auto gearbox diff ratio?

tmh983 · Post by **tmh983** » Sun Mar 13, 2011 8:37 pm

So i just bought a jap gt-b twin turbo automatic halfcut, does anyone have a list of front diff ratios for these cars because I don't know what ratio it has and i've search for ages and can't find a definate answer?

Is there some way i can could the teeth through the drain plug to tell the ratio?

H-top · Post by **H-top** » Sun Mar 13, 2011 9:10 pm

Nice buy!

What is it going in?

What is the code on the gearbox?

Post by **TOONGA** » Sun Mar 13, 2011 11:17 pm

two automatic diff ratios spring to mind 4.11 or 4.44

there may be others

TOONGA

RSR 555 · Post by **RSR 555** » Mon Mar 14, 2011 12:39 am

All aussie autos in that model are 4.11 and all JDM in that model are 4.44

tmh983 · Post by **tmh983** » Mon Mar 14, 2011 9:13 am

RSR 555 wrote:All aussie autos in that model are 4.11 and all JDM in that model are 4.44

thanks for that, how sure are you that all JDM models were 4.44's?

Here is the build plate, a quick search tells me that this halfcut started life as a gt-b wagon e-tune. Its going to find a new home in a 3gen outback.

RSR 555 · Post by **RSR 555** » Mon Mar 14, 2011 12:51 pm

tmh983 wrote:thanks for that, how sure are you that all JDM models were 4.44's?

Here is the build plate, a quick search tells me that this halfcut started life as a gt-b wagon e-tune. Its going to find a new home in a 3gen outback.

99.99% sure

From your ID tag...
B = Legacy/Liberty
H = Wagon
5 = 2.0 ltr (EJ20)

TV1A4YBAAB = Trip Tronic auto (B4)

Did you get the rear diff with your 1/2 cut?

tmh983 · Post by **tmh983** » Mon Mar 14, 2011 5:31 pm

didn't get the rear diff unfortunately

niterida · Post by **niterida** » Mon Mar 14, 2011 5:41 pm

From my research into the same issue - the Turbo auto's are all 4.44 as is the Gen 3 Outback Auto - so you should be good to bolt it straight in.

tmh983 · Post by **tmh983** » Mon Mar 14, 2011 9:45 pm

thanks guys.
If on the off chance the front to rear ratio is wrong after i've done the conversion, what symptoms could i expect to see? I figured that it would drive as if the handbrake was on, especially trying to turn tight corners? What about clicking or grinding from the gearbox? Or would there be no symptoms at all because the clutches in the auto box will take up the difference, and eventually overheat?

RSR 555 · Post by **RSR 555** » Tue Mar 15, 2011 12:58 am

On the blacktop you probably wont notice it until the centre diff fails but on the gravel you'll hear (keep the windows down) the rear tyres skipping but only travel at around 40km/h or you'll be fighting to keep the car stable.

tmh983 · Post by **tmh983** » Tue Mar 15, 2011 9:07 am

ok, thanks heaps for that.
I'll put some photos up when i start the conversion in about 3 weeks.

RSR 555 · Post by **RSR 555** » Tue Mar 15, 2011 2:46 pm

Sweet.. will be watching out for pics

tmh983 · Post by **tmh983** » Sat Mar 19, 2011 2:05 pm

just been looking at the '03 legacy FSM, it reckons the turbo automatic diff ratio is 4.11... My outback is a 4.44 and I need to figure it out 100% cos I can't afford to have the car undrivable while I chase up the correct diff...
Any thoughts as to what diff is in my halfcut?

Post by **TOONGA** » Sat Mar 19, 2011 3:32 pm

a quick question

is the FSM for the American Legacy or the Japanese Legacy?

American delivered Legacy has a different ratio to the JDM Legacy (as far as I know)

TOONGA

tmh983 · Post by **tmh983** » Sat Mar 19, 2011 3:58 pm

hmm good question, I can't see anywhere where it specifies what region. It covers both RHD and LHD, and at times it references specifically to different regions (for example has an asterisk for australia only models in the above pic), so I think it is a generic all-region manual... It is for MY03 vehicles, maybe they changed ratios for the later revision cars? I don't know what year my halfcut is, but its a rev A, so it must be an earlier model. I found FSM's for 99 and 00 legacy's but they don't cover the turbo engine models.

Pav · Post by **Pav** » Sat Mar 19, 2011 7:19 pm

couldn't you just get the car on stands and mark the tailshaft and turn the wheels by hand and if it is closer to 4 turns then it is 4.11, and if it is closer to 4.5 turns then it is a 4.44?
This is how I figured out my rear diff anyway, should be same as the front?

tmh983 · Post by **tmh983** » Sat Mar 19, 2011 7:23 pm

that would work, except that its a halfcut....

Post by **TOONGA** » Sat Mar 19, 2011 9:08 pm

does it have a dummy shaft in the back of the gearbox to stop the gear oil from leaking out?

If so put a white mark on that and you can still count the turns.

TOONGA

tmh983 · Post by **tmh983** » Sat Mar 19, 2011 10:13 pm

Isn't the rear drive disconnected by a clutch in the auto boxes? The ecu engages the clutch when the front wheels spin?
I'll give it a go anyway, good idea thanks.

Actually, on 2nd thoughts, turning the rear output shaft will turn one side of the center diff, which doesn't necessarily mean the front half of the diff will turn the same number of revolutions and therefore is not a 100% guarantee this method will work?

RSR 555 · Post by **RSR 555** » Sun Mar 20, 2011 12:28 am

I would run with the 4.44 but if you want to be 300% sure before you run it then the only way to be sure is to pull the front diff housing off the box and count the crownwheel and pinion teeth.