14 replies to this topic

[Badger1]

What's the highest power output anyone on this forum has put through the standard 5-speed drivetrain on a 06' WRX? Mine has been handling 225kw atw for about 50k now without an issue, in fact, it still feels as tight as the day I bought it. But with a recent power upgrade and another due in a week, I'm getting a little concerned the box may start spitting teeth.

Needless to say, I'm treating it with sympathy, no hard launches etc.

[LPM_B4]

06 onward boxes are pretty solid, as long as you don't put a harsh clutch in or give it a hard time they tend to last, depends how much power this next round of mods is going to increase it too.

[Badger1]

06 onward boxes are pretty solid, as long as you don't put a harsh clutch in or give it a hard time they tend to last, depends how much power this next round of mods is going to increase it too.

Thanks, that's a little reassuring. I avoid any shock loads through  the transmission. Power output at present is 260kw, my tuner estimates around 300 atw when he's done, hence my concern.

[PeeKay]

I'd be keen to hear how it holds up...260kw is already pretty impressive

[Robert]

300 kW will blow the 5 speed to bits if your not careful

I would wait to you blow the box up and then just do a 6 speed conversion.

[Badger1]

300 kW will blow the 5 speed to bits if your not careful

I would wait to you blow the box up and then just do a 6 speed conversion.

I'm not particularly keen on a 6-speed box. Ist and top gears are similar ratios in both boxes. With the motor's broad torque spread, I think the 5 speed is better suited to a daily driven city car. I'd love a six-speed if the gears were wider spaced.

[Robert]

Have you looked into a Liberty 6 speed box ?
They have much wider gears

I think a longer ratio box also existed in the sti 6 speed

[LPM_B4]

I'm not particularly keen on a 6-speed box. Ist and top gears are similar ratios in both boxes. With the motor's broad torque spread, I think the 5 speed is better suited to a daily driven city car. I'd love a six-speed if the gears were wider spaced.

MY06-07 6 speeds are longer as far as im aware my mates sits at about 2.5 at 110 on the highway and that would be what you would put in your car if you were to swap it i would think which is 3.54 final drive instead of 3.9. 

But as Rob said 260kw is doing well as is, 300kw will be pushing the limits 

[Badger1]

Have you looked into a Liberty 6 speed box ?
They have much wider gears

I think a longer ratio box also existed in the sti 6 speed

Thanks, I'll look into it.

[Badger1]

MY06-07 6 speeds are longer as far as im aware my mates sits at about 2.5 at 110 on the highway and that would be what you would put in your car if you were to swap it i would think which is 3.54 final drive instead of 3.9. 

But as Rob said 260kw is doing well as is, 300kw will be pushing the limits 

Mine is doing 100kmh at 3000rpm, so 2500rpm at 110kph would be a vast improvement.

The WRX's final drive is 3.7, where as the STI's is 3.545 (according to my research) which would equate with your figures. A taller top gear would be a major plus. 

Final power output is still speculative, so I'll wait and see before making a decision.

So far I haven't heard a peep of complaint from the box... Fingers crossed.

[Red Barron]

What about putting on "blast" plates

 

http://mooreperforma...ts/blastplates/

 

have some coming for mine although not pushing the kind off power you have got, but want to keep in one piece

 

Regards

 

Neil

[Badger1]

What about putting on "blast" plates

 

http://mooreperforma...ts/blastplates/

 

have some coming for mine although not pushing the kind off power you have got, but want to keep in one piece

 

Regards

 

Neil

Thanks Neil, they may be worth considering. 

[Red Barron]

Hi

 

One off guys in our club is an Engineering doing finite element control, so he did a model and looks like it stops box moving under load, which could be the weak link as to gears coming out off mesh and then chewing out, more tooth contact the better

 

Regards

 

Neil

[PeeKay]

Nice Neil, good t hear some science among all the hearsay/anecdotes. I'll likely grab a set when I need to do my clutch next

[Badger1]

 

I feel like there's an element of wishful thinking on my part, expecting it to handle 300kw no matter how prudent my driving is.