Big Rock Spur Gears keep getting eaten up, need help figuring out why

[Jeremy in WI]

During the span of these issues, have you tried a different pinion gear?

 

[thegunsmith]

During the span of these issues, have you tried a different pinion gear?

No I have not. I'm tryin not to throw money at it before knowing what's wrong but do you think that could be the problem? It looks fine to me, I can post a picture.

 

[Jeremy in WI]

No I have not. I'm tryin not to throw money at it before knowing what's wrong but do you think that could be the problem? It looks fine to me, I can post a picture.

They're cheap, and it might be the problem... It might be worth the few bucks.

 

[thegunsmith]

I don't tape where the gear is exposed and I don't loctite the slipper. So weird.

Do you run a dusty motors dust cover or anything? I'm thinking about getting one, or making my own out of screen and a zipper.

 

[bicketybam]

Do you run a dusty motors dust cover or anything? I'm thinking about getting one, or making my own out of screen and a zipper.

I do not.

 

[thegunsmith]

So upon further inspection, it looks like the pinion gear may have slightly rubbed on the back housing of the power module. Now I'm really confused, what could have caused this? Flex in the motor mount? Or maybe when the plastic housing heats up its able to move easier and it flexes causing play and in turn causing my spur to be torn up? Bought 3 new spurs today so I'm hoping that I can figure out the problem before I burn through all of them. I guess its better the spur is going rather than something else, as they're only $4.

 

[thegunsmith]

There is diffidently some play somewhere... In this picture you can see that the spur gear obviously has some play and is able to grind down a piece of the housing. I need help
EDIT: The crack that you see by the screw is new I just overtightened it and it cracked, it wasn't there before

 

[Jeremy in WI]

There is diffidently some play somewhere... In this picture you can see that the spur gear obviously has some play and is able to grind down a piece of the housing. I need help
EDIT: The crack that you see by the screw is new I just overtightened it and it cracked, it wasn't there before

Did You check the motor shaft for slop? There are usually some spring washers on the back side of the shaft inside the motor to make sure it stays pushed forward. Otherwise, didnt you have a motor that smoked the bearings in that truck? The damage could be reminiscent of that.

 

[thegunsmith]

Did You check the motor shaft for slop? There are usually some spring washers on the back side of the shaft inside the motor to make sure it stays pushed forward. Otherwise, didnt you have a motor that smoked the bearings in that truck? The damage could be reminiscent of that.

No slop in the motor shaft at all. No side to side play or any up/down play. Yes I did have a motor with bearings that went bad, it's possible it happened then and I just didn't notice until now.

 

[Jeremy in WI]

No slop in the motor shaft at all. No side to side play or any up/down play. Yes I did have a motor with bearings that went bad, it's possible it happened then and I just didn't notice until now.

How is the gear mesh when this thing is all back together? If it's too tight that could be part of the problem. I know it's pre drilled, but it could be a factory defect... Maybe? I don't know, I'm kinda grabbing at straws here. If it was me, I'd try the new pinion. If that doesn't work, maybe a HR adjustable motor mount or new oem motor mount from JRC.

 

[thegunsmith]

How is the gear mesh when this thing is all back together? If it's too tight that could be part of the problem. I know it's pre drilled, but it could be a factory defect... Maybe? I don't know, I'm kinda grabbing at straws here. If it was me, I'd try the new pinion. If that doesn't work, maybe a HR adjustable motor mount or new oem motor mount from JRC.

The mesh seems fine to me, I watched a few YouTube videos on it and everything looks as it should. I will try a new pinion, I ordered one yesterday

 

[stephen]

Im a noob to arrma, but not rc. Hopefully I can help in some way. You have a slipper problem for sure. The teeth are jack hammering every time the load shifts. Its basically sheering the teeth since theres no give..anywhere. The only "slip" the whole system has on a asphalt surface is the slipper. I bet you find theres less of a problem in loose dirt.

When I raced on road, there was a ball diff in the spur. You could adjust the diff to slip when the throttle was nailed. In your case, the same must apply. If you need to tighten the nut all the way to keep it from backing off, THATS a clue to where your problem is. You can add some blue loctite liberally to the nut, or just replace it. When the throttle is hit, the clutch should initially slip. A starting point is all the way tight, then back off one turn.
The nut should stay put, and should not back off. Loosen the slipper enough so you hear that initial slip.. the motor rpm will increase for a split second before the truck launches.

If your jumping your rig, let off the throttle just before the tires hit the ground

 

[thegunsmith]

Im a noob to arrma, but not rc. Hopefully I can help in some way. You have a slipper problem for sure. The teeth are jack hammering every time the load shifts. Its basically sheering the teeth since theres no give..anywhere. The only "slip" the whole system has on a asphalt surface is the slipper. I bet you find theres less of a problem in loose dirt.

When I raced on road, there was a ball diff in the spur. You could adjust the diff to slip when the throttle was nailed. In your case, the same must apply. If you need to tighten the nut all the way to keep it from backing off, THATS a clue to where your problem is. You can add some blue loctite liberally to the nut, or just replace it. When the throttle is hit, the clutch should initially slip. A starting point is all the way tight, then back off one turn.
The nut should stay put, and should not back off. Loosen the slipper enough so you hear that initial slip.. the motor rpm will increase for a split second before the truck launches.

If your jumping your rig, let off the throttle just before the tires hit the ground

Actually I have never driven on concrete or asphalt, I only drive in the dirt and most of it is loose. I have been using blue locktight and it was working well(the slipper never came loose) and I was running it at 1 turn from full tight. The spur still shredded

 

[Wags1]

Yes I am running the stock 15T pinion. just checked for play in the power module through the opening at the bottom and yes it does have just a tiny amount of play when I rotate it. I noticed that the whole slipper assembly has up and down play but I think that is only because the power module isn't installed in the truck. Both of the bearings are fine I recently replaced them with sealed bearings. Thanks

Mesh too tight?

 

[thegunsmith]

Mesh too tight?

It's possible but I don't think so. I'm still running the stock fixed motor mount so I can't change the mesh

 

[stephen]

Loosen the slipper more- half turn increments to get that intial slippage when you hit the throttle

 

[thegunsmith]

Well, another spur bites the dust... This time it was about 5 mins into my 3rd battery

Loosen the slipper more- half turn increments to get that intial slippage when you hit the throttle

I will try that

 

[Yonic]

Wow, I’m dying to know what it will be eventually. I don’t think it’s the slipper as some (ie @bicketybam) run them tight regularly.

Just to reinforce that this is not normal, for the last 6 months I run mine on 3s with punch set to maximum, 2-4 packs a week - and I’m still on the original spur.

Btw, not sure of this was addressed before. Did you run the 3 packs back to back? Do you check temps? Could it be that the pinion melts the spur?

 

[thegunsmith]

Wow, I’m dying to know what it will be eventually. I don’t think it’s the slipper as some (ie @bicketybam) run them tight regularly.

Just to reinforce that this is not normal, for the last 6 months I run mine on 3s with punch set to maximum, 2-4 packs a week - and I’m still on the original spur.

Btw, not sure of this was addressed before. Did you run the 3 packs back to back? Do you check temps? Could it be that the pinion melts the spur?

No I did not run 3 packs back to back, I ran them about 2-3 hours after each other starting this morning. I wanted to see if heat was the issue and apparently its not.

 

[Jeremy in WI]

Wow, I’m dying to know what it will be eventually. I don’t think it’s the slipper as some (ie @bicketybam) run them tight regularly.

Just to reinforce that this is not normal, for the last 6 months I run mine on 3s with punch set to maximum, 2-4 packs a week - and I’m still on the original spur.

Btw, not sure of this was addressed before. Did you run the 3 packs back to back? Do you check temps? Could it be that the pinion melts the spur?

I agree. I run mine around a half turn from tight, 2 trucks, original spurs. Whatever the problem is here, it's perplexing.