Subaru Impreza GC8 & RS Forum & Community banner

Thinking of converting...... to RWD

4342 Views 46 Replies 13 Participants Last post by  wop
Yeah, you read that right. I have been thinking about it more and more lately and it just makes sense. No more breaking of tranny's, I can drift all I want (note: it's DAMN hard in an AWD car to get a good drift going with so little power). I dunno, maybe I'm going nuts, but at least I wouldn't have to worry about breaking the trans anymore... talk about a massive load off my mind, that damn turbo has already imploded one of my tranny's. :-/

Now, I wonder... where can I get that rear diff I'll need to make it locked? Gotta find a used one...
1 - 9 of 47 Posts
you can drift an impreza... but without uber power... you will not be able to sustain a constant drift... like the JDM guys...

I like the AWD... but I feel in the dry... with better driver skill... a RWD would perform better...

-*** :flame:
meebs said:
If you are concerned about the tranny stress, what about getting better gears? or an STI tranny?

go price a STi tranny... then hope it will hold over 300 ft-lbs of torque... ;)

Graham said:
Don't convert o RWD, I think you will regret it later. The only reason one SHOULD do this is to be able to have their car dyno'd on a 2WD Dyno.
if you were not planning to keep it RWD why dyno it as a RWD car? that makes no sense... like shiv on the dyno with a FWD set up... LAME!!!

Graham said:
The Impreza was not designed as a RWD drive car,
it was not designed for drag racing either... but it can do the job (for those who choose that route)

Graham said:
and AWD is what makes it unique
unique! how many RWD impreza do you see? that would be unique!!!

Graham said:
and gives it its great cornering and drifting ability. People, every car has a driftability factor, and personally I think the Impreza's is VERY high, you just need to learn to utiltize and make the best of its abilities.

I will explain this in another thread.
explain all you want... but exteneded JDM style drifts will not be attained... with out UBER power... and even then I still think the RWD would be better for drifting...

Graham said:
I still am not convinced that the RWD conversion will dismiss all of your transmission snapping/drivetrain problems. Bottomline is that its still a weak tranny :( .

true... but for $400 ($600.00 new) cobbs RWD conversion is worth a try, right?


pros of RWD:

drifting, faster in the dry (I live in socal), to be different, possible longer tranny life etc...

and ponder this... why is the cusco impreza that is used in the JGTC RWD!?!?!?! (HINT... the rules state that AWD is allowed ;) but not used by anyone IIRC)

just my .02
See less See more
scoobyrs25 said:
Sti trannies are great for 2 liter turbos that don't have much torque. The rally teams all broke the STI gears, hardened or not. They are all running very expensive dog boxes now. On dirt, awd is the way to go. On the street, especially in Southern California, it may not be the greatist.

so true...

scoobyrs25 said:
*** always has to bring up the Japanese Grand Touring Car series.
why shouldn't I? it is a good point!

:stupid: :stupid: :stupid:

:D :D
Graham said:
Hey ***, I bid you check out the American Audi teams racing in GT Speedvision Touring Series. Are you even familiar with this? If so, you would see that the S4's that race in this series have practically destoyed every other RWD car in it (i.e. Corvette. NSX, Bimmers). I recall seeing one of the races which took place at Limerock, and to say the least, Michael Galati beat the rest of the field by over ten seconds, I can't recall the exact number, and it was quite incredible, and this was just one of the races. All of this of course is after they load the car down with large amounts of weight because its so damn fast. I am not familiar with the Subaru's from the Japan circuit. I imagine that the reason no one uses AWD there is because they would load them down with so much weight it wouldn't be worth it. So double check before you start claiming they don't use it because AWD is slower.

you have point... but I didn't mention this series cause there is no imprezas in it... FWIW in the JGTC the skylines are also RWD not AWD...

Graham said:
Guess what ***, not all of us live in Southern California where we have access to UPRD AWD Dyno, right?
kevin already answer this for me, so I will skip ahead ;) ...

Graham said:
It would make perfect sense for someone who wanted to get their car dyno'd without access to a AWD dyno to quickly switch to Front or Rear WD.
why would it make sense? you are not going to be driving just those wheels on the street are you?

Graham said:
Please don'tcriticize Shiv, he has done too much for the Subaru community,
I don't see the benefit of dyno time on only half the drive wheels... and I have seen his products and was very disappointed with the quality, that's all...

Graham said:
and knows SOOO much more than you.

nice assumption... know me do you? I thought not.

Graham said:
Once again, AWD is still choice for me.
ok... good for you.

Graham said:
If your concerned about the quater mile, I wouldn't be suprised if our times went DOWN with RWD, due to the slippage you would get off the line.

well... I am not a 1/4 person... but I was merely pointing out that even though the impreza wasn't designed for drag racing it works well in that application... so a RWD impreza might be amazing... but you seem afraid to try... also drag skylines switch the AWD off after the launch... so just the rear wheels are pushing the car... and if you set the car up correctly you can launch a RWD car quite quickly... and people in the drag racing world actually prefer just a touch of wheel spin right off the line this believe it or not makes for quicker runs...

Graham said:

There's nothing wrong with a good old fashioned debate.

very true.

See less See more
well kevin beat me to it... especialy about shiv... I will add this... I would like to think out of the box... thus I will have a RWD impreza... if it fails... I will go back to my plan of the cusco center diff (35/65 split)...


I would love to play some more but the bottom line is we need to test a RWD impreza for more than just a dyno pull or two... we need to know more about it rather than speculate... you with me?

it was fun arguing with you graham but...


See less See more

Graham said:
:biggest: :) :biggest: :)

Thats the FUNNIEST thing i've ever seen!!!!!

Indeed ***, we must press and try new things on the Impreza, and the RWD conversion sure wouldn't hurt. I would be VERY curious to se the turnout of the project, so you have my full backing and I will help out in any way I can.

And that sure was a good/fun/nasty at times debate!

Graham :D
right on.

when I was looking into the 35/65 cusco diff I received an email from Joel Gat off the i-club...

As you're probably well aware, the WRX, like all imprezas, understeers no matter what you do. I believe this is an intentional part of the design - rallyists tend to pitch the car into a turn and are quite happy using the understeer to straighten the pitched car out of the turn. This should be a pretty effective technique for very tight tarmac or for low traction surfaces. However, for race tracks, that's not very practical. Pitching scrubs way more speed than is necessary, is highly inefficient, and kills tires.

So, you need to get the car to oversteer slightly, naturally, to work well on the track. We thought we'd accomplish that in the neutral or power-on conditions by biasing more power to the rear of the car - so the 35:65 seemed like a great idea. In our search for oversteer, we've gone to some extremes. We were running 950 pound rear springs with 600 pound front springs. We
were getting ludicrous amounts of high speed oversteer with still some low speed understeer. We fixed that with a radical wing in the rear to plant the rear at high speeds and reduce oversteer, but we're still fighting the battle.

With all that stiffness, including a really stiff cage, we started getting issues of rear wheel lift-off. That's generally not a problem - see GTIs and other such cars. Rear wheels always come off in braking zones. But in trailbraking situations, what happened for us was that one wheel would lift. It would lock since the driver was on the brakes. When it locked,
the viscous center diff would try to feed the same power to the rear. That wheel with all the weight on it (the outside) was not going to double in speed (super sticky hoosiers), so what happened instead was that either the front wheels would have to speed up to compensate (since engine rpm is fixed) or the engine would have to bog down. Since the fronts can't
speed up (you're under braking and anyway, how can hitting the brakes result in acceleration?:)), the engine would bog down.

We went to that cusco diff to give us the rear bias under throttle, while hopefully not worsening the engine bog issue. What we discovered was not what we wanted. The diff is not a locked diff, as some people believe it is (as we did). It is definitely a limited slip differential - there is no other way to do non-50:50 power splits that I can think of. What we expected was when we got trail-braking induced inside rear wheel lift-off, was some form of anti-lock - since power had nowhere to go but the rear wheels, it should be harder to lock up the rears. That would help out immensely. But instead, what happened was a worsening of the engine-bog issue. It was nuts. Gary would trail-brake into a turn and completely fall off boost and out of the rpm ranges.

So that's my primary gripe with that diff. As for an advantage the rest of the time? We didn't notice much, but we were running close to stock power levels (intake, exhaust, but stock engine, turbo, boost, etc). I think you'll see more of an advantage on a car that can take advantage of powering the rears...

I hope that's not too long of a story. Lemme know if you have more questions.

Joel Gat
Crew Chief
Sheehan Motor Racing
1 - 9 of 47 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.