HobbyKing BSR BZ-222 gearbox by Schiksie

Last crawled date: 3 years ago

Here is a gearbox for a direct belt connection without the belt tensioner.
As most owners know the original gearbox has a big problem with the belt breaking.
The original design is from the_crack_fox who designed it to be CNC cut.
https://static.rcgroups.net/forums/attachments/3/9/3/8/8/6/a7856168-100-IMG_20150504_231729.jpg
I realy thank him for his design and stl file that i used to create this gearbox to be 3D printed.
Today i did the first testdrive and it's driving pretty good :-)
Must say installing it was pretty tight so i might have to move the holes that hold the motor plate just 1-2 mm. I removed the motor coverplate and after that installing it was more easy. Still some minor things i overlooked like the 2 front nuts that held the 2 screws just did not fit on because it was 2 close to the wall but with a little grinding i made it fit. I changed it in the stl file but have not printed that one yet so not sure the room i cut away is now enough.
The motorplate is held by 2 screws because the 3th hole falls in a spot where the belt is now running but it seems to hold up fine with one 2 screws in there.
I will still be making some small adjustments over time but for now this gearbox seems to be working great !
Belt i used :
6 mm 45 teeth 135 mm length.
https://nl.aliexpress.com/item/POWGE-Arc-HTD-3M-Timing-belt-C-132-135-138-141-width-6-9-15mm-Teeth/32818738308.html?spm=a2g0s.8937460.0.0.Nx8eaN
Printed mine in pla at 100 % infill. Also tried a PETG version but that seemed to had more shrinkage so parts did't fit to well.
Other parts you may need :
2 M3 20mm sunken bolts/screws
2 M3 30mm sunken bolts/screws
1 M3 20mm bolt ( normal)
1 M3 35mm bolt ( normal, i just cut a 40mm shorter)
optional >> sunken M3 bolt 10mm. This is for the hole with no nut.
6* M3 lock nuts.
Also maybe it's best to attach the shocktower with nuts also.
You will need :
2 M3 15mm sunken bolts/screws
2 M3 20mm sunken bolts/screws
4 M3 lock nuts.
Added a rev 1.1 with a straight line to hold the nut on the shocktower.
Update : 3-04-2018
After like 30 lipo's the belt is still holding in this 3D printed gearbox. I did break a arm that holds the wheelbar nut so i made a version 2.0. This one has stronger reinforced arms that should hold better in a crash. Also added a little window so you can keep and eye on the belt. Don't forget to print the cap ( printed mine with flex/nylon).
Update : 1-11-2018
Added a v3 version. Only some small adjustments, made holes that hold suspension balls a little smaller.
Update : 29-08-2019
Added a V4 version. Thinner walls since i did notice some wear on the belt because it was hitting the inside wall. Rear hole move a little so bolt and nut fit better. Reinforced wing holder.