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Introduction

Logitech Momo Force is probably the best force feedback wheel ever produced by Logitech. It was sold as PC wheel, but it has worked fine with most of the PS2 games as well.

However, in Gran Turismo 4, Sony and/or Logitech have decided that only real PS2 wheels should work.. So, ”PC-wheels”, are blacklisted and do not work! Apparently this is done to boost the sales of the new 900 degree PS2 wheel.

Some of my friends were using Momo Force with PS2, and were really disappointed when they noticed that it doesn't work in GT4. A solution had to be found, and here it is.. :)

Things you'll need:

Logitech Momo Force wheel and Logitech Force GP/GT wheel

You can click on any image to get a more detailed view!

So, we will be destroying one GT or GP wheel, to get Momo working. Sounds a bit silly but doesn't matter that much, GT and GP wheels are really cheap used. The picture above shows Force GP. GT model is the same but with blue plastics instead of red.

The modification is not very easy, you need to have good surface mount soldering equipment. Also there are some drawbacks, for example the white buttons in Momo will stop working, and also the two green LEDs are disabled.

Disassembly

You need to disassemble both wheels. Once you open the Momo wheel, you'll notice a black wire that is used to ground the metal frame to the D25 connector.. You can cut that wire and throw it away, it's not really needed. :) Just some CE-compliance issue.

After a while, you should have the circuit boards of both wheels removed. Then you need to remove the ST72632 chips in both boards, like this:

The Momo chip is labeled ST72632M1/NCI, GP/GT chip is labeled ST72632M1/LNS. At least the LNS-chip must be removed so cleanly that it can be re-soldered.

Modifying the PCB

As you probably have guessed already, the next step is to solder the ST72632M1/LNS chip to the Momo PCB. This way, PS2 and GT4 will think there is a Force GP wheel connected. The chips have slighty different pinouts. The exact pinouts are explained in a separate document, but you don't need to understand that if you just follow the instructions. :)

Picture above shows the GP Force chip soldered into the Momo PCB, and shows the required modifications on the top side of the PCB.

The trace starting from pin 10 of the chip must be cut. Resistors R10, R11 and R43 must be removed, near the white connector. Wire is added from R43 bottom pad to R6 top pad. All this can be seen on the picture above.

Also some modifications are needed on the bottom side:

Cut traces starting from pins 1 and 2 from the white connector. Cut two thick traces starting from the D25 connector, and connect those pins with wires as shown above..

Modifying the wires

The wires that go to the big white connector are nearly all in wrong order. So, remove the pins from the connector, like this:

The pins come out quite easily, just bend the plastic clip a little with a small screwdriver. You can remove the ferrite bead if you like, it makes handling the cable a bit easier, and doesn't really affect anything..

Then insert the pins back into the connector in new order:

The image is not very good, so here's the wires listed from left to right, when connector clips are facing up.. Gray, light blue, pink, brown, white, purple, green, yellow, red, dark blue, black. The pinout page has all these pins explained as well.

Also, the three pin cable going to the steering wheel potentiometer must be flipped, otherwise the steering will be reversed. :) This is quite simple when done on the potentiometer side, just remove and re-insert the connector like this:

Now, the wheel itself should be ready, and in theory you could re-assemble it now. However, it's better to just connect all cables and leave the case open for now, in case there is something still wrong.. Don't test it yet, wait until you have modified the pedals!

Modifying the pedals

Now you need to open the Momo pedals. There are a lot of screws on the bottom which all need to be removed. Below you can see a trained professional doing this task:

When you have the pedals opened, you can see the wires that are connected to the potentiometers with crimp connectors. Remove all the wires from the pots, then cut the blue and brown wires after the first connector. Solder these together and insulate properly.. Like this:

The newly built wire is connected between the center pins of the potentiometers:

The orange and yellow wires are connected to the brake pot, brown and blue wires to the gas pot. Like this:

The image looks really weird again. :) The wire colors from top to bottom in above image are: orange, blue/brown, yellow, brown, blue/brown, blue.

Final words

That's it, your wheel should work fine now with GT4. :) You can test it first unassembled, just connect all wires and see that the PCB doesn't short circuit anywhere.. Leave the force power unconnected so the wheel doesn't move. Test all buttons, including gear change, wheels and pedals.. If everything works fine, you can assemble the wheel and pedals.

Note that the green LEDs and white buttons don't work. If you like, you can connect them to something more useful.. See the pinout page for details. Force GP only has four buttons (+gears) so all of Momo's six buttons can't work..

I had some initial worries about loosing the amazingly good force feedback of Momo.. After all, the wheel now has the cheapy Force GP processor fitted, and feedback is controlled by that chip too!

However, we tested a modified Momo and unmodified Momo side by side with Toca Race Driver, and noticed absolutely no difference.. Apparently the ”intelligence” of force feedback is done in PS2, and it then sends commands like ”force motor left, force motor right” to the wheel. And obviously these kinds of commands are handled exactly the same way by any wheel.

Also note that you can do reversed modifications to the (currently deceased) Force GP -wheel, to get it working with the Momo processor. Then the wheel is usable in GT3 and other games, but obviously will not work in GT4..

Update 2015

This article was originally written ten years ago, in 2005. :) Since then, Logitech has released a whole bunch of new wheels that work just fine with Playstations. However I'm still using my good old modified red Momo. :)

If you have any comments or suggestions, feel free to mail me at zuikkis@zuikk.is

– Zuikkis