As days of racing take theie toll on your newest electric speed in a can, you tend to see a major loss in performance both in off the line power, and in over all high speed. You can clean the motor with the usual spray and take a comm stick to the brushes, but this will only delay the inevitable. When that day comes, and that new motor will no longer push the car, you say to yourself, this is such a waste. The magnets are still good and the can is in good shape as well, but the "comm" (commutator) has a rut in it the size of the grand canyon. But did you know that you can return that motor to its tip top shape with no more than a half hours worth of work?

Above: This is a shot of all the tools needed for the big job at hand.

There is however some expensive equipment needed to do this electro-revival from the dead including first and foremost, a comm lathe. Comm lathes should be sold by the gram like gold as far as I'm concerned. These allow you to return the motor back to a brand new condition, if not better. You'll also need a pair of needle nose pliers, some screw drivers, and different oils such as comm drops, bearing/bushing oil, and a good cutting oil. A little motor spray is useful as well. That's all you need to have a nice little motor repair shop on your own pit table.

1. The first step in the process before us, is to remove the motor from the car.

Above: Our engine will come from this B3.

2. the next step is to mark the can with a marker so you know the direction and position of the endbell relative to the can itself. For example just knowing that the diode on the motor below is on the label side of the can helps out a lot. The next thing is just to mark the endbell screws position for timing. This is not needed for closed can stock motors though, since to cut those you don't take off the endbell, you cut through it. For our demonstration, we are going to use a rebuildable stock motor as it is very similar to a modified motor. The process for a fix endbell stock motor is very similar however, and this article should prove to be helpful for that task as well.

Above: Here is our rebuildable stock motor in need of a new comm surface.

3. Now take off the springs that hold in the brushes in there hoods. Sometimes these guys can be on there nice, so used the needle nose pliers if you need to. Some motors these days will have a softer spring on one side of the can than the other, so be sure you know where each comes from.

Above: remove the brushes, and check them for discoloring on the ends.

4. Now lets give that motor a good washing of motor spray and clean things out a little. Now is also a good time to check your brushes and see if they are burnt at all. If they are, replace them now so when you break in you cleaned up comm, they will be able to break into the new smooth face of the comm.

5. Now we can disassemble the can. Lets take off the screws that hold on the endbell as shown in the picture below.

Above: Unscrew the endbell screws, but note your timing first.

6. Now remove the endbell and armature. Be sure you don't loose any of the shims that are used to space the armature in the can. In the photo below there is 2 on the top, and one on the bottom. Each motor is different on the spacing, just keep it at the factory placement and everything will work fine. Now that silver ring is what determines the timing. Rotate this ring till it comes out.

Above: Note the shim in the endbell, don't lose that, and now remove the silver ring inside.

7. From here, we get to set up the armature for the lathe. Put the arm on the lathe and see if there is any side to side slack. If there is, then you want to pick up as much of the slack here will some spacers on the ends of the shaft like in the picture below.

Left: This is the lathe for a mod motor, but we will use it for a rebuildable stock.

Right: Make sure there is no slag side to side and use some shims.

8. We can now set up the lathe with its 4 cell battery, and lube the two points at which the armature sits on the lathe with a little bearing oil.

Above: Use some oil in the grove to keep that shaft in good shape for the bearings/bushings in the can.

9. Now we should put on a little cutting oil for the comm, and then we get to use a marker on the surface of the comm as it spins. This is done so that when you cut the comm, you can see if you get the deepest rut. If you make a cut and still see the marker, then you need to cut a little deeper. The key here is to only cut off what you need to. You should be able to get 3 good cuts out of a comm before you can't cut it anymore, unless you tend to cut to much each time.

Left: Be sure to reverse wire!

Right: Use the marker while the armature turns, be sure to mark the entire comm.

10. Also, before you cut, make sure you have your slave motor on the lathe wired backwards. Yes, this is a common mistake by many, however, you need the motor to run in the opposite direction, so wire it backwards.

11. Now you can cut. Slowly have the bit cut thin layers off. It should take you around 15 seconds to make a sweep across the surface. If you still see blue, then keep cutting.

Left: Take your time here, and use the 15 second rule!

Right: There is still a hint of blue here, keep cutting.

12. When your done, your new comm should have a flat shinny surface. If it does not have this kind of a finnish to it you should go back and make sure you used cutting oil. Also, take a small knife and make sure the 3 groove on the comm itself are clear of all debris.

13. From here you just need to reassemble the motor making sure you put all the shims back in there same place and if your using a mod motor, make sure your timing is set the same way it was. Make sure you hose everything, except the comm, off with some motor cleaner, and oil everything back up. Use some comm drops on the brushes especially if your putting in new brushes now. This will help everything break in correctly. If you are a true die-hard, you can hook up a little 4 cell battery pack and break in the motor for about 30 seconds. This will make that motor ready to rip on the track. Good luck!