Loud spur gear after a tumble - ECX amp

Ecx_frills

Member
Messages
17
hey all,

My son took the amp off a pretty big jump and landed on it's rear. Drove for a bit more and realized it's making a rough sound. Looks like the engine slipped a bit.

I took it to a hobby shop and they had a look at the spur and pinion. It needed to be meshed again. So we did that.

Now I find it's still quite loud. Should I replace the spur gear? It's not slipping, the teeth look good. It is particularly loud in reverse and it drives well. It's you can hear the gears. How damaged does it need to be to be repaired?
 

X

Conspiracy of One
Staff member
Supporting Member
Messages
1,140
Remove the pinion. Now rotate the drivetrain. Does it feel smooth? It's possible you damaged something else, like the differential.
 

Ecx_frills

Member
Messages
17
Ok. I could not pull out my pinion gear, the hex screw is absolutely not turning for me which is fine, I just unmeshed the gears and turned the spur gear. Should it turn completely smoothly? I feel it turns quite smoothly but every once in a while I do feel a bit of the gears. Not much, but I do feel it. I am guessing that I'm going to have to take off the gear cover and have a good look at it.

It needs a good cleaning anyway, so I could do that.
 

Ecx_frills

Member
Messages
17
Alright, I took the whole drive train apart last night and went through it gear by gear. Everything looks to be in good shape, everything spins properly, I greased up the gear box and the drive shaft. Meshed the gear as best as I could (not too tight, with a piece of paper between to keep a small gap) and it is still really loud. At least now it's all clean and I'll just drive it and not worry so much. The motor doesn't seem hotter than normal so I don't know what I did but thank you for the help!
 

Ecx_frills

Member
Messages
17
Bearings?

Spur gear dirty? Dirt down in teeth.

I have had this noise before.
I do think the bearings need to be replaced. I actually bought all new bearings. I took the whole drive shaft apart and could not find the problem. I even used white lithium grease to grease it all up. Everything was spinning well, put it back together and the noise persists. I guess I am just going to live with it for now.

I did also bring it to a hobby shop who had a look at it and they said it was fine. but boy it is louder when going backwards that's for sure.

I wish I could find a solution!
 

kruzracing169

Well-Known Member
Messages
338
Location
ND, USA
I wish I could find a solution!
Post a short video......

Does it do it when up on a block or only sitting on ground and under load?

I have had it this way too....
I am trying to remember back, I think it was the slipper pad was bad. I roughed it up with some sand paper, and tightened spring down, and it was gone. I run my slipper at 1 to 1 and half turns out from tight.
 

Ecx_frills

Member
Messages
17
I don't know what a slipper pad is, but perhaps that could be an issue for sure. Would my process be:

1. Tighten it down until it is tight by hand.
2. Loosen it 1 to 1.5 full turns

See how that goes?

Thank you for the help! I haven't had time to drive it lately (which sucks because the nice cool weather is perfect) but when I do I'll record a video.
 

Ecx_frills

Member
Messages
17
I recorded a quick video. Give it a listen:

Also I have checked the gears and they are all looking good and running smoothly.

I really appreciate the help!

I just burned out my steering servo, so I'm on to the next problem now too!!
 

kruzracing169

Well-Known Member
Messages
338
Location
ND, USA
Ok, this sounds like a rubbing issue, not gears. It seems to me that forward, no noise, reverse noise.
Take body off, and see if drive cup screw is hitting on turnbuckle screw, or what is moving too much to rub.

Are you running stock motor? Stock gearing?

When upgrading servo, do not use stock.
You want discounted, go Power HD with like 20kg torque. Otherwise, go to local shop, just make sure they don't sell you anything less then 20kg, and you don't need it to be speedy.
 

Ecx_frills

Member
Messages
17
Ok, this sounds like a rubbing issue, not gears. It seems to me that forward, no noise, reverse noise.
Take body off, and see if drive cup screw is hitting on turnbuckle screw, or what is moving too much to rub.

Are you running stock motor? Stock gearing?

When upgrading servo, do not use stock.
You want discounted, go Power HD with like 20kg torque. Otherwise, go to local shop, just make sure they don't sell you anything less then 20kg, and you don't need it to be speedy.
I am running stock motor and gear but upgraded ESC. Yes, it's forward no real noise, backwards it's there.

So you're saying that perhaps one of the screws is not set 100% properly, that is quite possible. I'll look through them all and see what feels like it's loose.

For the servo, I bought a DSSERVO DS3225 Waterproof 25kg 180 degree digital metal servo. Finding the right answers on things can be quite hard, even just determining what angle is required for an RC car, seems 180 degrees is the right one. I figured, might as well upgrade a little bit right?
 
Messages
5
Location
Bedrock
For the servo, I bought a DSSERVO DS3225 Waterproof 25kg 180 degree digital metal servo. Finding the right answers on things can be quite hard, even just determining what angle is required for an RC car, seems 180 degrees is the right one. I figured, might as well upgrade a little bit right?
I also bought a 180 degree servo to upgrade my steering, only a 20 kg, not 25kg monster, but in reality, the servo only goes through about 90 degrees lock to lock.
 

Ecx_frills

Member
Messages
17
I also bought a 180 degree servo to upgrade my steering, only a 20 kg, not 25kg monster, but in reality, the servo only goes through about 90 degrees lock to lock.
Thanks, man, it was very hard to find out exactly what specs the servo I needed was. So much to learn! It's on its way, so when it comes I'll set it up and then I am back to figuring out this loud gear issue!
 
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