| LIMITED SLIP DIFFERENTIAL TUNING FOR FORZA MOTORSPORT 3 |
| Limited slip differential tuning in Forza Motorsport is one of the more underrated elements of getting the most balanced performance out of your vehicles. Learning to tune the LSD will yield tremendous benefits in balancing your car. |
| Limited slip differentials have a greater effect on oversteer/understeer characteristics than you might think. We spend so much time tweaking our Spring Rates and ARBs that the LSD, at times, gets overlooked. But if you think about it, the LSD controls the split of rotational speed at the driven wheels, so needless to say, this variation between the inner and outer wheels will affect the vehicle's balance, both under deceleration, and when we start putting the power down on corner exit. |
| Let me preface the information provided in the remainder of this section by saying that the tuning help is based upon what we've observed from our time playing Forza 2. Although the information here is based upon real world tuning, it's subject to change when we finally get our hands on the new version. So be sure to check the home page for updates on changes and additions to after we get rolling on Forza Motorsport 3. |
| For the purposes of getting a feel for how your LSD settings affect cornering, let's break down a corner into three phases of transition: |
| 1- TURN ENTRY 2- MID-CORNER TRANSITION: DECELERATION TO ACCELERATION 3- WIDE OPEN THROTTLE TURN EXIT |
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| In fact, a lot of fast drivers in Forza Motorsport will tune to a deceleration of 0%, which is essentially running an open (1 way) differential when you lift off the throttle. This allows the inner wheels to spin freely. By contrast, a deceleration setting of 100% would mean both driven wheels are completely locked and rotating at the same speed which would make the car push like crazy and a nightmare to turn in. Obviously, we never want this. |
| FRONT WHEEL DRIVE and ALL WHEEL DRIVE CARS - Run a deceleration setting on the front wheels of 0%. Between the amount of available traction needed for braking and turning, the car is going to understeer to begin with. Setting it to 0% will allow the front end of the car to turn in as sharply as possible. |
| REAR WHEEL DRIVE CARS - Honestly, I run most of my RWD cars with a deceleration between 0% and 10% at the most depending on the track. This also goes for the rear deceleration on AWD. Tracks with a lot of low speed, late apexing turns like Road America and Laguna Seca, I'll run 0% (open diff) and tracks with more high speed sweepers and larger radius turns like Maple Valley and Nurburgring I'll set the deceleration a little higher. |
| 2- MID-CORNER TRANSITION: DECELERATION TO ACCELERATION |
| There's a lot of stuff going on here, and what's happening will vary depending on the type of turn. Let's look at two different extremes, here: |
| 1- Tight radius, late apexing turn. 2- Sweeping turn. |
| A LATE APEXING turn can be a real pain in the ass. These types of turns can be identified, generally, by a radius of greater than 90 degrees. For a late apex, the key is to brake deeper into the corner before turing in. On a late apexing corner, a deceleration setting of 0% has the distinct benefit of a sharp turn in. A LOW DECEL and HIGH ACCEL setting lends well to transitioning from brake to throttle on tighter turns. A sharp turn-in, then a lot of 'giddy up' when you put the power down as a higher accel setting lends to oversteer as it pulls you through the corner. |
| It would seem that the acceleration setting, represented as a percentage, determines how much of the available engine torque is applied to the outer driven wheel. Keep in mind, a regular differential distributes engine torque evenly to both driven wheels. Since the inside wheel has a lot less grip in a corner than the outside (laden) wheel, the 'path of least resistance' principle makes the engine want to apply all the power to the inside wheel, which is really bad news since we need the power to be put down on the outside wheel for throttle steer (to rotate the car quickly), then pull us out of the corner. |
| This is why I am of the belief that the higher the acceleration setting, the more oversteer (and throttle steer) we get as we transition onto the accelerator coming out of the corners. |
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| A SWEEPING TURN is not as tight, has a larger radius, and has a longer duration. The distinct difference is the amount of steady state steering input needed to drive the corner. The optimal deceleration setting here is different than for a late apexing turn which presents a dilemma since many tracks have a mix of both. |
| If your car has a very low deceleration setting, it will turn in sharply, but in mid corner it will also continue to oversteer while you're looking for the inner wheel to lock up and spin closer to the speed of the outer wheel to make the car 'push' a little bit. The slower the sweeper, the more twitchy and difficult the car will handle in mid corner if the deceleration is too low. This is mainly an issue with RWD rather than FWD or AWD cars. |
| I'll also include double apex turns here as well, which obligates you to turn in, unwind the steering wheel slightly for a brief moment, then turn in again. My favorite examples of this are Andretti Hairpin (turn 2) at Mazda Laguna Seca and turns 2&3 at Sunset Peninsula. If the car is getting loose on you in mid-corner and you like your ARB balance, try raising the deceleration setting a few clicks to dial it out. |
| 3 - WIDE OPEN THROTTLE TURN EXIT |
| This is the point of the corner where you're past the apex, you've gradually increased the throttle to the point that it's wide open as you're unwinding the steering wheel. This is where your Acceleration setting is most noticeable. The higher your Acceleration setting, the more power you'll have to pull you through the last part of the corner and onto the straight. A high Acceleration setting will give you more oversteer, especially in a Rear Wheel Drive car, where it will help get the back end to rotate around faster. |
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| Generally speaking, set the Acceleration setting as high as you can without oversteer. In All Wheel Drive cars or Rear Wheel Drive cars that are tight and prone to understeer, don't be afraid to set your rear acceleration setting high to get a tighter radius on corner exit. If you find the car is understeering when you get on the throttle on exit and you have to lift because you're running out of track, crank up the acceleration setting until you can run the car with a Wide Open Throttle on exit without having to lift. |