safe to launch

shuffbag · Post by **shuffbag** » Fri Jun 20, 2008 9:20 pm

just wondering those of you with ej22+awd.

if some one in a large car is trying to engage you in a bit of wink wink off the lights, whats consided safe level of rpm to drop the clutch at? (considering it would be a once every now and then not day to day driving) i was allways under the impression the awd driveline was rather fragile

Gannon · Post by **Gannon** » Sat Jun 21, 2008 7:14 am

Subaru gearboxes are not fragile/made of glass like people on forums commonly make out.

The fact of the matter is, people try to do AWD burnouts/high RPM launches and expect everything to be dandy. If you drop the clutch at 4000RPM in a 2WD, your wheels will spin cos the amount of torque required to break traction is small. An AWD vehicle has more than double the traction of a 2WD one and thus requires more than double the torque to break the traction between the tyres and the road. Usually factory clutches are the next to start to slip, but if you have a high clamping force brass button clutch, you gearbox then becomes the weakest link and gears get stripped.

Rev your engine to what-ever you like (somewhere between 3-4K) and ease the clutch out. DON'T JUST DROP IT.

Subafury · Post by **Subafury** » Sat Jun 21, 2008 1:06 pm

trying to engage you in a bit of wink wink

hahahaha
thanks for that vital info on sti and wrx gearboxes. they cost more than the entire car.

here's a gearbox tip i learnt when 4x4ing - if ya get bogged dont shift quick into reverse to keep the momentum - its breaks reverse gear!

BrennyV · Post by **BrennyV** » Mon Jun 23, 2008 10:29 am

limiter or go home

even on my 6mt with semi slicks

AndrewT · Post by **AndrewT** » Mon Jun 23, 2008 10:48 am

haha Brenny, exactly how many gearboxes did you go through on the MY99??

D3V1L · Post by **D3V1L** » Fri Jun 27, 2008 3:33 pm

bahahh toooooo many....he wont even remember

...i was in the car for at least 2 or 3 of them :P

dave

Wilbur · Post by **Wilbur** » Fri Jun 27, 2008 4:39 pm

Silly question, silly answer time.
60 12 rpm is fine.

discopotato03 · Post by **discopotato03** » Fri Jun 27, 2008 5:51 pm

An AWD car having more than double the traction of a 2wd car ?

To put Subaru things into perspective in "2WD" mode meaning L/MY (part time 4WD) and poverty pak Libs and Prezas . They are 2WD meaning front wheel drive and if you thought all Subaru's are front heavy cars you guessed right .

Sooo if more than half the weight of the vehicle is on the front wheels (drivers) adding rear wheel drive does not give a 50% increase in tractive effort .
What it does mean is that 100% of the vehicles weight is bearing on its driving wheels instead of possibly 65% .

Now if you had direct drive through the transmission to front and back diffs it obviously takes more torque to spin all four than it would the front two .

Believe what you read about glass gearboxes in these cars because mountains of smashed transmissions are NOT an urban myth .
Take a look at purpose built off road machinery - the transmissions are VERY beefy in their gears/shafts/bearings/cases/diffs .
The Major problem is that Subaru started out with a front drive gearbox and added 4WD and ocassionally low range .
The shaft centers and gear diameters ARE NOT NEARLY strong enough to withstand higher than std torque loadings . It's a waste of time fitting the strongest parts the factory cases can contain because wider gears don't make appreciably stronger gears . Under competition loads the boxes casings twist meaning the gears are out of alignment and they break teeth off at their roots .
Dialing up a heap of revs and leaping off the clutch is something people with no mechanical sympathy do . If you like the idea of a gearbox change and buying a replacement box go for it .

A .

BrennyV · Post by **BrennyV** » Fri Jun 27, 2008 6:11 pm

i broke 5x wrx 5MT's late model double sync ver's also

Post by **Alex** » Fri Jun 27, 2008 6:14 pm

when i launch wanky i give her a rev limit in high range 4wd.

it will flog most cars off the line and then keep up with most 6cylinder cars

alex

Gannon · Post by **Gannon** » Sat Jun 28, 2008 7:52 am

discopotato03 wrote:An AWD car having more than double the traction of a 2wd car ?

Yeah i could have worded that better. I meant that if a 100Kw car can break traction with 2 wheels, its gonna take more than 200Kw to break traction with 4 wheels.

discopotato03 wrote: Believe what you read about glass gearboxes in these cars because mountains of smashed transmissions are NOT an urban myth .

Just because there are more broken Subaru gearboxes than say Mazda gearboxes , doesn't mean Subaru gearboxes are any weaker than any other mid sized car on the market. Its only because hoons try to do 4 wheel burnouts and traction overcomes the strength of the gearbox.

Wilbur · Post by **Wilbur** » Sat Jun 28, 2008 9:50 am

Stop kidding yourself. Any performance car would get a touch up. It's what you buy it for isn't it ? They are just a poor build like disco has already pointed out.

Point · Post by **Point** » Sat Jun 28, 2008 7:39 pm

Suparoo wrote:Just because there are more broken Subaru gearboxes than say Mazda gearboxes

don't worry. the 323 gearboxes break really easy too. AWD and FWD.

discopotato03 · Post by **discopotato03** » Sun Jun 29, 2008 9:17 am

The point really is that the torque/shockloads go beyond what these gearboxes cope with .
2WD cars don't necessarily make less torque but wheelspin means less load on the transmission .

Subaru are quite smart with Rex gearboxes , they KNOW that a std car (not abused) won't damage its transmission - they were not about spend money trying to make a hoon proof gearbox .

The fact remains that they started out with a reasonably light compact front drive transaxle assembly for what ? 1400-1800cc engines ?
Then in modified form (longer/4WD/viscous C diff/output shaft and bearings) they fitted it into heavier cars with higher torque output engines .
As I mentioned above widening gears is very limited it the strength returns and multi cone syncronisers don't make any difference to gear strength .
The propper way to make a gearbox cope with higher torque loadings is to have a greater distance between its shafts and larger diameter gears .
Doing all this costs lots in R and D and production tooling etc etc and if std models don't have gearbox issues why would they bother ?

Evo Lancers have a shorter larger diameter transmission that Zoobs and its the larger diameter gears on wider centers that makes them hardier than WRex boxes .
As a cheap jab the 5TH Gear crew pronounce Impreza "Impretza" , I wonder if this was refering to the pretzel gearbox .

Seriously you can only afford to abuse these gearboxes if you can afford to keep replacing them when they break , and they do .

A .

Subafury · Post by **Subafury** » Sun Jun 29, 2008 12:17 pm

better to just smash L seies 5 speeds then- cheaper to replace

discopotato03 · Post by **discopotato03** » Sun Jun 29, 2008 4:05 pm

Wanna hear a good one , yours truly was sitting at the lights many years ago with some hole proof hero - base ball cap on backwards you've all seen them - reving and posturing for a traffic light grand prix . I gave it a few revs and just sauntered off after the lights went green .
Can't have been a local because round the next bend was a notorious radar trap and an unmarked cop car .

I dunno who had the widest grin , me or the cop who witnessed everything .

He who laughs last ...

A .