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Old 10-10-2013, 08:38 PM   #1
Nicks06CGM
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Default MY AWD.... has no FWD

Here we go...

I have an 02 wrx...
I have a 06 sti transmission
With a 02 wrx rear differential.
I have the dccd pro with auto and manual mode...
When I pull into my driveway and only three wheels are on the ground (both front and driver side rear) only the passenger rear wheel spins...

so no power to the front wheels in auto mode, manual mode with diff locked, anndddd manual mode with diff unlocked...

I put the car in the air and all four tires spin... I understand theres no resistance, but even when I added resistance to the front tires they continue to spin, but obviously I cant tell whether there is any power there or not. Theres no clunking when the center diff is locked and wheel is cranked all the way to the left or right. but other than that I don't really want to try and do donuts or anything while I don't know if I have a problem in my transmission or not.

im super confused. I am inbetween e-mails with the guy from dccd pro, hes been a big help so far, but I still haven't been able to answer the ultimate question... why is my car currently in rwd?
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Old 10-11-2013, 01:07 AM   #2
FuJi K
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If everything was wired right, should work. If it doesn't work then your center diff clutch plates are worn.
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Old 10-11-2013, 07:40 AM   #3
Nicks06CGM
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probably no way to check the condition of them without splitting the transmission open is there?
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Old 10-11-2013, 10:16 AM   #4
Mr Wrex
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The center diff is in the transfer casing. You can pull that bit off with the transmission still on the car, but it's kinda painful...
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Old 10-11-2013, 11:34 AM   #5
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what you are seeing is normal. Despite having all sorts of trick diffs they are not strong enough to account for a wheel in the air.
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Old 10-11-2013, 05:23 PM   #6
Nicks06CGM
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I did a little more research on AWD and you are absolutely right, I still feel like I should be able to feel more of a difference when driving in circles, and locking and unlocking the differential... I have owned 3 wrx's. this is the first 6 speed though, and I think my expectations might have been to high, im going to keep driving and keep tinkering with car and see if I cant maybe learn how to drive the car a little differently, thanks to everyone for the input though!
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Old 10-11-2013, 06:27 PM   #7
jaxscuby
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02 wrx rear gear ratio is a 3.54:1
06 Sti has 3.90:1 in both diffs.

the 02 tranny had a 1:1.1..or the rear was over driven by 10%

from the other tranny swaps that did not get the correct gearing for rear end
it usually burns out the center diff.

so time to trouble shoot a $1000 center diff..
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Old 10-14-2013, 10:27 PM   #8
Nicks06CGM
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since I still have under steer does this mean I still have time (if the center diff is in fact the problem) the tranny has been on the car for under 1000 miles... im currently leaving it on jacks anyways to put on the collection of parts ive been saving for this project
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Old 10-14-2013, 11:46 PM   #9
69subaru360
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Quote:
Originally Posted by Turn in Concepts View Post
what you are seeing is normal. Despite having all sorts of trick diffs they are not strong enough to account for a wheel in the air.
Yea it's normal. The LSD in a stock wrx diff is not that strong.

Quote:
Originally Posted by jaxscuby View Post
02 wrx rear gear ratio is a 3.54:1
06 Sti has 3.90:1 in both diffs.

the 02 tranny had a 1:1.1..or the rear was over driven by 10%

from the other tranny swaps that did not get the correct gearing for rear end
it usually burns out the center diff.

so time to trouble shoot a $1000 center diff..
No, the 06 sti has a 1.1:1 transfer as well.
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Old 10-15-2013, 05:27 PM   #10
Nicks06CGM
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ok forgive me if I am reading this incorrectly... the 06 sti center diff and the 02 wrx rear diff have a matching 1:1.1 gear ratio... but I am still having an issue locking and unlocking my diff with the dccd pro. ( im trying to get my hands on an ohm meter so I can do the trouble shooting technique that the people from dccd pro had e-mailed me)

im currently having some exhaust work done but should have my car back together hopefully tomorrow night, or even possibly tonight. when I have the car moving again ill try and shoot a video and see if I cant explain or show whats happening a little clearer.
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Old 10-15-2013, 06:33 PM   #11
Back Road Runner
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You should experience a noticeable difference playing with the center diff settings. Now it isn't drastic mind you, and it shows quite a bit more when you are actually on loose surfaces. On asphalt you really only get a little more understeer when the center diff is locked. The difference is slight through the range. One benefit you do get with a locked center diff is better less than ABS braking. The brakes are front biased, so you get more understeer under braking and if you disable ABS less overall braking ability too. This can be improved with a locked center diff evening out the braking through the drivetrain. At the same time, you still get a little more understeer with the locked center diff, so handling is sort of a wash. You just get a little improved braking when the locked center. Even for auto-x I tend to lock the center. Whatever slight understeer I get I make up with in improved braking. Plus the power output is rear biased, so with a pretty neutral suspension setup, the car will be tail happy on throttle anyways.

With the rear diff design, it will act like an open differential when one wheel is in the air. You need to apply light braking to apply a small amount of resistance to the spinning wheel. This will engage the rear diff and make it work. By design, it needs the resistance to operate. Read up on torsen diffs. Yes, it's annoying. I lift my rear tire just enough in auto-x with a stiff rear sway setting to make this happen. It's annoying, and I'm stuck with a lower setting and a little understeer instead You can replace it with other diff types to allow lock while in the air.

Useful thread to get you started:
http://forums.nasioc.com/forums/show...php?p=15812529

From the torsen link in that thread:

Okay, so tell me how the Torsen differential works in non-technical jargon!

This, by far, is the most commonly asked question. The Torsen differential is simply a torque multiplier that works through the use of friction generated by thrust forces from the internal gearing. It multiplies what torque is available from the wheel that is starting to spin-up or lose traction and sends that available torque, multiplied by the TBR, to the slower turning wheel with the better traction.

What happens when I have a wheel in the air?
As mentioned above, the Torsen differential is a torque multiplier. The Torsen requires some type of resistance or friction in the system to function properly. A wheel in the air provides zero torque or friction on the system and as the Torsen multiplies the available torque, zero, by its TBR, the end result is still zero.

This is why you can apply some brake and generate torque at the wheel with grip. It's possible to have a modern ABS traction control system to perform the same task automatically when wheel spin is detected. Some torsen diffs also have preload to help this too. I don't believe the STI rear diff has any preload, but I can't say I've looked at details.
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Old 10-25-2013, 05:39 PM   #12
Nicks06CGM
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Default

PROBLEM SOLVED!!!! thanks to back road runner, I followed up on his link above and did some hard core studying.... after applying this new knowledge to my trouble shooting... I found that nothing was wrong.. mechanically.

When I went back through the wiring, everything was right, but then I noticed something very simple.. and very important...

I followed the wires to the controls... one manual and one auto... I noticed there was only three wires coming from the manual and four coming from the auto... the guy who hooked this up the first time had the auto/manual button connected to the wires that should have gone to the manual dial, and the manual dial wires connected to the auto/manual button (blue light).

So I apologize for the original post, the wiring WAS wrong. BUT! I must add that there is a very very very noticeable feeling when locking the diff, the entire car slows down a little bit, you can feel the resistance build, and a slight vibration. Most importantly not only can I pull into my driveway with ease and use this drivetrain to its fullest potential thanks to everyone for the help! I love my car
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Old 10-26-2013, 01:52 AM   #13
Back Road Runner
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You may notice resistance when the tires are not evenly worn. Also, I don't know what your rear diff gearing should be, but a quick search does seem to indicate the 02 WRX and 06 STI R180 are both 3.54 rear ends, so matching. I would just look at tires. If you're pretty worn, you may notice some light binding in the drivetrain as the tires wear slightly uneven over time.
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Old 10-26-2013, 10:23 AM   #14
Nicks06CGM
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Quote:
Originally Posted by Back Road Runner View Post
You may notice resistance when the tires are not evenly worn. Also, I don't know what your rear diff gearing should be, but a quick search does seem to indicate the 02 WRX and 06 STI R180 are both 3.54 rear ends, so matching. I would just look at tires. If you're pretty worn, you may notice some light binding in the drivetrain as the tires wear slightly uneven over time.

good idea, I did check my tires and the front have a bit more wear than the rear, ill keep the car in majority RWD and start tire shopping. Ive got some newer general studded snow tires(used for four months last year barely worn) up for trade if anyone has any potenzas or goodyear eagle gts they want to part with
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