I got my G25 last week. So far I'm quite impressed with it. It's a vast improvement over the DFP and red MOMO Force - even though there are several weak points too. For the Dutch speaking users, I wrote a review about the wheel for tweakers.net: Volgas met de G25 (Dutch only).

One of the most annoying issues I have with the G25 is the lack of buttons on the wheel. I'm quite spoiled by the amount of buttons wheels like the MOMO Force and especially DFP provide. So I thought of modding the G25...

Mission: The mission goal is to add more buttons to the G25 wheel.

Method: There are several ways of increasing the number of buttons. One user taped a gamepad to his wheel with duct tape. Although efficient, it's far from a nice solution. I wanted to take a professional approach. My previous wheel was a DFP. Since this wheel will no longer be in use because of the G25 I thought of "recycling" its electronics for the extra buttons. After all, the DFP boosts a stellar amount of 18 switches (2 in the sequential shifter, 2 in the paddles, 4 in the POV hat switch and 10 standard buttons on the wheel).

Problems: Just as the G25 the DFP performs a self test and calibration at startup or connection. During this calibration the wheel determines the lock-to-lock distance and center position (null position). If this test and calibration fails, the electronics refuse to submit pressed buttons information to the computer. So just mounting the DFP's electronics in the G25 is not going to work. Somehow we'll have to fool the DFP to make it believe the calibration succeeded. Therefore we also have to move the sensors from the DFP over to the G25, but... that's not exactly what the G25 is meant for.



Too bad I forgot to make pictures from the unmodded G25 (I'm quite sure someone else will), so the above picture already contains a few modifications by myself. Clearly visible are the 2 motors. The G25's electronics are normally mounted on a bracket between the motors.



What is not original? The optical sensor on the left motor, the extra wires through the steering axle and the optical null position sensor right below the axle. A closer look:



Only one of the motors in the G25 is equipped with an optical sensor. You can recognize it by the black dustcap on the rear of the right motor. This sensor is used to determine to movement of the wheel. It's not possible to simply attach the DFP's electronics to this sensor. Luckily the G25 has two motors and one is naked at the rear so it's very easy to put the DFP's rotation sensor on it. This required minimal modding. Only the hole for the axle had to be made bigger because the motors are not exactly identical between G25 and DFP.



A slightly larger problem is the null position detection of the DFP because the G25 does without it. In the DFP this sensor is mounted near the main cogwheel on the steering axle. A shiny metal plate on the cogwheel indicates the null position of the wheel. Unlike the DFP, the G25 has a pretty much closed case around the cogwheels. I didn't want to make holes in it to prevent dust and such to slip in between the cogwheels. Luckily there's a toothed rack on the bottom of the G25 that moves with the wheel. Just as in the DFP this is used for the 900° hard locks.

This was an excellent place to mount the DFP's null zone detector. The shiny strip you see on the toothed rack indicates the null position. When this is under the optical sensor the DFP knows the G25 is in centered position. One issue was that the rack is mounted under an angle. I had to mount the sensor under the same angle, otherwise it wouldn't pick up the reflected signal.



The wide connector is the one of the DFP peeking through the steering axle. Although you'll only count 8 wires it can address up to 16 buttons (there's a little extra electronics on the DFP wheel). Not sure I will use all of them though.

On the above picture the hole through the axle looks quite big, but when you look one picture back you see the other end of the axle. That's a lot smaller, isn't it? I had to dismount the connector and push the wires wire by wire through the hole. Not really a pleasant job, especially not for the last wires.



This the bracket on which the G25's electronics are mounted and which goes between both motors. However, on the above picture you don't see the G25 electronics, but those of the DFP. The idea is to mount the DFP's electronics on the bottom and the G25's on the top of the bracket. Even though the PCB of the DFP is slightly smaller than the one of the G25, it has only 1 mm spare on the left and right. Also the top and bottom is a case of millimeters. But it's the only place where I could fit the board.



If you are somewhat familiar with the contents of a Driving Force Pro you'll recognize the board, but you'll also notice a few missing parts. The cut-out rectangle normally contains a small board with only a microswitch on. This switch is used to determine the position of the DFP's hard lock (200/900° mode). With it removed, the DFP thinks it's in 200° mode. That's not an issue - we won't be using the DFP's rotation at all. We only need it to pass the calibration. The other microswitch indicating the 900° mode may remain on the board.

Als the left corner is different. I had to remove a header because otherwise the bracket wouldn't fit anymore. The header isn't used anyways. Normally it connects to the motor that operates the 200/900° lock.



The bracket is mounted back into the G25. You can clearly see the DFP's PCB on the bottom of it. Just for safety I attached a plastic sheet on top of the DFP electronics to make sure the cables through the axle don't get stuck between te components.



Now the G25's PCB is back in place. At first sight it looks like an ordinary G25, but a closer inspection reveals some extras.



Here I attached the PCBs that normally go in the DFP's wheel. This is where the bottons are placed upon. I won't be using that for my mod, but it's easy for testing purposes.

Power up, self test & calibration and... It works! The DFP's LED lits up to indicate its normal status. When I press buttons on the DFP, the Logitech software recognizes it!

Part one of the mission succeeded. The G25 was succesfully modded to some sort of a G25 "Pro" by adding the electronics of a DFP. This is of course not where it ends. Now I have to mod the wheel itself to attach the extra buttons. But I'm not that far yet. I still have to order nice buttons, I haven't decided yet how to mount them and worst of all; during the next weeks I won't have much time to work on it so it may take a while before I make a status update.

Stay tuned...

oh.my.god... Wow. I think I've just layed a cable...illepall

This guy is either a genius or a nutter....

Hope it all goes well!

I like my 300 euros intact with a two-year warranty, but all the good luck to you and your daring project!

hope you get it back together in one piece or more :P

It's already back "together in one piece". While I'm waiting for the buttons and ideas on how to put them on the wheel, I closed the housing (no need to change things inside anymore), reattached the steering wheel and I'm playing with it. Works just fine. No sign suggesting there's a DFP inside there

The warranty is void of course. But then again I'm one of these nuts who buys a 300+ euros Intel Core 2 duo CPU to immediatly void its three years warranty by lapping it (lapping is grinding and polishing the CPU's heatspreader for a more optimal heat transfer to the heatsink). I never had a failing CPU, so I never needed the warranty. It's always a risk, but I dare to take it. I'm far from the only one.

I had Logitech wheels before and none of them ever experienced an electronics failure. Yes, I experienced a broken clamping mechanism, worn out potmeters,... All mechanical failures I could easily fix myself. Of course it's possible that tomorrow the G25's electronics explode in my face (). In that case I'd be probably out of luck, although in case of warranty issues with a DFP the Logitech service department asked to cut off the USB/serial connector and send it to them as proof. They didn't ask for the wheel or pedals itself (probably to reduce shipping costs). So they wouldn't know it if someone modded his DFP. Not that I'm counting on that of course.

I was really dissappointed by the lack of buttons on the G25 when it was introduced - still I bought it. I tried playing with only two buttons, but after being spoiled by the DFP I couldn't get used to it. It felt as going back to my old Thrustmaster Formula T2 (which was btw an excellent wheel but with way too few buttons). Therefore I wanted to "upgrade" my G25 to my likings.

I'm not trying to convince you guys to do the same, but I just thought I'd share my mod with you.

Quote from SatCP :

But then again I'm one of these nuts who buys a 300+ euros Intel Core 2 duo CPU to immediatly void its three years warranty by lapping it (lapping is grinding and polishing the CPU's heatspreader for a more optimal heat transfer to the heatsink).

nuts? your just a ricer that wants a shiny CPU!

Quote from Jakg :

nuts? your just a ricer that wants a shiny CPU!

And boy, it DOES shine. I could use it as a mirror to shave myself if it wasn't that small

But temperatures dropped about 8 - 10 degrees (a lot more than I expected actually - seems like the heatspreader was really very concave). It's now clocking a lot higher than it would before.

Quote from SatCP :

And boy, it DOES shine. I could use it as a mirror to shave myself if it wasn't that small

But temperatures dropped about 8 - 10 degrees (a lot more than I expected actually - seems like the heatspreader was really very concave). It's now clocking a lot higher than it would before.

8-10? thats a fair bit - in fact thats no IHS temps!

Makes me wonder if i should for me old 4000

Quote from Jakg :

8-10? thats a fair bit - in fact thats no IHS temps!

Makes me wonder if i should for me old 4000

As I said I didn't expect such a temperature drop either. Previous lappings only achieved like 5 degrees. But I had to use a lot of thermal paste on this Conroe, so I think it was exceptionally concave. Other people didn't get a drop like that.

Whether or not it's worth it for you, you'll have to decide by yourself
But if you don't rush it and take good precautions there's few that can go wrong..

Wow man thats pretty impressive. Some nice work there.

Looking forward to seeing the finished product or the next couple of steps

Quote from SatCP :

It's already back "together in one piece". While I'm waiting for the buttons and ideas on how to put them on the wheel, I closed the housing (no need to change things inside anymore), reattached the steering wheel and I'm playing with it. Works just fine. No sign suggesting there's a DFP inside there

The warranty is void of course.

I was really dissappointed by the lack of buttons on the G25 when it was introduced - still I bought it. I tried playing with only two buttons, but after being spoiled by the DFP I couldn't get used to it. It felt as going back to my old Thrustmaster Formula T2 (which was btw an excellent wheel but with way too few buttons). Therefore I wanted to "upgrade" my G25 to my likings.

I'm not trying to convince you guys to do the same, but I just thought I'd share my mod with you.

Hi SatCP, correct me if I'm wrong: you now cannot use G25's Shifter or Pedals (clutch), and the maximum force you feel is lower than before.

G25 must feed two motors, therefore the PWBA is designed to take more current from the bigger power supply. DFP's PWBA is designed for about half that power.

BTW, you might try disconnecting the wires to the "centering opto" that you mounted on the 900 deg sliding stop to see what happens.

Quote from mcman :

Hi SatCP, correct me if I'm wrong: you now cannot use G25's Shifter or Pedals (clutch), and the maximum force you feel is lower than before.

G25 must feed two motors, therefore the PWBA is designed to take more current from the bigger power supply. DFP's PWBA is designed for about half that power.

I think you missunderstood me somewhere... I left the G25 as it is. So both G25 motors are still powered by the G25's electronics. What I did is adding the electronics of the DFP in the housing of the G25 to get more buttons on the wheel. But because the DFP performs a calibration at startup/connection I had to mount its sensors in the G25. Otherwise it refuses to work.

I did take power from the G25 power supply, but since there's no motor connected to the DFP board (only buttons), it doesn't draw much power. Thus now I have two USB cords coming out of my G25; the real G25 and the DFP.

So in other words, I still have the G25's clutch, shifter, maximum power,... because I didn't touch that part. I just added some stuff

Quote :

BTW, you might try disconnecting the wires to the "centering opto" that you mounted on the 900 deg sliding stop to see what happens.

Then the DFP fails its calibration and it doesn't work. I did quite some tests to determine the minimum required hardware to get the DFP working.

Quote from SatCP :

I think you missunderstood me somewhere... I left the G25 as it is. So both G25 motors are still powered by the G25's electronics. What I did is adding the electronics of the DFP in the housing of the G25 to get more buttons on the wheel. But because the DFP performs a calibration at startup/connection I had to mount its sensors in the G25. Otherwise it refuses to work.

I did take power from the G25 power supply, but since there's no motor connected to the DFP board (only buttons), it doesn't draw much power. Thus now I have two USB cords coming out of my G25; the real G25 and the DFP.

So in other words, I still have the G25's clutch, shifter, maximum power,... because I didn't touch that part. I just added some stuff Then the DFP fails its calibration and it doesn't work. I did quite some tests to determine the minimum required hardware to get the DFP working.

OK, got it! Very clever! So, correct me if I'm wrong (again ): you could use a corded USB game pad and do the same thing. Just mount the game pad PCB inside the G25 case, and then run wires from the game pad through the shaft up to the wheel to buttons on the wheel.

BTW; I think you got lucky with your set up; DFP uses a 40:1 reduction between the motor and the wheel (double reduction transmission). Then it uses a "reducer" at the optical encoder (the little gear on the motor shaft) to drive the encoding wheel. This was done to reduce the speed of the encoder wheel to prevent dropped counts. The total ratio between wheel and encoder is about 16:1. Since G25 (a single reduction transmission) uses a direct drive encoding wheel (at 16:1) no reducer was required. By attaching the DFP encoder to the second motor on G25 the optical encoder rotates at a 6.4:1 ratio (instead of 16:1), so it does not "see" the total number of counts it expects (it "expects 2400 lock to lock, but "sees" only 960), but that's where the centering opto saves you as it is a "default" center if the counts are "wrong". A standard DFP will boot up and calibrate without this centering opto. One other interesting thing about your set up is the fact that DFP goes through a defined 200 deg, then 900 deg, then 200 again calibration sequence. The firmware "expects" to see the 200 deg sliding stop switches switch back and forth, and in your set up they don't. I find this very curious and the only thing I can think of is the centering flag is saving you.

A cheap USB game pad can easily be taken apart an built into a slim board with 8-10 buttons. This can be attached to your wheel spokes without hampering any of the other controls, or you could mount it to the desk on the opposite side of the wheel to your shifter. Since LFS recognises two controllers (and USB gamepads are truly plug and play), this solution should set you back less than a six pack of beer and you won't need to reinvent the wheel. Alternatively you could build your DFP components into a nice sleek console and even use some of the axii for things like an analogue handbrake for example.

I agree that the G25 is lacking buttons where they should be, but there are cheaper and easier solutions than modding the new product. Not that I'm not interested in the modding of the G25, I am, but others should know that very good budget solutions can be found by using those old controllers or a cheap new one.

wow...just wow

lol, more buttons? im actually modding mine to have non, im putting my 350mm MOMO wheel from my FC on my G25. should be pretty straight forward.

Quote from SatCP :

One user taped a gamepad to his wheel with duct tape. Although efficient, it's far from a nice solution. I wanted to take a professional approach.

---
I still don't understand what is wrong with using a gamepad's internals? There are gamepads with 14 button and 2 analogue buttons available for a very cheap price. The best thing with these gamepads is that some of them are very easily moddable.

And you would still have a DFP in reserve if your G25 goes kaputt. Or gets stolen

Quote from mcman :

OK, got it! Very clever! So, correct me if I'm wrong (again ): you could use a corded USB game pad and do the same thing. Just mount the game pad PCB inside the G25 case, and then run wires from the game pad through the shaft up to the wheel to buttons on the wheel.

*If* I had a gamepad laying around I could do that. But I don't have any. I *could* get myself a cheap one, but I already had the DFP which was useless now I have the G25. So...

First I had been thinking about moving the G25's buttons from the shifter to the wheel. That was before I had opened the G25 or DFP. However, I was interested in the internals of both wheels and after I opened them and saw how small the DFP's board was the idea of the "transplantation" came up. That way I still have all buttons on the shifter for less common tasks and functions.

Quote :

BTW; I think you got lucky with your set up; DFP uses a 40:1 reduction between the motor and the wheel (double reduction transmission).
[...]

You seem to have quite some technical details about the DFP and G25
Do you have a source you can share, or did you determine all that by yourself?

Quote :

By attaching the DFP encoder to the second motor on G25 the optical encoder rotates at a 6.4:1 ratio (instead of 16:1), so it does not "see" the total number of counts it expects (it "expects 2400 lock to lock, but "sees" only 960), but that's where the centering opto saves you as it is a "default" center if the counts are "wrong". A standard DFP will boot up and calibrate without this centering opto. One other interesting thing about your set up is the fact that DFP goes through a defined 200 deg, then 900 deg, then 200 again calibration sequence. The firmware "expects" to see the 200 deg sliding stop switches switch back and forth, and in your set up they don't. I find this very curious and the only thing I can think of is the centering flag is saving you.

I didn't lookup the technical details as you did, but I went on with trial and error. I just unplugged cables to determine the bare minimum that's needed to get the DFP working. I don't think the total amount of counts is important, though. While I tested I could pass the calibration by moving the wheel only a few degrees left and right by hand (motor disconnected). My guess is that it's only counting the amount of counts it sees lock-to-lock without knowing how much there should be. Then it calculates the center position from that. What the null position sensor is doing there isn't exactly clear to me, but I really couldn't get the DFP working without it. The null zone didn't even have to be the physical center position. But I must say I didn't test the DFP with only this sensor disconnected. As soon as I started testing with the motor disconnected (while moving the wheel by hand) the null zone detector was a necessity.

I was afraid about the 200° - 900° sequence too, but in the end I never even noticed it. The wheel always worked just fine when it was "locked" in 200° mode.

*Maybe* the hardware is meant to be usable for a 200° wheel too? Has anyone ever peeked inside the newer 200° Logitech wheels? Maybe it's the same main board, but without the 200/900° microswitches on it.

Quote from Gunn :

A cheap USB game pad can easily be taken apart an built into a slim board with 8-10 buttons. This can be attached to your wheel spokes without hampering any of the other controls, or you could mount it to the desk on the opposite side of the wheel to your shifter.

Same answer as to "mcman".

I don't want the buttons somewhere near the wheel - I want them on it. Duct taping a gamepad on the wheel isn't exactly professional, so I'd still have to open the wheel to get the wires through the axle. To mount the buttons somewhat professional, I'd have to mod the wheel anyways. And to get the electronics of the gamepad inside the G25's housing, I'd probably also have make slight changes to it. If I can fit the PCB inside...

So doing this without touching the G25 isn't going to work, unless you're happy with the duct tape method

Quote :

Alternatively you could build your DFP components into a nice sleek console and even use some of the axii for things like an analogue handbrake for example.

I still can use the gas or brake axii of the DFP for a handbrake. I now have an extra set of 18 buttons (which I won't all use) and 2 analog axii. I can't use the analog steering axle because it's mounted to the G25's motors to pass the calibration, but that's not really much of a loss.

Mounting the DFP board in a separate box would be possible, but I'd still have to mod the G25 to contain the DFP's sensors. Otherwise it won't work.

No matter what approach you take, if you want sleek buttons on the G25's wheel you'll have to do some modding to it which will very likely void it's warranty - even if it's only a small hole in the houding to get a cable through.

In fact I did very little modding to the G25 itself (yet). The only changes that could void my warranty are two 3 mm holes in the bottom plate to mount the optical center position sensor on, a 3mm hole in the rear to let the DFP's USB cable through and 3 4 mm holes in the bracket where I mounted the DFP's board on. For the rest it's untouched or easiliy to bring back in original state. Not exactly tricky business - in fact there's very little that can go wrong. The only challenge was to make sure it all fit in the G25's housing and most important to make sure the DFP is able to pas its self test and calibration.

Things will change of course when I mod the wheel itself to put the buttons on it. Depending on how I want the buttons on it (not yet decided) I might have to drill large holes in it for the buttons, or small ones for screws. I don't know yet. This must be done right from the first time.

Quote from Panda :

lol, more buttons? im actually modding mine to have non, im putting my 350mm MOMO wheel from my FC on my G25. should be pretty straight forward.

Whether or not you want more or less buttons is a personal taste and greatly depends on the type of car you drive with (and the features the game supports). In a classic GT car as in GT Legends you see no buttons on the wheel, but in a modern F1 sim there's a shitload of buttons on the wheel. So adding more buttons to the wheel doesn't necessarely make it less realistic.

And let's not forget the sim racer has a serious disadvantage over a real race pilot. He can't look left, right or back without buttons (ok, there's TrackIR but I'm not using it), he doesn't have a copilot to perform some trivial tasks, not even a pit crew that can work out a new fuel/tyre strategy mid race or keep an eye on the car. You all have to do it by yourself, so I prefer to have buttons for all this close at hand. Less realistic? Maybe, but sim racing just ain't realistic - yet

Btw, what is a "FC"?

Anyway, sounds like a nice idea. The MOMO's larger diameter should be an improvement over the rather small G25 wheel. Is the MOMO wheel a lot heavier than the G25's wheel? I'm only wondering because the extra weight may make the force feedback effects less pronounced. Also the larger diameter will make the force feedback effect somewhat less powerful, but of course you can always increase the power.

How will you mount the MOMO on the G25's axle? Do you have a thread somewhere about your mod? I'm always interested in new ideas

Update...

I found some time to work on my mod. As you may remember from part one, there's a cable with 8 wires going through the steering axle connecting to the DFP board. In the DFP these 8 wires can address up to 16 buttons through a bit of electronics spread over 3 small boards inside the spokes of the wheel (see the last picture in part one). I *could* reuse these boards, but since I will be using different switches, a different layout and the fact I find those 3 boards a bit large in total, I decided to take the components off the DFP boards and put them on a new and smaller PCB.

Ever since I disassembled the G25 wheel it occured to me how thick the steering axle is compared to the DFP - 49 mm against 34 mm. The opening in the axle is 43 mm with a depth of 69 mm. Behind that point the axle becomes smaller. That's quite some room actually, so I thought about fitting the electronics inside the axle.



I said "electronics", but in fact it's no more than these 8 tiny SMD components. The ruler is a metric one, so you can image the size of the components. To solder this you need a soldering iron with a fine tip and more important, you need to glue the components to the PCB prior to soldering. Otherwise they just stick to the soldering iron. A drop of super glue does the trick.



First I was thinking about etching a new PCB, but since there's quite a lot of room inside the axle and only 8 small components should go on the PCB, I opted for a classic Velleman eurocard PCB. This doesn't look as nice as an etched board, but it works and saves me a lot of time. Don't forget the PCB will go inside the steering axle, away from people's eyes.

I chose the boards dimensions so it would only fit inside the axle with a tiny bit of force. This way the board is fixed and won't rattle around - and I don't have to worry about a mounting mechanism.



As you can see there are a lot of wires connected to the board (not all are visible on the above picture). 8 from the DFP board, 32 for the switches (2 wires per switch) and 2 for the status LED (I chose to keep the left status LED from the DFP - It shows when the DFP is working - I don't need the other one since it indicates the 900° mode which I won't be using).

In theory I could do with a lot less wires since the switches share 4 lines, but since I don't know the exact location of each switch yet I opted for 2 wires per switch. That gives me the most flexibility.



The PCB mounted inside the steering axle. The amount of wires looks impressive, but I probably won't be using all 16 switches, so I might remove some wires later on. I will also tear up the flatcable to make it more flexible.



Here's a close up of the PCB mounted inside the axle. Even though the board isn't small, it can slide a lot deeper inside the axle. There's a surprisingly large amount of space inside it. Once I tear up the flatcable the axle will be mostly empty again.

Well, all this may be nice but the question at everyone's lips is "does it still work?". I know the G25 mod worked with the 3 DFP boards connected, but does it with my PCB? So I hooked up the wheel again. After calibration the lit up status LED was a promising sign. By using a jumperwire I short circuited each pair of wires as if it was a pressed switch. And yes, the Logitech software recognized each "switch"!

So, that concludes part two of the G25 "Pro" mod. The only thing left to do is putting the buttons on the wheel and wiring it. Initially I inteded to drill holes through the G25 wheel to mount the buttons, but being such a nice looking wheel I decided not to do so. The new idea is to mount a 2 mm thick cut out aluminium or inox plate behind the spokes of the G25 wheel. On this plate the buttons will be mounted so their tops are about equally high as the two buttons on the G25 wheel. It's just an idea at this point. I still have to sleep a bit about it because the whole thing must be sturdy and above all; look nice.

I can't say when I will have time to work further on the mod. It may take a few weeks, though. Stay tuned!

You sir are a certified loony! Amazing work!

Awesome! I love modding Logitech wheels! Pity there's no G25 in Russia yet
Oh yeah, 2 days after my warranty time for the Momo Racing ran out, it looked like this:

Mind if I ask what kind of camera you have? Off topic, but these are nice photos