Hotshot II Carbon Chassis Rebuild/Restore

[cambragol]

Thanks guys! I hope it is still looking 'Hotshot II'ish, and not straying too far from the core.

Got my first electronics part today:

 

I am referencing @toyolien's great build for his Super Duper Hotshot. However, this Savox is a little larger than the black low-profile edition he opted for. I wonder if I can make it fit...

[toyolien]

3 hours ago, cambragol said:

Thanks guys! I hope it is still looking 'Hotshot II'ish, and not straying too far from the core.

Got my first electronics part today:

 

I am referencing @toyolien's great build for his Super Duper Hotshot. However, this Savox is a little larger than the black low-profile edition he opted for. I wonder if I can make it fit...

I struggled to fit a full size servo and get the electronics in there too. Also, the low profile servo only just fits against the chassis side so running a standard servo you'd have to square it up which might cause issues with the steering link angles. Worth having a go though 👍

[cambragol]

I think I got it, though not finished yet. I reversed the side compared to yours, and that spared up a few mms. Here is a quick shot:

The servo has direct line of sight access to the ball mount for all the crank's range. I need to get a horn, as the Savox ones don't fit in this tight space. Found a nice aluminum one with saver piece that should work well.

[cambragol]

Now on to the ESC. No idea what is best here. I do know I need 6v and 3A to fully power the servo. But, I am planning to run NIMH, and not bother with lipo. So, what does that mean for my ESC...power consumption etc. Yeesh. Complicated stuff. 

Any suggestions on a ESC? Currently I am leaning toward the Hobbywing 1060, as it seems to fit the bill, and is cheap, and ubiquitous.

[silvertriple]

3 hours ago, cambragol said:

Now on to the ESC. No idea what is best here. I do know I need 6v and 3A to fully power the servo. But, I am planning to run NIMH, and not bother with lipo. So, what does that mean for my ESC...power consumption etc. Yeesh. Complicated stuff. 

Any suggestions on a ESC? Currently I am leaning toward the Hobbywing 1060, as it seems to fit the bill, and is cheap, and ubiquitous.

3A servo is a good indication, but what is the motor consumption?

On brushless, I have quite a good understanding: generally a 13.5T would consume about 50A at peak. A 10.5T is close to 60A. The way I dimension the ESC is about 20% more than the max current draw from the motor.

If your brushed motor is anywhere over 50A current draw at peak, you should probably consider a 1080... But it really depends the motor first... (and then the problem is quickly becoming the room inside the limited space of the chassis)

[cambragol]

Well, no motor yet. But definitely brushed. Hopefully a nice old vintage motor. A Trinity or a Technigold or something like that. Powerful, but not overpowered for the car. I like realistic speeds. I think one of the Tamiya BZ motors could be a candidate too.

I didn't think the Motor could actual overwhelm an ESC, so I guess I better keep that in mind. Thanks!

[cambragol]

Anyone ever used the Ko Propo VFS-FR2?

https://www.kopropo.co.jp/en/products/view/40448

Seems decent, affordable, and gives me lots of options for motors. Made in Japan too.

 

[cambragol]

Well, I went ahead blindly and got the VFS-FR2. Hopefully it wasn't a bad choice. 

 

I also tweaked the mounting of the servo. Found a new arrangement that seems to be more 'aligned' with the chassis, and frees up some space, and has a more direct link to the steering:

 

I wouldn't think that mounting it upside down would be problem...or would it?

[cambragol]

Mounting on the side required the creation of a couple of 2mm thick spacers, which I whipped up using my good old steel pipe, the same pipe that I used for the sleeving of the suspension arms and mount points.

[Cynan]

Servos are mounted upside down on other kits so I can’t see it being a problem here!

[Kol__]

@cambragol This is an awesome build mate! Very slick with the carbon and ally parts, but still looks like a Hot Shot. When do you plan to finish her up?

[cambragol]

Thanks!

I am nearly done. I have the original vintage body shell, which I will use for running it. I will likely get a new reproduction shell though, and do my own livery. That may be a bit yet. I also need to get the receiver and transmitter combo sorted. Currently in Japan Tamiya controllers are sold out everywhere, and are fetching high prices. I may just utilize an old set I have, then when prices come down, and availability increases, get something specific for this build.

I'm also looking at using a Supershot underguard, so that means ordering and waiting. 

So a few weeks or months yet on this build. 

[lowspot]

beautiful looking Hotshot and an awesome built - thanks for sharing !

 

[cambragol]

Well, finally hooked up with a controller and a receiver. 100$ for both, and a bag to boot.

Next I got on to fitting in all the electronics. Not easy, as a lot of it was a tight squeeze.

 

 

The main shaft runs right through all the electronics and wires, so things have to be taped and held down pretty tight or they'll rub against it. I tried to space things out as well.

[cambragol]

So my antenna wire was just flopping around loosely. The original Hotshot body has a mount point for the antenna, which is on the small 'wings' above the battery. However, the Carbon chassis I am using lacks those. So no where to mount an antenna. I have been looking around for some kind of solution, when finally I realised I could just rig one up using some leftover pieces from here and there.

I used an old joint bearing, and two countersunk washers and came up with this solution:

 

I think it looks decent, like it was 'planned'. Added benefit of collapsing under pressure, during crashes, rolls etc.

Also, it lines up almost perfectly with the existing antenna hole in the original body:

[cambragol]

Starting to think about the body shell.

I was going to get a reproduction shell. However, I decided to try my hand at cleaning up the original body shell. Turned out okay!

I used hand sanitizer/ethanol....left over from the 'pandemic'. Soaked it for 10 minutes, then scrubbed. Paint came off fairly easy, but it took about 5 sessions to get everything off. I am not sure what kind of paint was on the original. It was brushed on in places, and thick, so may not have been 'polycarbonate' paint. In any case, the ethanol worked decently. I put a piece of freshly peeled lexan (from a boomerang msc cover) to compare the optical clarity. 

Now I have to think of colors.

[Cynan]

Nice. I’ve an old shell that I acquired with a bad paint job so I might give this a go to. Looking forward to see yours painted.

[cambragol]

It takes a bit of work. I just guessed on the disinfectant/Ethanol, as it seemed close to 'denatured alcohol' which I have seen recommend elsewhere. A big Tamiya shop opened up 10 minutes walk from my house, and they stock all the Tamiya PS paints, so I am going to think on the paint scheme a bit, then head over and invest. It'll be nice to not have to buy off the internet.

[cambragol]

On 11/20/2021 at 5:23 PM, Cynan said:

Nice. I’ve an old shell that I acquired with a bad paint job so I might give this a go to. Looking forward to see yours painted.

I don't think I can recommend the technique I used. I strongly suspect that the paint was not Tamiya or polycarbonate specific paint. I messed up a bit on my repaint, tried to remove with ethanol, and am having no luck.

[cambragol]

Big package came today with 4 beautiful items. These all came from the friendly Martin at MirageRC. Very nice guy and an amazing crafter of custom/special parts for Tamiya RC cars.

First up, an aluminum rear spoiler, in the style of the Hotshot II, not the original.

 

Next up, a new style aluminum bumper for the Hotshot, or Hotshot II. Drop in replacement.

 

Third we have a beautiful aluminum skid plate, similar to the Supershots. Drop in replacement.

 

Last, but not least, is an all aluminum body shell for the Hotshot II. What in the name of...

 

I may or may not add these to this build, which has stalled at the body shell (which I mangled the restore of just a bit...). I would assume at least one or two will be making their way onto this Hotshot restore though.

[Cynan]

Holly…. those look sweet!

[cambragol]

Oh, they are. They are.

MirageRC took my suggestion for the aluminum skid plate, and made it real. If he builds your suggestion, you get the first on free. You can order it now. So sweet.

[cambragol]

I put the wing together. Very nice. Definitely matches the profile/looks of the Hotshot II wing very closely:

[cambragol]

Before I add on some of these new pieces, I should maybe show the state of the build. 

I was working on the body shell. However, I really messed up the paint job, and ordered a second reproduction shell to try again. I haven't started on that yet. The messed up shell is not too bad, but I am not satisfied with it completely, so I haven't added stickers.

Here it is in any case:

 

Next up, aside from the body, is to decide on a final configuration for the rear suspension. The setups I have now, which vary based on whether I am using the aluminum knuckles, or the original Hotshot II knuckles, have either too much camber, in opposite directions. So either I makes an adjustable rear upper arm, or find a different knuckle.

[Andreas W]

For a messed up body I have to admit that it looks really sharp .