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Old 05-05-2011, 10:40 PM   #1
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Default First crash and break today, servo grinding no movement.

So I crashed today on the street in my losi 8ight 2.0 buggy that I just bought (used) and the steering servo is making a grinding noise and tries to respond to my commands (I can hear it moving) but nothing moves. I am new to the rc world and still trying to learn the basics. The servo that is not working is a JR Servo DS8417. I read in another post that there is such thing as a servo rebuild kit? I sure hope so because I dont feel like shelling out $114 for a servo after I just spent $600 on the car. I dont really know how a servo works but is it something that might have just come loose inside of it? Or is that not possible? Any input is greatly appreciated!

P.S. just read this from their site "Hardened steel and brass gear train that's virtually un-strippable" Hope I wan't lucky enough to do this on my first crash.
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Old 05-06-2011, 04:22 PM   #2
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check the servo arm.....might have stripped that. if not its probably in the gears in the servo. most servo companies sell replacement gear sets
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Old 05-06-2011, 04:28 PM   #3
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Prob stripped the gears. Check to see how tight your servo saver is. Look into a possible warranty repair. If it costs too much to fix, just get a nice Hitec. Love that 3 year warranty.
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Old 05-06-2011, 04:47 PM   #4
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Prob stripped the gears. Check to see how tight your servo saver is. Look into a possible warranty repair. If it costs too much to fix, just get a nice Hitec. Love that 3 year warranty.
I am new to the rc nitro hobby so I don't know if this even has a servo saver on it of it doesn't come from factory with on. The gear kit is $22 and I could have it installed by a buddy who is experienced in rc servos. Also I bought the rc car used so I'm guessing warranty work is out of the question.
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Old 05-06-2011, 04:50 PM   #5
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Sounds like the gears have stripped.
Im unfamillar with the JR servos but I know that you can buy a gearkit for the Futaba servos. Usually theres one plastic gear in all metalgeared servos and thats the most prone to breaking. I bought a set a few months ago with like 4-5 plastic gears, dont think it cost me more than a dollar and its fairly easy to replace yourself.
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Old 05-06-2011, 05:14 PM   #6
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Check out if you can replace the gears. If not, I have a NIB JR9100T digital high torque servo that's great for steering in the for sale threads.
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Old 05-07-2011, 02:18 AM   #7
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So here is the inside of the servo. All metal gears are fully intact, I cant tell if the white plastic gear had teeth or not because I don't know what its supposed to look like. If it did when I crashed it must have grounded them off pretty smooth. And on the other gear that little metal piece which appears to be a bump stop or something to keep if from spinning past a certain point looks like it might be bent or even broken off.

So my questions now are...

1. If the bump stop thing is in tact and not bent or broken can I just replace the plastic gear? Or should I just buy all new gears?

2. Why didnt they just make this gear metal like the rest? A chain (servo) is only as strong as its weakest link.


One other thing when the car is turned on that white gear just spins and spins all by its self and everything else stays still.
Attached Thumbnails
First crash and break today, servo grinding no movement.-jrservo.jpg   First crash and break today, servo grinding no movement.-jrservo2.jpg  

Last edited by waterisgood; 05-07-2011 at 02:37 AM.
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Old 05-07-2011, 03:07 AM   #8
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yip yourve stripped the plastic gear.
They make them plastic so it takes the strain off the other gears and motor and its called a sacrificial gear for this reason,
you can often get hybrid metal gears and I have done this to a kopro servo i had but not sure on jr but should be easy enough to get another plastic gear...google is youre friend.

also full gear sets can be very expensive so just get the plastic one if you can.
the plastic gear runs off the motor so that is why it spins so youre motor is fine but you have stripped the plastic cog that connects to the metal gear so reason it doesnt move the metal gears.
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Old 05-07-2011, 04:27 AM   #9
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Quote:
Originally Posted by waterisgood View Post
So I crashed today on the street in my losi 8ight 2.0 buggy that I just bought (used) and the steering servo is making a grinding noise and tries to respond to my commands (I can hear it moving) but nothing moves. I am new to the rc world and still trying to learn the basics. The servo that is not working is a JR Servo DS8417. I read in another post that there is such thing as a servo rebuild kit? I sure hope so because I dont feel like shelling out $114 for a servo after I just spent $600 on the car. I dont really know how a servo works but is it something that might have just come loose inside of it? Or is that not possible? Any input is greatly appreciated!

P.S. just read this from their site "Hardened steel and brass gear train that's virtually un-strippable" Hope I wan't lucky enough to do this on my first crash.
That servo does not have enough torque for your 2.0 buggy.
http://www.jrradios.com/Products/Def...rodID=JRPS8417

I try to use at LEAST 200oz. inch servo. I have looked for 250oz inch but cannot find one in the .06-.10 speed range.
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Old 05-07-2011, 05:05 AM   #10
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Originally Posted by mgtmadness2007 View Post
That servo does not have enough torque for your 2.0 buggy.
http://www.jrradios.com/Products/Def...rodID=JRPS8417

I try to use at LEAST 200oz. inch servo. I have looked for 250oz inch but cannot find one in the .06-.10 speed range.
maybe but he was running it outside on the street and most likely he hit the gutter and that strips plastic gears very easily compared to the track..200oz is probably overkill for a buggy...maybe a truggy..get a new plastic gear and see how it goes as the plastic gears get to a stage when they just fail and sometimes for no reason..give it another go before you pay out for another servo or later on shift this servo to throttle and then get a gruntier servo for steering...savox make some very well priced grunty servos
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Old 05-07-2011, 06:05 AM   #11
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First never run your stuff out on the street!?

Second the JR servo sounds a little cheap if it still has platic gears. For steering you need the JR9100T.

Third this seems to be a common problem with JR. I just send mine in be repaired. And JR does come with a 3 yr warrenty.

Last ive now switch to Savox and for half the price as JR and just as good.
1256 for steering and the 1257 for throttle.
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Old 05-07-2011, 12:41 PM   #12
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So I took the gears off today and this is what I found. The metal pin that is on the biggest gear dug itself into the servo casing making a indent and bent itself also (pics). Should I just get the plastic gear and run this servo until its death? I dont think I could get a replacement housing. Or i could just put it on the throttle where there is less strain on it.
Attached Thumbnails
First crash and break today, servo grinding no movement.-imag0490.jpg   First crash and break today, servo grinding no movement.-imag0491.jpg   First crash and break today, servo grinding no movement.-jrpsg8417.jpg  
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Old 05-07-2011, 12:56 PM   #13
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Quote:
Originally Posted by waterisgood View Post
So I took the gears off today and this is what I found. The metal pin that is on the biggest gear dug itself into the servo casing making a indent and bent itself also (pics). Should I just get the plastic gear and run this servo until its death? I dont think I could get a replacement housing. Or i could just put it on the throttle where there is less strain on it.
The DS8417 ultra speed with 80oz/in torque is inappropriate for steering. You need a torque servo with about 200+ oz/in. Even for throttle/brake, the DS8417 is a bit light. You could try it on the throttle/brake for grins.
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Old 05-07-2011, 01:46 PM   #14
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The DS8417 ultra speed with 80oz/in torque is inappropriate for steering. You need a torque servo with about 200+ oz/in. Even for throttle/brake, the DS8417 is a bit light. You could try it on the throttle/brake for grins.
Ok thanks. This is the servo that came on the car when I bought it. I have the stock steering servo that came with the car would that be a better one to run then this JR servo?
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Old 05-07-2011, 01:54 PM   #15
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Ask the guy that you bought it from if that was a "sale" servo or was it his normal one. It is way to small,for that buggy, especially off road racing. Save your self a future headache, toss that one and buy one, stronger, that will last. By rebuilding that one, you will have the same failure later down the road.
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