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Accelerator pedal fix (no more spikes)

First of all, it's important to know how the MOMO Racing works when you press down the pedals. The built-in electronics constantly monitors and stores all minimum and maximum values on all axis (brake, accelerator and steering). Using these margin values it automatically recalibrates itself, to allow precise control. This auto calibration starts when wheel is plugged into USB port and operating system has booted up. To erase stored values one of the following needed: OS reboot, disconnect from USB or unplug pedal connector from wheel. As you will see this method has both advantages and disadvantages.

The problem is, that under extensive and/or long usage, the gap between pedal shaft and bracket increases and allows a bit of sideways movement for the pedal. This means, when the pedal is fully pressed down, you can move it left and right without lifting off. When this happens the potentiometers in pedal set can turn a bit more than normally and report back increased values to electronics. After that the electronics re-adjusts usuable pedal range based on new marginal values, but those maximum values could not be reached reliably again.

So games and even DirectX thinks you did not press pedal completely down, as the maximum value was recorded by false reading. This phenomenon is called "spiking" and could decrease pedal range by 5-20%.

To make sure your pedals suffer from this effect, check proper connection between pedal set and wheel, then press down pedals completely and try to move them sideways, while checking raw axis values in DXTweak2 (link at the end). If the raw values bounce up and down, then it's clear. Usually brake pedal is not affected as it has two separate springs on each side, which decreases or completely removes the possibility of sideways movement.

There are four possibilities to cure the pedals:
unplug wheel from USB
disconnect pedal connector
restart OS

reduce slack on pedal shaft

I will talk about the fourth solution which seems to be a reliable and permanent one. First you have to clear all calibration data using a program created by Logitech (link at the end) and remove-reconnect USB plug. After this take pedal set apart, but be cautious and observe the original place of parts as it's a little tricky. You have to remove twelve screws, four of them are under the rubber pads. Watch out for position of carpet grip system parts!

Now you can see that the pedals (1) rotate in a plastic bracket (2), and there are two potentiometers (3) attached to them sitting in small retainers (4). Only one spring (5) is attached to accelerator, but two (6) to brake pedal to increase stiffness.

According to my observation, the spiking effect is caused by one or more of following reasons:
loose pedal shaft
loose connection between pedal and potmeter
(very small possibility)
loose potmeter in retainer
dirty / faulty potmeter

In my case it was enough to fix the first one to cure the problem, but for others the third one had to be done too. Some of them had to use a little super glue to fix it to the retainer (7). However I didn't do that as I don't want to place too big strain on the potmeters.

First I've taken out the pedals and removed springs. Cleaned them from grease and applied one layer of non-conductive tape to the end of the shafts (8) to reduce slack. Don't place there too much tape as the springs won't be strong enough to push back the pedals.

After this I've checked the pots too see if there is any grease in them or not. If you find grease on pots, clear them and use some electrical contact cleaner spray too. Next step is to make sure pots have smooth range, so checked values in DXTweak2 while turning them manually with my hand.

When everything was back in place I've checked values again, while holding pedal in bracket firmly with my hand. During re-assembly the only problem was with the carpet grip system, it's a bit tricky...

VERY IMPORTANT! Make sure that you use grease which won't harm the plastic! Don't tighten all screws completely, otherwise you may experience difficulties.

Step by step guide:
clear calibration data
remove-reconnect USB plug
take pedal set apart
watch out for carpet grip system
take pedals out, remove springs
remove grease from shafts
apply one layer of tape strip to shafts
put springs back
apply grease to shafts, use proper grease,
not to harm plastic
check if pots are free from grease
clean them if needed
check if pots have smooth range, by turning it
manually with hand, while checking DXTweak2
connect pot to pedal
put pots back to retainers and pedals to brackets

fix pots to retainers if needed (optional)

check again pots have full range when moving
pedals (hold pedals in place firmly with hand)
put back screws, assemble everything together
clear calibration data
remove-reconnect USB plug
make sure pedal set is properly connected
check DXTweak2 again for original problem

Click on pictures for more detail

DXTweak2, clear calibration utility:
Wingmanteam Gadgets page

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