AWD question (need answer quick)

[93Supra0wner]

I have my car apart right now and i just finished the front end installation of the AWD and was wondering do i NEED to change the REAR differential with the new red one? Is there any difference in the two? Also is there a difference between the stock and AWD rear arms??

[Micro S2000]

you dont need to. (i didnt) and if you feel the differential with the drive shaft stuck in there you'll see that there different. the all wheel drive comes with a ball differential and the slock (and front differential) are gear. so you dont need to swap the back out if you dont want to go threw it, but it is different

[93Supra0wner]

What differences will i find in the two??Also how much of a difference.

[Micro S2000]

the ball diff if tightend will act more like a solid axle. but not entirely. it might hurt turning but both wheels will spin if one is off the ground. try both and see which works best for you. its hard to say which is better

The ball differential is limited slip, and in a lot of ways, it's better. For instance, when I turn hard right, the car slows down a lot because the right rear wheel's off the ground and spinning free. With a limited slip differential, the car would keep some of it's speed while making those hard rights.

You may have also noticed that when you pick your xmods up off the ground and lightly hit the gas, one wheel spins faster than the other. That's because the differential is biased towards the right wheel for some reason. If it doesn't spin differently, then drag your finger on both wheels while light on the accellerator, and see the difference. apply pressure to the left, and the right wheel speeds up. apply pressure to the right wheel and the engine gets more load and the left wheel doesn't speed up as much as the right one did.

Theoretically, the new ball differential should fix both of these problems. The drawback though, as someone stated before, is that turning will be hurt. He's talking about turning where both drive wheels stay on the ground, such as if you have a nice hard suspension and you're not pushing the limits of traction on your car.

The white differential is what we call an "open differential" and it's the same thing that almost any of us have in our daily drivers. If you've ever tried to peel out and left one really dark skidmark, while the other one was weak or non-existant, you've suffered the wrath of the peg-leg open differential. When turning, the inside wheels will spin slower than the outside wheels because they have less distance to cover. Basic physics right there. The open differential allows both wheels to turn completely independently of each other, while still adding forward motion from the driveshaft (or transaxle) to the wheels.

Conversely, taking a hard turn, the inside wheel tends to lift off the ground a bit and spin freely if your suspension tune isn't perfect, or if you have too much power going to the wheels. In this case, the outer wheel that's got more traction, slows down because the brunt of the "positive force" from the drivetrain is being absorbed by the wheel without any traction.


The ball differential is like "posi-trac" or "LSD" what you might hear car guys talking about. The limited slip differential acts like an open differential, except it doesn't allow completely independent movement. Some of them offer "clutched" movement, where there's a lot of resistance to the differential action, by means of pressure plates, like miniature brake pads inside the differential. Other limited slips offer limited-range differential capability, where the gears inside can only move a certain amount before locking into place and not allowing any further differential action. what happens to the wheels here is that the outside wheels are not allowed to turn as fast as they need to, so you have some friction slowing you down in the turns.

When cornering hard, the inside wheel will lift, but the outer wheel with the most traction still gets it's share of the power from the drivetrain, which equates to more speed.


Drag racers use limited slip differentials or solid axles (no differential) so that both wheels spin equally, even if one wheel decides to lose traction because of too much power going to the wheels. this helps cars accellerate better in a straight line.

In short:

In a perfect world, you don't need the red ball differential if you never apply too much power to the wheels while cornering, and if your suspension setup is extremly appropriate for the conditions. If you drag race a lot, I'd be using the ball differential for those races anyways.


By The Way, I am buying the AWD kit JUST FOR the ball differential. The drivetrain power loss of AWD isn't usually worth the hassle unless you really need AWD for a slick launching surface such as a hardwood floor, and you're serious about winning. on a good surface, AWD will slow you down because there's more parts for the motor to push around, and that is absorbing more energy that could be making it to the rear wheels alone.

[teamdeadbunny]

Maybe I am confused but I am pretty sure the question asked was if the red rear arms were needed instead of the yellow stock ones with the AWD kit... not differential?

Anyhoo, I personally went ahead and put the red ones on, just so I knew (and anyone looking) that it was not stock. While I had both off, I looked at each closely and saw no difference in size, shape, or softness/hardness of the plastic or flex in the arms themselves.

And, as the instructions say they are not required for the AWD kit to work.

[Micro S2000]

Originally posted by 93Supra0wner
and was wondering do i NEED to change the REAR differential with the new red one? Is there any difference in the two?

your just confused, he mentions the rear arms but he was asking about the differential too

[93Supra0wner]

Yes thats correct i asked about both.