Granite 4X4 BLX V3 - sudden clicking noise *FIXED + UPGRADE PARTS*

[fknrad]

Hey eveyone,

Hope you all are doing well!

My beloved RC truck suddenly started making a clicking / grinding / something seems out of phase in the there kindof noise. I am new to the hobby, but I made sure to take diligent care of the RC every time I was done with my sessions.

Yesterday I flipped the thing quite a few times trying a jump (I play in the snow). All of sudden I hear a clicking/grinding noise that follows throttle and intensifies with speed. I immediately turned everything off and went home. I’ve been looking for an answer to what the noise is, but as any noobs do; I can’t.

Did something come loose? Is something stuck in the transfer case? Did I grind a gear?

I’m very mechanically inclined (I own a Fiat 500 Abarth after all ), so I know my way around. Nonetheless, if there would be any kind souls here to guide me in this first troubleshooting, I would be ultra grateful. I don’t want to break the thing more than it is.

Thanks so much in advance for the precious help!

Cheers,

David

 

[RCBro80]

I would say there are a few options: pinion stripped the spur gear, input gear stripped the front or rear diff ring gear.

First I would pull the drive shaft, which will eliminate the front diff as the culprit. If the griding persists, pull the power module (motor + slipper), you can inspect the spur and check your pinion mesh. If that's all good, I would focus on the rear diff.. it's not that hard to pull out and inspect.

If the diffs look fine externally, there could be damage inside, but I think this is probably one of the least common failure modes in the drivetrain of the 3S line up (could be wrong).

Good luck, there's lots of people here who can help if you get stuck!

 

[aneft]

Hey eveyone,

Hope you all are doing well!

My beloved RC truck suddenly started making a clicking / grinding / something seems out of phase in the there kindof noise. I am new to the hobby, but I made sure to take diligent care of the RC every time I was done with my sessions.

Yesterday I flipped the thing quite a few times trying a jump (I play in the snow). All of sudden I hear a clicking/grinding noise that follows throttle and intensifies with speed. I immediately turned everything off and went home. I’ve been looking for an answer to what the noise is, but as any noobs do; I can’t.

Did something come loose? Is something stuck in the transfer case? Did I grind a gear?

I’m very mechanically inclined (I own a Fiat 500 Abarth after all ), so I know my way around. Nonetheless, if there would be any kind souls here to guide me in this first troubleshooting, I would be ultra grateful. I don’t want to break the thing more than it is.

Thanks so much in advance for the precious help!

Cheers,

David

My bet is it’s the pinion going to the ring gear. Most likely rear.

 

[RackwitzG]

I remember an advertisement slogan: Look in and find out.

 

[fknrad]

Hey guys,

Thanks for the quick replies!

I took a video of the truck running, and also of me turning the rear wheels by hand. The cracking noise is coming from the rear differential. I wish I could post them, but it is what it is.

I tried adjusting the slipper clutch, but that was fine (just a btw that I have looked at this). Nothing looks worn out on the motor and transfer case + driveshaft end points.

When the wheels are turned by hand, the cracking comes when the wheels suddenly have to stop and then go in the opposite way.

When the truck is running, the sound is terrible because of the torque ans thrust produced by the motor I guess?

I guess I broke the pinion gear in the rear diff? Is this common? Had the truck for about 2 months now.

 

[HanDy69]

Open the rear diff and find out, with the 3s blx platform is quite straightforward.

Mine did a similar sound (like metal grinding metal) and it was one of the motor bearingns.

 

[RackwitzG]

I not the superexperienced RC Car modeler, but this can happen. I suppose mostly when your on the throttle when you land. The jerk that goes through the drive chain breaks the weekest part.

 

[fknrad]

Welp! I guess there’s only one thing to do and it is to order new parts?

Pinion (input - as pointed out by RCBro80), gear is shot. Do I need to change the ring too since they ground together?

 

[RCBro80]

View attachment 125217
Welp! I guess there’s only one thing to do and it is to order new parts?

Pinion gear is shot. Do I need to change the ring too since they ground together?

Likely both are damaged, but you'd have to take a look.

BTW, that's not referred to as the pinion, rather its the input gear (as in: input to the diffs), specifically "HD input gear" as Arrma refers to it (because they also had finer pitch gears in the driveline of the older mega series).

 

[fknrad]

If this can help anybody else encountering the same scenario I did, here's a fix that ''should'' make the differential ''bulletproof'':

AR310772 Composite Diff Case BLX 3S
AR310885 CNC Mtl Crown Gear 37T BLX 3S
AR310886 CNC Mtl Input Gear 13T BLX 3S

The crown and input gear are CNC metal, and are made by Horizon themselves. One will also need a composite diff case to survive the metal parts.

I am doing both front and rear at the same time because I like to think both the parts are operating under the same rotating assembly; although the rear gets the hell beaten out of it much more.

If one does both at the same time, one will need x2 of all the parts mentioned above.

I bought them from a distributor in Ontario (I am in Québec) - Horizon is out of stock on the diff case at the moment.

Two sets of these parts ran me around 163$ish (Canadian dollars).

If this had already been highlighted in another thread, sorry to repeat!

My bet is it’s the pinion going to the ring gear. Most likely rear.

If only you had bet money on that! You were right on it!

I would say there are a few options: pinion stripped the spur gear, input gear stripped the front or rear diff ring gear.

First I would pull the drive shaft, which will eliminate the front diff as the culprit. If the griding persists, pull the power module (motor + slipper), you can inspect the spur and check your pinion mesh. If that's all good, I would focus on the rear diff.. it's not that hard to pull out and inspect.

If the diffs look fine externally, there could be damage inside, but I think this is probably one of the least common failure modes in the drivetrain of the 3S line up (could be wrong).

Good luck, there's lots of people here who can help if you get stuck!

You were also very right, thank you very much for your input!

 

[HanDy69]

Glad you find it out, you will be bashing in no time

 

[fknrad]

Glad you find it out, you will be bashing in no time

Next week-end I'm back to bashing for sure!!