Edgar Mejia

Hi guys my vehicle is a 2003 Subaru wrx. Recently, few months ago I swapped over a full MY 01-MY02 V7 STi Non DCCD 6 speed full transmission swap from the gravel series wagon STi running the wrx 4 pot/2 pot. Well, yesterday I was at the dyno shop on a dynapack and they couldn't perform dyno pulls on my car due to the front wheels spinning sooner and faster then the rears which tuner showed me this! I was shocked! They also mentioned some loud whining. So today at work I had the car on the lift and popped the clutch in the air to see the speeds of the tires if they all matched. So far so good. So then my co worker suggested to do some launching and I have never launched it since the swap so I gave it a shot and what do you know the front driver side locks up while the rears do the spinning and break traction. I can feel the car like buck to the front driver side and I'm pretty sure its bc of the lock up it's doing. The Pass side front spins according to my co worker but slow compared to the rears. So my question is, does that lead to my center diff being bad? If So, will subaru part # 38913AA112 work for my non dccd Jdm 6 speed? How can the center diff be tested?

Rev. Rob Large

iTrader: (11)

What's the transmission code (TY856-something something on a sticker near the front of the bell housing on the collar)? Did the swap include the rear differential? Pre-2006 6MT had 1.0:1 transfer ratios and 3.90 rear differentials whereas your 2003 WRX had a 1.1:1 transfer ratio and a 3.54 rear differential so mating the two would result in the rear wheels spinning at a slower rate than the front (3.54 turns versus 3.9 turns).

If this is the case, stop driving the car. You'll end up destroying either the center diff, the rear diff, or both. You need to find a 3.90 rear diff to match the 6MT.

Whoever suggested you try hard launching the car to diagnose a potentially failing differential deserves a punch in the junk.

stupidchicken03

iTrader: (38)

Yea make your coworker, who suggested launching it, pay for a rebuild

UnderTheRadar

iTrader: (1)

Edgar Mejia

Lol the swap was a full sti drivetrain swap out of a GGB-B wagon sti with the wrx 4/2 pots. It's non dccd, 3.9 FD. I took it to anotheg shop and had the scan it with a snap on scanner and look at wheel speeds through the abs sensors and all wheel speeds match each other under different throttle loads. I'm not sure why the car was acting up in the first place to begin with. Maybe they had the machines set up wrong? Can anyone confirm this if all wheel speed inputs match, then there's probably nothing wrong?