Force Feedback
Reader Suggestions

Brad DuTemple:
Modifying Your Logitech Pedals
Kevin Caldwell:
Keyboard Clearance
Increasing Rotation
Setup and Installation
Spring and Damper Effect
Peter Prochazka:
Oscillations and Latency
Sticky Wheel
Putting Ball Bearings in your Logitech Wheel

Brad DuTemple

Modifying Your Logitech Pedals (revised Nov 19th 1999)

It's time to dig out your Logitech pedals, and give them one more chance. With a simple modification, you can increase the travel of the brake pedal by a full 40%.

Brake Pedal Spring

If you haven't already done so, this would also be a good time to replace the brake pedal spring with a slightly heavier one, available at most hardware stores for mere pennies. Take your old spring with you when you get your pedals apart, and find a replacement of equal size, but heavier gauge.

Note from Alison: see here for details about the springs I used. Also, the newer Logitech units have stronger springs and probably don't need to have their springs replaced.

Brake Pedal Travel

The brake pedal in the logitech pedal assembly is actually compressed quite a bit (about 13mm). I measured the stock pedal travel at approx 25mm, with the wheel assembled. I measured 38mm with the top off and the brake pedal resting on the spring. Freeing up the brake pedal to make use of some of this wasted compression (travel) turns out to be fairly simple.

With a few minutes time, a small hacksaw blade, a phillips screwdriver, and a small file, you can reclaim that wasted (and precious) brake pedal travel.

As delivered, the topside of the base has a 25mm X 45mm hole that the brake pedal comes through,

You need to get some of that plastic out of the way to let the brake pedal rise up a little higher through the base.

To mark the cut for the brake pedal slot, put the pedal in the top half of the base so that it comes through the hole and rests against the bottom of the top. Mark either side with a razor blade, or sharp knife. Cut the slot to 26mm and adjust to length with a small file.

Cut a 17mm wide X 28mm vertical slot directly under the hole where the brake pedal comes through the top of the base, thus allowing the brake pedal to protrude higher through the top of the base, like so:

         --------------      ^     
        |              |     |
        |              |     |
        |              |    45mm
        |              |     |     original brake pedal hole
        |              |     |
        |              |     |
         --          --      X     new cut starts here
           |        |        |
           |        |       28mm 
           |        |        |
            --------         v

NOTE: The length of the slot determines the amount your brake pedal will rise. You want a little compression on the spring, so that it will stay in place. Don't cut this slot too long, or your brake pedal spring will not stay in place. Don't get greedy! Best to cut the slot a little shorter to begin with and adjust it to length with the small file. Neatness counts here, and keep the dust out of your pots.

Bevel the sides of the cut to help guide the arm of the brake pedal, and ensure that it travels freely without scaping either side. I now have a full 10mm more brake travel, when measured vertically on the compression spring centerline.

The base has suffered no ill effects due to this modification, and is as sturdy as ever. (now over 4 months daily use)

Acclerator Pedal

The accelerator pedal is not compressed very much at all, so there is very little to be gained with a similar relief slot. However, you can remove the adhesive rubber bumper inside the base unit that sits under the gas pedal. This will gain you approx 3mm of travel, but will allow the spring to bind a little under full compression.

Removing the bumper under the brake pedal will show a similar gain in pedal travel, but ONLY if you use the stock spring. A stiffer spring will bind before it even hits the rubber bumper, so there's nothing to gain by removing it if you have replaced your stock brake spring.

Completing the Project

After installing the heavier brake pedal spring, I noticed the pedal base had an increased tendency to slide on the floor during use.  I found a scrap piece of 1/8" Mahagony door skin, and a short length of 3/4" Plywood from a trimmed shelf.  I took measurements from the wall behind my monitor with my wheel and pedals in driving position, and assembled the base to match.  I fastened them together with wood screws to form a T-shaped base for the pedals.  The pedal base unit is secured to the 1/8" Mahagony with 4 Dry-wall screws into the bottom of the base.  NOTE:  Make sure you don't hit anything with the screws!  

I have a small mark on the baseboard of the wall, so that I can quickly put them in the correct place.  They are always in exactly the same position relative to my wheel and monitor, which I think is important for consistent driving in GPL.  They are VERY solidly braced against the wall, and they NEVER move.

Total time invested in the project, ( it took me longer to write the article!) 1.5 hours.

Total monetary investment, pocket change.

The improvement over the stock Logitech pedal unit is phenomenal!

- Brad DuTemple

Kevin Caldwell

Thanks for all the info on FF. I've been struggling with mine, and your settings are far better than anything else I've tried.

I'm running the LTFF (USB) and CH pedals (gameport on a SB Live!).

Just a few comments:

Keyboard Clearance

I too had problems with my keyboard tray and the LT. I ground off the collars on the clamp thumb screws, and gained about 1/4" of clearance. This was enough to let my keyboard tray work. Just used a Dremel tool, and didn't disassemble anything.

Increasing Rotation

I removed the stock bump stops on the wheel, and put thin tubing on instead. This gains maybe 10 degrees of wheel rotation, and doesn't require any other changes.

Installation and Setup

I uninstalled the Logitech Wingman Profiler. The wheel still works fine. I find it way too confusing with the game controller settings, GPL settings, DXTweaker, and Profiler settings, all affecting the same parameters in different ways. I haven't found that the DXTweaker effects GPL at all, so I stopped playing with it too. Basically that leaves the linearity slider and steering ratio in GPL, and the force feed back settings in the game controller and the core.ini - that's enough for me! I find it easier to drive without the Profiler non-linearity.

I found I can plug the CH pedals into the gameport, and they work fine with the LT on the USB port. I made a custom 2 axis controller I called CH pedals, and if I install two copies of it at ID's 1 and 2, with the LTW USB at ID 3, they happily co-exist. I don't lose the pedals or anything when I make changes to the LT settings.

Spring and Damper Effect

I also found this at the LT web site. If I read it correctly, the damping and spring effect is actually called up by the sim FF. Maybe it should be on slightly at least? I don't like the effect of much damping either, and was getting close to your settings on my own. I am running the force at 220 in the core.ini. I like a little more force for my $200Can!

Q. What does the "Damper Effect Strength" slider do for force feedback gaming controllers?

A. The "Damper Effect Strength" slider is a feature of LWS accessible only by force feedback gaming devices. This slider controls the strength of the damper forces within force feedback games. Damper forces slow down the movement of the gaming device in a particular direction. Examples of damper forces would be items such as water or mud. By moving the slider beyond 100%, the damper forces get stronger, and the gaming device will feel more sluggish when you encounter a damper force. By moving the slider below 100%, damper forces will not affect your gameplay as much.

Q. What does the "Spring Effect Strength" slider do for force feedback gaming controllers?

A. The "Spring Effect Strength" slider is a feature of LWS accessible only by force feedback gaming devices. This slider controls the strength of the spring forces within a game. Spring forces are the effect of the wheel/stick being pulled into a certain direction by the game/software. The farther that you move the handle away from the direction that the force is pulling in, the stronger the force effect will get. By moving the slider above 100%, the stronger that resistance will be. An example of this would be trying to pull out of a dive in a flight simulator. The more you try to pull out of a dive, the more resistance you will encounter.

The default centering spring that centers the joystick handle or steering wheel in games that do not support force feedback will not be affected by this slider. However, games that support force feedback may or may not disable the default centering spring.

- Kevin Caldwell

Peter Prochazka


About the DXTweak settings: I think, that GPL gets its input data from a 'deeper level' (directly from the wheel driver?) than DXTweak is able to come into play. If you use a non-FF wheel in GPL with the Direct Input driver, you must calibrate the wheel in GPL regardless of having it calibrated in windows or not. DXTweak seems to tweak the windows calibration, but GPL doesn't use this. The Logitech Profiler obviously tweaks the 'calibration' of the LWFF driver itself. But all this is my speculation, since I don't really know how the combination LWFF, its driver, Direct Input and GPL works.

Oscillations and Latency

About oscillations and latency: I also had the idea that the rapid oscillations of the wheel could be decreased with the right latency setting. If the wheel is not centered on high speed (for example when coming out of a fast corner), the force wants to center it. If the force comes too late and so stays too long it will throw the wheel over the center, which in turn induces an opposite directed force, which also comes too late and so on...

But the problem are not really the straight line oscillations, but with too low latency the wheel will 'snap back' too violently in some situations. Maybe this is what you meant, when you wrote that the wheel 'bites' you, when you handle the car too rough.

With my old FF settings (the 'high damping' ones), I set the latency by trying to eliminate the oscillations. I found that a value of 0.103 eliminated them pretty much and also reduced the 'snap back' tendency. With your 'zero damping' settings (which feel WAY better...) it is more difficult to eliminate the oscillations. The problem is that I never know if the latency is too low or too high (which shows the same symptoms as a too low setting). It seems that a latency around 0.1 reduces the oscillations for me.

Such a high latency gives a quite 'notchy' feel around the center of the wheel, but I think I can get used to this better than having a wheel, that 'bites' me, whenever I push hard.

Note: I discussed the latency and prediction issue with Dave Kaemmer just before receiving these comments from Peter. Like Peter, Dave felt that the oscillations were an effect of the latency, and that increasing GPL's prediction was a good way to eliminate the oscillations. He felt that the prediction setting which eliminated the oscillations corresponded with the actual latency of that particular FF device.

I'm not sure I entirely agree with Dave and Peter. Oscillations occur in real cars too. I think that they tend to be more noticeable in GPL because we have a faster ratio steering than in real cars, and correspondingly lower forces at the wheel rim. Therefore, it's easier to make a sharp enough input to excite the car into a high amplitude oscillation. Also, in a real car, the seat of the pants feel from handling the car roughly tends to discourage overly abrupt steering inputs.

I'd guess that some of the tendency to oscillate is due to latency in the wheel, but not all. I continue to prefer minimal prediction and minimal damping, and deal with the oscillation by driving smoothly, and - I believe - more realistically. - Alison

Sticky Wheel

About your 'sticky' wheel: I don't have (and never had) the impression, that my LWFF is too sticky or has too much friction. Of course I never expected a FF wheel to be so smooth as a high quality non-FF wheel. But recently there was a post on RAS from a guy, who had the guts of tearing his LWFF apart and mounting ball bearings into it. He reports about this on his site: Maybe this could solve your problem (if you dare to do it, I don't... :-)

- Peter Prochazka