Granite Guess Bickety was right about the sliding driveshafts.

[sadlerbw]

It’s kinda funny: Before this week, I only had one of the axle shafts on my Granite fail on me. This week, the other three all let go! It was like they all got together and decided to go on strike or something. All of them failed in the same way, with the ‘star’ in one of the joints popping out. Three of them had the outer joint by the wheel fail, and one had the inner joint fail. It’s just interesting to me that three of the four failed so close to one another.

I haven’t really tracked number of miles or packs, but I can say that I’ve had the truck for around 6 months. Given how much I run the truck 6 months isn’t terrible, but i guess I will now have to agree that the U-joints on these sliding axle shafts could user a more durable design. Maybe Arrma can work on that for the 2020 models!

 

[2015GTRBE]

Wait... what failed??? The metal pivots popped out from the plastic?

 

[sadlerbw]

Yep. The metal 'star' in the U-Joint popped out of the plastic 'ears' on one side of the joint. The first time it happened, I tried just popping it back in, but the truck didn't make it a full pack before it jumped back out. Those U-joints basically have small, metal pins fit into holes in the plastic parts. Keeping the pins small probably cuts down on friction so they don't need a bushing or anything to keep from melting the plastic, but it does put a lot of compression and bending stress on the plastic, and I guess it eventually loosens up enough that it can't hold the pins in place anymore.

I'm not sure what ARRMA could do about it either. The plastic has to be flexible enough that they can assemble the thing in the first place, so just adding more plastic or using a more rigid plastic may not be viable. They could just switch to dogbones and metal drive cups, but that probably costs more. A tricky problem, but one that ARRMA certainly should have on their radar, at least for the 3S trucks. I'd guess these sliders are probably plenty durable for the brushed trucks, but I can't deny that they are a weak point on the 3S trucks.

 

[BRUK]

Do the replacement drive shafts already have the M3 screw installed for the wheel axle?
Today I had the head of this screw shear off. Managed to get the rest of it out but putting a new screw in meant awkwardly bending the 'ears' to remove the U joint.

 

[Mongoose]

Do the replacement drive shafts already have the M3 screw installed for the wheel axle?
Today I had the head of this screw shear off. Managed to get the rest of it out but putting a new screw in meant awkwardly bending the 'ears' to remove the U joint.

Yes, they come with the screws.

 

[sadlerbw]

Yeah, those screws on the wheel axle are tricky. They loctite the crap out of them at the factory, and there is no good way to get any heat on them without melting the plastic parts.

 

[2015GTRBE]

Yep. The metal 'star' in the U-Joint popped out of the plastic 'ears' on one side of the joint. The first time it happened, I tried just popping it back in, but the truck didn't make it a full pack before it jumped back out. Those U-joints basically have small, metal pins fit into holes in the plastic parts. Keeping the pins small probably cuts down on friction so they don't need a bushing or anything to keep from melting the plastic, but it does put a lot of compression and bending stress on the plastic, and I guess it eventually loosens up enough that it can't hold the pins in place anymore.

I'm not sure what ARRMA could do about it either. The plastic has to be flexible enough that they can assemble the thing in the first place, so just adding more plastic or using a more rigid plastic may not be viable. They could just switch to dogbones and metal drive cups, but that probably costs more. A tricky problem, but one that ARRMA certainly should have on their radar, at least for the 3S trucks. I'd guess these sliders are probably plenty durable for the brushed trucks, but I can't deny that they are a weak point on the 3S trucks.

The ears are flexible that’s why. My guess would be to add glue or something to stiffen that up

 

[dillon_mitko]

Yeah I had this happen my BRCC about 2 months after buying it. Then it kept happening every run.... then I finally just bought the hot racing ones and haven’t had any problems since.?