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Old 07-04-2009, 05:40 AM   #1
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Default LRP Sphere TC - DX3R - X12 4.0T

Hello any help/tips would be much appreciated

LRP Sphere TC - in the instructions under (7. Mode Programming) and at section Mode 3. (Initial Brake) there is a (Team Tips) sentence and it says "A good starting point for the brake setting on your radio is 80% (bonded) and 70% (sintered) for all classes. Make sure you do the radio-setup with all settings on the radio on 100%"...Okay I have setup up my radio on 100%. So what setting do I change in my DX3R to change it to the recommended 70% (sintered)? I still want to have the 'Launch-Control' feature enabled w/full-brake, i.e. 'Blue solid light'

ALSO-

LRP Sphere TC settings - 1,5 (brushless), 2, 2
Xray T2'008 - 100T Spur and 40T Pinion (4.25 gear ratio) setup for high speed straights.
LRP X12 4.0T w/stock internals and timing - I have this issue when I initially apply about 10-15% throttle with the car stationary and starts to take-off...I hear somewhere in the transmission a kinda loud 'clank clank' krrrrrrrrR' grinding noise for about a quick 1 second then when the car finally starts to build momentum going forward and not as much torque from the motor is needed to get the car to roll....the sound automatically stops and sounds smoooth. I checked if any teeth were being stripped or any signs of it...but to my luck that was not the issue...like say for instance...put the front of the car directly in front of a wall and try to throttle it with quick flicks...you will see the car try to push forward and hear that 'clank clank or krrrrrrrrRR' sound as if the teeth/gears are stripping/giving way. I just don't know how and where this sound is coming from exactly...could it be from within the motor?? Maybe a feature of the motor where it senses binding in the transmission? I tried to give as much detail as possible. Please fill me in if you know anything!

Note: I read this in another post the proper name of the sound/action might be referred to as 'cogging or bogging'. I also tried going down to value 4 (smooth x4) with the same effect.

Thanks in advance~
J.T.
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Last edited by jt415gz; 07-04-2009 at 04:11 PM. Reason: added info
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Old 07-04-2009, 07:53 AM   #2
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remove the pinion

squeeze the throttle slightly and not for too long , see if the noise is still there

if it is , check the sensor wire for damage , sounds like there is a problem with the sensor or cable or speedo , if there is nothing damaged on the car

as for your speedo settings i would use program 2 or 3 with a 4 turn motor , with auto brake off and drag brake about 3 or 4

more people will be along soon to help too , i only race stock so i used progam 8
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Old 07-05-2009, 12:20 PM   #3
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Quote:
Originally Posted by sidecarphil1 View Post
remove the pinion

squeeze the throttle slightly and not for too long , see if the noise is still there

if it is , check the sensor wire for damage , sounds like there is a problem with the sensor or cable or speedo , if there is nothing damaged on the car

as for your speedo settings i would use program 2 or 3 with a 4 turn motor , with auto brake off and drag brake about 3 or 4

more people will be along soon to help too , i only race stock so i used progam 8
Follow up: removed pinion and the motor sounds fine (smooth).
changed settings to 3 power, 4 initial brake (70% expo), 0 auto-brake.
Unfortunately it still creates the bogging/cogging noise in the tranny somewhere.

Note: If I gradually apply throttle consistently (very slowly increasing) I can avoid the noise/binding. BUT if I slam on the throttle at about 10% as most people would at the starting line the cogging/bogging noise will remain. AND pinion/spur gears are showing no signs of stripping.
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Old 07-05-2009, 01:08 PM   #4
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Is possible, you have a small pulley in the center axle, striped out, and the belts striping there or the front belt donīt have the proper tension.

For 4.0, is ok to program 3, but the initial brake is more high, here in mods we run with 2-4 program and 0,0, brakes, (2-3-0-0 or 2-4-1-0) for example, and for 4.0, the final ratio 4.25, is a lot large, i donīt know is you run in oval, but for large 1/8 tracks, 7.5 - 8.5, is more proper for this motor, and you gain more brake.

Sorry for my english, greetings, Luis C.
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Old 07-05-2009, 05:43 PM   #5
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Quote:
Originally Posted by luic View Post
Is possible, you have a small pulley in the center axle, striped out, and the belts striping there or the front belt donīt have the proper tension.

For 4.0, is ok to program 3, but the initial brake is more high, here in mods we run with 2-4 program and 0,0, brakes, (2-3-0-0 or 2-4-1-0) for example, and for 4.0, the final ratio 4.25, is a lot large, i donīt know is you run in oval, but for large 1/8 tracks, 7.5 - 8.5, is more proper for this motor, and you gain more brake.

Sorry for my english, greetings, Luis C.
I reprogrammed the Sphere TC to (1-4-1-0) and tightened both front/rear pulleys (1 notch @ bulkheads), plus I have a Belt Tensioner so the belts have enough tension and I still hear that sound.

To answer your question. I don't run Oval but started to club race in fairly large parking lot track setups. Yeah, I chose the 4.25 gear ratio to test out my max speed with the most rollout running straight (will this be too demanding on the motor, how come?) I am still learning about FDR's and Gear Ratio's, Electric on-road...since I came from 1/8th scale nitro on-road. Can you tell me how and why a 7.5-8.5 GR will better suit my 4.0T motor (I noticed that it will greatly reduce rollout).

Also, why does LRP recommend to set the break setting in your radio to 70% for sintered rotors? And where do I find that setting in my DX3R?

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Old 07-06-2009, 02:35 PM   #6
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I donīt have any experiencie in parking lot races, because here in Europe arenīt more popular.
Well, in motors one of the more important factor is the torque, this is the force the motor have to move the axle, (in general words), when you decrease the number of turns (10.5 - 7.5 - 5.5- 4.0, .... ) decrease the magnetic force which is capable of coiling, decrease the torque, and decrease the resistance, this make an increase in Intensity, in electric motors, increase the power, and RPM.
(Well, is a basic explanation, but i hope you help).

In laboratory, and track, motors are tested and their strength to create a table that shows that gears ratios can move, based on the force.

For example a 7.5 motor have double of copper wire that 4.0, double magnetic force, (here are more influence for rotors, but this other history), generate more torque, but less rpm, for compensate this, taking advantage from torque for move more ratio (into 5.5 - 6.0).

You need to test your proper ratio for your track, but if you rollout is more long, the motor you may not have sufficient strength for move it, this cause a more high current across the copper, (for create power), to a point where you drop and burn, in other hand is possible the motor work but they can not reach up to the maximum speed, you have to test some pinions and see how work the motor and see the temperature.

The indication in the manual, is only a start point, for me 70% of brake is much, with sintered rotors i go with 35 - 45 %, for me is sufficient, i donīt know how work DX3R, i reduce the brake adjustament in my tx.

I hope my explanation is clear, do not master English very well, and I have difficulty explaining technical things, but i used to practice and learn

Greetings, Luis C.
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Old 07-06-2009, 03:33 PM   #7
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Quote:
Originally Posted by luic View Post
I donīt have any experiencie in parking lot races, because here in Europe arenīt more popular.
Well, in motors one of the more important factor is the torque, this is the force the motor have to move the axle, (in general words), when you decrease the number of turns (10.5 - 7.5 - 5.5- 4.0, .... ) decrease the magnetic force which is capable of coiling, decrease the torque, and decrease the resistance, this make an increase in Intensity, in electric motors, increase the power, and RPM.
(Well, is a basic explanation, but i hope you help).

In laboratory, and track, motors are tested and their strength to create a table that shows that gears ratios can move, based on the force.

For example a 7.5 motor have double of copper wire that 4.0, double magnetic force, (here are more influence for rotors, but this other history), generate more torque, but less rpm, for compensate this, taking advantage from torque for move more ratio (into 5.5 - 6.0).

You need to test your proper ratio for your track, but if you rollout is more long, the motor you may not have sufficient strength for move it, this cause a more high current across the copper, (for create power), to a point where you drop and burn, in other hand is possible the motor work but they can not reach up to the maximum speed, you have to test some pinions and see how work the motor and see the temperature.

The indication in the manual, is only a start point, for me 70% of brake is much, with sintered rotors i go with 35 - 45 %, for me is sufficient, i donīt know how work DX3R, i reduce the brake adjustament in my tx.

I hope my explanation is clear, do not master English very well, and I have difficulty explaining technical things, but i used to practice and learn

Greetings, Luis C.
I kinda get it now. It's just like rotational mass...the increase in mass will decrease max rpm and vice versa. I just learned that out of a single speed transmission the driver has the choice of choosing either gearing for acceleration, top speed or a middle balance between the two. And a higher gear ratio equals low-end torque (acceleration) and a lower gear ratio equals high-end torque (top speed)...so my understanding is that since a 4.0T motor would have less of a rotating mass then it would create less low-end torque, compared to like say a 10.5T using the same voltage and gear ratio.

So I *geared down* (higher gear ratio) to 27/116 for 7.3 GR (I want to reach 20/100 for 8.5 GR later on) and I noticed a much faster acceleration characteristic off the line using this GR, but it will yield my top speed in return.

As for the brake adjustment in my DX3R...I wonder if that would be adjusted through exponential, travel programs?
I am thinking it can't be through the travel settings, because if I decrease the brake's travel from 100% I will no longer be able to initialize the 'Launch Control' feature (blue solid light on Sphere for 5 sec's)... I also asked this on the official LRP forums and have yet to receive a reply.

That bogging noise is still present and it won't go away.
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