Nylon Spur Gear for Spider Center Diff
 

Ok,
So, as we all know, Kyosho makes a nylon center diff spur gear, but it is a 4 hole, not a 6 hole, like the Ofna spider diff needs.
Due to my using a Novak HV4.5 motor for my conversion, I am under the impression that I need to undergear my buggy so I am going to use a 9T gear, but that gear is not so hard, and I would be replacing often with a new one.
So...
Via, a drill, a dremel and some JB weld I bring you....
http://mcclive.com/files/rc/nylonspidergear.jpg
I matched up the steel stock gear to the nylon gear, retained two of the original holes, I then drilled out 4 new holes, and covered the two old holes with JB weld.
Additionally I dremeled out the inside of the spur to match the stock (stock is sunken in, kyosho is slightly raised).
Then to account for the slack in the outdrive staft I put a brass washer between the bearing and the fatter part of the outdrive.
Because I drilled my own holes I have to go back several times and smooth out those holes so that I would get a good seal once the diff was filled with fluid. I also put some PTV silicone on the diff to replace the little orange o-ring gaskets.

I appologize for the shine on the diff in the picture, I hadn't cleaned all of the spilled diff fluid off at that time (10k wt diff fluid doesnt seem to like to come off to cleanly).

It has been sitting in my kitchen for almost a week and has not leaked, Hopefully my 0610i charger will show up today, and I can actually test everything out.

Nice work! Let us know how it works out when you get to run it.

I got outside and ran with the modified nylon spur and it ran fine. I only ran for around 10-15 minutes, but there weren't and fluid leaks that I have been able to find.

Update on the modified spur gear:
It broke....
The end that the bearing goes on snapped off due tothe nylon being to thin (because I had to dremel out from the center). In order for the spur gear to be strong enough I would need to have some sort of spacer/extended diff cup so that I wouldn't need to take out so much material from the spur.
If I figure anything out, I will post.

it was looking promising.. :(
is there any other options for hyper spiders?

just get a hardened pinion? Or harden your own by heating it to glowing and quenching in oil.

hi there paralyzed, ive got an oxy welder at school, that i could easily heat up a pinion. this would make it much more brittle though, would cooling naturally be better, just leave in in a vice or something or would oil be better... not exactly great at chemistry, i just know it becomes really brittle!!

would it be suited when using a metal spur or what?

sorry for these questions,
ryan

Depending on the material the pinion is made off, the heat and quench may or may not work. I use a torch, and 10w30 motor oil. Slowly heat it up till it is red, taking care to not melt the metal. I use a metal can with the oil in it. Carefully knock the pinion into the oil, be careful it will smoke and hiss! Do not try to grab it with pliers, as this can damage the hot metal. I use a vise, or anvil to heat on, the place the can next to it and tap the pinion in with a screwdriver.

Let it cool, and do it again. The second time will help harden it further. I had success with the emaxx internal gears that I made into pinions, but they are decent steel that can be hardened. Trial and error will show if you pinion is made of decent material...

are certain brands better than others? are rrp and good? hpi? those 2 are the ones available @ my lhs... also, are mikes ones suitable to do it with? i think id just let it cool slowly, then redo it. or is it needing to be cooled quickly... thanks:)

The quench in oil give it the hardness.

For the price, just get a hardened pinion from mike. They are rr pinions, and are extra hard. They work fine, and will last.