Thrustmaster T-LCM Loadcell pedals hard to modulate

Sk3ptik0n

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I just purchased the Trustmaster T-LCM load cell pedals and I am having some issues getting used to them.

Primarily, I'd like to hear from other users if my impression of this pedals (and the load cell in particular) are correct or if I maybe have a defective load cell.

For starters, the stock springs are very soft and the harder springs are not much better either, so for about 50% of the brake force the load cell effectively measures distance as opposed to pressure. That seems to defy the purpose.

I decided to try a trick I used with my old G25 brake, which was to augment the spring with rubber stoppers. That makes the pedal much more alike a real brake pedal, but then I noticed that regardless of springs or rubber stoppers, the brake is very difficult to modulate between 100% and about 25%.
While reviewing replays in ACC (and others, but ACC makes it easier) I noticed that if I pushed the pedal all the way, I'd get 100% brake pressure, but when I tried to release some of the braking force, it would drop well below 50% and more often around 25 to 30%.

I should also note that when first pushing on the pedals, is pretty easy to arrive at around 80% of pressure and takes additional force to reach 100%, but releasing the pedals they tend to drop very quickly from 100% to 25/30%.

I tried all kind of adjustments, but it seems that the load cell is simply not that precise in the range between 25% and 100% which makes trail braking very difficult. I suspect that either the springs or the rubber stoppers my be releasing energy too abruptly after reaching 100% braking, since I can sort of modulate on the way up, but not on the way down.

I hadn't been simracing for a while and I just came back to it, but I seem to remember that one of the sims (rFactor maybe? or iRacing?) had the ability to modulate the pedal force with a curve. I think that would help in allowing me to better apply pressure.
At the moment it's just too hard to modulate the brake effectively. The difference between 100% and 25% seems to be minimal, so it is really hard to apply 75% pressure and it's even harder to gradually scale back pedal pressure for trail braking.

Is this something others have noticed?

Unfortunately, I don't have a way to compare my pedals to other brands and before I contact Thrustmaster I wanted to hear from someone else if this is an issue with all their pedals or just mine.

Also, if anyone is interested in seeing pictures of my mods, I'll be happy to add them to the post.
Thank you.
 
I assume you calibrated them properly using Thrustmaster's software tool, which is separate from their control panel utility and requires the pedals to be connected to a USB port?

Regardless, I haven't experienced anything of the sort you describe with my set, which I have had since two days after they were released last year and have now used for more than 700 hours.

In fact, my issue with my set is pretty much the opposite of yours, which is that I'm having difficulty with modulating them at the bottom of their range, such as when I brush the pedal to settle the front end of the car while driving around a sweeping turn on part-throttle or release the pedal as I finish trailbraking.

Aside from that quirk (and the fact that I wish the spacing between them was adjustable, because I have large, wide feet (13EE in U.S. terms) and even after adjusting the pedal faces, the soles of my shoes often rub against each other), I'm happy with the overall performance of my set, especially for the money. :)

Good luck with solving your problem!
 
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alexSchmurtz

SpeedyMite Racing
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I don't have those pedals (they were not on the market when I bought the CSL Elite) but it seems normal to have trouble at first when switching to load cells. It is more natural for our body to rely on pressure than on travel, but it took me a few days to get use after year with a basic Thrustmaster pedal set.
 

Sk3ptik0n

Premium
1,062
283
I assume you calibrated them properly using Thrustmaster's software tool, which is separate from their control panel utility and requires the pedals to be connected to a USB port?

Regardless, I haven't experienced anything of the sort you describe with my set, which I have had since two days after they were released last year and have now used for more than 700 hours.

In fact, my issue with my set is pretty much the opposite of yours, which is that I'm having difficulty with modulating them at the bottom of their range, such as when I brush the pedal to settle the front end of the car while driving around a sweeping turn on part-throttle or release the pedal as I finish trailbraking.

Aside from that quirk (and the fact that I wish the spacing between them was adjustable, because I have large, wide feet (13EE in U.S. terms) and even after adjusting the pedal faces, the soles of my shoes often rub against each other), I'm happy with the overall performance of my set, especially for the money. :)

Good luck with solving your problem!

I did use the software tool, in fact, I use it daily trying to find the "Magic setting".
Yesterday I had a revelation and I took the hard rubber stoppers and put them on my drill, then I proceeded to remove some of the rubber around them.

That made them more pliable and for a glorious 20 minutes I had the perfect pedals. I could modulate pressure both at the low end and high end and I lowered some of my lap times by 2 seconds just by virtue of braking much later and with more authority.
That is, until one of the rubber "springs" flattened out and broke apart.

I found a set on Amazon I ordered (https://www.amazon.com/gp/product/B...6&pd_rd_w=aYq0N&pd_rd_wg=vuP0f&ref_=pd_gw_unk) and this time I am going to be careful to prep them properly (not too close to the ends).

While they lasted they were great. My brakes had a short preload and after that it was all pressure. Clearly, the stoppers are too hard and removing some of the rubber works fantastic. I just need to be careful when turning them into "rubber springs" to not introduce failure points like I did yesterday.

When I am done I will publish some photos of how my mod works.
Thank you for the kind reply
 

RasmusP

Premium
7,079
4,301
Germany
Just to clear up some confusion about all this "Pressure vs Distance":
When you have a spring that takes 50kg to compress (this should be in Newton but anyway) and you compress it completely, the loadcell will have "50kg input" of pressure.

So vom 0kg to 50kg input from your foot, the loadcell will get increased input the further you compress the spring.
When the spring is linear, it will just feel completely the same as potentiometer pedal.

Which is why if you get used to your potentiometer pedal and you put a stiff enough spring into it, you will easily be fast.

Problem is that most springs are way too soft, while loadcell pedals are not.

Also in reality you have an exponential increase of resistance from the brakes.

And now comes the important part: If you put a 3 stage spring and a sponge for example into a potentiometer pedal, it will FEEL like a real brake but now the last part of the pedal distance will take a lot more pressure, while the input will still be linear -> still the movement of the potentiometer.

With a loadcell, the resistance will become higher at the end but the input will still be totally linear to your pressure!
That's the big difference.


In theory you could also build a loadcell pedal with a spring that goes linear from 0kg to 200kg. You would never get the pedal completely compressed.
Then set the loadcell to be at 100% input at 100kg and you have some weird setup.

It will always seems to be "distance based" but it's still based on pressure. The difference is that you will always have the same pedal movement, when you linearly press harder.


And now comes the next important part: the human body can't do fine, controlled, detailed input when moving!
But the human body can be very precise once the muscles are "locked in against a barely moving resistance".

Which is why you mostly set loadcell up in a way that you will have barely any movement as soon as you press a bit harder.

However you need SOME initial movement to know when you actually start giving input.

In theory you could be more precise with the throttle if you'd make it pressure based too. But there are 2 reasons against it:

1. In karts and older cars, you actually press a cable that opens the throttle flap. So it would be super weird to change this "tradition"...

2. You often keep the throttle at 100% for longer periods. Making it pressure based would mean having to keep the pressure at 100%, which would be exhausting.



Not really helpful for your problem but I just had to wait for my home-office-work-stuff to get done rendering/compiling something so I thought I'd write down some anecdote about loadcells :)
 

Sk3ptik0n

Premium
1,062
283
Just to clear up some confusion about all this "Pressure vs Distance":
When you have a spring that takes 50kg to compress (this should be in Newton but anyway) and you compress it completely, the loadcell will have "50kg input" of pressure.

So vom 0kg to 50kg input from your foot, the loadcell will get increased input the further you compress the spring.
When the spring is linear, it will just feel completely the same as potentiometer pedal.


Not really helpful for your problem but I just had to wait for my home-office-work-stuff to get done rendering/compiling something so I thought I'd write down some anecdote about loadcells :)

Thank you for the extensive explanation. Some of it I had arrived by myself. But before I go any further I have to tell you how very intimate I am with the way brakes, gas and clutches worked in older cars.
When I was in the Italian Army, a freshly minted Lieutenant, I didn't have much time to care for my beater car I drove on base. It was a 1969 Renault 4 that had several things going wrong at different times and sometimes in concert.
For instance, I'll never forget the faces of the people stuck in traffic with me when I stalled the car and, since my battery was dead, I simply walked out, went to the front of the car and I crank started it.
You could do that with the Renault 4. It even had a hole in the front bumper to fit the crank (which was also the jack handle and the wrench for the bolts.
The car always started at the first turn.

Once I was driving from Venice to Rome, to go visit my parents, and my gas cable snapped. Of course it was a Sunday and no repair shops were open and I was way outside Florence. No cellphone either (it would be over a decade before they existed).
So I found a piece of rope, I passed it through the firewall between engine and cockpit, put it around the silly, umbrella like, shifter typical of the Renault 4, and drove the rest of the way to Rome as if I were Ben Hur on a quadriga.

A couple of days later, I hadn't fixed it yet, but the clutch snapped. So I had to rev match all the way to the parts shop in addition to drive the car by hand.

Do I know how old gas pedals worked? Do I ever!

Anyway, back to the T-CLM, with the soft spring it is definitely not pressure based vis à vis the driver's feling. Yes, it is based on pressure, but it's really no different than the regular brakes (I have a set that came with my T-500 wheel, so I compared).

I am guessing that for people used to potentiometer brakes like the G25/27/etc. it makes a difference, but from even before I stopped simracing, I had modded my G25 pedals by substituting the useless internal spring with various combinations of rubber stoppers inside the shock absorber like piston thingy.

I had it so the first 50% of the travel was hard but easy to push with the foot (I used 4 small stoppers) then I had two larger stoppers I had carved to approximate the feel of a load cell, and it worked.
I have since seen people selling very similar kits and I even tried one of the first load cell mods for the G25, but my rubber stopper solution was very good. Almost as good as the T-CLM mod I just finished.
The only reason I bought new pedals was that my pots needed cleaning every time I used them or the gas would bounce between 70% and 100% very quickly.
My first race against the AI I set them real low and they still were blowing my doors off on the straights. That's when I finally turned on the brake indicator and realized I was using, on average, 80% of the gas. I fixed it with contact cleaner, but it got old real quick, hence new pedals.

My G25 pedals were inverted, which is much nicer. One of the reasons the T-CLM seem funky to me is that they are not inverted.
Thrustmaster says they cannot be inverted, but I call bullshit on that. In fact. I'll probably use the same rig I built for the G25 to try the T-CLM inverted. Just not right now. (Did I mention that one of the first times I was taking apart the T-CLM the assembly for the brake sprung out of my hands and went absolutely everywhere? Took me hours to find every piece and some bushings for the lower part of the load cell had fallen inside the brakes. What a pain to find them.

I plan to make a short video, or at least a post, once I have the brakes dialed in correctly. I am waiting for a delivery of rubber stoppers, so I can try different sizes and cuts to see which has the best balance between stiffness and usability. You don't want a completely stiff pedal. It's as hard to use as a very soft one. You want a bit of play, some softness for the first 50% or so and then an easy push to 100% without too much spring return.

To be continued…
 

RasmusP

Premium
7,079
4,301
Germany
Thank you for the extensive explanation. Some of it I had arrived by myself. But before I go any further I have to tell you how very intimate I am with the way brakes, gas and clutches worked in older cars.
When I was in the Italian Army, a freshly minted Lieutenant, I didn't have much time to care for my beater car I drove on base. It was a 1969 Renault 4 that had several things going wrong at different times and sometimes in concert.
For instance, I'll never forget the faces of the people stuck in traffic with me when I stalled the car and, since my battery was dead, I simply walked out, went to the front of the car and I crank started it.
You could do that with the Renault 4. It even had a hole in the front bumper to fit the crank (which was also the jack handle and the wrench for the bolts.
The car always started at the first turn.

Once I was driving from Venice to Rome, to go visit my parents, and my gas cable snapped. Of course it was a Sunday and no repair shops were open and I was way outside Florence. No cellphone either (it would be over a decade before they existed).
So I found a piece of rope, I passed it through the firewall between engine and cockpit, put it around the silly, umbrella like, shifter typical of the Renault 4, and drove the rest of the way to Rome as if I were Ben Hur on a quadriga.

A couple of days later, I hadn't fixed it yet, but the clutch snapped. So I had to rev match all the way to the parts shop in addition to drive the car by hand.

Do I know how old gas pedals worked? Do I ever!

Anyway, back to the T-CLM, with the soft spring it is definitely not pressure based vis à vis the driver's feling. Yes, it is based on pressure, but it's really no different than the regular brakes (I have a set that came with my T-500 wheel, so I compared).

I am guessing that for people used to potentiometer brakes like the G25/27/etc. it makes a difference, but from even before I stopped simracing, I had modded my G25 pedals by substituting the useless internal spring with various combinations of rubber stoppers inside the shock absorber like piston thingy.

I had it so the first 50% of the travel was hard but easy to push with the foot (I used 4 small stoppers) then I had two larger stoppers I had carved to approximate the feel of a load cell, and it worked.
I have since seen people selling very similar kits and I even tried one of the first load cell mods for the G25, but my rubber stopper solution was very good. Almost as good as the T-CLM mod I just finished.
The only reason I bought new pedals was that my pots needed cleaning every time I used them or the gas would bounce between 70% and 100% very quickly.
My first race against the AI I set them real low and they still were blowing my doors off on the straights. That's when I finally turned on the brake indicator and realized I was using, on average, 80% of the gas. I fixed it with contact cleaner, but it got old real quick, hence new pedals.

My G25 pedals were inverted, which is much nicer. One of the reasons the T-CLM seem funky to me is that they are not inverted.
Thrustmaster says they cannot be inverted, but I call bullshit on that. In fact. I'll probably use the same rig I built for the G25 to try the T-CLM inverted. Just not right now. (Did I mention that one of the first times I was taking apart the T-CLM the assembly for the brake sprung out of my hands and went absolutely everywhere? Took me hours to find every piece and some bushings for the lower part of the load cell had fallen inside the brakes. What a pain to find them.

I plan to make a short video, or at least a post, once I have the brakes dialed in correctly. I am waiting for a delivery of rubber stoppers, so I can try different sizes and cuts to see which has the best balance between stiffness and usability. You don't want a completely stiff pedal. It's as hard to use as a very soft one. You want a bit of play, some softness for the first 50% or so and then an easy push to 100% without too much spring return.

To be continued…
That was an awesome read, thanks for the stories! :roflmao::geek:

I wish you quick success and fun dialing in the feel of your t-lcm!
I have the fanatec v3 and they have some initial movement for about 1cm, increasing the resistance quite quickly during this 1cm and then they become really stiff.
Not impossible to still have some compression stiff, but stiff!

I have set the minimum dead zone so that I don't have any brake input before the pedal is starting to move.
So my foot can lean on the pedal and I only brake, when I start to feel movement.
Upper limit is dialed in so that I have the feeling of "yep, this should be full on brakes".
Takes some time with the pedals overlays to know where this limit is...
I could still compress the pedal further though, but then it feels more like pushing your car way beyond the abs limit on a dry road...

So the lower limit is easy to feel: start of movement
Upper limit took me some weeks until the muscle memory would stay consistent no matter if I'm tired or energized.


Feeling good with the left foot but with the right foot it's a brick with 1cm of movement :laugh:

They basically feel like if your modern road car would start at 90%, right before the abs kicking in.
But in these road cars you don't really have brake resistance until your passenger is already hanging in the belts haha
 
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My G25 pedals were inverted, which is much nicer. One of the reasons the T-CLM seem funky to me is that they are not inverted.
Thrustmaster says they cannot be inverted, but I call bullshit on that. In fact. I'll probably use the same rig I built for the G25 to try the T-CLM inverted.

(bolding mine)

I just inverted my T-LCM pedals, but I can see why Thrustmaster said it can't be done: it's just not very straight forward and involves ripping it apart and extending some wiring.

I can post a 'how-to' if anyone is interested.
 

maxilogan

Premium
235
337
Thank you for the extensive explanation. Some of it I had arrived by myself. But before I go any further I have to tell you how very intimate I am with the way brakes, gas and clutches worked in older cars.
[...]

Amazing stories @Sk3ptik0n !

I'm also interested in knowing how you did end up in configuring / modding the T-LCM as I also have it and I'm overall happy with it but I bought it to replace a self-modded T3PA which had too short a stroke for my liking. Unfortunately, the T-LCM seems to be on the opposite side, I'd like to have a shorter stroke, maybe I could get it by using one of the 3DRAP mods.. but I'm tired of modding and testing and prefer racing :roflmao:
 
(bolding mine)

I just inverted my T-LCM pedals, but I can see why Thrustmaster said it can't be done: it's just not very straight forward and involves ripping it apart and extending some wiring.

I can post a 'how-to' if anyone is interested.

Can you share on how you inverted these. I just received mine last week and would love get them inverted.

Thanks!
 

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