Tuning your force feedback: gain, base power, and headroom

You have two volume knobs in series, and confusing them is why a 15Nm base can feel weaker than a Thrustmaster T248. The base software sets the absolute torque ceiling; the in-game gain multiplies the sim’s steering force and sends it to the wheel, capped at that ceiling. Felt weight comes from gain. Headroom comes from Nm.

The two settings and which does what

The first knob lives in your base’s software — Moza Pithouse, the Fanatec tuning menu, Simagic SimPro. It sets the absolute torque limit, the hardest the motor is allowed to push. Set it to your base’s rated peak and leave it.

The second knob is in-game gain (iRacing calls it Strength, others call it Gain or FFB). It takes the steering force the sim calculates, multiplies it by your gain percentage, and outputs that to the wheel — never exceeding the ceiling from knob one.

These do not stack into a simple multiplication. A 16Nm base run at 30% gain does not become a 4.8Nm wheelbase. Normal cornering feels around 4.8Nm average, but the full 16Nm ceiling is still there, ready for a curb strike or a wall. Gain sets the average; the base sets the peak.

Why higher Nm is headroom, not a heavier wheel

A 15Nm base set so cornering feels moderate still has unused torque sitting above that average for the spikes — kerbs, lockups, contact. A weaker base hits its ceiling on those spikes and flattens them. That is the whole reason to buy more Nm, and the wheelbase torque guide walks through the same 5/8/12/15/20/25Nm framing when you are deciding how much to buy.

This is why “15Nm seems not enough” is almost always a gain problem, not a torque problem. The base is rated to 15Nm; if your gain maps normal cornering to a small fraction of that, the wheel feels light because you set it light. Turn the gain up. The Nm number is the ceiling, not the weight in your hands.

What clipping is and how to see it

Clipping is when the sim asks for more force than the ceiling allows. The output flatlines at max, and every detail above that point — the difference between a hard curb and a crash — disappears into the same dead, vague maximum. People describe it as numb or notchy.

In iRacing, watch the force/“F” bar. Green is healthy; orange and pinned at full means you are clipping. Topping out orange only on the biggest curbs and bumps is fine. Topping out in normal cornering means your gain is too high for your base. If a title feels “always clipping no matter the FFB strength,” it is sending more force than your ceiling can hold, and the fix is lower gain, not higher.

A starting method that avoids clipping

iRacing

Set Wheel Force (Max Force) to your base’s rated Nm — 8 for a boosted CSL DD, 12 for an R12, 15 for an Alpha. Drive two or three laps to warm the tires and find your pace. Then hit the auto button in the force display: it sets Strength to the highest value that does not clip. Run auto after a warmup or quali lap and again at the end of quali. Do not run it on the grid; the numbers there are not representative. iRacing’s Controller Setup and Calibration guide documents this Wheel Force and auto workflow.

Assetto Corsa, ACC, AMS2

There is no auto button, so lower in-game gain until clipping stops. Realistic starting figures: AC around 55% gain to keep all cars clip-free on a 12Nm peak; ACC around 50% gain on a 15Nm base, since GT3 steering forces run roughly 10-14Nm; AMS2 often near 90% with a good custom FFB file. Note that “100% gain” is not 1:1 with simulated force — it is a multiplier on the sim’s force model, which is exactly why a 15Nm base still needs about half of it.

Minimum force / reconstruction filter

Small static forces below the motor’s threshold vanish entirely. Without a LUT, set minimum force around 3-12% so those light forces register. With a LUT, set it to 0% — the LUT already linearizes the low end. Do not crank minimum force to “feel more.” It only adds a constant floor under everything.

Heat: why maxing everything makes FFB fade mid-stint

Running base power maxed and gain high makes the motor work hard, and a hard-working motor heats up. Once it hits its thermal limit the base cuts torque to protect itself — this is the Moza R9 owner reporting “weak FFB after 30 minutes.” The wheel was not broken; it was overheating. Leaving headroom in the base or running gain a notch lower keeps the motor cooler and your force consistent for a full stint.

A sane default starting point by base tier

• Entry DD (5-8Nm): Moza R5 5.5Nm, Fanatec CSL DD 5Nm / 8Nm with the Boost Kit, GT DD Pro 8Nm boosted. Base at rated peak, gain high — these rarely clip and you want every bit of force.
• Mid DD (9-12Nm): Moza R9 9Nm, Logitech G Pro 11Nm, Moza R12 12Nm, Simagic Alpha Mini 10Nm. Base at rated peak, gain around 60-70% and trim per car.
• High DD (15Nm+): Moza R16 16Nm, Simagic Alpha 15Nm, Alpha Evo Pro 18Nm, Simucube and similar 20Nm+. Base at rated peak, gain around 45-55% — you are buying headroom for spikes, not a heavier everyday wheel.

In every tier the move is the same: set the ceiling once in the software, then tune felt weight with in-game gain until the spikes stop clipping. See hardware: wheelbases for picking the base in the first place.