Double Impact!

[Heli Mod Man]

Hey Guys!

I wanted to start a new thread about the Tamiya Dark Impact cars I have been setting up to supplement the previous thread I began regarding this (then upcoming) project.

Anyway, this all began when I realized how much RC stuff (heli stuff mainly) I had lying around. I also had some RC bike stuff taking up space and not being used (a Novak 5800 brushless system and a Novak HV Maxx brushless system). I have alot of lithium packs, motors, speed controls, radios, etc. etc. etc.

I realized I could setup quite a few cars with what I had lying around. So I began the hunt for a couple decent 4WD cars to throw some serious gear into.

Back when I was a teenager (20 years ago), I was heavily into Tamiya cars. I even owned a hobby shop when I was 16. So, I felt a sence of nostalgia to that brand. When I looked into what they had available, I settled on the "Dark Impact" (kind of an odd name for a car ;)).

Now, I setup two cars with different arrangements (but identical cars). One is running the Novak 5800 on 2S3P lithium pack and the other with the HV Maxx on 4S with a custom CNC carbon fiber pan chassis (I own a small machine shop). I quickly realized that the HV Maxx would run fine, but was a bit too explosive for the car and heavier than I wanted. But, I have a bunch of heli stuff I could use. So, I went to a Hacker C40 12T motor (heli motor) with a Kontronic Jazz (Heli) ESC, and 3S2P Thunder Power lithium packs. Also, the steering servo is a digital heli tail servo (Futaba 9253). That is a super fast and accurate servo.

Anyway, the Hacker is a phenominal motor! First I set it up on 4S and it had WAAYYYY too much power and RPM. It was every bit as bast as the HV Maxx with a bit less violent hit. It is also far lighter (about 80 grams lighter). And, the HV Maxx was running hot. The Hacker and the ESC are running very warm, but not hot.

I decided to go down to 3S to reduce the huge performance of that setup. That makes the Hacker powered car just a bit faster than the Novak 5800 powered car, but running alot cooler and longer. I am getting 30 minutes out of a charge with as much power as the tires can deal with!

Here are a few pics of the cars. You will notice the majority of the pics are of the Hacker car with the CF chassis.

If anyone has questions on how to make this car tolerate huge horsepower, let me know. There are a couple tricks I learned to make the rear diff survive.

For $152, this is an absolutely phenominal car.

I think I will order a 3rd one! ;) :D

Matt

[TueLe]

wow. just look at the tires and see how most of the spikes are gone lol. :)

[ronmeister]

Matt, what are the "tricks" to beffing up the diff?
I had one laying around in the attic for years, because I was too lazy to order a new diff.
But I will just order one soon and apply your "tricks" to it.
Thanks

[Heli Mod Man]

There are two solutions to the diff problem;

The best solution is to use the front diff cups on the rear diff. The rear diff (for some stupid reason) uses plastic spacers between the cups and the thrust washers. These plastic spacers smash down with heat and overtightening of the diff screw (the diff screw needs to be very tight when running high horsepower). However, the front diff uses diff cups that do not require those plastic spacers. They are hardened steel all the way to the diff washers. I found that the front diff cups are a direct fit onto the rear diff with no modifications required what-so-ever.

So, again, just order the front diff cups and install them on the rear diff. You will want to tighten the diff screw all the way down. The screw will lossten up once or twice. But, just tighten it down again and after a couple retightening jobs, it will stay tight.

With that diff mod, the rear differential will tolerate almost anything.

If you run more than 400 watts, it may be necessary to epoxy the diff solid. However, that screws up the handling (great for drag racing, though ;)).

Oh, the next thing I plan to do is install a heli tail gyro for the steering servo. If I am correct, the car will be very easy to drive that way. The steering should self correct with the Gyro installed. On 3S, it isn't needed. But, on 4 or 5S, the car is almost undriveably fast. The Gyro is needed to keep the car going straight under hard accelleration when wheel spin gets insane. :D

Oh, yes, the tires will burn all the way up to speed, even on pavement. That is why the tires are bald.

After a couple good hard runs on asphalt, the tires are so hot, I cannot touch them!

Matt

[rcmaster1029]

That CF chassis is nice! I would love to see a video!

[Heli Mod Man]

I picked up a 3 chanel radio for it so I can install a heli tail gyro (3rd chanel is required for gain adjustment). That way I can run full throttle and let the gyro countersteer.

I know, what a cheater! :D
But, the car is violently fast and undriveable at full throttle.

Matt

[TMetalMan]

If you don't mind, I'll post a bit about my Dark Impact. First the pics:

http://img.photobucket.com/albums/v132/4x4pede/Dark%20Impact/IMG_3116.jpg
http://img.photobucket.com/albums/v132/4x4pede/Dark%20Impact/IMG_3114.jpg
http://img.photobucket.com/albums/v132/4x4pede/Dark%20Impact/IMG_3092.jpg
http://img.photobucket.com/albums/v132/4x4pede/Dark%20Impact/B4_slipper_on_DI_1.jpg

This is a powerful Dark Impact, and probably the cheapest it can be for what it is. The brushless system, the Mamba Max 5700 by Castle Creations, was free for me as I was a beta tester for it. Normally, this system is $212, and it's way more powerful than any other system with a similar pricetag (including Novak and LRP). Due to the limited cooling, especially with the body on, I added a fan. There is also a body cutout directly above the fan.
The battery on the car in the pics is a Maxamps 2s 6000mah battery, perfect fit except that I had to cut the chassis a bit to allow for the side-exiting wires. Now I also have a True RC 2s 6400mah 10C battery that I'll be doing a review on shortly. For this battery I had to cut the chassis a litte more for the wires, but it fits. Both batteries provide excellent runtime and power, it goes about 40mph top, and I haven't even been able to do a complete discharge of either battery without stopping (I'd estimate at least 20mins runtime).
And how does the DI handle the power? There's a guy in England who makes custom slipper clutch shafts that use B4 parts, so I got one. I use B4 spur gears, too. Also, Tamiya has released their own slipper clutch, but you have to use the odd-pitch gears (B4 gears are standard 48p). So far none of the gears have been stripped in the gearboxes, but I fear that I may have melted the rear diff. Before I got the slipper clutch, I did buy two spare sets of gears, so I would be prepared.
The front driveshafts are Tobee Craft universals, found here (http://www3.kcn.ne.jp/~tobee/English.htm) (click on DF03). One of them broke right away, but the owner shipped me a new one that I should be getting pretty soon. The other universal is doing fine. Also from Tobee Craft is the blue aluminum adjustable turnbuckle set. So far they are working great, and they look much better than the non-adjustable stock pieces.

So far the DI is a great car. It's very durable, but my biggest problem is that the shock ends on the rear are stripped out so the shock shafts can pull out from them rather easily (only happens on really rough cartwheels, though). I'm looking forward to the DF03 aluminum shocks (haven't heard the best things about the DF02 shocks), but it might be a while before they come out.

[everydayflyer]

Those are some very nice BL set ups guys. make me wan to convert my Rustler to BL and see what all I can break. :)
I have been reading about the new CC Mamba Max 5700 and it is tempting.
Sometimes I wish my Revo 3.3 was BL but I am not willing to spend the big bucks to get a few thousand watts in it.

Charles

[Heli Mod Man]

It is good to see another Impact guy out there! :D

On 2S, your 5700 is very similar in performance to the Hacker 3600 KV on 4S I am sure. 40 is probably a good estimation for top speed.

I will be installing the gyro this weekend as well as setting up a 5S pack. That should yield about 70,000 RPM. I am not sure if the tires will handle the speed. But, I will find out!

Tmetalman, there is no need to worry about stripping gears from my experience. The rear diff is the concern. Use the front diff cups and you should be OK. If not, the only other thing to do is epoxy the diff. But, that hurts cornering (though with all the wheel spin generated anyway, the rear diff doesn't do alot for the handling). The biggest issue beyond the rear diff (in high horsepower applications) would be the rear axles. I have twisted and broken 6 of them so far. However, I do not have a alipper clutch on mine.

Matt

[defMondo]

Hey guys,

Thats prety impressive stuff, I just got one of these buggies just cause it looked like a bit of fun to run.

I see you guys have already tried what I wanted to try so it's good to read that it works.

Matt any chance of posting a couple more pics of the Novak installation? I will be using the Novak brushless motors and trying to fit the speedy in as well.

Thanks,
Tony

[Heli Mod Man]

I currently have that car apart for service.

However, I can tell you, the motor fits in, but the wires hit the gear case in one spot. Not a big deal, but something you should know. Also, the ESC fits sideways in the left well of the chassis.

The Novak system is fantastic! I would definately order front diff cups and use them on the rear diff. Then tighten the diff screw down tight and use blue Loctite on that screw. That will make the diff survive.

Matt

[defMondo]

I currently have that car apart for service.

However, I can tell you, the motor fits in, but the wires hit the gear case in one spot. Not a big deal, but something you should know. Also, the ESC fits sideways in the left well of the chassis.

The Novak system is fantastic! I would definately order front diff cups and use them on the rear diff. Then tighten the diff screw down tight and use blue Loctite on that screw. That will make the diff survive.

Matt

I just tried the motor in the car and seems to just fit nicely, I'll just solder the wires on the endbell side of the circuit board. I might mount some corally tubes on there as well make it easier to service the motor and not have to solder right next to the plastic chassis.

Good to know the pseedy fits in as well. I'll probably have the GTB speedy in it (it's a tad smaller) and if I'm feeling lucky I might try a 4.5 or 5.5 turn motor in the car as well. It'll be fun trying.

I have a bunch of stuff coming (including a slipper clutch) for the car so will rebuild the rear diff with the front outdrives so should work nicely.

Thanks for the info I'll post some pics when I get the car ready to fly.

Tony

[Heli Mod Man]

Update.

I decided to put some time into one of my Impacts today.

I installed a Park BEC to reduce glitches I was having with the high voltage (the ESC-BEC was not up to snuff). I also installed a new 3 chanel reciever (Futaba 3PM-FM radio). That was done to harness the Futaba GY502 gyro for the steering.

I setup the gain at 50% inntially and went out for a run.

All I can say is WOOOOWWWW!!!! This thing is phenominal! I am running a locked up rear diff on this car. So, it is hard to keep straight especially with so much power (on 4S). At any rate, the gyro totally cured my difficult to drive issues with the car.

The road is slightly damp and I have been punching it repeatedly down the road (50+ MPH). The tires spin and stand up, but the car goes PEFRFECTLY straight without any input from me what-so-ever! :D

Now, the car is so fast, it still requires skill to drive due to how much ground is covered in such a short time. However, the car ALWAYS goes exactly where I point it.

This thing is magical! It is super fast, and runs where you want it to go. Also, if the car spins out, the gyro lets it spin (very rapidly) 360 degrees and catches the car perfectly in the direction you told it to go before it spun (sort of self recovering). Very cool!

Also, I though it would kill my fun factor and my driving skill. However, what this has done is opened up a door that allows me to focus on my line in and out of a corner without being so focussed on counter-steering. I love it! :D

I do have another few gyros I could put in my other cars. But, honestly, I do not want all of them augmented. This car is special in my fleet and I want it to remain unique.

What am I saying?! I think I will setup all my cars this way. I think I have 3 more gyros lying around!

Enjoy the pics.

Matt

Oh, as a side note, I had most of these components just lying around. If you want to set something like this up, the car would cost over $1,000. So, this is NOT a cheap endeavor. But, this is BY FAR the fasted and best driving car I have ever owned and that is compared to all my cars including my MP6 with a Picco G1 Paris mod motor.

[TMetalMan]

That's awesome! How much does the whole gyro setup weigh? Would you be able to get a video of this "great driving car"?

[Heli Mod Man]

I do not know what the gyro weights, but the entire car weighs in at 55 ounces (1554 grams) as shown with pack.

Also, I am getting over 20 minute run time out of the car with about 40% capacity left in the pack (Tanic 4S 2480 pack).

This thing is really strange to drive. The car has no rear diff. So, it is squirly without the gyro. But, the gyro takes nearly all of the squirly behaviour away. However, if I exit a hard corner and throttle it too hard, the outside rear wheel will load up, hook too hard, and spin the car around 360. But, that is pretty easy to avoid. If I can get a rear diff to hold up, this thing should run perfect because that would eliminate the outside wheel hook up/spin around issue. However, even as it is, the car is phenominally well planted. In fact, I am going up from 4S to 5S shortly, a previously undriveable setup. This arrangement pushes the car somewhere over 50MPH. At 5S, it should be in the mid sixties. :D

Oh, the rear tires are HOT at the end of a good solid run! ;)

Matt

TMetalMan,

It is cool to have someone else pushing a DI to the limit.

I may need to go with the slipper clutch. Can you refer me to the guy who makes it? I have looked into making one for myself (I have a machine shop). But, the work involved versus the benefit is not worth it for me right now especially since I can run it locked up with the gyro keeping it straight. ;)

I am on dial-up. So, a video is not possible. Hmm, I cvan ask a buddy who has a server in his garage to get some for me.

[TMetalMan]

I sent you the guy's email address that makes the slipper clutch shaft for the DI.

Normally I would be pushing the DI harder, like I do with my Rustler (heavily modified) that runs 4s 6600mah Lipo and a motor that can push an E-Maxx. But, I have decided to not make a custom chassis for the DI due to the materials. It'd only be worth it to use CF or G10 (Garolite). Both materials require protection from breathing the particles in, and when I cut my chassis for my Rustler from G10 I went through 15 blades (scroll saw). So, I'm sticking with 2s Lipo for now, and LONG runtimes - my two batteries are 6000mah and 6400mah, both can give 20mins easy.

Do you know of an inexpensive and small gyro that I could fit onto my DI?

[Heli Mod Man]

Most good gyros require a spare chanel for gain. However, a JR 410 gyro does not require a thrid chanel for gain, is a good gyro and does not cost and arm and a leg. :)

I got your PM. Shoot me a call when you have a chance.

Oh, I may be able to cut you a CF chassis if you want. I would have to figure out the cost of it. Let me know if you are interested at all.

Matt

[TMetalMan]

I would be interested in a CF chassis, assuming it'd be affordable for me. My budget is currently a little tight (being 17 in a summer college class lessens the number of hours I can work). Other things I need to account for are other hopups and various other parts for the DI, as well as my two other vehicles (Rustler and a custom-converted electric 1/8 buggy).

The gyro will definitely end up waiting a while, especially since I'm hopefully going to start racing and breaking parts.

[Heli Mod Man]

Well, it's official, 54 MPH!!

I just installed a Venom speed meter. I calibrated it and ran the car up to speed. When I downloaded the max speed, it read 48 MPH. So, I regeared and remeasured my setup distance (meter programming) and went back out. When I came back, it read 54 MPH! And that speed was with a low lipo pack (15.7 volts at idle rather than 16.8 volts for a full pack) and it was not considering tire expansion. I am charging the car now. I am guessing it will read 56 to 57 MPH with a fresh pack and, again, that is not taking into account the wheel expansion. That is bound to add at least 3 or 4 MPH. However, untill I can get it radared or time through a trap, there is no way to know that for sure other than maybe measuring the OD of the tire when expanded and recalculating.

I am setting up a 5S pack for the car soon. That should put it at 65 MPH, maybe 70!

This thing is nuts!

Oh, by the way, it hits 0 to 54 in 2 seconds flat. :D

I will report back with more info and pics of the setup.

Matt

[TMetalMan]

Sounds fast! I've had my Rustler up to 57.5mph GPS verified, and that was a handful! Of course, it's 2wd with tires that get to be twice the size of 1/10 buggy tires. 5s should definitely do something different, my Rustler runs 4s and it's already too much!

Anything broken yet from high speed?

[Heli Mod Man]

I keep going through dog bones. But, that is with a solid diff. When the car loads up on one wheel, that shaft REALLY gets alot of stress.

I will be experimenting with diffs to see how I can make the rear diff survive. That should help the dog bone issue. I am also notching out the diff and wheel cups hugely!

It is really not a handful to drive at all. The gyro does all the hard work of keeping the darn thing straight. :D

I will let you know about the 5S run when I get around to it. It will probably have to wait untill the weekend.

Matt

[Heli Mod Man]

I just got in from a run on 6S. :)

Hmm, does anyone know of a good tire for high speed runs?

This thing is absolutely crazy and violent! I cannot get it wound out now. The rear tires get so large and skinny that they begin to shake as soon as the throttle is applied. If I could get the tires to settle down I know I would see 70MPH. If I hold the car in hand and throttle it up, the speed meter reads 81 MPH. With previous runs, the car loses 11 MPH consistantly with drag. So, if that is correct here, the car is capable of 70MPH. However, the tires will not take the RPM. I may install my second set of fronts on the rear. The front tires seem to be able to handle it, but the rears definately cannot.

Anyway, assuming the car loses 11 MPH in drag, 70MPH seems to be the number I can expect. Also, again, tire expansion will add to that. So, 72 or 73 should be the actual top speed.

At any rate, I will try the fronts and get back to you.

I am also planning to contact Proline tomorrow to see if they have any advice for me.

Oh, the motor and ESC get pretty hot VERY quickly. The car had about 30 seconds of hard running and the motor was at 120 degrees. The tires were too hot to touch. :D

Matt

[Heli Mod Man]

64 MPH! :D

OK, I got up early this morning and installed my spare front tires on the rear of the car. I went out for a shakedown run to check everything over before a full throttle blast. When I came in from the shakedown run, I checked the speed meter. It read 58MPH. And that was a relatively short run that never hit full throttle. I waited for all cars to clear the road and proceeded as far away as I could properly see the car. At that point, I turned around and headed toward myself. As the car neared me, I rolled on full. The tires expanded while the spun HARD. The car fought to what seemed like top RPM and I let it keep going to wind itself and attain the highest speed possible. When I let off and began applying the brakes, the car veered to the side and cartwheeled through the wet grass. Apparently one rear tire lost its CA glue bond on the rim (tore loose) and that overloaded one wheel. That dog bone lost its pin and made the car veer.

At any rate, no other damage was done. When I checked the speed, it read 64MPH!!

Very cool! :D

So, I am pretty happy at this point. I will contact Proline for some better tires. I would really like to see 70MPH. I think that is possible with my current setup if I can get the car to hook and run smoothly (no tire shake).

The car and tires seems to have a practical limit of 50 to 55 MPH with the tires and chassis. However, I am totally thrilled with the run.

Enjoy the pics.

Matt

[TMetalMan]

Wow...

Since the DI uses 12mm hexes, you should be able to get touring car foams for tires/wheels.

[rcmaster1029]

That is crazy that it goes that fast! We need a vid.

[Heli Mod Man]

Horsepower and RPM are not an issue at all. The entire limiting factor from breaking the 70MPH mark is tires.

I contacted Proline this morning. They suggested "Strapping" the tires (running 2 layers of duct tape on the inside of the tires). That is supposed to help reduce the tire expansion tremendously. I also picked up some street tires for it today. They did not have any touring car tires. So, I got 10th scale street tread tires. I will strap them and CA them tonight and report back tomorrow.

Oh, I ordered another DI to use for spares. Some DI parts are hard to get right now. :D

Matt

[trdmatrix]

I'm thinking about buying a dark impact for street racing and would like to know the e-mail to that guy who makes the slipper clutch shaft.

Also, where do you guys get tamiya parts? are there any aftermarket hop ups out there?

[TMetalMan]

I've gotten my parts from Tamiya USA (they're conveniantly located about 30miles from me) and Ebay. On Ebay there are lots of aftermarket parts from several different companies. Take a look:
http://toys.search.ebay.com/df-03-df03-df-03-dark-impact_Radio-Control_W0QQcatrefZC12QQfromZR8QQfsooZ2QQfsopZ3QQs acatZ2562QQsatitleZQ28dfQ2d03Q2cQ20df03Q2cQ20dfQ20 03Q2cQ20darkQ20impactQ29QQsbrsrtZl
That is a search that will find anything Dark Impact-related. Also make sure to check out the Ebay stores as that's where most of the replacement and aftermarket parts are.

[NoS]

alright i gotta same something here with these crazy impacts and that txt1 heli mod man made. heli mod man is the official or has to be the most innovative person on the car message boards. thats definitley my opinion. i have never seen a air plane brushless motor in a truck. also these impacts just came out and u already did somnething crazy. you should open a online store to sell cf chassis for impacts.

my big .02 cents

[TueLe]

yea. i think a lot of people will be interested in cf parts, especially for cheap ones lol :) ...

[Heli Mod Man]

It is funny, when you get into the high end of helis, everything else seems so simple. Car technology is very easy to adapt to when you are used to helis. Also, heli stuff is far more expensive. When a hobby shop guy says "Those shocks are $100 a set." I say "Is that all? What a deal!" :D I am used to paying $2000 for a heli and fighting for 2 weeks to get the darn thing flying the way I like it. Car stuff is alot more forgiving and less time consuming to setup. Plus I have alot of heli stuff still lying around. I even picked up a third DI today to install all the aftermarket goodies on (slipper clutch, alloy shocks, etc) as well as my own CF chassis.

Oh, I tried some new street tread tires on the car. It was really wild. I ramped it up to about 45 or 50 and hit the throttle, at that point, the car just wheelied! I let off and rolled the throttle on a bit slower and it still wheelied! It is bizzar watching a 4WD off road car wheelying at 50MPH on the street. :D

Matt

[TMetalMan]

I've not been having the greatest luck with my DI lately. Last weekend at the track I managed to swipe a wall, snapping a c-hub. It turns out the cause of that was that the bottom screw holding the knuckly was missing, allowing the knuckle to flex the c-hub. The cause of that was a stripped hole in the knuckle. My fix:
http://cgi.ebay.com/FS7034-Five-Stars-Front-Knuckle-Tamiya-DF03-Dark-Impact_W0QQitemZ250015782898QQihZ015QQcategoryZ340 63QQrdZ1QQcmdZViewItem
The screw holes won't get stripped, and I used blue Loctite to make sure that the screws don't loosen themselves and cause another c-hub to break.

But last night, I was driving around in the street while it was dark out, and managed to smack into a curb. The result: a cracked chassis (the front portion that keeps the battery from sliding forward). Now I'm in the market for a new chassis, and if anyone (:cough: Heli Mod Man :cough:) has an upgrade chassis for sale, I might buy that. Otherwise I'll just get another stock chassis and then work on some designs so I can cut my own chassis out of carbon fiber.

[triplepizza]

Last night I was so amazed by your adventure with this wild DI that I decided to buy it immediatly on eBay. Mamba max 5700 will come very soon. Does someone :) cough: Heli Mod Man :cough :) have a cf chassis for sale?

[Heli Mod Man]

I only made that one CF chassis. Sorry.

I am in the process of building another DI with my 9 year old son right now. It is running a MM 5700 on 4S. That should be good enough. But, the way to go would be another Hacker. Maybe a 9L on 7S. That would be good for about 1500 to 1800 watts reliably. But, the car couldn't put that much power to the ground anyway. :D

Matt

[triplepizza]

7s :eek: ? i'm shocked...which is your esc :confused: ? not the castel creation for mamba max I think :p
Very soon i'll put on the ground my DI with the castle creation 5700 motor/esc kit. I think I'll start running with a 8 cell ni-mh. Do you think it will be ridicolous? Considering that by now I've the stock chassis, and no hop ups prabably my DI will not handle very well not even this set up.

[triplepizza]

Ah, sorry, could you explain me what do you means for the "diff cups" ? sorry but i'm italian and I can't understand very well everithing you wright. I read there is some problems with the rear "diff cups", it's right? could you give me the code of the spare part so I can search it? thanks a lot.
And, sorry again, when you made your cf chassis did you draw it using a cad program? if you have the project I'll be infinitely grateful to you if you can give it to me.

[Heli Mod Man]

The diff cups are the steel outdrives that come out of the differential. Basically, the front diff cups are all steel. The rear cups are (for some seemingly stupid reason) have a plastic thrust washer backing plate. This backing plate cannot take huge horsepower and the flat will round out. However, the front cups are a direct fit on the rear. So, I recommend ordering the front diff cups for the rear.

Matt