Digressive clutch for Logitech pedals

[Panicpete]

I recently upgraded from a Logitech G25 to a Fanatec CSL DD but wanted to keep using my G25 pedals. I'm generally quite happy with them after putting a pair of load cells into the brake pedal and replacing the pots of the throttle and clutch with the hall sensor mod developed by @GeekyDeaks and @Neilski (big shout out to those guys). As I was already using an Arduino Micro for my button box and DIY handbrake, I just used the Arduino library by RamjetX to also run my pedals and shifter through it (had to rewire the button box and add in shift registers to free up some pins, otherwise it was quite straightforward).
The only thing that I wasn't really happy with was the linear feel of the clutch, so i decided to replace the stock spring with something that gives me a digressive force curve. My aim was for the whole thing to still fit into the stock housing and keep modifications to the original parts to a minimum.
I created a spreadsheet where I calculated the force curves for several setups with just two straight levers between the original spring mounting points, putting various types of springs (tension/compression/torsion) in different locations but couldn't find anything I was fully happy with. Eventually, I arrived at a setup with a connecting rod pushing a pivot arm, which in turn presses on a rather stiff compression spring. The maximum force should be somewhat similar to the stock clutch pedal, but appear far earlier in the pedal travel (unfortunately, my stock clutch spring broke, so I can't do a direct comparison). I can adjust the pre-tension of the spring as well as the length of the connecting rod to influence the the shape and height of the force curve to some degree. You can see a diagram of the (theoretical) force curve below.
The SketchUp Model can be viewed (and downloaded) here.

 

[plastaman]

nice work!

 

[Sithhy™]

I know I'm late but I would love something like this for the Thrustmaster T3PA and/or T-LCM pedals. I can give you measurements for the former if you would want to prototype a solution

 

[Panicpete]

I just had a look at the Sim Racing Garage Video where Barry takes the T3PAs apart. From what I can see, it seems to be more difficult to do a mod like mine as the spring is just sitting on a stub instead of the spring housing with nice pivot points like the Logitech pedals. Therefore, you would either have to drill you own mounting/pivot points (which I wouldn't recommend with the plastic pedal arm), or make an adapter for the stub (which is difficult with the limited space). I will try to find CAD data for the pedals and see if I can find a solution

 

[GeekyDeaks]

I totally missed this when you first posted. Love the simplicity of the mechanism. I now have another project to add to my list!

 

[Panicpete]

I know I'm late but I would love something like this for the Thrustmaster T3PA and/or T-LCM pedals. I can give you measurements for the former if you would want to prototype a solution

Unfortunately, the only 3D data I could find for these pedals is this SketchUp model, which doesn't seem to be very accurate. If you could provide sketches of the mechanical parts with complete measurements, I could create the 3D models myself and work on concepts for a digressive force curve.

 

[stigs2cousin]

I copied this aproach on my T3PA pro´s, but found it not worth the hassle:

But:
to date I havn´t found a "bite point simulation" that really helped me with clutch starts.
On the HSV Sprints I use (with shortened trow to get them nearer to the modified clutch of my street car) I can feel the"flipover" point only when pressing with my hand.

So your mileage may vary

MFG Carsten

 

[Panicpete]

To be honest, for me it wasn't a preformance upgrade but an immersion upgrade. It just felt weird pressing a linear clutch pedal. Also, it was a fun little project to plan and build

 

[stigs2cousin]

It is your rig, do it the way you like it

I myself have spend a lot off time mulling over and tinkering with clutch simulation.
I think a discernable bite point would really help me with clutch starts.

Even though extensive testing on several vehicles showed that bite point is mainly not felt in the pedal but in the sound and vibration of the engine and the beginning movement of the car .

(and while typing this I had another idea for a "sensation add on" for my clutch pedal )

MFG Carsten

 

[BoogieBusiness]

I copied this aproach on my T3PA pro´s, but found it not worth the hassle:

But:
to date I havn´t found a "bite point simulation" that really helped me with clutch starts.
On the HSV Sprints I use (with shortened trow to get them nearer to the modified clutch of my street car) I can feel the"flipover" point only when pressing with my hand.

So your mileage may vary

MFG Carsten

Hi!

HSV as in Heusinkveld sprint?

How did you manage to shorten the throw?
I'd love to know

 

[stigs2cousin]

Hi!

HSV as in Heusinkveld sprint?

How did you manage to shorten the throw?
I'd love to know

I restricted the movement of the clutch lever by glueing a piece of plastic (aprox. 5mm thick) under it´s endstop.
So when it´s not pressed the pedal rests on the plastic instead of the metal plate and the trow is that much shorter.

BTW; after a little experimentation I gave up on the whole "bite point" thing, not worth the hassle.

MFG Carsten

 

[BoogieBusiness]

I restricted the movement of the clutch lever by glueing a piece of plastic (aprox. 5mm thick) under it´s endstop.
So when it´s not pressed the pedal rests on the plastic instead of the metal plate and the trow is that much shorter.

BTW; after a little experimentation I gave up on the whole "bite point" thing, not worth the hassle.

MFG Carsten

Ah! Okey.
Thanks for the reply
Really wish there'd be a factory way of reducing travel as I find the default to be just a bit to long for speed and comfort..