What happened?

[jakebullett]

Any idea what could have cause this melt down? The housing around the spur gear melted onto the spur gear. Sucky.

doh
why does this load two pics?

 

[bill_delong]

When was the last time you rebuilt the car and inspected/cleaned your bearings?

https://www.rcgroups.com/forums/showthread.php?4308293-Maintenance-Tips

Normally the car will "feel" different long before damage occurs... if the car is driving slower and/or temps are increasing with subsequent runs, then I suspect poor maintenance is the culprit. That includes regular inspection for worn/cracked parts that can trickle down and cascade to other parts.

A seized bearing can melt plastic on no time

Be thankfaul that all you damaged were a few plastic parts and didn't burn out your electronics!
https://www.rcgroups.com/forums/sho...eed-to-run-for-upgraded-electronics-in-my-car


*** UPDATE ***
Side note... I recently noticed a funny "whirring" sound coming from my engine on my full scale truck... it was approaching 100K miles and I figured the water pump was approaching its service life. Sure enough, within a week my engine over heated due to the water pump leaking fluid from a blown bearing seal. I was able to pour some fresh water in the radiator and took it straight to the shop to have the water pump replaced. In a perfect world, I would be able to replace those bearings in the water pump for a few bucks and could probably get another 100K miles on the truck, but that's not how the auto industry works... fortunately for us in the RC car industry we can clean and repack our bearings as often as we like to significantly extend the service life of all our other parts

 

[jakebullett]

When was the last time you rebuilt the car and inspected/cleaned your bearings?

https://www.rcgroups.com/forums/showthread.php?4308293-Maintenance-Tips

Normally the car will "feel" different long before damage occurs... if the car is driving slower and/or temps are increasing with subsequent runs, then I suspect poor maintenance is the culprit. That includes regular inspection for worn/cracked parts that can trickle down and cascade to other parts.

A seized bearing can melt plastic on no time

Be thankfaul that all you damaged were a few plastic parts and didn't burn out your electronics!
https://www.rcgroups.com/forums/sho...eed-to-run-for-upgraded-electronics-in-my-car


*** UPDATE ***
Side note... I recently noticed a funny "whirring" sound coming from my engine on my full scale truck... it was approaching 100K miles and I figured the water pump was approaching its service life. Sure enough, within a week my engine over heated due to the water pump leaking fluid from a blown bearing seal. I was able to pour some fresh water in the radiator and took it straight to the shop to have the water pump replaced. In a perfect world, I would be able to replace those bearings in the water pump for a few bucks and could probably get another 100K miles on the truck, but that's not how the auto industry works... fortunately for us in the RC car industry we can clean and repack our bearings as often as we like to significantly extend the service life of all our other parts

Bearings were fine actually. The clutch still works too. I maintain my rigs pretty frequently so I don't think it was a lack of that, maybe poor maintenance but deff not a lack there of lol. In fact, the diff was in perfect condition too. I did maintenance on that that a while ago when I changed out the diff housing. This is a Kraton 4s by the way V2 i think. It might have been the plastic sleeve around the drive shaft, I did notice that distorting a bit a week ago or so. Didn't think much of it at the time. We were just driving in the dirt and grass, nothing too crazy. Then, I smelled it. At first I thought it was the electronics from the very noticeable plastic smell. Luckily, it was actually plastic and not the electronics.

When was the last time you rebuilt the car and inspected/cleaned your bearings?

https://www.rcgroups.com/forums/showthread.php?4308293-Maintenance-Tips

Normally the car will "feel" different long before damage occurs... if the car is driving slower and/or temps are increasing with subsequent runs, then I suspect poor maintenance is the culprit. That includes regular inspection for worn/cracked parts that can trickle down and cascade to other parts.

A seized bearing can melt plastic on no time

Be thankfaul that all you damaged were a few plastic parts and didn't burn out your electronics!
https://www.rcgroups.com/forums/sho...eed-to-run-for-upgraded-electronics-in-my-car


*** UPDATE ***
Side note... I recently noticed a funny "whirring" sound coming from my engine on my full scale truck... it was approaching 100K miles and I figured the water pump was approaching its service life. Sure enough, within a week my engine over heated due to the water pump leaking fluid from a blown bearing seal. I was able to pour some fresh water in the radiator and took it straight to the shop to have the water pump replaced. In a perfect world, I would be able to replace those bearings in the water pump for a few bucks and could probably get another 100K miles on the truck, but that's not how the auto industry works... fortunately for us in the RC car industry we can clean and repack our bearings as often as we like to significantly extend the service life of all our other parts

And you are right, it did feel different. It was not popping wheelies like it should and it did not have the speed either. That's when I brought it in and noticed the smell.

 

[WickedFog]

Looks to me like your slipper clutch was too loose, slipped constantly, generated heat, and melted the plastic.

 

[bill_delong]

Looks to me like your slipper clutch was too loose, slipped constantly, generated heat, and melted the plastic.

I think you made the right call on that being the cause for this failure. I'm not familiar with the slipper on the Kraton, but I used to go through slipper pads often on my Traxxas Slash... it would get so bad that even tightening the slipper all the way would still slip too much. I probably had to replace the slipper pads every 12-16 hours of run time, never realized actual damage could occur by not replacing the slipper pads... the car just wasn't drive-able otherwise for me, ha!

 

[WickedFog]

I think you made the right call on that being the cause for this failure. I'm not familiar with the slipper on the Kraton, but I used to go through slipper pads often on my Traxxas Slash... it would get so bad that even tightening the slipper all the way would still slip too much. I probably had to replace the slipper pads every 12-16 hours of run time, never realized actual damage could occur by not replacing the slipper pads... the car just wasn't drive-able otherwise for me, ha!

@DavidB1126 I think had this happen on one of his Traxxas kits. I have seen it a couple times over the years. One of my old RC10's had the spur gear nut come loose. When I took the engine cover off, thinking my pinion grub had loosened, the slipper assembly was so hot I blistered my thumb.

The root cause may not have been the slipper was too loose, but a rock may have gotten in the motor module assembly and locked it up, causing the slipper to break friction. With that, it wouldn't take much more than a few blips of the throttle to get things smoking. Arrma kits are kinda notorious for this. That module is a terrible design.

 

[tntpoof]

no one noticed the rock wedged in last picture? so well maintained is not holding water (maybe like a sponge) several rocks and pine needles

 

[WickedFog]

no one noticed the rock wedged in last picture? so well maintained is not holding water (maybe like a sponge) several rocks and pine needles

That's why I mentioned a rock stuck in the spur might have been the culprit. Every time we run our Granite, which has the same module, there is debri that has to be removed. Sometimes it makes that module nearly impossible to remove. It's a stupid design. Using screws to hold that module in would have made it much easier to maintain.

 

[biggman100]

Any idea what could have cause this melt down? The housing around the spur gear melted onto the spur gear. Sucky. View attachment 164823

View attachment 164824


doh
why does this load two pics?

I've had a stock diff in a V1 Granite do that from a seized bearing, but, IIRC, there isn't a bearing in that spot.

 

[jakebullett]

no one noticed the rock wedged in last picture? so well maintained is not holding water (maybe like a sponge) several rocks and pine needles

Ha yeah that was from this last run. It had be a bearing. Nothing else makes sense. the plastic is melted all around that bearing. I replaced the entire assembly. Works great again. I had to 3d print the shaft cover thing because it did not come with either the clutch or the new drive shaft kit. What a shock! I like the orange cover, matches the ec5 nicely. I'll post apic in a bit.

 

[jakebullett]

here's the 3d printed shaft cover thing. Seems to work like a champ.