Granite Granite 3s bent motor mount, front motor bearing destroyed

[slick2500]

Hot off the build plate... Rear motor bracket

View attachment 46949

I think the 6s rigs could benefit from one of these as well.

 

[Popokesmoke]

I would guess that yes, the bent motor mount caused the pinion to sit at a weird angle to the spur and put a lot of side forces on the bearing which caused it to blow up.

I would also guess that you ran into a tree/curb/car/whatever and bent that motor plate due to bad driving and I don't see why you would think Arrma should warranty a part due to bad driving.

Haha I'm reading post and just yesterday I smoked a curb and bent my motor mount and thought Warranty.. then I thought nah I hit a curb head. My bad. Lol.. I was beating on it to get it straightened plus drilling the preset holes longer to get a better gear mesh. Even tho the motor plate is not ? making that gear mesh less tight and it's running smother then before.. gears are running straight too ?

 

[GRC]

Granite locked up on me today and when I got home and started narrowing things down, I noticed that it's the motor that's locked up solid and motor mount is bent crooked. Pulled the motor apart and the front bearing where the shaft comes out falls to pieces. Do you guys think the bent mount caused that bearing to fail? Has anyone gotten Arrma to replace their motor mount and do you thinky they should/would replace my motor? I got the truck in June for fathers day, so it's only a few months old. Is there a brace or mod that can be done to prevent the mount from bending?

I had a failed motor bearing that crumbled so badly I couldn't get it out. The motor itself was fine, but unusable since I couldn't get the bad bearing out. Horizon Hobby sent me a full replacement motor under warranty.

Hard to say which happened first, bent motor mount or bad bearing. Bent motor mounts are often from bad hits, which wouldn't be covered under warranty. But in combination with the bad bearing, I would put in a warranty claim for both the motor and motor mount.

You can also try to bang the bent motor mount straight. If the motor still works and you can get the bad bearing out, a new bearing may be all you need. Send the photos and put in a warranty claim as well.

That motor bearing going bad every few months is a known issue. The stock bearing gets dirty and locks up. You may want to take steps to prevent it from happening again. Just rubber sealed bearings may be enough, I went the whole nine yards.
- Rubber sealed motor bearings. (Getting the stock ones out and getting the new ones in not easy. I needed a bearing pusher, the "bread trick", and a combination of heat and freezing.)
- HPI Gearbox Spacers - Part #101291. I put one shim in the back of the slipper so it doesn't rub the power module and create that black dust.
- I sealed up the power module as described here: https://www.arrmaforum.com/threads/help-me-upgrade-my-senton-3s-for-sand.20322/post-297587 This is a great tip. It keeps dirt and debris out of the power module.
- Used an o-ring and washer to seal off the motor as described here: https://www.arrmaforum.com/threads/blx-motor.20999/page-2 Even with the shims and sealed power module, the gradual wearing down of the slipper gear and pinion still creates fine dust which can get into the motor.

 

[DoNoHarm]

The front bearings in these motors are known for going bad really fast.

It is highly unlikely that the mount bent then caused the bearing to explode.

Most likely what happened is the bearing locked up and the force from the motor locking up caused the mount to bent, if that is the least of the damage then I say you came out good. When the motor locked up mid backflip on my Outcast it took out both front and rear diffs, the crown and pinion gears were toast, the internal gears in the front were toast and I broke a pin in the rear.

? holy crap dude that thing ruined your drivetrain

 

[slick2500]

? holy crap dude that thing ruined your drivetrain

Yeah it did.

 

[GraniteFox]

I think M2C racing is coming out with a motor mount but I do not see it on their site.

 

[slick2500]

Okay gentleman I cleaned all the unnecessary banter out of this thread, keep it on topic or do not post.

 

[fish5man]

Same boat here .bent motor plate one after another .installed hr plate no issues yet .I do seriously beat my truck 20 ft jumps are normal .I’d be intrested in a rear motor bracket .also a must if you jump big is suspension limiters and proline sus arms .otherwise metal gears through out .truck is pretty much bullit proof with all that .alluminum shocks without the limiters blow apart just like the cheap arrma ones if you land wrong .and GPM drive shafts are trash save your cash .

 

[GraniteFox]

I think the only real solution is the m2c mount set if you send it really hard. Hr plate is better and I would like to try the new 6mm Arrma mount….. seems to me you need a support system around the motor can itself. Even with all the sealing you still need to open it up and check it about every 15-20 packs. The motor bearing will fail. If you catch it before it explodes it’s an easy fix.

 

[PatMarcus172]

In terms of motor mount - the M2C version or the CRCU one.
I hit a kerb at full speed yesterday (finger slip while carrying too much kids crap) and of all the things that broke, my CRCU motor mount wasnt one of them.
Not even a scratch.

 

[1.21 Gigawatts]

There is a hole in the chassis right next to the mount between the motor and chassis lip. Seems that a simple triangular brace could be placed here to support the motor mount and prevent it from bending. Maybe a 3d printed bracket with an interference fit where a protrusion on the bottom of the wedge pops into the hole, or a simple piece of aluminum threaded for a screw.

 

[jondilly1974]

There is a hole in the chassis right next to the mount between the motor and chassis lip. Seems that a simple triangular brace could be placed here to support the motor mount and prevent it from bending. Maybe a 3d printed bracket with an interference fit where a protrusion on the bottom of the wedge pops into the hole, or a simple piece of aluminum threaded for a screw.

Or just put some rubber orings over the end of the motor can.

 

[1.21 Gigawatts]

Or just put some rubber orings over the end of the motor can.

Is the problem the weight of the motor twisting the mount, or does the entire mount bend forward on the unsupported (motor) side during a frontal impact? If the former is the failure mode, it would seem that the heat sink on the V3 already addresses the issue since the fins extend to the chassis floor.

 

[Velodromed]

Is the problem the weight of the motor twisting the mount, or does the entire mount bend forward on the unsupported (motor) side during a frontal impact? If the former is the failure mode, it would seem that the heat sink on the V3 already addresses the issue since the fins extend to the chassis floor.

Look closer, there is a small gap under the heatsink. I went with the o-ring idea and it fits just right.