TycoLover

That's a neat setup. In my case I'm trying to do sort of the bare minimum to make it a functioning car again... Not looking for a whole lot of improvement. I'd complain about the cost of the set on Shapeways, but I just spent most of my Saturday doing the cad work to be able to print a new front plate / bumper assembly, so I must not value my time much.

It looks like we're sort of getting there, doesn't it?

Either style of tire would be fine. I actually prefer the earlier knobby tires, even though that's not what originally came on my car. I think the Turbo Hopper tires are approximately the same height regardless of the version (the wheels are different, as is the tread). This all does thoroughly answer my question, though... Indeed the Tamiya 1/10 scale buggy rear tires are quite a bit taller than those on the Turbo Hopper. Appreciate the side-by-side @67CamaroSS. Thanks guys!

Thanks for the suggestion. Yes, they are 3mm.

By the way, not sure why some of my uploaded pictures are showing sideways. They don't show like that on my computer and I don't see a way to correct the orientation in the post.

All put back together and ready for a test drive...

I took some pics of the new part printing, but something went goofy with my phone. Anyway, here's the new arm in it's new home. There are a couple of weak spots in the print that could be improved, but it's a lot better than the nail-and-wire trick.

So one thing I've learned about the distinction between "toy grade" stuff and "hobby grade" stuff, is that toys were never meant to be taken apart. The kingpin is pressed in, so to move the wheel and spindle to the new arm, it needs to be pressed out.

The gearbox seems to be working better than I expected. It's started slipping, which I think is the spur gear slipping on the axle. I just pressed it in as a "mock up" but it was tight enough that I've been running it around that way. My plan has been to cross drill for another pin and then hold the gear against it with a collar. Comically, the steering was going really out of whack at intervals when I was running it around with the kids last night. I pulled the bottom plate off of the front end to be reminded of what I'd done so many years ago: I had to laugh. No wonder she was driving so terribly. After thinking it over for a day, I decided to take a crack at printing up a replacement. I can't see any very good way of repairing this arm.

Here's about what this one looked like back in the old days: I'd forgotten that it was also missing the spare tire:

My original car was a red standard "27" car with skinny wheels like the red one shown here: https://rctoymemories.com/2012/05/06/tyco-taiyo-turbo-hopper-1986/ It had a pistol-grip type transmitter, so I think maybe it wasn't the very first one, but if I were going to buy one as a collectible this would be the one I'd seek. The car I have now, yes, was a "heads-up" model that I bought from my sister as a replacement for the one I broke. I always hated the little head turning back and forth, and I think one of the first things I did was remove this and the associated linkage. You can still see the groove for the little arm, and the pivot for the head in my pic though. Interestingly, I haven't seen any of the "heads-up" models for sale on eBay. Does this mean they're more or less collectible I wonder? I think the little head, as well as the different tires, were constant reminders to me that this wasn't actually my original car... Funny, that I mentioned to my wife that original examples of the Turbo Hopper can be had in reasonable condition for (only) around $200. "Good Lord," she says, "They want $200 for that." These little ECX cars are light years more capable and sell for about $100.

@KEV THE REV, I read over your work on upgrading to hobby grade electronics, and it was a neat project well executed. If I had a decent looking Turbo Hopper with faulty electronics I might do the same. In my case, the radio and front end are really the only thing original. The body is long gone (interested in some replacement or substitute). The thing drives terribly, but is about what I remember. From here, my to-do list: Get some sort of body on there... I'm actually thinking a mini-scale baja buggy (VW Beetle) might look cool. 3D print a front bumper. The original broke off long ago. Print a gear set in Nylon when the PLA ones inevitably fail. It's also geared too high, partially owing to the silly tall wheels, so also: Get some more reasonable rear wheels.

Finally, some new shock mounts (so I didn't have to further cut or drill on the chassis) with the ECX shocks mounted. Also soldered in a new set of motor leads, charged up the most recent NiCad pack that I had and ran her around the garage a little, giggling like a little kid:

And then printed the final PLA set. I'd intended to print these again in Nylon, but for now the PLA set with some silicone grease seem to be doing okay.

Confident I could print gears that would work, at least for a short while, I mocked up the 2nd stage: