R/Cing 21st Century 251.

[jackalope]

This build has been in the works for QUITE a long time! Once I bought a 21st Century 251 I wanted to make it R/C so I started doing some research and found that no one really makes one so I knew I had to R/C the toy. The search was on! I needed parts! I didn't want to use the cheap crap vinyl tracks it came with so that was my first adventure and I found a set from Asiatam, PRICY but I needed them so I ordered them. A month later 3 tracks and a shit load of rubber track pads arrived.....but I only needed 2, and then they were V E R Y long so I shortened them to fit the 1/18 scale truck that meant I had enough track links to build 2 trucks! Yeah I didn't want to do this twice so I sold a set for half price to my friend Mr.Painless for HIS 251 build! These pics are mostly for him so he can see if he wants to follow me or go his own route.

So I got a dual gearbox setup from Tamiya, the Asiatam tracks and some nice thick sheet plastic and a SHIT load of screws!
Here's what I have so far, yes I need to trim the screws down so the suspension works and I think I'm going to re-do the main plastic side parts cause the idler wheels sit too high for me. Thanks to Painless for measuring his stock trucks height, I added only 4mm height to my R/C version scratch build over the stock toys height, 1mm of that being the thickness of the tracks themselves. Forgot to mention the drive sprockets are from Christian as well as the front tires and suspension that I'm waiting on 2mm and 1.6mm screws and nuts to arrive so I can assemble it. Radio gear is 2.4gig set up from a Taigen tank.

[palepainter]

Those conversions are a lot of work, but you pulled it off very nice. These types of builds really open up a lot of possibilities. Nice work,
Pale

[PainlessWolf]

Jack,
Thank you for posting the pics. This gives me some ideas. ;o)
regards,
Painless

[jackalope]

Thanks guys, still has a long way to go but the hardest part is about done.

What do you think about the idler wheels, are they too high up?

[silversurfer1947]

Looking at photos of the original, the idler wheel look to be only very slightly higher than the idlers, if at all.

251 half track.jpg (22.93 KiB) Viewed 2267 times

[jackalope]

Thank you Mr.Surfer for the pic, I can see I'll have to lower the idler a couple mm mine are just too high. The drive sprockets from Christian are 1/16 scale so they are a little larger in diameter then the 1/18 scale ones were however the ones from the truck were ruined trying to remove them hence the need for the new ones. They may be larger but I don't think they're too bad looking.

[HERMAN BIX]

Looking at photos of the original, the idler wheel look to be only very slightly higher than the idlers, if at all.

251 half track.jpg

Taking a punt here, but the weight of men and assume materials in the subject photo would very likely compress the suspension enough to bring the height of the idler wheel down closer to the tops of the roadwheels...........

[jackalope]

I can't move the road wheels any further upward if I do the drive sprockets will be on the ground. If I raise the drive sprockets I'll have to cut the floor out of the truck so they're as high as they can go. The only thing I can do is lower the idler wheels a couple mm. I know the truck is taller then the toy by 4mm again due to the drive sprockets and their gearbox and the floor. 4mm I'm not too worried about I think that's close enough to not worry about.

But please if anyone can think of anything else I could do to it please by all means I'm 100% open to suggestions.

[ALPHA]

Just wondering Jack...Why dual motor gearbox for the drive? are you going to steer from the rear? or using the front wheels


ALPHA

[jackalope]

Just wondering Jack...Why dual motor gearbox for the drive? are you going to steer from the rear? or using the front wheels


ALPHA

Both! . The electronics are out of a Taigen tank, now true I could have just used 1 motor supply to run 1 motor however looking at how the truck is made with such long tracks and hardly any room between them and the steering axle I thought the truck wouldn't steer worth a damn other then very broad turns. So to fix that problem a dual gearbox setup seemed to be the easiest way to fix that. For broad turns I'll steer it using just the front tires but for a sharper turn I'll steer the front tires and slow down or stop the inside track thereby allowing it to turn sharply. The dual gearbox will work just like it would in a tank and I plan to modify a servo to be wired into the turrets rotation control, this way back and forth and track steering will be done just like a Taigen tank with the right stick of the controller and the front tires steering will be done with the left stick instead if a turret.

Again, thoughts are most welcome.