Not Sure What Happened ?

[TRXaddict]

Still seems to me that some how the brake was being applied and then the throttle glitched. Maybe i just can't comprehend it but i dont see the engine revving as loud as it did just because there was no load on the engine. All the other times I've stripped spur gears it was because maybe my motor mount screws were loose or if my mesh was wrong and i would be driving and suddenly hear it strip the gears. Where in this case every thing seemed to run properly besides the truck running at its absolute best. But Even if a few teeth were broke out i can't see just a few teeth causing the engine to rev so high. Also in person i can hear like just the engine revving then after about a second or 2 of revving i then heard the spur gear strip.

It seemed to me... that the spur gear was actually being held somehow still and the engine i believe was infact strong enough to start to strip the teeth. I mean they make these plastic gears with an actually pretty soft plastic i literally can just gently rub a flat head screw driver on them and plastic just shaves away with no pressure at all.

I know your saying the engine isnt strong enough to strip the teeth alone, but i mean it happened some how... I know my mesh was correct because after i shut it off and spun the spur gear around on the good side where the teeth are still in good condition it was spot on.


*EDIT* guess ill just drive this for the mean time

 

[Snook Man]

A few broken spur teeth indicate 1 or a few broke on a hard on throttle landing or similar.
Stripped teeth all the way around indicates bad gear mesh.
I have a lot of different engines and none are strong enough to strip/break a correctly meshed spur gear the way you are describing. Its doubtful a good Brushless and Lipo setup could break a spur that way.

Imagine the front of the truck against a wall. Give it a little throttle and the clutch bell will try to spin the spur gear. As long as the spur is intact with no missing teeth the truck just pushes against the wall with a load on the engine.

Now imagine 1or 2 of the teeth on the spur is broken. Same situation with truck against the wall with a little throttle input. If the broken tooth section of the spur meets the clutch bell the engine will rev higher because there is no resistance with the spur. When it happens several more teeth usually get broken in the process.

I could see the wheels spinning when the truck was on its lid a few times in the video. The wheels will only spin if the idle speed is too high when everything else is operating correctly. On level smooth ground the truck would have most likely not stood still and crept forward slowly increasing speed due to the off tune/high idle without the brake being held.

The high idle moved the truck forward enough for the spur to rotate the broken tooth area to the clutch bell and the engine rpms increased to the point you thought it was running WOT.

I’ve seen it happen many times at the track when someone would strip a spur (for whatever reason) and the engine rpms would sky rocket like yours. They almost always would start checking the transmitter and servo operation thinking the engine was running at WOT for some electronic reason when all it was, was a bad/lean tune or an idle gap too large which caused the high rpms at idle with no throttle input and no clutch bell resistance against the spur gear.

Rule of Thumb: If the spur is trying to spin at idle, the engine isn’t tuned correctly or the idle gap is too large.

 

[TRXaddict]

A few broken spur teeth indicate 1 or a few broke on a hard on throttle landing or similar.
Stripped teeth all the way around indicates bad gear mesh.
I have a lot of different engines and none are strong enough to strip/break a correctly meshed spur gear the way you are describing. Its doubtful a good Brushless and Lipo setup could break a spur that way.

Imagine the front of the truck against a wall. Give it a little throttle and the clutch bell will try to spin the spur gear. As long as the spur is intact with no missing teeth the truck just pushes against the wall with a load on the engine.

Now imagine 1or 2 of the teeth on the spur is broken. Same situation with truck against the wall with a little throttle input. If the broken tooth section of the spur meets the clutch bell the engine will rev higher because there is no resistance with the spur. When it happens several more teeth usually get broken in the process.

I could see the wheels spinning when the truck was on its lid a few times in the video. The wheels will only spin if the idle speed is too high when everything else is operating correctly. On level smooth ground the truck would have most likely not stood still and crept forward slowly increasing speed due to the off tune/high idle without the brake being held.

The high idle moved the truck forward enough for the spur to rotate the broken tooth area to the clutch bell and the engine rpms increased to the point you thought it was running WOT.

I’ve seen it happen many times at the track when someone would strip a spur (for whatever reason) and the engine rpms would sky rocket like yours. They almost always would start checking the transmitter and servo operation thinking the engine was running at WOT for some electronic reason when all it was, was a bad/lean tune or an idle gap too large which caused the high rpms at idle with no throttle input and no clutch bell resistance against the spur gear.

Rule of Thumb: If the spur is trying to spin at idle, the engine isn’t tuned correctly or the idle gap is too large.

Yeah i was explaining that in the video that it was idling to high but i just wanted to get some footage. Also, i was keeping and eye on the truck when i tried to take off.. the truck didnt creep even an inch, it stayed perfectly still revving witch is why i was given the impression something was putting resistance on the spur gear.

Another thing is after i took my engine out the idle gap surprisingly was alittle less than 1mm so it must have been my LSN.

Also i feel that even if the idle was to high or my tune wasn't correct that it still wouldnt rev as high as it did even with out a load.

I always listen to my truck closely when i drive it, thats why i kept complaining about how it was running. and I'm pretty sure i would have be able to notice any missing teeth because of the specific sound a spur gear makes when teeth are missing.

Also a few mins ago i was looking more closely at the wires of the servo and found this.

I still can't believe i missed this but about 10 mins ago i wanted to check around just in case.

I'm thinking maybe when i installed this servo it was pinched between the body it was mounted to but not 100% sure

 

[Phins Fan]

WELL!, WELL!, WELL!. What do we have there? Is that a split servo wire I see?

 

[MudSlinger33]

Still seems to me that some how the brake was being applied and then the throttle glitched. Maybe i just can't comprehend it but i dont see the engine revving as loud as it did just because there was no load on the engine. All the other times I've stripped spur gears it was because maybe my motor mount screws were loose or if my mesh was wrong and i would be driving and suddenly hear it strip the gears. Where in this case every thing seemed to run properly besides the truck running at its absolute best. But Even if a few teeth were broke out i can't see just a few teeth causing the engine to rev so high. Also in person i can hear like just the engine revving then after about a second or 2 of revving i then heard the spur gear strip.

It seemed to me... that the spur gear was actually being held somehow still and the engine i believe was infact strong enough to start to strip the teeth. I mean they make these plastic gears with an actually pretty soft plastic i literally can just gently rub a flat head screw driver on them and plastic just shaves away with no pressure at all.

I know your saying the engine isnt strong enough to strip the teeth alone, but i mean it happened some how... I know my mesh was correct because after i shut it off and spun the spur gear around on the good side where the teeth are still in good condition it was spot on.


*EDIT* guess ill just drive this for the mean time

Id probably sell the savage and bash around that little guy.

 

[TRXaddict]

WELL!, WELL!, WELL!. What do we have there? Is that a split servo wire I see?

Yeah ha, there was a user who asked on here if there was a cut or damaged wire and when i took the servo out i think i just was looking for like a complete cut. Its just in the 6 and a half years I've never had the engine rev out on its own because of a stripped spur gear. even when i was a beginner and couldnt tune at all and just turned screws and seen what that would do i never had an engine rev the way mine did on its own.

Id probably sell the savage and bash around that little guy.

haha yeah that would be intense huh

 

[TaterX]

I stripped a spur gear the exact same way while making a video the other day and it did the exact same thing. My servos are all fine. There are a lot of reason it can eat the teeth off the spur. This time my lock nut had backed off just enough to let it slip free. The thing is when that plastic gear spins free with no resistance it will flex because its not made to spin free at these rpm's. Also I'm sure it would have a speed wobble with only a brass bushing which are primarily for low rpm applications. misalignment of the gears for any reason will cause this. Then with no resistance on the engine and good bearings it will rev if there is fuel getting in the carb. The same amount of fuel that keeps it idling with resistance will cause it to rev with no resistance.
[ame]http://youtu.be/K2tAiTGUxmY[/ame]

 

[TRXaddict]

I stripped a spur gear the exact same way while making a video the other day and it did the exact same thing. My servos are all fine. There are a lot of reason it can eat the teeth off the spur. This time my lock nut had backed off just enough to let it slip free. The thing is when that plastic gear spins free with no resistance it will flex because its not made to spin free at these rpm's. Also I'm sure it would have a speed wobble with only a brass bushing which are primarily for low rpm applications. misalignment of the gears for any reason will cause this. Then with no resistance on the engine and good bearings it will rev if there is fuel getting in the carb. The same amount of fuel that keeps it idling with resistance will cause it to rev with no resistance.
http://youtu.be/K2tAiTGUxmY

Thats so odd to me, my other trucks like t maxx and jato just idle normaly when the spur strips. It just wouldnt idle soo high, so i guess its not the servos. but i still find it odd...and can't understand it no matter how much i read around on here about their explanations on here it just doesn't seem like it would work like that.

Like soon as the spur gear strips , when you let off the gas that instantly should mean the CB is not active. But in our cases when you let off the gas the engine wants to rev out... I know someone on here said it wasn't at WOT but for me personally it was LOUD LOUD and it did sound like it was at least half throttle. And considering my idle gab was no more than 1mm it shouldnt of revved so high.

 

[TaterX]

I forgot about this post the other day.
https://www.rcnitrotalk.com/forum/showthread.php?t=94475

 

[Phins Fan]

Yeah ha, there was a user who asked on here if there was a cut or damaged wire and when i took the servo out i think i just was looking for like a complete cut. Its just in the 6 and a half years I've never had the engine rev out on its own because of a stripped spur gear. even when i was a beginner and couldnt tune at all and just turned screws and seen what that would do i never had an engine rev the way mine did on its own.



haha yeah that would be intense huh

Only took a stab at it as it happened to me before on my MGT (The radio tray crushed my steering servo wire). I found out about mine as I was blasting some donuts and the truck decided to stop turning 1/2 way thru them.

 

[Assassin]

I've stripped spurs completely & the engine did not rev up at all, It just stayed at idle fine, and when I hit the gas it would rev up fast, with the truck sitting still.

I've also stripped spur gears (plastic ones) with a perfect mesh, just forcing the truck through ish I shouldn't, like up a slide. Under normal circumstances NO you shouldn't strip a plastic spur gear they should hold up fine. However when you get stuck, like you did on the jump, and then give it gas, truck doesn't move, you give more gas, eventually get her over. Well while you were on the ramp you heated up your clutch bell trying to force it over, so at that point your CB is hot.

Yeah the tune is off, but is it so off that with the spur gone completely it would rev up like that? That seems a little bit too high for that tune.

The frayed wire on the other hand is a smoking gun.

That tells me most probably the frayed wired cause the servo to glitch holding your throttle open (not necessarily WOT) The already hot CB went right through the plastic spur, I'm not surprised at all.

 

[NITRO FEVER]

I had EXACTLY the same thing happen to me I was only on my 3rd tank of fuel and I posted it on here about a week and half ago. I'm really concerned about the engine being pinned wide open like that causing some damage. Let me know what you do about yours