Stock Drivetrain Limits

GT4604 · 03-23-2008, 08:04 PM

I was looking around and I can't find any information on the stock STi drivetrain components and if there are any general limits before breaking them. I have an 04 STi about ready to go with a larger turbo and the last thing I want to do is break what looks like extremely expensive drivetrain parts. I have 70,000 miles on it.

I see high horsepower STi's all over the board but it never seems like much is changed besides the transmission itself or at least gearsets. Are the differentials and axles that stout? Is there anything I can do besides fluids to lessen the chance of breaking these parts?

Thanks

***Draco-REX*** · 03-23-2008, 09:57 PM

Do your proper maintennance and the gearbox is pretty much bomb proof. I believe the axles are the first to go, but that's on lots of hard lauches at 500rwhp or so.

GT4604 · 04-02-2008, 09:03 AM

Wow I'm impressed.

STI_Mike · 04-02-2008, 09:15 AM

Quote:

Originally Posted by Draco-REX

Do your proper maintennance and the gearbox is pretty much bomb proof. I believe the axles are the first to go, but that's on lots of hard lauches at 500rwhp or so.

i would agree as long as you treat the tranny right with no dumping the clutch it should be fine!

AllWheelDriven · 04-02-2008, 10:14 AM

There are STi's at MZM pushing over 530whp on a mustang dyno that stock sti's measure at around 200-215 whp that are drag raced and driven like they are stolen on completely stock drivetrains with no issues.

axles are the weak link but plenty of people seem to be pushing serious torque with no issues.

as far as dumping the clultch or slipping it goes.

dumping the clutch will give you some wheel spin and isn't as hard on the clutch and fly wheel as slipping it.

By dumping I don't mean side stepping it at 6000rpm.

***solovus*** · 04-02-2008, 10:33 AM

Quote:

Originally Posted by GT4604

I see high horsepower STi's all over the board but it never seems like much is changed besides the transmission itself or at least gearsets.

This is what you call not much? Does this sound funny to anyone else?

rabbisti397 · 04-02-2008, 12:08 PM

"Granny shifting not double clutching like you should."

Marteinn · 04-05-2008, 08:03 AM

my 02,02 '07 STi only driven 24,000 km gt3076 @ 18 psi only driven 2000km died today :S crap :/

i had 03 sti before just with 3" exhaust, still alive after 100,000 km :S

polyol · 04-05-2008, 08:17 AM

Quote:

Originally Posted by solovus

This is what you call not much? Does this sound funny to anyone else?

No...not really.

The stock drivetrain is know for being quite robust. Axels go first but I think that is in the design...let them break before something else more expensive goes.

***sciolist*** · 04-05-2008, 08:45 AM

In and of itself, I don't think you'll have too much trouble with power. What's going to start busting stuff is power + grip. I have over 1000 hard launches on my stock drivetrain. That's with a variety of tire/wheel combinations from OE up to 275 V710's on 10.5" wheels. My car only has about #360 of torque though.

I do have a twin plate, so it picks up fast, but I also understand how to launch reasonably safely.

Based on anecdotal evidence, I would expect axles to start snapping when you got up into the low-mid 400's, on race tires, launching full-bore, off the tree. For standard-format autoX, you could probably build out a SM car on OE axles. For Pro's or drag racing, you'll probably need to do the axles, and then obviously there will be a greater chance of popping stuff upstream of the axles.

I think it would be totally reasonable to build an upper #400-ish car for launching on race tires and expect to get several seasons out of it before anything went - assuming you can launch effectively.

If you have any weak (defective) links in the chain, they'll probably manifest themselves right up front.

I imagine there's probably some torsional strain on the axles over time. It might be wise to pinstripe them. I would have done that myself if I'd thought about it.

Hope that helps.

GT4604 · 04-09-2008, 10:49 AM

Thanks that makes me feel better about this car.

jays05 · 04-09-2008, 10:55 AM

Stock drivetrain (axles/tranny/diffs) ==> YouTube - Jays gt35r STI 22psi in-car pulls + sick launch

My only drivetrain upgrades so far have been upgraded mounts/bushings (besides the clutch of course)... 150+ quarter mile passes and hundreds of hard launches later.

**TopSpeed** · 04-09-2008, 11:35 AM

Use proper gear oil from Subaru. And when you are driving the car hard. Don't miss Shift! We have worked on and tuned countless 500whp+ STi's on stock transmissions. Never an issue. Wrx's on the other hand. Lets just not go there.

Tray M
TopSpeed Inc.
866-94SPEED

wrrrx · 04-09-2008, 06:43 PM

I would also be wary of running too much boost for too long (like on a long straight at a race track). If I had it to do all over again, I wouldn't go past 23-24 psi on a stock short block.
If you want to run higher pressure than that, you'd better get yourself some nice purty forged pistons.

03-23-2008, 08:04 PM	#1
GT4604 Junior STI Driver Posts: 116 Join Date: Jan 2007 Trader Rating: (0)	Stock Drivetrain Limits I was looking around and I can't find any information on the stock STi drivetrain components and if there are any general limits before breaking them. I have an 04 STi about ready to go with a larger turbo and the last thing I want to do is break what looks like extremely expensive drivetrain parts. I have 70,000 miles on it. I see high horsepower STi's all over the board but it never seems like much is changed besides the transmission itself or at least gearsets. Are the differentials and axles that stout? Is there anything I can do besides fluids to lessen the chance of breaking these parts? Thanks This ad is not endorsed by this member. Please register or login to hide this ad.

03-23-2008, 09:57 PM	#2
*Draco-REX* Black Dragon STI Car: 07 OBP STi 03WRB WRX Fav Mod: My whole suspension Location: Columbus, OH Posts: 1,528 Join Date: Jan 2005 Trader Rating: (0)	Re: Stock Drivetrain Limits Do your proper maintennance and the gearbox is pretty much bomb proof. I believe the axles are the first to go, but that's on lots of hard lauches at 500rwhp or so.

04-02-2008, 10:14 AM	#5
AllWheelDriven Junior STI Driver Car: OBP,2005,STi Posts: 69 Join Date: Nov 2006 Trader Rating: (0)	Re: Stock Drivetrain Limits There are STi's at MZM pushing over 530whp on a mustang dyno that stock sti's measure at around 200-215 whp that are drag raced and driven like they are stolen on completely stock drivetrains with no issues. axles are the weak link but plenty of people seem to be pushing serious torque with no issues. as far as dumping the clultch or slipping it goes. dumping the clutch will give you some wheel spin and isn't as hard on the clutch and fly wheel as slipping it. By dumping I don't mean side stepping it at 6000rpm. Last edited by AllWheelDriven : 04-02-2008 at 10:19 AM.

04-02-2008, 12:08 PM	#7
rabbisti397 STI Driver Car: Blue 06 STI Fav Mod: FP Green Location: So Cal Posts: 230 Join Date: Oct 2007 Trader Rating: (2)	Re: Stock Drivetrain Limits "Granny shifting not double clutching like you should."

04-05-2008, 08:03 AM	#8
Marteinn Junior STI Driver Car: 07 euro STi White Fav Mod: i love them all ! =) Location: iceland Posts: 59 Join Date: May 2006 Trader Rating: (0)	Re: Stock Drivetrain Limits my 02,02 '07 STi only driven 24,000 km gt3076 @ 18 psi only driven 2000km died today :S crap :/ i had 03 sti before just with 3" exhaust, still alive after 100,000 km :S

04-02-2008, 09:03 AM	#3
GT4604 Junior STI Driver Posts: 116 Join Date: Jan 2007 Trader Rating: (0)	Re: Stock Drivetrain Limits Wow I'm impressed.

04-05-2008, 08:45 AM	#10
*sciolist* Spiteful Old Codger Location: Bend, OR Posts: 2,345 Join Date: Jul 2003 Trader Rating: (1)	Re: Stock Drivetrain Limits In and of itself, I don't think you'll have too much trouble with power. What's going to start busting stuff is power + grip. I have over 1000 hard launches on my stock drivetrain. That's with a variety of tire/wheel combinations from OE up to 275 V710's on 10.5" wheels. My car only has about #360 of torque though. I do have a twin plate, so it picks up fast, but I also understand how to launch reasonably safely. Based on anecdotal evidence, I would expect axles to start snapping when you got up into the low-mid 400's, on race tires, launching full-bore, off the tree. For standard-format autoX, you could probably build out a SM car on OE axles. For Pro's or drag racing, you'll probably need to do the axles, and then obviously there will be a greater chance of popping stuff upstream of the axles. I think it would be totally reasonable to build an upper #400-ish car for launching on race tires and expect to get several seasons out of it before anything went - assuming you can launch effectively. If you have any weak (defective) links in the chain, they'll probably manifest themselves right up front. I imagine there's probably some torsional strain on the axles over time. It might be wise to pinstripe them. I would have done that myself if I'd thought about it. Hope that helps.

04-09-2008, 10:49 AM	#11
GT4604 Junior STI Driver Posts: 116 Join Date: Jan 2007 Trader Rating: (0)	Re: Stock Drivetrain Limits Thanks that makes me feel better about this car.

04-09-2008, 10:55 AM	#12
jays05 Spec C Club Fav Mod: when it's not blown up Location: Upstate NY Posts: 1,561 Join Date: Nov 2004 Trader Rating: (0)	Re: Stock Drivetrain Limits Stock drivetrain (axles/tranny/diffs) ==> YouTube - Jays gt35r STI 22psi in-car pulls + sick launch My only drivetrain upgrades so far have been upgraded mounts/bushings (besides the clutch of course)... 150+ quarter mile passes and hundreds of hard launches later. Last edited by jays05 : 04-09-2008 at 10:58 AM.

04-09-2008, 11:35 AM	#13
TopSpeed Authorized Vendor Car: 96 Time Attack RS Fav Mod: 06 STi swap Location: Alpharetta, GA Posts: 677 Join Date: Apr 2005 Trader Rating: (8)	Re: Stock Drivetrain Limits Use proper gear oil from Subaru. And when you are driving the car hard. Don't miss Shift! We have worked on and tuned countless 500whp+ STi's on stock transmissions. Never an issue. Wrx's on the other hand. Lets just not go there. Tray M TopSpeed Inc. 866-94SPEED

04-09-2008, 06:43 PM	#14
wrrrx Junior STI Driver Car: '04 WRX STi Fav Mod: PDXTuning! Location: Portland, OR Posts: 122 Join Date: May 2002 Trader Rating: (0)	Re: Stock Drivetrain Limits I would also be wary of running too much boost for too long (like on a long straight at a race track). If I had it to do all over again, I wouldn't go past 23-24 psi on a stock short block. If you want to run higher pressure than that, you'd better get yourself some nice purty forged pistons. This ad is not endorsed by this member. Please register or login to hide this ad.