View Full Version : Transposed brush mod for the ATOMIC bb can....

2007.01.04, 07:23 AM
OK. This mod is still in the early days of testing, but it's so easy to do and is showing some promise so I'd thought I do a quick write-up for it. The goal being that I hope someone else tests this out and see what their results are like.

The aim of this mod is to reduce drag friction from the brushes onto the commutator. By finding out which way is always forward we can tune the brush setup to take advantage of that. My main assumption here is that a brush that is being "pulled" by the commutator will retard less than a brush that is being "pushed" by the commutator.

You need to the following to do this mod.

1 x ATOMIC bb can based motor (be it ATM pre-made ones or homemade).
1 x ATOMIC motor brush set (AR008)

In the brush set you get 2 pairs of brushes.


In the pic below, use the left pair if you're running a mini-z of some type. I've confirmed on all models but the F1 that the left brushes will result in the goal of being "pulled" when in the forward throttle direction. The XMODS EVO is the other way. Not too sure about Gen1 XMODS.


To get an idea of what's going to happen, orientate the brushes so one is shown facing down. Note in the picture below, the armature will be moving clockwise to achieve forward.


Since the other brush is transposed and aligned the other way, you need to cut of the terminal or it will get in the way of too many things.


Here's a picture of the transposed brush and it's assembly. Notice that I have put a dab of solder on the top blank area of the brush to accomodate the motor wire.


All that is left is to install some noise supression caps (eg: 103 or 104 values) and then break it in. I dry break in motors for 20 - 30 minutes in the direction they are to go forward. DO NOT BREAK THIS MOTOR IN THE OTHER WAY (REVERSE). Just break it in using 1 x 1.2V AA battery or similar.

Once it has been broken in AND caps have been installed, it's ready for install.

In my mr-02 below I have also added some heatshrink around this motor to protect it. My main running/racing surface is concrete, dirty bloody concrete. This heatshrink over the end cap thing seems to be working well.


So there you have it. So far I have noticed an increase in top speed. It is also a lot more quiter than when it was the regular brush setup. Not too sure about torque, I think it has increased but not by much. More tests to do. Well see how it goes. I would like to see other people try this mod and see if it's worth it. I am very interetsed to see your results.



2007.01.04, 01:07 PM
this is a pretty straight forward mod, and in theory, it will be much better for performance because the brushes are now 180* from each other rather than the 170* from them mounted on the same side of the can.

2007.01.07, 08:53 PM
wow, nice work. in theory, it should wear consistently and evenly as well. I will definitely do this mod to my t2 when it arrives. One question though. I know that the t2 and z2 (maybe some others) use one silver and one carbon brush, which one needs to be replaced and modified? sorry if the info is elsewhere, but I couldn't find anything with the search. Once again, nice work ph2t, I'm sure this mod will become very popular.

2007.01.07, 09:01 PM
I just looked up the t2 again, and it seems that it's the silver brush that needs to be changed.