4:1 Diff Anyone?

[Battle_Tested]

Anyone running a 4:1 diff upgrade? Looking at upgrading the diff on the 4.2 6mt. Wanted some feedback..

[allroadmark]

On what? What is your current r&p? Most people that have done a 6speed 01e opt for the 4.11.

[V1nny]

it is a good upgrade, helps with understeer.

[JediJoker7169]

On what? What is your current r&p? Most people that have done a 6speed 01e opt for the 4.11.

OP is referring to the center diff torque bias ratio, not the rear diff final drive. My advice, OP: don't do it. I don't have any firsthand experience, but I know how the center Torsen behaves. The stock 2:1 bias ratio provides a good deal of predictability in terms of where the power gets put down front-to-rear because no more than 66% of drive torque will go to either end. Upping the bias makes it less predictable, and also less RWD-like with weight transferred forward (up to 80% front). If you're looking to upgrade the driveline, I'd look into a rear LSD first, whether that's a clutch-type or helical-type. After that, if you want more static rearward bias, without enabling too much dynamic forward bias, look into this.

[V1nny]

.. also less RWD-like with weight transferred forward (up to 80% front). ..

I think you got it wrong. From JHM explanation:
So if you are tired of going through corners while using a lot of throttle and still getting "understeer" then this product is for you and will help you get a little more "oversteer" and allow you to drive the car a little more like a RWD car but still have the superior control of AWD.
https://jhmotorsports.com/shop/catal...only-p-46.html
As for Bulgarian T3 adapter, it sounds interesting, but they are the only company producing it, and there are no good reviews of the outcome.

[JediJoker7169]

I think you got it wrong. From JHM explanation:

So if you are tired of going through corners while using a lot of throttle and still getting "understeer" then this product is for you and will help you get a little more "oversteer" and allow you to drive the car a little more like a RWD car but still have the superior control of AWD.

No. They are accurately describing the performance of the 4:1 diff under acceleration, with weight transferred rearward, when it will send as much as 80% of available drive torque to the rear wheels. I was accurately describing its performance under deceleration/braking, with weight transferred forward, when it will send as much as 80% of available drive torque to the front wheels. So, with a 4:1 T2 center diff, the car behaves: 1) the same when cruising at a constant speed, 2) more like an RWD car under acceleration, and 3) more like an FWD car under deceleration/braking. Not nearly as predictable as a 2:1 T2 car, which can only send up to 66% (2/3rds) of drive torque to the tractive (read: dynamically weighted) end of the car.

Regardless, a high-bias center diff will make less of a difference to handling than a rear LSD.

As for the ProSpeed T3-to-01E mod, they seem to use it to great effect in their replica Sport quattro S1:

[allroadmark]

OP is referring to the center diff torque bias ratio, not the rear diff final drive. My advice, OP: don't do it. I don't have any firsthand experience, but I know how the center Torsen behaves. The stock 2:1 bias ratio provides a good deal of predictability in terms of where the power gets put down front-to-rear because no more than 66% of drive torque will go to either end. Upping the bias makes it less predictable, and also less RWD-like with weight transferred forward (up to 80% front). If you're looking to upgrade the driveline, I'd look into a rear LSD first, whether that's a clutch-type or helical-type. After that, if you want more static rearward bias, without enabling too much dynamic forward bias, look into this.

Haha, duh. I actually have a 6 speed conversion with 4:1 torsen from advanced automotion waiting to be installed. Does anyone have any feedback on these?

[Robsa6]

I did the 4:1 conversion in the center diff and I drive the snot out of my car every time I'm in it and under normal conditions I don't notice a difference. On my favorite fire roads consisting of some gravel and hard packed dirt it's AWESOME all the time. The car rotates way better, it's much more like a rear wheel drive in that aspect with the front weighing in just enough to be able to keep the car from getting too far out of shape with careful throttling and correct steering input. I don't notice it on the brakes much if at all. My favorite driving in my car is the curvy mountain roads here in VA and NC. Every drive I take it on I find myself rotating the front tires to the rear of the car when I get home because the rears are more wore than the fronts leading me to believe the modification works much like it's "believed" to. I run 18z's on the front and have replaced the rotors twice in 2 years because I refuse to be easy on the brakes entering turns and in my observation the car pushes MUCH less with the modded center diff coming into corners. I do however brake early and accelerate thru the corners. I have no real experience trying to plow thru a corner hard on the brakes loading up the front end it's just not a practical way to drive a car especially a AWD car! After living with it better than a year and several thousand miles I see/feel NO adverse drivability effects from it. Go for it it's a worthwhile mod and endless fun in the snow too. BADASS video BTW that car sounds so good ripping thru the gears!

[V1nny]

I had my for over 2 years on stage 3 allroad, and the only disadvantage some rumbling in tight tuns on very low speed, only noticeable when getting into or out of tight parking spaces.

[Widebody4.2]

its not worth the hassle. i have it done to my swapped s6.

the only time i notice a difference is in the snow its a little bit more tail happy other then that i dont notice it. hell i forget its done.

[V1nny]

its not worth the hassle. i have it done to my swapped s6.

the only time i notice a difference is in the snow its a little bit more tail happy other then that i dont notice it. hell i forget its done.

sounds like V8 does not produce enough torque.

[Robsa6]

sounds like V8 does not produce enough torque.

This^ LOL

[JediJoker7169]

sounds like V8 does not produce enough torque.

Uh... You smoking crack? S6 4.2 produces 310 lb.-ft. That's 60 more than a stock 2.7T. The curve is different, of course.

[Widebody4.2]

no im saying its a 4000+ pound car that is heavy . . . the diff doesn't change that, or the torgue amount.

[Audibot]

Uh... You smoking crack? S6 4.2 produces 310 lb.-ft. That's 60 more than a stock 2.7T. The curve is different, of course.

Yeah but most people doing this to a 2.7T will not be stock, meaning their crank torque will be likely be higher than the 4.2's.

[julex]

I have that and I like it. The original 2:1 on K04 25psi would cause the front to go wiggle happy, lift the front and sometimes lose front traction which is just silly on AWD. Now a 4:1 with Tial 770 at 34psi can cause the rear to get squirmy at times but otherwise the car feels much more RWD under heavy accelaration, no longer front lifting and losing traction. by heavy accel I mean 550+ AWTQ , god knows how much that is on crank.