Hotshot ReRe Motor and parts question

[Aviator 17]

Hi, I'm new to the forums and also new to RC cars. Back in the 80's the Hotshot was my dream car, but I never got it, until now with the rere.

I realize I should have spent more time on research before getting the kit, as my build is now on hold while I'm waiting 6 weeks for replacements for the plastic "bearings" and the pin screws for the wishbones/a-arms. I am now trying to be way ahead by ordering dual suspension rebuild/upgrade parts and a brushless setup now.

Suspension upgrade

Starting with the front I figured out I need the Super hotshot parts for the stay, BB27/BB28∕BB17∕BB18. However the screws/washers/spacer do not seem to be included. In order to attach dampers I seem to need BA3 screw/BB6 washer/BC11 tube/BC10 spacer/BA7 nut for upper on each side, and BC1 screw/BB6 washer/BC11 tube/BA7 nut (and BB1/BB6 to attach the stay)  for lower on each side. In order to get these parts it seems like I have to buy the whole suspension bag for the Super Hotshot, which seems a bit excessive as I plan on not using those dampers. Is there another way?

Brushless motor

Coming from Racing drones I have a solid aversion towards brushed motors, however I do realize Tamiyas legacy and that these cars originally came with these. But they did replace the mechanical speed controller with an Electronic one and could might as well replace the motor. I've been studying some kits and found a cheap option from Aliexpress: HIINST Waterproof B3650 4300KV Brushless Motor w/ 60A ESC Combo Set for 1/10 RC Car L824 for US$ 28. The description states this is a 4 pole 12 slot does that translate to a 12T motor? And does this whole thing physically fit and is a good match for a rere Hotshot on 2S/3S Lipo setup?

Thanks in advance

 

 

[Nobbi1977 1793]

Hello and welcome to the forum.

Where abouts are you based? If you put a location in your description people can better assist with recommendations.

 

I have no idea about Hotshots so cannot be of more help

[wolfdogstinkus 1893]

Brushless motors.

3650= dimensions (same size as Tamiya 540 motor silver can.) 36mm diameter x 50mm long.

KV 4300= 4300 RPM per volt x 7.2volts =  30,960RPM, More than double the standard set up.  

Then if you want more speed, just add more volts. 4300Kv x 3s Lipo@ 11.1volts=47,730 RPM (Stupid fast)

[Juggular 4964]

Recently, I've been thinking about the amp bottleneck.  

4500KV motor has a max amp of 75A.  3900KV has 69A.  3500KV has 62A.  But... GoolRC gives you 60A ESC.  So... if you put 3S, and a tall gearing, and your battery is rated for a high drain like 100C?  You could burn out the ESC.  So, if you want 4500KV, 80A ESC would be a good idea.  If you have wide open space, you could go for the fastest record.  When they developed it 33 years ago, I doubt that they ever dreamed of mounting a 47000 RPM motor.  But it's a hobby!  You can do whatever is fun for you. (including a spectacular smash)

Brushless motors have a lot more torque.  So, if speed is your goal, you could get a smaller 380 sized brushless motor. (They have fins on the motor body).  They have less torque than 3650 sized motor.  I have a suspicion that (full-sized) 3650 brushless might have 5 times the torque of a brushed motor.  Since you can't really use 5 times the torque, why not get a smaller motor with higher RPM?  

Even if a smaller brushless motor loses 60% of torque when compared to the larger one, it would still have more torque than high-end brushed ones.  But the same 4500KV rating would use 50A on a smaller brushless, instead of 75A.  The ESC would not bottleneck, it could give you the full 4500KV.  33,000 RPM is still too fast for narrow places, in my opinion.  

Of course, if your car was a heavier car like the Clodbuster, I'd recommend torquey 3650 sized motor.   

Edit : "you could get a smaller 380 sized brushless motor"  (I had written brushed...)

[Aviator 17]

Thanks for your detailed reply Juggular.

As I'm new to RC Cars I can only draw experience from the racing drone world. Brushed motors would wear out quickly and often be notoriously unreliable in that application. We did have a race to own the most overpowered and fastest (brushless) drone in the beginning. However a rocket with an insane thrust to weight ratio was **** near unflyable on a track, that requires fine control in level flight. A method to rectify overpowered motors was to limit the throttle curve on the transmitter. We used Frsky radios with open source software that allowed us to limit max throttle to say 75% and then stretch the throttle authority over the full travel of the throttle stick. In that way you also limit the max Amp draw so you could avoid fried ESCs and puffed Lipo batteries. 

My main objective in the car is to have a reliable no-maintenance motor. I'm not looking for speed. I am so new to RC Cars, that I will most likely faceplant the car in a wall if it's too fast anyway.

[Snakehands 124]

1 hour ago, Aviator said:

My main objective in the car is to have a reliable no-maintenance motor. I'm not looking for speed. I am so new to RC Cars, that I will most likely faceplant the car in a wall if it's too fast anyway.

Silver can 540s are 3.27UKP at Hobbyking. https://hobbyking.com/en_us/540-6527-brushed-motor-90w.html

[Juggular 4964]

4 hours ago, Aviator said:

Thanks for your detailed reply Juggular.

As I'm new to RC Cars I can only draw experience from the racing drone world. Brushed motors would wear out quickly and often be notoriously unreliable in that application. We did have a race to own the most overpowered and fastest (brushless) drone in the beginning. However a rocket with an insane thrust to weight ratio was **** near unflyable on a track, that requires fine control in level flight. A method to rectify overpowered motors was to limit the throttle curve on the transmitter. We used Frsky radios with open source software that allowed us to limit max throttle to say 75% and then stretch the throttle authority over the full travel of the throttle stick. In that way you also limit the max Amp draw so you could avoid fried ESCs and puffed Lipo batteries. 

My main objective in the car is to have a reliable no-maintenance motor. I'm not looking for speed. I am so new to RC Cars, that I will most likely faceplant the car in a wall if it's too fast anyway.

Somebody who wants control rather than raw speed!  I can respect that.  (yet, it's so hard for me to resist the pull of the fast motors!)

I think the ESC your Hotshot came with is TBLE-02S?  If so, you might want to consider a 13.5t brushless motor.  A sensored brushless would give you more control, and plenty of speed.  As you have done before, you can limit the EPA to 75% until you get acclimated to a ground vehicle.  Sensored motors have a bit less punch than sensoreless, because the ESC has to work with the feedback from the motor.  If you are just bashing around, sensorless 3500kv would be fine too, they are often waterproof.    

Going back to sensored, I am guessing that Tamiya's own motors are a bit more tame. (I cannot verify that, but the Tamiya's 60A ESC says it's good up to 10.5t of Tamiya's own motor, I don't know if other brands' 10.5t would be fine or not)  A 13.5t could be anywhere from 2800kv to 3300kv.  7.4v would translate that to 20,720 to 24,420 RPM.  That might not look impressive, but the stock brushed motor produces 14,000 rpm (without load).  With load, it's reduced to about 10,000 rpm, which is 30% rpm loss (more powerful motors lose about 20%).  Brushless loses a lot less because it's got 4-5 times the torque.  If so, 13.5t could be twice as fast as the silver can (supplied motor in the kit).  

You may need to solder some wires.  I just got my 13.5t at general recommendations of other TC members like Jonathon and Juls1.  I haven't soldered the wires yet.  

 

[Jonathon Gillham 4607]

13.5T with a 17T pinion is perfect in a Boomerang, but they are the pinnacle of RC cars. I assume they would be good in a Hotshot too since they share gearboxes...

I run a cheap Trackstar V1 which is about USD35. Speed Passion are good for bashing too. These are older motors now which still work well in a fun car but would get cleaned up at a racetrack by the newer offerings. If you want newer and still cheaper then look at SkyRC Ares, Surpass V4S which give good performance at a good price (people claim these are awesome and will win races, as i can't win races I can't verify that)

[Aviator 17]

3 hours ago, Jonathon Gillham said:

13.5T with a 17T pinion is perfect in a Boomerang, but they are the pinnacle of RC cars. I assume they would be good in a Hotshot too since they share gearboxes...

I run a cheap Trackstar V1 which is about USD35. Speed Passion are good for bashing too. These are older motors now which still work well in a fun car but would get cleaned up at a racetrack by the newer offerings. If you want newer and still cheaper then look at SkyRC Ares, Surpass V4S which give good performance at a good price (people claim these are awesome and will win races, as i can't win races I can't verify that)

I see a lot of these motors come with just solder pads? for the phase connectors. I'm totally comfortable with soldering but it just seems like a weak spot on an exposed motor.

[Snakehands 124]

4 hours ago, Aviator said:

I see a lot of these motors come with just solder pads? for the phase connectors. I'm totally comfortable with soldering but it just seems like a weak spot on an exposed motor.

 

 

Won't be a problem, I promise you.

[Jonathon Gillham 4607]

Yep, but I've never had a problem with the solder tabs. The motors also have a lot of mounting holes so you can mount them with those tabs pointing in any direction rather than the 2 holes for a silver can

[Juggular 4964]

9 hours ago, Jonathon Gillham said:

13.5T with a 17T pinion is perfect in a Boomerang, but they are the pinnacle of RC cars. I assume they would be good in a Hotshot too since they share gearboxes...

I run a cheap Trackstar V1 which is about USD35. Speed Passion are good for bashing too. These are older motors now which still work well in a fun car but would get cleaned up at a racetrack by the newer offerings. If you want newer and still cheaper then look at SkyRC Ares, Surpass V4S which give good performance at a good price (people claim these are awesome and will win races, as i can't win races I can't verify that)

I was wondering where I should install the 13.5t.  I thought "Zahhak? but it already has a 19t brushed with advanced timing..." 

As it happens, I am very susceptible to sensible suggestions, so I got myself a Boomerang, which is whole lot better-looking than Bigwig.  Besides, you can't just have a hotshot and a bigwig and skip the mono-shock evolution entirely. (If you are susceptible to suggestions like me, that could be a hint, Mr. Aviator)  The mono-shock of the Hotshot has the compression points at the bottom of the spring, not at the center.  This creates a bit of an upward pressure.  This was "improved" in Boomerang and the Fox.  So these later versions operate smoother in my opinion.  

Anyway, my Boomerang is in need of a motor, so it shall have the 13.5t with a 17t pinion.  (I wanted to run a Boomerang and a Bigwig and see which is the pinnacle indeed--because the Bigwig came later. But my Bigwig has a GT tuned motor, so I have a vague suspicion that 13.5t Boomerang will come out as a winner)  

Thrust bearings just arrived too.  (Don't worry. Re-released kits come with these, but vintages don't)  These are 0.5mm thicker.  It didn't fit.  Luckily, three pieces are not bound in anyway.  I just had to replace a grooved washer with a thinner washer the vintage chassis came with.  That was a perfect fit.  Thrust bearings in Hotshot series are not tight. They just rattle about. So these are not really necessary, but my OCD commanded it.