[WIP] Tamiya Hot Shot RC

[msk6003]

Last year I bought Tamiya's Hot Shot RC model.
I think it's design is very good since when I was very young so I wanted to buy it and did in Christmas in last year.

Of course not just for build and control this model, I wanted to build it as lego model so main reason is for comparison with model I will make.

I started few week ago but posted in here now.

At first I started on chassis. Surprisingly original model's rear tire can fit in medium racing wheel so I bought 2 set of those tire.

I use BW3 and 2 BW motor for 4WD drive. And like original model, both front and rear use mono shock. I know this shock is more accurate with original model but I use those yellow hard shock which is little more common because I want make instruction and post on rebrickable. In this version, drive gear ratio is 16-28, 16-28 3.06:1

But when I test chassis gear starting to skipping on both front and rear. So I rebuilt gear train and make gear ratio 24-24, 20-28 1.4:1 but can change gear ratio to 8-8-24, 20-28 4.2:1 or 28-20-28 1:1 too.

And add one more shock in rear for better stability.

After fix gear skipping, I built remain body without bumper, wing and light.

 

But now I stopped build more. Cause BW3 keep turn off when I drive model 1m. After lot of trying to fix this, I throw BW3 away and change to PF system with Sbrick.(2 L, 1 Servo, 1 rechargeable battery) Now it can drive more but to much slow and don't have much torque.(gear ratio is same 1.4:1)

I need to find other way for drive this thing. Than I will finish it's bodywork.

Edited January 10, 2023 by msk6003

[gyenesvi]

Cool rebuild, you kept the spirit of the original nicely. I like the suspension especially.

It's a pity that it shuts down so fast. Have you tried what happens with say 80% power? As far as I remember that helped for others with a similar gear ratio. Or just experiment with decreasing power until it does not shut down. It should definitely work at some point of the power curve.

[Lixander]

Nice MOC!

I like the style of the retro RC buggys and truggys too; I recently finished 2 truggys.

 I first went with a 4x4 - I still need to take the rest of the motors for it, then I wanted to do something more simple.

For the 2nd variant of the simple truggy, I was inspired by the Kyosho Optima Mid.

Anyway, keep up with the good work!

Edited January 10, 2023 by Lixander

[piterx]

that's awesome dude :) I love it

[mla2]

Really nice! It's a shame the BW3 doesn't work for this. Perhaps a CaDa white top battery box will?

[msk6003]

Thanks for comment everyone.

3 hours ago, mla2 said:

Really nice! It's a shame the BW3 doesn't work for this. Perhaps a CaDa white top battery box will?

 

11 hours ago, gyenesvi said:

Cool rebuild, you kept the spirit of the original nicely. I like the suspension especially.

It's a pity that it shuts down so fast. Have you tried what happens with say 80% power? As far as I remember that helped for others with a similar gear ratio. Or just experiment with decreasing power until it does not shut down. It should definitely work at some point of the power curve.

I also thinking that cada's battery/motor combo but I don't have that. Second, I think use BW2 but I can't believe it anymore. Than I made it PF version but now I thinking use C+ hub with 2 large angular / spike large motor with 1:1.29 gear up or keep same 1.4:1 reduction. C+ large is to big to keep both 1.4:1 ratio and side '3' plate.

[msk6003]

Progress 4

BW3 is keep turn off after drive just 1m straight due to low current limit so I change to Cada's motor and battery now work very well. I tested C+ motors also but it is to much slow. Original 1.4:1 gear reduction is also work but it also make turn off after 30 sec free drive so I reduce ratio to 4.2:1 and it's work fine.

After that, I changed roof to use tile and add headlight, bumper and wing. Still need to tweak but now I can say it is 95% finish.

Edited February 9, 2023 by msk6003

[msk6003]

Progress 5

CADA's battery work very well but I found it has low capacity.

So remove cada's battery and keep for other use, I back to BW3.

But this time, I use 2 BW3 insted 1. Now I can't finish Hyundai N74 due to use my all BW3 on this but hot shot is more important project than N74.

So, I drive it with 8-8-24, 20-28 gear reduction but suddenly car don't move.

I disassemble and find this happen...

Yes. Second 8t's axle is melted and stick to beam. I'm very suprised because this is first time I seen melted axle.

Anyway, I think this happen because 8-8 gear is spin to fast, I change to 20-28, 20-28 gear reduction.

And it works very well! Even can change gear to 12-36, 20-28!

Than I starting make this on studio for make instruction.

Due to original tire don't have in studio, I use landrover's tire.

I found front bumper I made before is to low than original so I remove it. It will make soon again.

[Toastie]

54 minutes ago, msk6003 said:

I'm very suprised

Are you really surprised? Don't think though

LEGO MOCs using nothing but LEGO/3rd party ABS elements translates to non-lubed, full friction ABS on ABS surfaces. And when you spin things much faster than the lame original LEGO components allow you to do, well - meltdown is around the corner, isn't it?

I'd go lubed full metal jacket to spin things as fast as possible, to be honest.

Best,
Thorsten

[aFrInaTi0n]

This will be for you... MTP's parts allow better performance with non-melting parts due to the ballbeared parts... but as they only have a 5L liftarm ballbeared at the mid, you may also take a look at https://tf-engineering.at/flangebearing/

[Lixander]

22 hours ago, msk6003 said:

Than I starting make this on studio for make instruction.

If you want more realistic renders, you can paint the tires in ”Rubber black” (it is in the black/white colors, but it is a little lower than the standard colors)