Tamiya Quick Drive Midnight pumpkin project and a little help needed

[Nikonite]

I bought this unseen from the internet, I thought (my fault) it was a full size midnight Pumpkin but it wasn't. It was the cut down version the QD that took AA batteries

Anyway the electrics where a mess, and although the all in one board was included someone had already started by hacking in a MSC which didn't work at all.  I decided to set about converting it to a 2.4ghz as I didn't have the generic controller required to work with the standard all in one electrics.

 

It was simple enough, rip all the electrics out and start again. Initially I swapped in a new MSC from an M02 chassis I am missing bits off, I also fitted a throttle servo and fiddled with the steering servo and low and behold it worked with my flysky receiver. Only problem was the weight of the battery under the bodyshell meant the original suspension just didn't work. I looked at fitting oil filled dampers and after a few trial fittings I noticed the rear axle was not a million miles from the grasshopper I also own. As luck with have it I had a spare axle from the grasshopper so with a bit of chopping and changing on it went. This allowed me to fit the oil filled shocks on the rear and also the much larger than QD silver can. I had to drill the chassis to accommodate the top shock mounts on the rear as they needed to be further back. To try and strengthen it I added a sort of turnbuckle I made from a chassis support bar from a 1/10 Nitro. I will add some mini u brackets at some point though. The front I used the standard mounts and to tension the top mounts i just used a cable tie for now, i will fashion something better at some point (suggestions welcome) Unfortunately the silver can is getting very hot, to hot to touch so I need to know should I change pinion, motor, esc or all 3? I don't know too much about electrics so appreciate any advice on that. Its running a 20t pinion and silvercan from the M02 chassis I had right now, the grasshopper motor was the same though, way too hot. 

The wheels where a bit of a pain, they are fitted using a small brass hex on the original but of course changing to the grasshopper rear meant I lost that. in the end I cut a groove in the rear of the wheels to accommodate a pin through the hole in the grasshopper axle, it works fine for now! The last thing I have done is fitted some front and rear LED lights, I had a pair of vintage filament spots that came on the front of a bodyshell and as luck would have it the lenses were exactly the same size as the painted headlamps on the car. After a bit of dremel work they are fitted and i think look great. they are activated on/off by channel 3 on my Transmitter. I am planning on trying to find a small lipo pack that will fit in the old AA compartment under the car to power them as they go off at lower battery state under motor load.Hoping it will also help with the high centre of gravity due to the 3200 NIMH under the shell. The bodyshell is yet to be painted, it looks like that after stripping with thinners its not deliberate, I just run out!

Id really appreciate any advise on the motor overheating and any other suggestions welcome.

Sorry for the essay!

 

 

 

Edited August 10, 2016 by Nikonite

[Kpowell911]

To stop the motor over heating id normally suggest gearing down the pinion, however, what you are trying to achieve is kinda pointless and not worth the hassle IMO. Id try to sell it on as a QD and get the hobby grade Midnight Pumpkin if thats what youre after really? As This is just going throw up problem after problem

[Nikonite]

Im not sure why its pointless? I wanted to do it, it was fun to do. Maybe if I was trying to make money from it or put it on a shelf but I'm not pointless to me is buying cars to leave in unopened boxes. My 3 year old boy thinks it's great,  worth all the work to let him have a car of his own. 

Edited August 10, 2016 by Nikonite

[NuttyProfessor]

well don't forget, effectively you have geared up with the bigger wheels by a few teeth so yes, you will have to drop your pinion size by at least 3 teeth so 16-17t is your starting point. If its got the pin drive on the rear, you can pop a 12mm hex on there so you can run standard Tamiya wheels or any with a 12mm hex. Id normally agree with Guns but you have already done the work and its cost you minimal as you had the bits already.

[Nikonite]

I think the total cost so far has been around £34. I'm happy with that. Thanks,  will order a few pinions now and see how I get on. 

[NuttyProfessor]

is the motor mount a fixed pinion size? Some Tamiya vehicles have fixed points like the TL-01 with 19,21 and 23t screw mounts for the motor or is it a free mount?

[Nikonite]

It's a fixed mount like a standard grasshopper. 

[Kpowell911]

what gearing options does it allow you? Is the gear pitch the same on this as it is on the "proper" Midnight Pumpkin.

 

The issue I think you may have is you cannot gear low enough without a custom made mount. What made you go with the the 20 tooth pinion? Was it just something you had lying around?

 

The reason I said its a waste of time and money is because its going to be alot more trial and error, and may not even potentially work out, and youre already £34 in (which seems alot to me) Id maybe suggest a crawler 35t motor and some low pinions, but I dont know what pitch you need. Its potentially going to have to be you trying £3 pinions at a time untill you get something to work. And then once youve got the correct gearing, its gonna be a lottery to what the gears can take. I cant see anything on google similar to this for advice, so youre going to have to be a gineau pig and invest on something that may not work out, and before you know it youve got "proper" Midnight Pumpkin money invested in a bunch of bits and pieces.

Edited August 10, 2016 by Guns

[Nikonite]

I was already £25 in by mistake,  I bought it thinking it was a full size. The rest was a set of lights and controller. I have quite a lot of Tamiya bits that came from a lot of nitros I bought. They were just doing nothing as to build them into compete cars would have been expensive. Im hoping  a smaller pinion will sort it out well enough for my boy to use and I'm learning I  the process. Hobbies are expensive,  I've yet to find one that doesn't cost me money! 

[Kpowell911]

If you are going to contiue with this, start by attempting to fit the smallest pinion you can (as I say I dont even know if QD use the same pitch gearing). IF that doesnt cure the heat, potentially youre going to have to find a slower motor, something like a 35t crawler motor, but then youll have more Torque and I cant confirm if the gears will take it. Other option would be a 380 sized motor?

[Nikonite]

The qd used a 280 sized motor,  that's my surprise really. It manages to push along the car just fine. As I have swapped the complete rear axle assembly (which includes the casing and all internal gearing)  to the grasshopper with bigger motor I had hoped that would if anything better cope with the weight (albeit with the extra weight of a nimh pack) I also swapped the plastic bushes for bearings which I'd hope helped. It's now a lot faster than it was which isn't needed at all so hopefully the pinion will sort it out. 

Edited August 10, 2016 by Nikonite

[NuttyProfessor]

you should only have 3 pinion size options then hopefully, if a 20t is on there, should be 18-22t mount. Check the grasshopper manual for optional gearing guidelines as that will shed light on your options. How many AA's did it run on? Couldn't you get a lipo pack in there and run an alarm? Id run a new ESC, hobbywing Quicrun 1060 is a nice cheap upgrade with the added bonus of a lipo cut off, around £25.

Edited August 10, 2016 by NuttyProfessor

[Nikonite]

Thanks will look into it

[XV Pilot]

Your car runs big wheels and tyres like a real Lunchbox/Midnight Pumpkin, right? And now you have a Grasshopper rear end installed, it runs a hobby-grade gearbox powered by a hobby-grade silver can like a real Lunchbox/Midnight Pumpkin, right?

 

So all you need to do to get appropriate gearing and mesh is to fit a pinion and motor mount from the real CW-01 chassis as used by the real Lunchbox/Midnight Pumpkin!

 

The mount will bolt straight onto the Grasshopper rear end, and the smaller CW-01 pinion is spot-on for the bigger tyres. It is after all designed for them.

 

Problem solved!

 

[chewbacca]

Once again, the Tamiya Guru provides a detailed and easy to understand answer having fully read the OP's first post. May his Tamiyas always run as sweet as the day he built them.

[Nikonite]

The wheels are actually from the Qd they are a little smaller than the full size but yes essential everything is the same. Full size grasshopper gearbox,  axle,  motor and battery. Slightly smaller than full size wheels. I'm going to try an 18t and go from there. I understand that it's not everyone's cup of tea bit I sometimes do things because I can and I find it interesting. By the time this is done I could have likely bought a used full size Midnight pumpkin. But then that's what I'd have,  the same as everyone else. 

Edited August 10, 2016 by Nikonite

[chewbacca]

That's what the hobby is all about though. Being different, modifying, coming up with new stuff. 

 

 

Keep it up.