CRT.5 conversion Need advice

[phatmonk]

Originally Posted by Shark413

While it finally let up (rain) enough for me to run the CRT.5 up and down the street for testing. I was running a half charged (3.9 volts per cell) 2s2p lipo, Mamba Max ESC/7700, 13T pinion and a 46T spur. I have about 50 feet of smooth road to use and I clocked it with a Bushnell speedgun. It was averaging about 35mph at the end of my 50 foot run. I made about 8 runs and the temps were: Motor 85 degrees, Battery 72 degrees and the ESC was 109 degrees. The temp outside was 68 degrees. Seems the ESC was running a little hot. I will try lower gearing (12T pinion) but it looks like it is going to start raining again.

Can somebody confirm that I should go lower on the Pinion (go to a 12T from the 13T) to bring the ESC temps down?

Yes a smaller pinion should bring the temps down.

[GO-RIDE.com]

Originally Posted by Shark413

While it finally let up (rain) enough for me to run the CRT.5 up and down the street for testing. I was running a half charged (3.9 volts per cell) 2s2p lipo, Mamba Max ESC/7700, 13T pinion and a 46T spur. I have about 50 feet of smooth road to use and I clocked it with a Bushnell speedgun. It was averaging about 35mph at the end of my 50 foot run. I made about 8 runs and the temps were: Motor 85 degrees, Battery 72 degrees and the ESC was 109 degrees. The temp outside was 68 degrees. Seems the ESC was running a little hot. I will try lower gearing (12T pinion) but it looks like it is going to start raining again.

Can somebody confirm that I should go lower on the Pinion (go to a 12T from the 13T) to bring the ESC temps down?

With the 7700 you will probably need a 10 to get the temps down. Are you running the stock buggy tires or larger truck tires.

[Shark413]

Yeah I am using the stock wheel/tires. I may try a 47T spur as well. I will also try the 5700 motor which should run cooler than the 7700. Thanks for the feedback.

[phatmonk]

I was surprised this Neu 1512/2d/f even fit.With a 11.1v 3s2p 6000 maxamps lipo battery.It doesnt cog at all after tweaking the usb/cc link settings.It clears the chassis by the thickness of a piece of notebook paper.Iam running a 15t pinion and the motor is 2600kv plus larger tires I ran it about 15 minutes in a parking lot and it has crazy torque and speed and runs cool allthough where I live the temp is 28

[Shark413]

Ok, more performance info. Keep in mind these setups may not be perfect, I just wanted to get some baseline info and see how different motors performed. I will start fine tuning when it stops raining and I get my 3s2p lipo.

Battery = Maxamps 2s2p 6000mah.
ESC = Mamba Max (no fan).
Gearing: 46T steel spur and 13T hardened steel pinion.
Motor = Mamba Max 5700 and 7700.
Weight of CRT.5 with body and battery (ready to run) = 4 lbs 10 oz.
CC UBEC.
Track = pavement.

Run #1
Motor MM 7700.
Ambient temp 68 degrees .
Top speed (50 foot distance) = 35 mph.
After 8 runs (top speed then max braking): ESC 109, Motor 90, Battery 73 (degrees Fahrenheit).

Run #2
Motor MM5700.
Ambient temp 63 degrees.
Top speed (50 foot distance) = 30 mph.
After 6 runs (top speed then max braking): ESC 90, Motor 74, Battery 67 (degrees fahrenheit).
Max Watts = 378
Max (burst) Amps = 61.16

I still have a 3s2p lipo on order, and I will rerun the MM5700 test when it comes in.

[GO-RIDE.com]

Those temps look really good. I would expect a 7700 to have more top speed than 35mph. It probably just doesn't have the torque to get that vehicle up to top speed in only 50ft?

I guess it all comes down to the type of driving you will be doing with the crt.5. I take mine to the track and will run it for up to ten minutes non-stop. This generates a lot more heat than your average bash session. I don't have a MM or Mamba motor, but others here have had heat issues with the 4600 on 2S when it's run for 5 min. straight on a track.

My personal setup is geared for nearly 40mph (probably goes 35mph) and has not had any heat issues even when draining a 4800 2S lipo, to the lvc, in a non-stop run (10min+).

[Shark413]

Just to clarify, the reason I am testing at 50 feet is because that is how long the main straight is at the track I run my trucks at (short tight track). So I need the fastest speed I can get for that distance, while retaining good acceration and reasonable temps. 35 mph is very fast for that part of the track (probably too fast), my 1/8 scale buggy with a .21 OS V-Spec hits about 28 mph down the same straight-away.

[Shark413]

Update:

Finally got my 3s2p battery and took the truggy for a test run.

Converted Jammin CRT.5 with extended chassis.
MM ESC (fan) with 5700 motor.
3s2p Maxamp 5000mah lipo
gearing 46/13T
Stock tires.
Distance 100 feet.
Ambient temps 71.
Max Speed 40 mph.
Test run on pavement.

I also took the truggy out on the track this weekend and it was insanely fast, much faster than stock nitro CRT.5's (there were several on the track). It would easily close a 10 foot lead by the end of the main straight and if I was not careful it would wheelie almost anywhere if I got too heavy on the throttle. Temps were all good (109 on the ESC, 118 on the motor and 89 on the battery) and it was so much fun I hardly drove my nitro 1/8 scale buggy/truggy. I have a Feigao 9L I was going to put in thinking the 5700 wouldn't be powerful enough for the CRT.5 but after running it at the track I think I will stick with this setup for a while.

P.S. in the previous post I stated the distance was 50 feet, it was actually closer to 100 feet (30 meters).

[phatmonk]

This is my CRT.5 Brushless Truggy.It has a Neu 1512/1.5D/S and a 3s2p 11.1v 6000 lipo battery and a Mambamax.This thing is very smooth and the kids can drive around the house I just dial down the throttle end points.It has very smooth starts and no cogging.We have had so much snow I havent had the chance to realy drive it outside allthough I did do some speed passes on the only clear road in town.










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[Shark413]

phatmonk, nice CRT.5 conversion. My CRT.5 is setup for racing so a top speed of about 30 mph is what I was looking for. I have MM 5700, 7700 and Feigao 9L motors to choose from and so far the MM5700 is working well (speed/temps). I hear the Neu motors are the best, I have a 1/8 buggy with a Feigao 8XL and I would really like to put a Neu motor in there.

[Shark413]

Ok, it's been a while since I updated this post. I have been busy working on my 1/8 brushless buggy, hooking up the mechanical brakes. But I have taken the CRT.5 out to the track and all I can say is this thing is amazing. Fast and handles better than I thought considering the extra weight. I discovered that the truggy has so much power it was wheeling when I punched it down the main straight and with neutral throttle over jumps it would have a tendency to nose up, which required braking to bring it down. I decided to make the truggy handle more neutral and provide more traction by moving the battery forward about 12mm. I removed the tray and drilled a new set of mounting holes and I extended the forward slot which allowed me to move the tray forward. I can now adjust where the CG is via the battery position. It works out great, it really hooks up now and is very controllable. Before it would hook up all right but the front wheels would lift and I would lose some directional steering. It now flys nice and level as well.