The gearbox was one of the first things I took apart. I wanted to see how the most important part of the car looked inside. This would be similar to examining the heart of a patient if you’re a doctor. I verified that the car was indeed not an Edinger because it had only one spring clip for the gear shaft attachments. The outdrive shaft was held tight (or not so tight) by a nut and not by the Edinger-style spring clip. In this particular gearbox there were at least three major problems. The first two problems were that both of the shafts held onto the aluminum center plate were not secure. They were both wobbling around. The third problem was that the independent outdrive halves, which are supposed to have two ball bearings installed each for rigidity, only had the flanged outer bearing installed. The excessive slop in the gearbox, caused by loose gear shafts and caused by lack of rigidity in the part that gets a lot of torque, resulted in wear in the aluminum plate holes that hold the shafts in place and resulted in excessive wear in the two plastic idler gears. The idler gears were so badly chewed up that new ones had to be ordered, coming from the re-release Associated parts selection. To secure the outdrive shaft to the aluminum plate the nut was tightened with a substantial amount of torque after putting red thread lock onto the nut and threaded end of outdrive shaft. As for the idler shaft, instead of using the spring clip, a flat clip was used instead. The spring clip is nothing more than a flat e-clip that is bent in an arc. The particular e-clip is a 3/16” e-clip that can be found in U.S. hardware stores. I decided that more strength in the idler shaft would be had by fabricating a shim that would sit between the aluminum gearbox center plate and e-clip. Shaving off a few hundredths of a millimeter at a time I filed a shim to be just the correct thickness to provide a tight fit, anticipating that an even tighter fit would happen once glue was applied to the shaft flange on the other side of aluminum plate. Reaching this ideal thickness I then applied JB Weld to the shaft flange and re-installed the shim and e-clip. The assembly without glue was holding securely enough for all practical purposes but I decided that the addition of glue would make the assembly even more bulletproof. Heat is used to relieve both red Loctite and JB Weld epoxy. Not an excessive amount of heat is needed to de-bond these substances; there is no danger of melting the aluminum plate or steel shafts when reaching that temperature.
The inner non-flanged bearings were missing (as mentioned earlier) on the outdrive halves and were sourced. We made sure to use period-correct metal shielded bearings in all places where bearings were missing or needing replacement. The internal clip securing the ball bearings in place is a 3/8” internal housing ring that can be found at U.S. hardware stores. I assumed that removing the original housing ring was nearly impossible without damaging it, and instead of spending too much time assuming the contrary I decided to go with the assumption that I would be visiting the hardware store in order to find this part.
I didn’t take photos of the inside of the gearbox but it’s quite beautiful. The aluminum gearbox plate was sanded with 1500 grit sandpaper to restore it to looking brand new. The original felt seals were intact and in pristine condition on the original car and were re-used. The four long black steel #4-40 socket cap screws holding the gearbox together were put away and similar screws made from 7075 T6 aluminum were used, in plain aluminum finish. The metal gears (outdrive halves and spur shaft gears) had serious burrs on the edges, enough to cause damage to the brand new plastic idler gears. A lengthy period of time was spent de-burring these metal gears with a small file, at the outer edges of metal gears. This must have been a standard feature on all early RC10s, namely that in order to be able to sell such a cool toy for only two hundred bucks some shortcuts in machining processes had to be taken. Black thrust bearing grease was used on thrust bearing and clear diff lube was used on diff balls, in very small amounts of course. The original spur gear is in great shape. This isn’t the 48 pitch re-release spur gear. It’s the original large tooth gear. Finding a good pinion of the same pitch will be fun – luckily I have at least three in my drawers. Instead of using double-sided tape to dust-proof the bearing that is visible on left side of the gearbox (as per Edinger instruction manual), a semi-circular piece of very thin Lexan was cut out and glued on using Shoe Goo. A touch of Shoe Goo was also used to keep the white plastic left felt dust shield cover from falling out, even though it was already holding relatively snugly all by itself. The aluminum diff spring receptacle/plate had dents in the cylindrical section that receives the diff spring. I carefully bent the aluminum using a hard cylindrical object of slightly smaller diameter to restore the original shape. Finally, a #5-40 6061-T6 aluminum locknut with purple nylock material holds the diff assembly in place with a truly beautiful touch.
The outdrives are held onto the gearbox plate with button head screws (still steel on this car – but these screws can be removed without disassembling the gearbox). The instructions have you put a 1/16” thin nylon washer next to the button head screw, so that the nylon washer sits between the button head screw and the dog bone. Again, an appropriate nylon washer in the correct color was found at local hardware store. I compared the newly sourced nylon washer with originals that I had sitting around from thirty years ago and they’re very similar.
(Continued in next post.)
|