Project Fast and Cheap: just how fast will an Exceed Drift Star go? - RC Groups
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Jan 22, 2013, 02:13 PM
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Project Fast and Cheap: just how fast will an Exceed Drift Star go?

I've decided I want to go fast, very fast. I also want to do it cheaply. Normally fast and cheap don't go together. Anyone can build a fast car, and anyone can build a cheap car. The challenge(and fun) for me is to see if I can put the two together. My goal, as seem to be the most common for speed run cars, is 100 MPH. The chassis I chose to use for my project is an Exceed Drift Star. It is also rebranded as the HSP Flying Fish, and Redcat Lightning EPX, so parts are cheap and fairly easy to come by. Nitrorcx also has a monster truck and a buggy based on the same basic platform.

I have dubbed my car the Fast and Cheap, and designed a logo for it. I thought I'd start with a brief review of the car. It's your basic 200mm AWD electric. Without the body, it looks similar to most other cars in it's class. I got the brushed version RTR for about $100 at I won't go into the obvious, since there are other reviews of this chassis floating around the net. There are some things that aren't so obvious though, so I'll focus on those.

First, this car uses ball bearings throughout. They are all metal shielded, and are oiled, not greased. Second, as has been noted by others, the pistons in the shocks have giant size holes in them. 60W oil(the heaviest I have at the moment), feels like almost nothing. We'll need to use 90W or higher to get good dampening with them. Third, all the stock electronics are waterproof(I haven't tested them, but they all say "waterproof" on them.
Fourth, and very surprising to me, the diffs in this thing are HUGE. They use all steel gears, and are sealed with o-rings. Check out the pic. The diff on the left is the DS diff, the diff on the right is from my Slash 4x4. Yeah, this $100 car uses diffs as beefy as the Slash's. They are filled from the factory with some generic brown grease. It's pretty thin grease so there is no posi action. I cleaned all the grease out and replaced it with Mobil 1. It's thicker so I get a bit more limited slip action. It probably lubricates better too(and if you're only using it for RC, a single tube will last you a lifetime). Since the diffs use o-rings, actual diff oil could probably be used too.

So, how does it work? As a drifter, it works great. The brushed motor and NiMH battery are more than adequate. It's my first on road car, so I don't have much to compare it too, but I'm happy with it's drifting performance. Take a look at my first test drive:
First drive with an Exceed Driftstar (4 min 10 sec)

Here's the same video without the music for our Canadian friends(and anyone else who's country blocks the Beach Boys)
Drift Star first drive, no music (4 min 9 sec)
Last edited by Bugman Jeff; Feb 02, 2013 at 05:54 PM.
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Jan 22, 2013, 02:28 PM
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Next up, if we want to go fast, we'll need to be sticking to the road a bit better than drift wheels will allow. I bought a set of THESE wheels and tires for it. I don't have a ton of drive time on them yet, but so far they grip adequately for the price. With some grippy tires, the car actually handles very well. It sticks to the road, but will still spin out with the correct application of brake and steering.

One thing that became very apparent with sticky tires is that the servo isn't very good. It does not center well, so getting it to track consistently straight is a challenge. The stock servo is fine for drifting, just not good enough for gripping. Since the video was taken, I've replaced it with a Solar D771 from The stock waterproof servo is now serving a the lift servo in my Slash 4x4 plow truck.

I set up my trusty(and surprisingly accurate) Hot Wheels radar gun, and did some speed runs. The car, all stock except for a 2S lipo and the tires, topped out at a blistering 19 MPH. The problem with the HW radar is that it picks up real cars great, but for something as small as an RC, you need to pass within a few feet of it. This lead me to my first crash. On the last run of the video, I smacked right into my test stand. The ABS body cracked, but all else seemed fine. Until, that is, I tore it down later. Turns out I bent the dogbone on that corner. It was easy enough to straighten though, and replacements are only $5/pair if I do ever break or lose one. They also rub very slightly on the outer drive cups at full steering throw. Turning the steering rate down will fix that.

Here's my stock baseline speed testing:
Speed testing an Exceed Driftstar...and a crash! (1 min 30 sec)
Last edited by Bugman Jeff; Jan 23, 2013 at 01:21 PM.
Jan 22, 2013, 04:28 PM
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Can't see the first video (copyright claim has it blocked up here), but I can see the second one.

Are those speeds on the stock brushed stuff still? That's actually not bad for the motor/ESC in it!
Jan 23, 2013, 01:34 PM
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Yup, that's stock brushed motor, stock ESC. Apparently, the music copyright blocks it in Canada, so I've reuploaded it without the music for our neighbors to the North and added it to the first post
Jan 24, 2013, 12:51 PM
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The "cheap" part of the Fast and Cheap is limiting myself mostly to parts on hand. That includes my motor and ESC choice. Making do with what I have on hand means I'll need to ger creative with some custom parts. No Castle 9000Kv for me, I'm going to use the motor from my Slash 4x4, a Tacon 3650 3500kv. The motor is limited to 3S too. With limited motor RPM available, and the small little wheels that 1/10 on roads use, I'm going to need some gear. Lots and lots of gear. The stock spur is a 64t 48p gear. Not only are there way to many teeth, 48p gears just aren't going to cut it for what I want to do. This is where it's time to go big or go home.

I've decided to use Mod 1 gears. Obviously, Mod 1 gears aren't an off the shelf swap for the car, so I had to get creative. I decided to use Traxxas Revo Mod 1 spurs, they're cheap and are available all the way down to 36T. I made up a custom adapter to adapt the Traxxas spur to the DS chassis. You can how my new spur compares to the stock unit.

This also left me with another problem. The stock die cast pot metal motor mount isn't long enough to slide the motor out far enough for the giant sized pinions I'm going to be running. I decided to make a new one. I'm using 6061 billet aluminum. The stock motor mount is needlessly complex too. Even though it looks like the chassis mount holes are in line, they're not. Every single mount hole on the thing is on a different plane by .050" or so, and there's no good reason for it to be like that. The mount hole to bearing location is extremely critical too,if it's off the motor mount bearing will wear out in no time. I extended the mount out sideways as far as the chassis would allow, so now I've got plenty of motor adjusting room

Math says I'll have the sheer wheel speed that I'll need, but with limited power the rest is going to have to be aerodynamic trickery
Last edited by Bugman Jeff; Jan 24, 2013 at 01:14 PM.
Jan 24, 2013, 01:24 PM
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Nice crash Keep it on.
Jan 26, 2013, 03:01 AM
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I wouldn't exactly describe the 350Z body that came with my Drift Star as "brick like," but it's not the most aerodynamic. With limited power available, I'm going to have to cheat the air as much as possible. To that end, I started playing with a body for the Fast and Cheap. I've got a vacuum former, so I can make my own body once I've got a buck to form. I've had this pan car body laying around for years with nothing to use it on, so I started hacking it apart. I narrowed it up an inch to bring it down to the right width and had to move the cockpit forward so that the front shock tower is covered.

I'll monkey with it some more tomorrow, but I might decide it's more work than I want to do. If I can find one I like for a price that agrees with me, I might just haul off and buy a body.
Jan 26, 2013, 10:53 PM
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The DS chassis has the motor sitting low...very low. So low that the chassis is dished under the motor for clearance. With the giant pinions I'm using, I need to slide the motor way out, so I had to extend the dish further out to keep the motor off the chassis. I'm using a Hobbywing Xerun 150A ESC, again because I have one on hand. It almost fits in the chassis, but I had to grind down the sidewall of the chassis so the ESC can stick out just a bit. I don't have a pic of it, but I also had to clearance the spur slot in the chassis top plate. My spur adapter just barely rubbed in the stock slot.

With everything clearanced, it's time to mock everything up. Everything is super tight in the chassis and with the super low body I'm making, I have virtually zero free space. 10 lbs of potatoes in a 5lb bag... It's mocked up with 38/28 gears, but I've got the room for 36/34 if need be You'll also notice that my dogbones are blaze orange. I make a habit of painting them this way. If/when I break a knuckle or arm, it makes the dogbones much easier to find.
Jan 27, 2013, 12:50 AM
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I played around with my body some more. I think it might actually work for me. If tomorrow goes as planned I'll know for sure.
Feb 02, 2013, 06:17 PM
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I finally got my body cast. I use Plaster of Paris for all my casting. It's cheap, and easy to use. It does have one downside though, without reinforcement it's not very strong. It tends to chip and crack easily. There is a simple solution to this though: Elmer's Glue. You can buy it by the gallon at stores like Home Depot. I mix it in at about 3% using the TLAR method(the looks about right). It makes the plaster much stronger. It also extends the set-up time which is very important when mixing such a large amount of plaster.

I made a mold stand that is the exact width I want to end up with. I also put shims on the narrow sides, and shims under the bottom of the mold. Without all this, the mold will bow and flex, and you casting will end up all warped and twisted. My body is actually about 3/8" to short too. Using duct tape around the perimeter of the mold allows me to extend it, making the whole thing taller. I used clear packaging tape to cover the rest of the holes in the mold(it leaves a smoother finish than duct tape).

Anyone who tells you that you can't mix 25lbs of plaster in your kitchen is lying The set time on PoP is around 20 minutes, and I did it in two pours. I just can't mix it fast enough to get it all in one. By the time the second is mixed up, the first is just starting to set. Fortunately, plaster sticks to it's self very well. DON'T pour any down the sink, plaster hardening in your pipes is a very, very bad thing. Just leave any extra in your mixing bucket. Once it's set, the whole block will pop right out. It's also best to mix your plaster when your wife, girlfriend, or mother is not home
Last edited by Bugman Jeff; Feb 02, 2013 at 06:34 PM.
Feb 02, 2013, 10:26 PM
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Plaster's all set up. PoP is an exothermic compound, meaning it heads up as it cures. When I make molds like this, I wait until the plaster cools back down before pulling the casting, in this case it was around 3 hours. The plaster is still very damp and relatively soft. It will continue to get harder over the next few days. This particular casting weighs 28 Lbs, roughly 1/3 of that weight is water that will slowly evaporate out over the next few weeks.

The casting is a bit rough and lumpy, so I'll be sanding it to the exact shape I want. When I get it the shape I want, I'll using it as a buck to vacuum form plastic bodies.
Feb 04, 2013, 08:53 AM
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Nice work on the mods so far. Good luck with the next test drive.
Feb 08, 2013, 11:41 PM
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Finally had some time to do some more work. The downside to using plaster is that it makes a heck of a mess when you sand it(and I've got a lot of sanding to do). Definitely not a livingroom activity, dust floats everywhere I got the rough shaping done, and it's starting to look like something. Next up, I'll add some plaster to the low spots, sand, and repeat until it's just how I want it. I also have more reshaping to do on the back end. It's also taller than it needs to be so I've got room to trim the body to the height I want.
Feb 10, 2013, 11:38 PM
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I mixed up more plaster and spackled it on where I needed it. One of the nice things about plaster is that it sticks to it's self very well. What you see here is the second round of filling. It's pretty sloppy, but plaster sands very quickly. Hopefully, I'll only need to touch up a few small places after the next round of sanding, then I'll be ready to pull a test body
Feb 11, 2013, 01:14 AM
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Body is shaping up nicely. Looking forward to the first results of the vacuum forming

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