Pedal troubleshooting: drift, calibration, and DIY upgrades

Almost every pedal problem lives in one of two layers, and fixing it starts with knowing which. The hardware/driver layer (Logitech G HUB, Fanatec/Moza/Thrustmaster software, or Windows joy.cpl) reports your mechanical travel: rest should read 0%, full press should read 100%. The in-sim layer (iRacing, ACC) then maps that signal to game braking and throttle. If a value is wrong in the driver, no amount of in-sim calibration will save it. Always confirm the lower layer first.

Calibration drift: brake or throttle won’t stay set

The iRacing release-to-5% throttle trick

When iRacing prompts you to calibrate the throttle, press it fully, then release to about 5% activation, then click Done while still slightly pressed. This sets the resting point just above true zero so idle jitter doesn’t register as phantom throttle. It’s the fix for “my car creeps at a standstill” and iRacing support confirms the method.

”Pedals won’t reach 100%” or Save does nothing

If your brake tops out at 56% or throttle at 91% with full travel, and hitting Save in-sim changes nothing, the cause is almost always one of two things: the wrong axis is bound to that pedal, or the hardware calibration in the driver is clamped short of full travel. Re-run the driver calibration first (push each pedal through its complete range), then re-run the sim calibration — the full sequence is covered in pedal calibration and tuning. A small top deadzone of 5–10% also guarantees you hit 100% when the hardware tops out a hair short.

Inverted or backwards axis

Pedals that “calibrate backwards” (full press reads 0%) are an inverted axis, not a broken pedal. Tick the invert checkbox for that axis in the sim, or confirm you’ve assigned the correct axis. This is common after switching pedal sets, where the new hardware reports the axis in the opposite direction.

Stuck, spiky, or ghost inputs: the dirty potentiometer

The potentiometer is the most common failure on Logitech G29/G920/G923 and Thrustmaster T2PA/T3PA pedals (the sets bundled with the T300). The throttle moves to ~50%, hangs, then jumps to 100%; or the brake flickers phantom input after 20 minutes of use. Both are dust on the resistive track of the pot at the base of the pedal.

Quick fix vs proper fix

Blast an air duster at the base of the pedal as a first pass; it sometimes clears a light layer. The proper fix is to disassemble the pedal and apply an electronics-grade contact cleaner (DeoxIT F5) directly to the pot track. Avoid generic lubricants.

When to stop cleaning and replace

Cleaning is a stopgap. The pot’s resistive track keeps wearing, and on Logitech pedals roughly a year of regular use before trouble is common. If you’re cleaning the same pot every few weeks, it’s time for a load cell conversion or new pedals — see pedals: buying guide by budget for what to step up to.

Deadzone settings that actually help

Run throttle and brake deadzones at 0–2%, with 0 being ideal on healthy hardware. Add up to 5% at the bottom only if the pedal jitters at rest (ghost input). Add a 5–10% top deadzone only if the hardware tops out before reading 100%. Most sims, ACC included, also let you set a brake “cut” / max-force so full game braking happens before the pedal bottoms out — one ACC user cut 19%, so pressing to 81% travel reads as 100% brake.

Load cell pedals calibrate on force, not travel

A load cell measures force, not travel, so the pedal barely moving is correct, not broken. New owners of the Simsonn Pro X Ultra and similar panic when the sensor “ball” doesn’t sweep a full range. Instead, calibrate max force in the pedal software to the hardest you intend to press; the bar in the calibration UI shows applied force, not distance. Brake feel after that is shaped by the in-sim force curve, which is separate from the hardware max-force setting — don’t confuse the two when the brake feels too stiff.

DIY brake mods before you buy new pedals

Logitech G25/G27/G29/G920/G923 share pedal internals, so these all apply.

Free: the rubber block and wine cork

Inside the brake spring sits a small black rubber block. Remove it to soften a too-stiff brake, or replace it to firm up. Better: cut a rubber wine cork to the size of that block and insert it in the spring. It gives a progressive, firmer brake with shorter travel and quicker response, for free.

About $15–70: progressive and conical spring kits

Variable-pitch springs raise resistance as you press, mimicking load cell feel. The TrueBrake V2.2 GT Edition (AXC Sim) runs about $70 (GBP 54.99) and ships with four springs; the standard green one tops out around 23 kg (50 lb) of max force. The MVH variable-pitch spring, 3DRap printed kits, and MORICHS kits on Amazon (~$15–25) do the same job.

Load cell conversion kits

To replace the pot and rubber with a real force sensor, Alien Mods sells a load cell kit for the Moza SR-P Lite. Note that Moza’s own SR-P Lite “Performance Kit” is a stiffer spring, not a load cell — a frequent point of confusion. The Thrustmaster T-LCM ships with a factory load cell and swappable elastomers if you’d rather buy than mod.

Skip the fake “dampers”

The gas-strut “dampers” bundled with budget pedals (Simsonn, SimJack) have no valving — they’re just extra springs. They don’t smooth travel and make the throttle twitchy. Skipping them saves about $30–40.

When a mod isn’t enough

A spring kit buys you a firmer, more repeatable brake, but it can’t add the absolute force consistency of a real load cell. If you’re hitting the same brake marker lap after lap and still want more, the upgrade path is a load cell set — see Sim racing pedals for the buying guide, and load cell pedals or wheelbase first if you’re deciding where the next dollar goes.