate to reduce wear. You can pull it out of the current gear on the way in to save time. Shouldn't really increase shift time all that much. I shift pretty hard, and it doesn't miss or lock out.

Also at that rpm and power level, if you care about the synchros you can do a lot to save them. Reducing the mass of the clutch disk will exponentially increase the life of your synchros. 4-puck or 6-puck is a great idea. Not that hard to drive on the street, contrary to popular belief.

Lightened components (namely flywheel, debatably pulleys) will help your revs match faster both up and down, saving syonchro life as well, but not nearly as much as a lighter clutch disk, as the rotational inertia of the clutch disk is directly dissipated (or increased) by the synchros on upshift or downshift..

[Ultramaroon]

Originally Posted by Spartarus

Oh man. Not again. Yeah, I said horsepower, and I had a good reason to say it.

Thank you for being adequately technical for the level of detail required to accurately describe the issue at hand.

[flat4-86]

I rarely take the car to the max and will be considering that even more so once the build is finalized. As to Rev matching, I consider myself an above average driver and maybe 1% of the time I do choose to Rev match, I miss time it. For the 45k miles on the car not a single gear has ever been ground or missed.

As to the clutch, I want going to go puck, even FBM steered me away from that option with this car being my DD. I've felt a few puck clutches and did not think they were very steerable (in traffic jams of course) which I find a lot of in my area where I live. Nor do I EVER power shift or shift without using the clutch. Will these driving habits greatly increase life of not only the synchros but life of the transmission as well?

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[spitfire481]

i dont want to sound like an ass, but doing a fully built block but never really taking advantage of it just seems like a waste. might as well just roll with a stock motor around 300ish with a full face clutch setup and be done with it because it seems thats about all you're after. there is no getting around wear and tear once you start making more power with the stock trans. its a roll of the dice as to what/when something will happen to it.

[flat4-86]

Originally Posted by spitfire481

i dont want to sound like an ass, but doing a fully built block but never really taking advantage of it just seems like a waste. might as well just roll with a stock motor around 300ish with a full face clutch setup and be done with it because it seems thats about all you're after. there is no getting around wear and tear once you start making more power with the stock trans. its a roll of the dice as to what/when something will happen to it.

Got it. And you do bring up a very valid point. Once that power is under my foot there will most likely be more moments than I want to admit to where I'll "take advantage of the power" as you put it. Also keep in mind that over next summer the car WILL be autocrossed. That's a 100% guarantee. So hopefully over the next year or so more transmission option will come to the market. As for now I'll be driving with my fingers crossed lol. And keep everyone on here up-to-date on how things hold up in the drive train.
But from I've been told and read, I will inevitably be replacing that thing within 30k miles or way less. It already has 45k on it so I'm not expecting it at this point to last much longer once the built engine is installed

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[Spartarus]

Originally Posted by spitfire481

i dont want to sound like an ass, but doing a fully built block but never really taking advantage of it just seems like a waste. might as well just roll with a stock motor around 300ish with a full face clutch setup and be done with it because it seems thats about all you're after. there is no getting around wear and tear once you start making more power with the stock trans. its a roll of the dice as to what/when something will happen to it.

I don't necessarily agree. I believe that you can take almost* full advantage of most extra power without causing egregious wear.

*I said almost:

Autocrossing and drag racing consistently prove that most of the worst wear and tear on cars happens when you're trying to squeeze the last few seconds (or tenths on the drag strip) out of it.

[flat4-86]

I'm in no way going to go "stig mode" on the car. .. if you get that reference to top gear lol. But the car will be driven. And again I stress, PROPER DRIVING TECHNIQUES. I'm no amateur when it comes to driving/racing. I'm against power shifting personally and think that it not faster. The linkages can only work as fast as they can work, that's it. Trying to force a gear or shift faster than the car already can will amount to nothing but pure abuse on the transmission.
Knowing all of that I don't see how just a measly 350wtq or a little bit more will simply shear a gear with w.o.t. driving with proper shifting and the right clutch setup. An I wrong to think this? Do I have more faith in Subaru transmission than others or am I to put it simply, just thinking like an amateur when it comes to power levels like this.

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[Ultramaroon]

Originally Posted by Spartarus

I don't necessarily agree. I believe that you can take almost* full advantage of most extra power without causing egregious wear.

The real skill and discipline are in holding back and staying smooth.

[flat4-86]

Originally Posted by Ultramaroon

The real skill and discipline are in holding back and staying smooth.

Clearly, if you cannot shift gears without spilling an unlidded cup of water for example that is nearly full (not in race scenarios as g's will spit it obviously) why are driving standard at these build levels? ? I'm sure someone out there will knit pick this theory of mine, but for those not taking it literally, you should understand what I'm talking about

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[Ultramaroon]

Originally Posted by flat4-86

Clearly, if you cannot shift gears without spilling an unlidded cup of water for example that is nearly full (not in race scenarios as g's will spit it obviously) why are driving standard at these build levels? ? I'm sure someone out there will knit pick this theory of mine, but for those not taking it literally, you should understand what I'm talking about

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Knowing the inherent weakness of 4th gear, just for fun, I try holding back on it. I don't think I could restrain myself in a competitive situation.

As Spartarus noted, the torque limits are not published. Several people have found it but without instrumentation, the numbers remain a mystery.

[flat4-86]

Guess we will just have to let time figure out the true answers to all the questions with the transmission in this car. I myself have a HIGH faith in Subaru building strong transmission. Especially worth factory turbo ones over seas and the concept STI BRZ. Subaru will have known this car will have been built and I'm just hoping they built the car according to that. Especially since the drive shaft and diff seem to hold these power levels well...

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