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Discussion Starter #3
Are the 5 sti transmissions, non US, stronger than the 5 speed wrxs? Or, are they the same as the wrxs?
 

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The 5spd STi RA gearsets are the same gear width as in the 03-07 WRX.

I'm not too well versed in the specific years the RA gears came on though.
 

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Discussion Starter #5
What 5 speeds have a one piece housing for extra strength?

I am going to install the 03 WRX and see what happens with a 1,900 lb car and 430 ft-lbs of torque and 476HP at the rear wheels.

I will only use 3-5. Any idea what will break first?
 

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Guess I'll chime in on your threads here because I actually have a couple of concerns with this build.

If you're going to be using a WRX transmission, note that 2nd and 3rd gear can and likely will give out simply because of the power you're putting through them, and the abrupt on/off power delivery experienced through racing. If you were hooking this trans up to a stock-ish WRX engine, it wouldn't be near as concerning, but you're probably going to be throwing a lot of money at this thing in little to no time.

Another issue is that if you're converting the transmission into a transaxle, you're going to be dealing with that horrible open front diff. I really don't know how well that's going to handle all of that power going down to the road, probably peg leg alot, which is going to make for some really interesting cornering. Limited slip options are available, just as an FYI.

I've been reading up on people doing the conversion from the standard 914 transmission over to the WRX trans, and you've got some fab work ahead of you, unfortunately. Should be interesting at least.

I'm excited to see how this turns out, but just wanted to express my concerns, just so I'm sure that you know what you're getting into with this.
 

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Is there a way to use a type 901 gearbox with a Subaru motor instead?
 

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Discussion Starter #8
Kennedy Engineering makes the adapter to fit the two together.

I have been using a 901 trans with the 2.5l Subie for the last 2 years. It has a pump, cooler, and 3 oiling points for the gears and pinion.
The problem is it shears off 4th gear from the torque and the replacement gears are hard to find. The 915 and 930 gear boxes have the same problem with replacement gears.
 

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Kennedy Engineering makes the adapter to fit the two together.

I have been using a 901 trans with the 2.5l Subie for the last 2 years. It has a pump, cooler, and 3 oiling points for the gears and pinion.
The problem is it shears off 4th gear from the torque and the replacement gears are hard to find. The 915 and 930 gear boxes have the same problem with replacement gears.
I see. My feeling is that you may be simply improving parts availability by going to a Subaru gearbox, not reliability ultimately. The stoutest WRX gearboxes with 5 speeds are reportedly the v5 and v6 STi RA units but you would be dealing with an AWD gearbox that would need some work to suit your purposes, and I honestly don't know how strong the high gears really are in those.

Other people say the 4.44 output gearboxes are the ones that break the most, but again I don't know what the reality is.

Sand rails sometimes use Subaru motors and/or gearboxes FYI.
 

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My personal thought is... there will be quite a bit less stress on the gears when you go to 2wd.
 

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My personal thought is... there will be quite a bit less stress on the gears when you go to 2wd.
Considerably, yes. The question is, though, will the gears stand up to racing, sticky tires, and constant strain due to excessive power? He's trading one kind of stress (AWD), for another (power, racing), so I still don't see the gears lasting very long.

And again, that open front diff....ewww.
 
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