VXL Drive Shafts
: Part# TRA6852X (http://www.amazon.com/Heavy-Duty-Rea...8983150&sr=8-1
) The installation of new drive shafts are also a must with an upgrade to a brushless system. You will want to order 2 of the item above if you want to replace both drive shafts, which I would advise doing. I replaced mine while doing the metal transmission gears, since I already had the entire transmission housing out of the truck. Letís start with the replacement of the half shaft portion that connects to the differential (the big ďgearĒ that sits inside the transmission housing). First, obviously, youíll have to take off the old shafts. They are held on with a small hex bolt (I donít know its official name). Itís a small bolt that goes through the shaft. You simply unscrew it, then pull the unthreaded portion out of the shaft, and pull the plastic half-shaft off the differential. The new shafts that you put on will have a few modifications made to them before they will fit properly. If you look inside the new shafts, you will see two flat ďwallsĒ of sorts on the inside where youíd fit the shaft of the differential in. To fit this onto the ECX differential shaft, which is completely round, unlike the Traxxas differential shafts, you will have to drill out these two flat edges on the inside of the shaft. I used what I believe is a 5mm drill bit to do this. Whatever size bit you use, it should fit perfectly into the round portion of the shaft, as you donít want to make this part any larger in diameter than it already is. I found that I also needed to drill a bit further back into the shaft as well to get it to fit all the way onto the differential shaft. What I mean is that with the drill bit in the half-shaft, drilling out the two flat sides, drill a bit further back. This allows the differential shaft to fit properly inside and will allow proper alignment for the shaft hex bolt and the hole it goes through. Be sure not to drill too much out, though, as you donít want to drill a hole all the way through the back of the plastic shaft. After this, youíll want to sand down the ďlipĒ on the edge of the half-shaft that will be pointing towards the transmission housing (see attached picture, figure A.). Youíll only have to sand it down about 1mm or so, for it to fit properly on the differential shaft. Sand a little, test fit, sand more, test fit again. You want to avoid sanding more than needed. Once you see the differential hex bolt holes aligning perfectly and the bolt fits through the hole, youíre golden. Repeat the process for the other side.
Now, for the installation of the half shafts that connect to the wheels. The only modification that needs to be made here is to take the same drill bit used for the steps above and slightly expand the holes that go through the stock wheels and the hex behind the wheel so they fit onto the new shaft (see attached photo, Figure B). The stock ECX shaft had a small portion that was not as large in diameter, so the wheel and hex fit right on. The Traxxas drive shaft doesnít have this. Once complete, you can slide the new shaft through the bearing on the suspension arm and, if necessary install a few washers (http://www.amazon.com/gp/product/B00...00_i02_details
) to remove the extra space between the bearing and the small pin in the shaft. NOTE: The installation of washers is very important. I recommend installing at least one between the small pin that goes through the axle that sits inside the hex. I had an issue where the hex was rubbing the body of the car and kept causing my tire bolt to come loose and, subsequently, my tire to fall off. Don't forget this step! For more information, you can reference this YouTube video: http://www.youtube.com/watch?v=f_uPtpum_Bo
or the URC thread: http://www.ultimaterc.com/forums/sho...d.php?t=128675
(Last edited by EcxTorment1985 : 2.14.12 at 11:17 pm)