I would check for binding anywhere in the drive train like Dustin mentioned before.
Profile 2 I also think has the throttle PWM set pretty high like at 16000hz try taking it down to 9600hz.

I'm guessing this is in a Short Course truck based off that gearing.

I think you are too low on your pinion.

I ran a 7.5T in my SC10 geared 19/84. If I was to run a 9.5T in it, I would run 21/84. That translates to a 10.4 FDR (spur / pinion * 2.6 ). I would start in that ball park and see how that is.

If you are running the SC10, try 21/84 or 22/87. If you are running the 22SCT, try 21/87 or 20/84 since it has a 2.43 trans vs the AE's 2.6.

I would also lower the PWM frequency down to the 8000-10000 range to get a little more snap and less heat.

Thanks Bob, you are correct, its a 22SCT. Soooo I really want to understand that FDR. Since I run on a tight carpet/ozite track (12-13 sec laps), I thought a higher FDR is better for short bursts since is gives more lower end. Am I wrong on that? I asked Bob Zahn the same question as he runs a similar track and he runs his 22SCT with a 24/76 I think but haven't heard from him yet. Such a low FDR but he is kicking butt. What am i missing on that?

Thanks, No binding at all. I lower the freq and try that out too.

It just means it works for him. Try my suggestions.

Run it for 3 min of good clean laps where you are keeping the motor working and then check the temps. Adjust accordingly, but you should be fine.

I like my gearing with the torque/temps now but if I need a bit more speed on a long strait would adding a bit of timing be best? Motor is only getting to 140.

adding timing is tricky because while it adds power, it changes the power band of the motor. If you add timing, you may gain top end but lose some bottom end. You'll also usually gain heat in the motor. I would start by going up 1 tooth on your pinion or down on your spur before I messed with timing.

Remember going down on your spur 3 teeth is the same as going up 1 tooth on your pinion (for 48 pitch).

What I find I have to do is have a buddy watch my car and give me feedback. I have thought I needed to change my gearing many times in the past only to have Fred tell me I'm dead on and vice verca. Our view from 'behind the wheel' doesn't always give us a true representation of what the car is doing.

Case in point, I watched my 17.5 main from Sunday and while I knew my car had a push, I had no idea how bad it was until I saw it from a spectator's perspective. I was going to just make one small change, but now I know that I need a larger change.

I was looking up ratios and 19/84 should be right between 19/87 and 20/87. If I feel I need more top end I might try the 84 spur.
Also couldnt I set the rpm range where it would mostly affect the upper rpms that I would mostly use down the long strait? I dont know electric motors though like I do gas engines so im just speculating.

when you say motor set at factory settings,are you speaking of timing on the end bell.because my first day with a 7.5 3 minutes at an indoor track we all said whats that smell it was the motor burning, because factory setting was 30 degree timing with boost added in the profile.the first day i installed my esc/motor combo the capacitors had internal failure sent it all back under warranty when i reinstalled it all and it finaly worked,assumingthe settings would not do any harm to the system,was i wrong.everyone i know that has a viper speaks of running warm,or warmer than they think it should comparing it to others the have owned. i was just happy to get it to run cool enough to not melt the servo tape holding esc to chassis.

For what it's worth, if I can throw out some free advice here. So please take it from someone who has been doing this for 20 years.

There is no better tool to have in your toolbox than information and experience. Especially when it comes to setting up motors / ESC / gearing / timing / etc.....

Tip #1 - Learn the details about your car. The transmission ratio, the EXACT size of the tires, etc....

Tip #2 - Learn how to calculate the Roll-Out for that car. There are many on-line calculators and phone apps for this, but you can always reference the formula also. This is the BEST way to figure out your gearing. Period. It's the best because it is the real ratio of how far the car will go forward with one revolution of the motor.

Associated has a cheap App for both Android and iOS that has ALLOT of racing information on it. Whether you are an AE fan or not, I recommend it.

You can find a great article on gearing here

Tip #3 - Once you know how to calculate Roll-Out, and you are comparing setups from other people, calculate their Roll-Out rather than "guess", most particularly if they are using different sized tires or spurs. Rules like "2 teeth on the spur = 1 tooth on the pinion" are not correct, because it depends on how big a diameter they are. There are some on-road applications where you are approaching pinion gears that are 70-80% the size of the spur gears. In that scenario it is almost tooth to tooth. Be scientific, throw the guessing out the window, and use REAL data.

Tip #4 - TEST! Understand that if you read Dustin Evan's setup, one out of the manual for the car, or even a setup here on RC Tech, that many variables go into these setups.

For example. If someone is running a 17.5 motor in the same car you are, and they are geared at 76/36, you have to understand that the power-band on their motor may be different than the one you are using. Don't throw on some aggressive gearing and go out and take a 15 minute test run right out of the gate. Start conservatively and stop after a minute and check the temps on the motor AND the ESC. If everything checks out, run another minute. Check again. Ease into it. Going in uneducated is setting your self up for failure.

When I am starting off with something new (new motor, new ESC, new car,e tc.....) I start with information.

For example. If I can find data on the motor for example. You can compare the Kv rating of your motor to the Kv rating of the motor the other person was using on their setup. The Kv rating represents the "peak" power that the motor has. If your new motor has a higher Kv rating, then off the bat that tells me the motor likes to run at a higher RPM.

Next, look at the Watts. This data is not usually as easy to find, but helpful if you can. Watts represent torque. So, if the motor you are testing has more Watts vs the other setup, you can assume it can pull a larger pinion gear.

Beyond that, you have to consider thing like track conditions. Slicker tracks tend not to give you as much grip, so you will find that things don't get as hot (cause you plainly can't get traction). Damp tracks with loam also tend to get motors hotter quicker.

Consider things like the weight of a car. Heavier cars get motors hotter. A truggy needs to be geared lower than a buggy. Even when considering they might have the same identical roll-out.


Just some tips on how to trouble shoot things when it comes to temps and track conditions.

FLHX1550 do you know if I can add timing just in the upper rpms to add speed for the long strait at my track? Im going to the track tonight be nice to try something out. VTX10 with the 8.5 I like my gearing where its at now for 90% of the track.

Yes you can add top speed timing with the progauge.

Alright so whats the best way to find what rpm range is the upper rpms for your motor?

assuming your 8.5 is a viper VST, iirc it is a 4000Kv or 4000 rpm/volt, 8.4 volt x 4000= 33,600 max RPM on a full charge. more realistic is to go by about 7.6 volts which puts you right over 30,000 max RPM.

Try this instead http://www.viper-rc.com/forums/index....msg302#msg302