Mrowka

My only experience with eBay special alloy parts is with some universals that I fitted to a rather hot Kyosho Javelin. They cost maybe 1/3 of what genuine Kyosho equivalents cost and lasted a few months. Under the circumstances, probably better than I had a right to expect. FWIW, genuine Kyosho universals fitted to another Javelin are still going strong. YMMV.

I have put Brat tires on Optima (not Turbo Optima) wheels.

I believe that the OG Optima/Javelin offered something similar. You could probably get away with it on loose dirt or grass, just as a dedicated 1:1 mud bogging truck may have different gear ratios in the front and rear - if you were to drive that on tarmac, you'd quickly blow up the transfer case from windup.

You'd think that Ford would be thrilled at the prospect of free advertising.

FWIW, "Grom" in Russian means "thunder"

My Fox originally came with 3D printed gears. I probably blew up the original gears more often than the 3D printed ones, but the originals were a touch smoother.

They do sell front and rear gold shock sets (as well as various spring sets) but the shocks have been hard to come by lately.

Five cars. One of which is Tamiya, the others are Kyosho. Countless helicopters.

Sorry, Optima, not Ultima.

So I can just use Turbo Scorpion tires/wheels on my Ultima?

Well, my Fox definitely likes to wheelie.

Get on eBay and you can get a flysky transmitter for less than $90, shipped. I have used several, new and used, and all have worked flawlessly to date. Hobbyking and Banggood also sell rebadged versions of these radios. Speaking of, Hobbyking/Turnigy/Banggood batteries and servos are usually fine if you are on a budget. I agree that steel pinion gears and ball bearings are good ideas.

What am I trying to do? Make money or make Mrowka happy? What kind of time horizon are we looking at here?

Keep in mind that the Spektrum radios use a semi-proprietary binding protocol (DSM2/DSMX), so make sure your receiver is a DSM2/DSMX model. Also, you can repair a balsa wood airframe, but it will never be as good or as pretty as new. That's one thing I love about helicopters - they are modular, so even a helicopter that looks like it was owned by someone who really doesn't like helicopters all that much can be made as good as it was from the factory.

I'd like Tamiya to provide consistent parts support for the buggies it already reissued.