TC4 rear differential issue

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emf411

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Hi everyone,

I'm returning to RC after many many years. I won't say how many, lol!

A few years ago I built a TC4 FT kit. This is my first touring car, back in the day I had a Team Losi JRX (I think that was the name, I still have it actually). The build went smooth, I put in a brushless motor (last time I did RC everything was brushed) and got all of the electronics working.

For some reason when I pull my throttle to full, my TC4 seems to lack any type of punch to accelerate. Is this normal? If it's on a flat surface in my basement, 5 inches away from a low carpet, it doesn't seem to have enough juice to make it up onto the carpet. I'm using brand new lipo's and the battery currently is reading 69% capacity.

I'll be looking through the forums for anything similar. In the meantime, does anyone have any suggestions for what I can try to fix this?

Thank you in advance!!
 
WoodiE

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@emf411 what brushless motor, ESC, and LiPo battery are you using?
 
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emf411

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@WoodiE
Motor: LRP Vector K4, pretty sure 21 pinion

ESC: LRP 80230 spin super reverse brushless

LiPo: Zeee 2S 5200 50C 7.4v
 
Rolex

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There's a possibility that you need to program your ESC or your transmitter. With brushless motors, ESCs and computer radios you can program the traction control, exponential settings for trigger response, steering control, etc.
Keep us posted. We'll get it figured out.
What radio are you using?
 
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emf411

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Sounds good. I’m going to take the rear diff apart and rebuild it to see if that helps.

My transmitter is a Spektrum DX5C.
 
Rolex

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Okay, then it's a computer radio and you can program it accordingly.
Disconnect the final drive from your rear diff and turn both wheels by hand. If it's hard to turn you have a problem in there.
If, while trying to drive it the motor gets hot, you'll know something is binding and needs to be corrected.
 
olds97_lss

olds97_lss

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Yeah, brushless esc's have to be calibrated to the transmitter. Should tell you how to do that in the manual. Usually is just turning it on while having the the transmitter on at full throttle. Then lights flash and you go full brake, more lights, then neutral. Then it flashes some more and you shut off the receiver/turn it back on and it's set for your radio system.

See if you can find a manual for your ESC. They all differ a bit. One of my has a setup button. All my others are just a "power on with transmitter at WOT" kind of thing.

Found the manual:
https://www.lrp.cc/fileadmin/product_downloads/instructions_en/80230.pdf

Calibration:
Ensure that the speed-control is not connected to the drive battery.
  • Remove motor pinion or ensure that the wheels of the model are free to rotate.
  • Switch the transmitter on and set the transmitter throttle stick to neutral.
  • Connect the speed-control to the battery, now press button to switch it on and keep it pressed (~3sec) to enter radio calibration (green LED starts flashing).
    • no the green LED flashes until radio setup is completed now.
  • Leave transmitter in neutral position and press the button once.
    • Neutral setting is stored , yellow + green LED‘s flash and motor beeps.
  • Hold full throttle on transmitter and press the button once.
    • Full-throttle setting is stored, red + green LED flashes.
  • Hold full brake/reverse on transmitter and press the button once.
    • Brake/reverse setting is stored, red + green LED‘s glow permanently.
 
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emf411

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Alright, I'm happy to report that I have figured out the problem and fixed it. I took the rear diff apart and noticed that both of the composite outdrives were stripped down where the diff ring sits. I picked up a new set of outdrives, rebuilt the diff, and my car is now as speedy as I would expect!
 
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