Aluminum Idler Gear

One of the more common tasks that involves opening the transmission is to replace a stripped idler gear. If you have a powerful modified motor, I would highly recommend that you purchase the Aluminum Idler Gear. The plastic idler gears do not last long, and the aluminum one is a worthwhile investment. You can ignore the information about only using the aluminum idler gear with the Delrin Top Gear. First of all the Delrin Top Gear can be hard to find and even if you do find it, it then becomes the weak link in the transmission. The only reason to run it anyway, is to prevent radio interference from two metal gears running against each other. As long as you apply a light coating of grease between the stock top gear and the aluminum idler gear you should have no problems. I know of countless people using this method, and I run the aluminum idler gear with the stock top gear on four Stampedes with no adverse effects. I've found that both the Traxxas Silicon Grease and MIP's Differential Lube work well for this purpose.

To replace the idler gear follow the instructions to disassemble your transmission and then remove the stock plastic idler gear. Remove the bearings from the plastic gear and then put them into the new aluminum idler gear. Then place the aluminum idler gear into the transmission.

One other thing I should mention. I've noticed recently that several people have been complaining of problems getting their bearings to fit into their aluminum idler gear. In my opinion I do no think this is the fault of Traxxas in the manufacturing of the idler gear as it comes from a mold and the gears should be exactly alike. I believe this is a result of slightly different tolerances between bearing manufacturers. A 5x11 bearing from one company make be a fraction of a millimeter bigger than the 5x11 bearing offered by another company. I'm using Dynamite Red Seal bearings in my aluminum idler gears and I have not run into this problem. I also haven't heard of anyone running these bearings having any problem getting them to fit in the aluminum idler gear either. So you may want to consider this if purchasing bearings to use in your aluminum idler gear.

If you have already bought the bearings and are experiencing difficulties getting them to fit, you might try putting the aluminum idler gear in the stove and let it warm up. This will cause the idler gear to expand, making the opening for the bearing slightly larger. Be careful when removing the idler gear from the stove as it will be very hot. You can also place the bearing in the fridge or freezer to cool it down and make it contract slightly. The differences in the expansion and contraction of the two parts should help you assemble the idler gear and bearings.

Notice the difference between the two idler gears. The plastic idler is on the left, while the aluminum is one the right.

The bearings will simply pop right out of both sides of the old idler gear.