wondering how you tune your motors? how you adjust gearing and timing. Do you set a specific amp draw and tune from there or do you do it by ear or motor temp? Post em up!

I am hoping this thread will be a place for racers to share their knowledge for others to learn and experiment from

What car would this be for?

blinky 21.5 usgt 21.5 any 21.5 class......their is not much info on tuning the 21.5 motors on the web.....

For best results you would want to invest in a dyno, but next best thing would be a motor analyzer at a bare minimum. Check your motor manufacturer for what they recommend to set motor timing based on amp draw. The value for timing is irrelevant and every brand of motor is different for peak amp draw efficiency.

I don't race 21.5T anymore so I can't give you any specifics but what I explained is how I would do it... if the motor manufacturer can't provide you a value to set the amp draw, then go on to the next brand of motor before you buy one.

I'm partial to Trinity which is one of the fastest motors at the club in my area, but there are plenty other fast brands too... good luck!

I like the team powers motors (which are fast in my area ) and it all depends on personal preference. Feel free to experiment to see what happens but don't let your motor go over 150 F.

monster max results
#1 55 deg 2743kv 21946rpm 5.9amps
#2 50deg 2550kv 20404rpm 3.9a 48-52-51
#3 53deg 2717kv 21743rpm 5.4 amps 51-56-52
#4 56deg 2924kv 23106rpm 7.7amps 54-59-55

which to run? 4 is fastest but poss too much heat? Diff btwn 2-3 ?

what do you guys think?

Most of the newer motors are between 3 and 5 amps for their sweet spot. You really don't need a dyno just a motor analyzer of some sort. As long as you can maintain the same voltage throughout your testing. What I do is do 2 degree increments and write all the numbers down. You will start to see the amp increasing more than the rpm and power number.

Lap times. The point is to go faster. You can set timing based off amp draw, and compare numbers on dynos, but ultimately the point of adjusting anything is to go faster. I run esc's with data logging capabilities so I can see the numbers as the car is doing what it does, instead of how an analyzer is just running a motor unloaded. I make all my adjustments and check them on track to see how the lap times are impacted. I start with motor timing how it is set out of the box, and gearing I know is safe. Run the car, make a change and run it again. Usually if a motor stabilizes at about 150°F after a full battery, the motor is running in the sweet spot. This is my method for my 17.5 2wd buggy, but the method works for any spec motor class.

Trying to tune a motor on an unloaded motor analyser to some arbitrary amp figure won't get you anywhere. Setting a timing value varies between motors, the "sweet spot" is best described as the point where increasing timing increases amps significantly more than it increases rpm. It's best done by feel and practice.

21.5 is a Battery war, you want to minimize voltage drop over a run, that's why the attempt to stifle 21.5 locally by implementing a control motor has just meant people are saving $50 on the motor but paying an extra $100 for that super high discharge 9000mah lipo (Anyone who says it's not is lying to you)

Best advise? Practice. Get your lines down, your consistency to under 0.2 a lap, I've won 21.5 races with a 3 yr old motor that wasn't "Set up right"

Hmm, this is exactly what I do, and while I don't claim to be anywhere close to as fast as some pro drivers in my area, I do occasionally make the podium for regular club racing and once every blue moon might take a win in the local stock buggy class when fewer chassis sponsored drivers are running (I don't have a chassis sponsor), but nobody can pass me on the front straight with my generic $50 packs, the money I spent on my motor analyzer was worth every penny to give me both optimal efficiency and performance because my punch holds all the way through each race, and there's no way you can set the timing to adjust for this tiny fraction of a turn on the end bell to gain that efficiency without an amp measuring device
Thornhill Racing Circuit :: Triple Threat Wednesday :: Qual Points (best 2 of 3) :: LiveRC




*** Also worth pointing out that Trinity recommends checking the amp draw on the motor analyzer periodically because the timing on the end bell can get bumped out of alignment.

*** I am currently saving up for a dyno too, though the motor analyzer is certainly working for me based on the recommendation that Trinity provided me

Higher timing will yield more RPM and heat and less torque, requiring you to go down 1 or 2 pinions. Lower timing will give more torque, less RPM, allowing you to gear up one or 2 teeth and will have lower temps.
I generally try to keep the motor below 120 in temp, anything over 150 and you damaged your rotor magnetic strength.
It really depends on your track. Bigger tracks (outdoors) you will spend more time in the higher RPM ranges, thus higher timing. Small tracks you will use the full RPM range, thus lower timing. I race mainly in small tracks, thus my timing is normally in the 41-45 range, and my FDR for touring car is in the 4.2 to 4.4 range.

Each motor is different, thus you need to find the gearing that the motor likes for that particular timing setting on your motor.
Higher timing will yield more RPM and heat and less torque, requiring you to go down 1 or 2 pinions. Lower timing will give more torque, less RPM, allowing you to gear up one or 2 teeth and will have lower temps.
I generally try to keep the motor below 120 in temp, anything over 150 and you damaged your rotor magnetic strength and will need to replace the rotor.

It really depends on your track. Bigger tracks (outdoors) you will spend more time in the higher RPM ranges, thus higher timing. Small tracks you will use the full RPM range, thus lower timing. I race mainly in small tracks, thus my timing is normally in the 41-45 range, and my FDR for touring car is in the 4.2 to 4.4 range. USGT will be in the 4.1 to 4.3 range. Most my motors pull under 2.8a unloaded. That whole 6a thing was in the brushed motor days. I don't know why it is even relevant now. ANd this isn't a nitro motor, so don't listen to people who say it needs to be around 160 to have power. Around 100-120 is fine. Always use a fan to protect the motor if possible.

Motors of choice in USGT are: Monster Max, R1, Team Scream, Motive MC3 and Fantom V3 at our local track.
As for the monster max, on an Xray T4 configured for 21.5 USGT you will want to use a 100/43 or 44 pinion and timing between 45-50 to start with at an indoor track. Not sure about outdoor yet, our season hasn't started and snow only disappeared 2 weeks ago.

Each motor is different, thus you need to find the gearing that the motor likes for that particular timing setting on your motor. As for your readings. It is unloaded correct? Unloaded won't tell you much. On track performance will. Its always best to start with lower timing, than higher. Funny thing is the motor will get hot if it is under geared or over geared, so there is a range of only a few pinions that will be in its sweet spot. Once you get the sweet spot, You can go up in timing by 5 degrees, go down 1 pinion to stay within range.and compare what is best. High timing, motor feels flat at low end, but pulls strong mid to high. Low timing, motor pulls out of the corner but feels soft mid to top.

I don't know if this was directed at my post, but if so please go back and reread what I said.

Also, permanent damage is not done to Neodymium magnets at 150° F. Noticeable heat fade happens above 160ish° F, and permanent damage is done above 180ish°F. The shape of the magnet has a lot to do with the temperature where damage occurs in neodymium magnets.

I sent an email to Trinity, explained that I was running in a 13.5T Super Stock Buggy class and that I bought a Monster Max and was running into temp issues with readings coming off around 200°F and then experiencing fade. I sent my motor into them to inspect and they said the motor was perfectly fine (no damage to the rotor, etc) but they noticed that I was running a Turquoise rotor and recommended that I upgrade to a High Torque Copper rotor and gear up about 4 teeth on my 48P pinion. They also recommended for me to invest in a motor analyzer and set the timing to 5.6A draw. I was nervous that there was something still wrong with the motor so I bought an extra team motor to compare on the track. They explained that the first motor I got had exceptionally low resistance readings (10.5mΩ - 10.6mΩ - 10.7mΩ) and the team motor I bought offered readings of (10.6mΩ - 10.3mΩ - 10.6mΩ) which are within the best 5% of motors they produce. I then set both motors to precisely 5.6A and my lap times were virtually identical with both motors (within a tenth sec/lap fast lap times), the second (newer) motor felt like it had a pinch faster acceleration, but both motors felt to have identical top speed and I no longer experienced any fade with the first motor. I should've trusted Trinity in the first place that there was nothing wrong with the motor.

Here are some pics with both nearly identical motors and nearly identical performance with the same 5.6A draw, yet different Timing, KV and RPM readings:

Motor #1 (the one I sent to Trinity for service)




Motor #2 (5% Team Spec)




There have been other racers at my club having difficulty with their gearing/temps (just like me) and I've helped them break down their motors to shim the space between the magnet of the rotor and the sensor board which is very important to do regardless of the brand of motor you buy. This is one of the services offered when you buy a "Certified Motor" but really any average joe (just like me) can do it. Once I set their timing based on Amp draw, these drivers were amazed at the results... no more guessing and cool temps averaging 140°F coming off the track after 5 min quals without a cooling fan on the motor!

I actually found my lap times to get a pinch faster without the fan, I believe it's because of less weight and less power draw, possibly a warmer motor performing better where maybe there is a magical sweet spot on motor temp, of which I have no idea what temp is ideal, I'm just using the settings that Trinity provided to me after they've spent all the effort in testing their own product, so why reinvent the wheel?

*** UPDATE
A motor analyzer will give you the true timing of the motor, where the endbell timing is just an estimate and rarely close to the true measured timing.

*** Rotor selection is key... talk to the manufacturer and get the right motor for the class you are running, I foolishly bought a touring car motor when I should've bough an off-road buggy motor which I think is a contributing factor to the temp issues I was having.