Sorry about the delays guys, I have been working on it but still can't get it perfect. It seems to drive the wheels ok, but binds quite a bit. I did a little testing today in my lounge room and the motor didn't get too hot so it isn't too bad. This is what I have done with plenty of pics to show details:
First, these are the gears I was working with
Standard - 39T 17T
Yokomo - 40T 17T
Active Hobbies Stage 1 CS Kit for Yokomo SD - 36T 20T (no pic)
Active Hobbies Stage 2 CS Kit for Yokomo SD - 43T 13T
To start I didn't want anything that was overdriven too much at first, so I just used the Stage 1 kit (36T, 20T) in the rear diff. If I worked out correctly this would give me about an overdrive ratio of about 1.3. As previously mentioned there was a need to customise the gears to make them fit a spool as they are designed for ball diffs.
I had to pull out the die grinder and cut off the rear shaft on the bevel gear and also cut in a slot for the retaining pin to fit into.
There was also a need to increase the size of the inside hole and grind off the inside of the teeth on the ring gear so it fit onto the spool mounting position. I have also added 0.2mm of shim on the inside of the ring gear against the spool mounting position. Just a note here, I am not the best at using the die grinder so my work isn't great, this may also be contributing to my binding issues.
I then lubed all the bearings and gears and put it all back together.
I am still to do any real driving tests, but from driving it in my lounge, it seems to be ok. Depending on how it drives on the track, I may look at putting the Stage 2 kit into the front diff and put standard gears into the back for a ratio of about 1.45 and see how it goes. I will be doing my first real testing on Saturday this week and will let you all know how it goes.
Cheers
Chris