Granite Final Build? I think my Granite upgrades are done

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, and others.
For any 3s/4s Arrma you need these parts:
https://www.arrma-rc.com/en/product/center-brace-pin-2/ARA320529.html
https://www.arrma-rc.com/en/product/center-brace-mount-set/ARA320528.html
https://www.arrma-rc.com/en/product/center-brace-rubber-dampers-3/ARA320530.html
https://www.arrma-rc.com/en/product/center-brace-connectors-2/ARA320531.html
https://www.arrma-rc.com/en/product/cap-hd-screw-m3x10mm-10/ARAC9711.html
https://www.arrma-rc.com/en/product/nylon-nut-2.5mm-4/ARAC9761.html

For short wheelbase models (Granite, Vorteks) you want the 200mm center brace bar from the Outcast 4s
https://www.arrma-rc.com/en/product/center-brace-bar-200mm/ARA320533.html

For long wheelbase models (Senton, Big Rock) you want the 240mm center brace bar from the Kraton 4s.
This length will also fit a Typhon chassis, but I've been told the center brace bar doesn't fit under the low Typhon body.
https://www.arrma-rc.com/en/product/center-brace-bar-240mm/ARA320532.html

In the 4s Outcast and Kraton, the center brace mounts are held in place by the 4s body mounts. I don't think you need the 4s body mounts though. There are other ways to hold them in place. Some drill holes for screws. I wrapped Gorilla tape around the 3s body posts to make them thick enough to hold down the center brace mounts. (This isn't a concern in the Vorteks, since it has the center brace mounts integrated into the shock towers.)

View attachment 214819
Thank you!! Exactly what I needed to know.
 
I just found out the shock shaft hole on Arrma pistons is slightly larger than on Tekno pistons. The Arrma pistons worked great for over a year in my Tekno SCT410 shocks. But today, a shock shaft went completely through an Arrma piston from a hard landing. So, Arrma pistons are not recommended for Tekno shocks.
 
By reducing rear end flex, the 4s center brace avoided stripping the rear diff and input gear for a long time. However, I eventually stripped them again. Got the metal rear diff and input gear. So far so good.

I also re-tried the chassis block that comes with the M2C motor mount. The last time I used it, I stripped a new rear diff and input gear after 2 jumps. But I didn't have the 4s center brace at that time. I was thinking both together might work well. However, it took one session to shatter the rear slipper housing and crack the chassis in two places. The cracks in the chassis were in front and behind the chassis block. I've NEVER cracked there before and it wasn't even from a crash, just a rear heavy landing.

So, now I'm convinced that by stiffening the middle of the chassis, the M2C chassis block creates leverage points that force the areas in front and behind to flex even harder instead of flexing evenly. The M2C motor mount itself is great, it has stayed straight with or without the chassis block. So, no reason to use the chassis block, it's just extra weight and nothing but trouble. (Custom RC Upgrades in Europe and KC-RC in Canada sell 7075 aluminum motor mounts for less than the M2C motor mount with chassis block.)

I also fried the 3200kv motor, so I tried the BLX3668 2400kv motor that comes with the 4s line. Paired it with an 18t pinion to make up for the slower rotation. Ran it on 3s with the stock BLX100 ESC. Overall, it performed really well and runs MUCH cooler than a stock 3200kv with 15t pinion. I'm guessing top speed may be lower, but for ramp bashes, I didn't notice any change in speed. With more torque, it may even provide better launch.

Finally, I thought the lower kv was preventing me from pulling triple backflips, but later found out my slipper had loosened up. After re-setting the slipper, the 2400kv motor with 18t pinion triples on 3s without a problem. I'm giving up on the plastic slipper nut. At first I liked it, but over time it's failed repeatedly. I've gone back to loc-tite.


 
Last edited:
Hi @GRC,
Great thread! Thank you for sharing. I am away from home and bought a Granite Boost to build into a stunt truck and use evenings and weekends.

Your build thread is a great resource and very much appreciated!

Thank you
 
Back
Top