Last updated: October 21st, 2022
It’s known that people who have lost a sense tend to develop other senses to compensate for the loss. In a similar but far less serious situation, I think sim racers are much the same in comparison to experienced track drivers. Because you can’t “feel” the physics of a real car in the sim, you learn to take other signals into account. Your hearing (for example) learns to detect understeer over the speakers. And while you can’t feel the rotation of the chassis in your body, you do become extremely aware of over-rotation with your eyes and through the opposing forces through your steering wheel.
It’s not difficult then, to make a case for any update to a sim that gives you more, better or entirely new feedback on what the car is doing on the track.
A lot of people are buying motion sims for this exact reason.
More than a bit more down to earth, budget wise, are rumble motor kits for your sim racing pedals.
What’s a rumble motor?
A rumble motor (or, eccentric rotating mass vibration motor, “ERM”) is a small, low power DC motor that has an improperly balanced weight on the rotor shaft. When the motor turns, it creates a vibration.
A rumble motor kit for your brake (and sometimes throttle) can be used to create vibrations through your pedals that approximate a tyre lockup under braking and wheel slip on the throttle and during an understeer moment.
Testing Sim 3D’s rumble motor kit for Heusinkveld Sprints
I happened upon Sim 3D on a Facebook thread talking about Simucube PSU brackets. It’s funny how you discover small new businesses like that. Anyway, Calvin, the owner gave me a call to check my order. We got talking about Sim 3D’s other products and by the end of the discussion I was completely sold on the idea of testing his rumble kit design.
The Sim 3D Rumble Kit is an Arduino based kit that uses Simhub’s “Wheel lock” effect and “Wheels slip” effect. Both effects do exactly as they sound, a configurable vibration to warn about tyre locking and your rear tyres breaking traction (slipping).
Configuration is easy (and there’s plenty of support available from Calvin himself and via their Discord community)
Too long, didn’t read
If you’ve come here to ask if you should try one on your Heusinkveld Sprints, Ultimates, Fanatec CSL Elites, Thrustmaster TLCM’s and so on, the answer is a definite yes. Setup is easy (I talk about the setup in just a moment) and the reward is striking.
While you’re driving, if you’re approaching the threshold of grip under braking (read my article about threshold braking and how to calibrate your pedals here) then it’s very difficult to “feel” any physical signals that you’re locking up. That is, except the noise, tyre smoke, FFB signals, missing the apex and so on. But by that point, it’s much too late.
What’s clever about adding a rumble kit is you can set it up to pre-warn you about a lock by making it sensitive to early moments of under rotation. Under rotation is the point where the tyre is on or slightly past the maximum grip level under braking. Any more brake pressure will lock the tyres. This is very difficult to sense in the simulator, in fact, I’d say it’s one of the hardest parts of learning to become a sim racer.
With the rumble kit installed, you feel this under rotation and a lock through the pedals.
This is clever, and very useful, for two reasons.
Firstly, you have a warning when you’re getting the most out of your brakes. So you can feel a lot more confident when you’re nibbling away at the brake point. In theory, this will make you faster (with some practice!) but critically, it should make you safer.
Secondly, I think having this extra feedback through the pedals can help you calibrate your maximum brake pressure more accurately. As I’ve written before, I reduce the max brake force in Smartcontrol to the point just where the chassis starts to lock up. This is called the threshold, hence the phrase “threshold braking”.
During testing the rumble motor kit, I found about another 3% of additional maximum brake force in the pedal. Getting the most out of the brakes is where all the lap time is.
How to install the Sim 3D Rumble Kit to your Sprint pedals
Installing to the Sprints is easy, all you need is an Allen key. Each rumble unit fits neatly behind the pedal with the screws already in place.
The cables all come supplied, with only the little motor connections that need any real care as they’re quite small.
Here’s a closer look:
I found installing the system really easy, with a few tie wraps to hold the Arduino box in place. Excuse the cable tidiness!
Connect your rumble kit to a USB port and you’re ready for the next step. You might notice when you boot your PC that Windows installs a serial USB device driver. I did, so at that point, I knew something was working.
How to setup Simhub for Arduino / motor effects
I’m assuming you’ve already installed Simhub. If not, here’s my post on dashboards with Simhub for a useful primer.
Open Simhub, and head to the Arduino menu option on the left hand side of the window.
From there, select “Single Arduino”. I initially had nothing in the detected hardware box (below), so I installed the Windows driver for Arduino via this link.
As soon as the driver had installed, Simhub detected the device:
Next, head to the Shakeit Motors option (left hand nav) and select “Motors output”
Clicking “Arduino motors and fans”, select “Enable”.
Here, you select which effects should be active. It’s good first to use the “Test now” link, just to work out which channels your throttle and brakes are on.
You can rename the channels to “brake” and “throttle” which can be handy.
Scroll down the effects list. Enable all options for “Wheels lock” on your brake channel and your rears for “wheel slip”. I later went on to enable all four tyres for wheel slip to see if I could get understeer feedback. Still testing and tuning!
Next, select “Effects profile” from the option tab at the top. This is where you tune the rumble motors.
Here’s a useful how-to from Calvin explaining the wheels lock and slip settings (mine are in the screenshot of course!)
As Calvin explains, gamma factor, threshold, minimum force and input gain are all vital for tuning the feel of the system.
- Gamma Factor deals with “responsiveness to minor feedback”, specifically how early would you like a warning that you have under rotation headed towards a brake lock? I like to get a large window of information through my pedal so that I can play with the chassis at the limit of grip.
- Threshold allows a certain amount of lock before you’re warned
- Minimum force controls a steady curve of vibration intensity as you approach a lockup
- Input gain – some sims may need this increasing above 100 (iRacing is fine at 100)
First drive and tuning
Like any new sensation, it takes time to adjust to the new pedal feel. My best advice is to drive completely normally and slowly adapt to the vibrations. As you’re driving, try to brake later and harder and respond to the feedback you’re getting.
I found that I wasn’t getting feedback as early as I would like, so I dropped the threshold setting down to 0. I also turned up the brake channel and reduced the volume of the wheel slip channel, as I wanted to focus more on brake control than rear traction.
I’m planning to play with minimum force next, as I’d really like to experience a bit less vibration for the minor under-rotations and small locks.
I really like it when a mod is actually useful. I think I’ve been plain enough about brake mods that don’t work that well in the past, but with the rumble mod, I must say I’m really surprised. For me, it’s the additional confidence in braking I’ve found.
As I type I’m practicing for the Sebring 12 hours in a Porsche 911 RSR. As anyone who has driven this car will know, adjusting to the brakes is hard. Locks happen easily and it takes time working with your brake pedal settings to find a driveable solution. With this rumble kit, I’ve got an amazing early warning system that is helping me to find more confidence in braking. If you’re considering this kit for your setup, go for it.
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