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Help gearing my 8ight 2.0 conversion

Help gearing my 8ight 2.0 conversion

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Old 02-13-2010, 07:00 PM
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Default Help gearing my 8ight 2.0 conversion

I have a 2.0 buggy with a 45 tooth spur gear and a 12 tooth pinion. Running a Mamba Monster ESC w/ a 2200KV motor. There is so much power, that I can't race with it as it is. Granted, we were testing on concrete but the front end lifts up off the ground if you just blip the throttle. First time I set it down and accelerated it ended up on it's lid and even knowing that it was hard to keep the buggy under control. (Separated a wheel and lost a foam after a couple of test runs too.)

I have a 9, 10 and 11 tooth pinion on order and Losi doesn't make a bigger spur gear. My timing is as low as it will go for power conservation.

Any advice for me?

I haven't adjusted my suspension for the change in weight yet, just added preload to keep it from bottoming out. So I know I can firm it up a lot to take the additional weight. Will I be in business with an adjusted suspension, 9 tooth pinion and dirt under the wheels?
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Old 02-13-2010, 07:45 PM
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what battery are you using?
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Old 02-14-2010, 10:09 AM
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5s 5000mah 25c Turnigy lipos. I plan to race this with nitros until the electric class takes off at my club track.

Does lowering punch affect amp draw at all rpm or just initial takeoff? Basically which part of the throttle input would it soften?
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Old 02-14-2010, 10:11 AM
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Originally Posted by AndrewClaycomb View Post
5s 5000mah 25c Turnigy lipos. I plan to race this with nitros until the electric class takes off at my club track.

Does lowering punch affect amp draw at all rpm or just initial takeoff? Basically which part of the throttle input would it soften?
Go down too 4s.
Thats plenty
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Old 02-14-2010, 10:19 AM
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Losi does make larger spurs (46 and 48)...or someone does, that fit. I have the 48 on Tekno converted 8. Unfortunately, I got this used, so I can't confirm if they're Losi or another. I'll try and see if I can find what mfr they are for sure and post back up.
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Old 02-14-2010, 10:27 AM
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Default Here ya go...

Numerous options here...

http://www.amainhobbies.com/advanced...8+spur&x=5&y=6
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Old 02-14-2010, 10:27 AM
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Originally Posted by NitroOB4You View Post
Losi does make larger spurs (46 and 48)...or someone does, that fit. I have the 48 on Tekno converted 8. Unfortunately, I got this used, so I can't confirm if they're Losi or another. I'll try and see if I can find what mfr they are for sure and post back up.
Thanks, I appreciate it. I did a quick search on A Main in the 1/8 conversion section and the only bigger gears are made by Associated.

EDIT: nevermind you found them, thanks.

EDIT AGAIN: I'm not seeing larger Losi plastic gears, made for an 8ight. Does something else bolt up?
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Old 02-14-2010, 02:01 PM
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2200kv on 5s is nuts, defiantly go down to a 4s. I have a 1700kv on 5s and it's almost too fast.
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Old 02-14-2010, 02:07 PM
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With that motor I have 4S and it is fast also. I would like a 3S with the 2200. The 1800KV is plenty fast on 4S also.
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Old 02-14-2010, 02:13 PM
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50 tooth spur with 15 tooth pinion gear 4cell 70 % punch control on esc and low start power will do the trick, you have to dremel a slot in your chassis for the 48 and 50 tooth metal pinion to fit but this did the trick for my buggy she runs like a raped ape but very controllable!!!!
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Old 02-14-2010, 03:16 PM
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Default Your speed is fine, you have too much TORQUE

What you are seeing has nothing to do with how fast it is geared. You just plain have way too much power for the chassis. Ask most racers, and they will say, "You can never have too much power" but I have learned that is dead wrong now days with the brushless systems available. Going to a smaller pinion is actually making the situation worse, as you are getting more and more torque, which just makes it turn th wheels even harder, up until you finally top out the motor. Sure, it will top out at a lower speed, but jerk the trigger at anything less and the car ends up on it's lid. You bought a truggy motor. Imaging a blown big block in a corvette. You can dial down some of it in the ESC and run fewer cells, but until you limit torque, you have a problem. My "solution" was going with a much smaller motor with a higher internal resistance. Yes, gearing became much more important, and it does run hotter, but I can drive it. I have done over 45 minutes of track testing on it, and the motor temp is fine after 18 minutes on 4S and I still have more torque than I can use, as I was still over driving and had to tone down my trigger finger for best lap times. In fact, I dropped to just a 3S and my lap time was only .3 second slower, even though it was much slower on the straight, I didn't gear up for the lower rpm. I don't think you can throw away enough torque to make the big Castle 2200 (Neu 1515 clone) driveable in a buggy. The 2650 or the new 1800 (Neu 1512 size) are better suited, but still capable of serious torque. My motor is a tiny Medusa 36mm x 50mm 3300 KV (I should have gotten the 2200 KV). I had a few others try driving it, and those that have all agree, it is the easiest to control e-conversion around here, especially since the track was dusty and not well groomed. In great cnoditions, maybe a hair more power could work, but I am close to the limits with over 2 HP in an 8 pound car.

One possible solution is the RC-Monster Slipperential. I have to say, they are certainly onto something. Having a slipper clutch that you can dial in to soften the blow right below the point where the tires light up or the buggy wheelies could make a huge difference, but you will still want to calm your trigger or the slipper pads will fry in a single run. My little motor is topping 1600 watts on course, yours can handle much more than that. If the slipper is taming all of it, that is turned direcly into heat. With grip, my buggy did manage to pull the front tires just 2 inches off the ground for about 3 feet from a standing start. Any more torque and it would have been upside down in a blink. On the track, I had to just ease my trigger finger a little to keep from spinning all four tires.

Run low timing, low start power, and dial in about 10 to 20% punch control. Be careful not to use too much. Punch control works by limiting the rate of throttle increase. This does work for taming the launch, but it also limits the rate of wheel spin up when in the air. And that can stop you from being able to lift the nose off of a jump. 10% is working well for me.

I don't know your ratios, but target about 40 mph on 4S and you should be in pretty good shape. Mine is geared to top out at 39 on 4S. This was easilly faster than the nitro guys were able to hit on the track. On 3S, it works out to only 30 mph and except for the last 1/3rd of the long straight, I could not really tell a difference. I had to pull the trigger a tick further, but that just reduced my over driving.

The real test will be this Tuesday night, I plan to be entered in 1/8 electric at Hot Rod Hobbies for the club race.
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Old 02-15-2010, 11:47 AM
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Run time is the reason I'm going with such large batteries. I need to be able to race in nitro mains and a 5s seems to be a good way to keep the temps low and the power up. I still need to gear down because I don't have a useable throttle range, but by adjusting punch I've been able to control the car at takeoff.
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