Gifted Fox

[losiXXXman]

So my daughter is playing in the street with her friend and and the friend's dad I and start talking. Turns out he used to be way into RC until he graduated to real cars. He tells me about his Fox and Astute and such... I tell him I always wanted to check out a Fox, that there was a rere a few years back that I still missed. What do you know he says shoot you want it, you can have it, and goes and get's this...

I look it over and at first glance all I think I need is front arms awesome! I ordered some up and took it out for a spin. Its got some clicks and its rough, but this thing drives better than any Tamiya buggy I ever had. (save my sons DT02.)

After a full cleanup though, I realize the clicking is a damgaed gear, the rear arms are all cracked at one or more hing pins, the chassis has multiple cracks too. I'm not looking for a money pit, but I think this car could be fun to have. It was gifted after all.

So I'm leaning towards not replacing the ABS arms, but lokking for either a retro/resto-mod solution or going to 3d print. Should my rejuvination of the fox involve longer arms or keep them similar in length to retain the character of the Fox? SHould I look at ways to "indpendentize" the fromt suspension? I'm definately sizing the treads up to 2.2, but should I go with Turbo Scorpion 5 spokes, or the standard race style dishes?? Get a re-re body from Tamiya or shoudl I get creative with another retro repop body? (I've thought about the RPS SE, Terra Scorcrher, or Madcap - any other suggestions?)

Love to hear everyone's thoughts before I start making orders for parts.

[mtbkym01]

Arms cracking around the screw pins was/is a common problem, the original rear wheel hubs are also prone to cracking. The best solution I’ve seen for rear arms where some that were cnc cut out of delrin that someone had made about 8 years ago. Finding arms now could be tricky, and definitely not cheap. You can run modern 2.2 wheels with 12mm hexes as long as you get some nice wide hex adapters and some barrel/tube nuts. For wheels, another option is JC Racing pepper pots for the ultima (you would just need to use 850 (8x5xw2.5) bearings in the front wheels (and possibly some shims). I have 3 built Fox’s, my original from mid 80’s in the middle, another barely run original, and a new built Re-pop that has 2.2 wheels on it ( I also have a NIB original, a NIB junior and a TTG Fox Mini). I a bit obsessed with these as it was my first Hobby Grade RC and took me ages to save up as a teenager to get one

[RC10th]

I always wanted the Mini Fox, I bought the Mini Frog in Berkley CA before the Fox was available and that was as far as i got.

[mtbkym01]

I always wanted the Mini Fox, I bought the Mini Frog in Berkley CA before the Fox was available and that was as far as i got.

All the TTG’s are highly sought after now, wish I had the Frog, Hornet, Rough Rider, And in particular Hotshot to go with this one

[losiXXXman]

I drew these up awhile back, but only recently got a set of calipers to ensure the measurements were correct.

Arm Model.png (174.44 KiB) Viewed 2999 times

Arm Model.png (174.44 KiB) Viewed 2999 times

A colleague from work gave them a print on his machine and they fit perfect. I want to make some refinements to them, but its a start. Geometry identical to stock just added one additional shock mounting hole a little farther out.

[mtbkym01]

THey turned out great

[losiXXXman]

The arms my friend printed fit great. But after seeing them I think they may be a little weak upon running. So I added some thickness and a little more material around the hinge pin and shock mount holes.

I also modeled some rear upper arms and a rear hub to try. One of my principle efforts was to make a symmetrical design so that the arm, upper arm and hub could all be used on either side. Seems crazy to have L&R, Upper and Lower specific arms. Once I have confirmed all of this is working out okay, I'll throw them on Shapeways to help out you other Fox owners. I'm actually surprised that no one has done that already, though I did see some Fox arm files available on Thingiverse.

My guy has these files so hopefully I'll have some prototypes soon. Real pics on the car will follow as well as a test on the road / in the dirt.

[losiXXXman]

Finally threw those arms on the Fox and got some new rims and tires. She looks good and runs well with this setup. But a head-on with the DT02 this weekend put her out of commission again. While I was working on it, I found enough rod ends and ball studs to put together a stabilizer for the front, but don't know what diameter music wire to pick up. Suggestions ? Or could one of you get me a measurement on one of the Novafox or vintage Fox wires? Have any of you experimented with other bodies on the Fox? Initially I was thinking of a semi- restore, but I am now considering OldRC/Sabulatech's SRB/Mears/Funco SS, the PB Mini Mustang, or maybe even the Boost.

[losiXXXman]

One more thing - anyone got suggestions for springs? The rear end of this think is super bouncy. I tried cutting a few coils out of the spring and then stretching it but it's bad. Next step was to pick up the DT02 or DT03 spring set and find the soft ones. Is there a better solution?

[coxbros1]

Thicker oil?

[mtbkym01]

What pistons are in the shocks? The original kit came with about 3 options, 1 with 4 big holes that would barely do any dampening, if they’re in there, that could be the issue

[losiXXXman]

Thanks for the tip in the pistons. I did drain rinse and refill the shocks as I was cleaning it up to run, but didn't note the pistons. I will check them out this weekend. I noticed that my chassis was cracked too this past week, where the tranny bolts to the upper chassis half. I've ordered a replacement chassis, and went ahead and snagged the last gearbox I saw on ebay just to have on hand. I'm going to give a go at abs cementing that front suspension mount together for now, and start drawing up an improvement to have my buddy print for me.

With these purchases I'll have to wait on a body again. But better to be able to run naked than to watch it sit and only look pretty.

Can anyone help on the sway bar thickness?

[Coelacanth]

Shocks that bounce instead of dampen could be addressed a few ways...any or a combo of these characteristics: bigger holes in the pistons, thinner oil, softer springs.

Also, simply cutting the shock springs isn't an ideal solution as it causes the springs to bow outward in one spot when compressed, because one end of the springs doesn't sit flat anymore. I noticed this when I made custom springs for my Barney Optima, and you can see what happens here; when compressed, the springs end up bowing out one direction and will rub the shock bodies:






Here's how I solved the problem. I cut off a section of the spring, but kept the flat part at one end...I then used some copper tubing, bent around a tube or something until it had the same diameter and curvature of the original spring, then inserted both cut ends of the spring into the tube, and crimped it on securely; it works like a charm and since at least a half-inch or more of each spring cut end goes into the copper tubing, it'll never come out.

[losiXXXman]

Thanks for the suggestions Coel. After disassembling the shocks I found that they did have one hole pistons, but they were TINY holes. I opened the hole up with a 5/64 bit, and stretched the springs. I left the Tamiya soft oil in there and put it all back together. It is less bouncy by far, but I think now with the big hole in the piston the soft oil is not providing enough damping. I have some AE 30wt that I will try next. But it is much improved.

Last weekend I reassembled the whole car with new chassis, gearbox case, front suspension mounts, and rear hubs. I also included the second version of my 3D printed rear lower arms as they are thicker. I hope to put a few runs in today and not have any breakage this time.

[losiXXXman]

It’s been quite awhile, but in case anyone wondered how it all turned out, here it is.