yakfish

My Feedback: (27)

I may end up trading for a HPI sprint 2 drift. it isn't the brushless flux version and I'm not really a drifter. I am a nitro guy who is giving electrics a try. my questions are how fast are these cars stock? will it be compareble to the stock HPI Nitro RS4 Evo 3 or the Associated NTC3? will it get into the 50's MPH? or will it be slower than that? If I do the trade I will eventually convert it to brushless and turn it into a high speed drag car. This car probably wouldn't be my first choice for an electric onroad but it is what i am being offered. will it be a good candidate for a brushless/Lipo upgrade and will it satify needs as it is stock?
Thanks

theunleet

After reading around a bit I can safely say it is not really meant for speed runs... not the Brushed version anyways, although you can go 9.6v or 10.8v NiMh(Nickel Metal Hydride) batteries and it might be ok fast on brushed.. It is more a drifting car. If you can get your hands on a flux model... I would do that instead. Or go for a Tamiya chasis from what is being said on the forums around here, here is a link to one.http://www.tamiya-store.com/shop/tam...-90015787.htmlOf course it would be a roller. You just need a motor, a Speed Controller(ESC), servos+radio, and a body, and you are all set. I can't load HPI's website right now to give you specs on the RTR Sprint 2 Drift, but they also have a "Sport" version too.http://www.hpiracing.com/products/en/750.html andhttp://www.hpiracing.com/products/en/760/ , but I suppose if you went brushless it would be a pretty fast little car.

gokemidoro

Yakfish,

I am a drifter and have a Sprint 2 drifter. I have seen a Sprint 2 set up for speed on Youtube, and it was mad fast, but he crashed and the car was toast. I have a few ideas, but generally, if you want speed, go with a high Kv motor and gear down (running something like a Castle Mamba w/7700 Kv motor will get you up to speed, so to speak). The Castle is so flexible and can take a 3-cell lipo, and the profiles can be tailored so you don't overtax the drivetrain. You can conceivably gear it for 60+ MPH.
There is a trade-off any time you want more speed. Heat. That's why I advise gearing down, to avoid this. I did an E-Maxx w/ a dual Castle system, and it shredded anything in it's path! Unfortunately, it was always smoking hot after every run. I geared down, lost about 10 MPH, but the motors stayed cool enough to run through two dual battery packs w/o overheating. The E-maxx is gone, but the Castle systems I ran in itare STILL going strong in other cars!

Since the Sprint 2 is belt-driven, you shouldn't have a problem w/ durability, though I run my Mamba that's in it at 70%. That's good enough for drifting. You may want to check out chassis that were made for what you want to do, though.
Also, having a radio system that is adjustable is a good idea. That's what I meant about flexibility. I run a Spektrum DX3R for just that reason. Best bang for the buck. If you really want to go Sprint 2, go to stronger parts in the drivetrain, CVD's, Aluminum hexes, that sort of thing. Of course you know this.

Hope I helped, in any case.

yakfish

My Feedback: (27)

Thanks for the replys. I have looked at the flux and the rtr versions of the sprint and the motor, ESC and tires seem to be the only difference from what I can tell. am I missing something else? If I do get this car there will be a nice brushless sytem in its future for csure along with some grippier tire which from what I can tell are the mojor upgrades nessasary? for any speed car if you crash you will break stuff no matter how well built the car is. but how strong are the diffs and other drive train parts?

gokemidoro

yakfish,

If you've seen other threads here, atRC Universe, on the Sprint 2, you've probably seen the rear diff housing mod- cut away the cover that is molded into the rear bulkhead. Use a Dremel to cut away the back half, so rocks and debris don't trash the rear belt and/or pulley (you can take the time and remove the bukheads to cut the cover off, as I did, makes the job look cleaner). You can also make a cover for the exposed side of the diff, same result- no more trashed belt/pulleys. As you've read, I'm now having trouble w/ my rear diff, but that's because I've altered it, so it was not unexpected.Of course, if you want speed, you don't want to lock it, they should be plenty durable for you.
There aren't any major upgrades you need, to run the Sprint 2 at speed except maybe aluminum hexes. The plastic ones I'm sure won't last long. They were the first thing I replaced on mine, even though I'm not a speed merchant, anymore.
There's some slop in the bellcrank system for steering, but it's not a big deal, and you shouldn't notice anything unless you are going ballistic w/ speed.

Yah, the Sprint 2 is a great little car! Affordable, well built and easy to work on. I purchased mine as an ARR (almost ready to run) and added my own electronics. If you do want to upgrade to better parts, HPI has a gangload of option parts available for it.

Hope this helped.

yakfish

My Feedback: (27)

Thanks for that. I think I will go ahead with the trade as it seems this car will work. what is the top speed of this car in stock form (with softer tires)? does anyone have any suggestions for a descent lipo to go with it? will a 3s or even 4s fit?

gokemidoro

yakfish,

Unfortunately, the Sprint 2 doesn't have the room for a 3 cell. I'm running a Venom hard-case 2-cell 20C, and it's a tight fit. With my Castle Mamba Max, it puts out gobs of power (which is why I'm running it at 70%)! So, if you want to run something in excess of 7700 Kv, it should have enough power and speed to suit you! Be aware that your battery won't last too long, though.
I put it's top speed (w/ stock gearing) at around 55 MPH. That's w/ a Castle system. They put out the most of any system I've tried, and are darn near bulletproof. I've gone waaaay outside it's recommended limits and voided the warranty on one combo, and they're ALL still working great! I've blown Novaks and LRP's just staying within their design limits. I guess you can say I'm a Castle devotee.

Let us know how it works out for you!

yakfish

My Feedback: (27)

I have been looking at castles site. I think the 9000kv system would go nicely!

gokemidoro

yakfish,


WHOOOOWEEEE!!!!! Major Tom to Johnson Space Center, igniting boosters, now!!!

You may want to go over the steering bellcranks, then. There's play in the left bellcrank pivot, as well as the right. most of it can be taken out w/ a small shim placed under the lower bearing on the left, and ashim (0.0010) on top of the servo saver on the right. This will not take it completely out, but it will be better than stock. Also, see about changing the links up front (just steering, camber links you can leave alone) to the type used in off-road or monster trucks, using the stock threaded rods, to keep the lengths correct. This will make the front end stronger, in case of a tumble.
These will keep to a minimum, the tendency to "cockroach" at high speeds, also.

Castle is now including a coupon for a free link chip for the Castle link, or a programming field card for $10.00 w/ their Mamba Max Pro combos and single ESC's! Choose whichever one will work for you. I have both, and use the chip at home, and the card wherever I happen to be driving at. The card is not as detailed w/ programming as the Castle Link is, but can do some things where there isn't access to a laptop or PC. I think you may need them!

Again, let us know how it turns out! I'm seriously curious, now!

alexchen86

yakfish,

In regards to gokemidoro's statement about 3S lipo not fitting into a Sprint 2 Flux you can as long as you get a soft case. The battery case is adjustable you maybe able to squeeze a 7 cell NiMH in there too. The Sprint 2 Flux was designed to really just run 2S lipos max but you can squeeze a 3S in there. As the Flux system is just a rebranded Sidewinder ESC it can handle 3S just monitor the temps. Make sure you run foams though No matter what glue I tried after cleaning, and what molded firm foams from HPI on their wheels/D compound tires they still balloon and the sidewall explodes.

I've cleaned and reglued several times before running foams now. 3S only for speed runs no more than 4000mah on open smooth lots and make sure you have a spoiler.

I've gutted my front and rear windshield and installed a wider spoiler on the rear. I also cut out a hood scoop as well.

gokemidoro

alexchen86,

Thanks for the update. I don't normally run 3S or higher (runs too hot, and have to gear waaay down), but I don't think yakfish is too concerned about that. Still, it's nice to know it IS possible to shoehorn a 3S in the Sprint 2!

yakfish,

I found a way to tighten up the steering on the Sprint 2, so it won't "cockroach" on you at high speed.

See "New servo I have questions please help" by leadfootdriver. It works! I've been running it now for four days worth of drifting, and it's still tight! Check it out!

yakfish

My Feedback: (27)

I just got the car today. I ran it a few minutes ago for the first time and it run nice with the stock brushed system but it is too slow for me. I am feeling the mamba 1/10 9000KV system in the next little while! I have some oroad foams from another car that will fit I just need to put them on and see how it handles driving and not drifting. i think drifting would be fun for just a few minutes at a time but I can't get enough of speed!!!!!

gokemidoro

yakfish,

Yah, it took me a couple of years (and LOTS of money later) to get the speed bug satisfied. I was able to get a Revo to do 68MPH on the highway here, where I live, and burned up a few non-Castle products in the process, but since then, I've found drifting to be a much more challenging segment of RC, and it doesn't cost much if you don't do option parts like crazy. It's a personal thing.

I think you'll be happy w/ Castle systems. If you have a question (they'll be happy to answer SPEED questions), call their tech dept. Nice guys, all! Ask for the supervisor, as he will know how to answer your questions.

And check your steering out, as well. I'm pretty sure you'll find LOTS of play in the bellcranks. Tighten that up, and you'll be ready for Mach1! : )!!!!

iMOD

you wont be able to control 9000kv unless u have a good finger.

gokemidoro

Oh, it's possible, even with a ham-fisted trigger finger. The Castle system yakfish has in mind is extremely tunable w/ the castle Link, and the profile can be tuned for drag. Though foams do squirm at high speed, that can be ameliorated somewhat by CA on the sidewalls.

yakfish, have you seen my "fix" for the steering slop in the Sprint 2? It works. I've been running it now for a week, and it's still tight. Drifting really uses steering a lot, and I've got spot-on steering. It's on another Sprint 2 thread. I figure for drag, it would cure the wander, or "cockroaching" at higher speeds.

Happy Rocketeering!

alexchen86

Gokemidoro,

I second that notion on applying CA to the foams. Just don't put too much...keep in mind it is foam and it will soak like a sponge if too much is applied.

I am running foams on my 1/10 Sprint 2 Flux as the rubber does not adhere to the wheel no matter what CA I use. From super thin (WORSTCHOICE), to thick (mediocre for 1 run on a 5000mah 2S), to the new slightly flexible CA(best so far but still did not hold). I run HPI molded foams hard and glued them to the wheel after cleaning everything of course with alcohol.

With a 5600kv motor on 2S or 3S you NEED to run foams other wise once the tires heat up they will rip apart at the sidewalls. I ran a 4000mah 3S and a 5000mah 2S back to back on Flux on foam tires and they hook up better plus they have absolutely no wear on them yet.

Foams are a must if you run brushless touring. Unless you want to keep replacing tires and wheels.

gokemidoro

alexchen86,

Thanks, but I can't take credit for the CA thing.....Got it from Tony Phalen. I went through the rubber-tire balloon thing, split a pair right down the middle of both tires. Like you, I found foams don't expand. They don't work much better than rubbers (at least on asphalt or concrete), so everything's equal. I found out the same thing on wear....Foams just don't wear on asphalt or concrete! They do chunk on occasion, but the asphalt has to be somewhat rough for that to happen.

FYI, I submitted the bellcrank fix for the Sprint 2 to Extreme RC Cars Magazine, and just got a reply from them. They said If they can, they'll publish it.They couldn't promise, but they'd try. That's all I can ask! I used to do the same thing for pubs in the Army. The tech-heads (small arms)loved that stuff! BTW, the fix is STILL working! I'm going to run a log, so I will see how long it takes for it to loosen, if it ever does. Maybe HPI will get wind of it, and do something about it on further model years. I like my Sprint 2, it drifts well, easy to adjust, and with a front one-way and locked rear ball diff, is easy to transition left/right/left, now. It would be a handful on carpet for grip driving, but for drifting, it's a dream!

alexchen86

gokemidoro,

What is this bellcrank fix you speak of? I know the steering is a bit loose and wobbly. I tightened the crank a bit but there's still wobble.

I tried the search on the forum can't seem to find it do you have a link?

Thanks!<br type="_moz"/>

gokemidoro

alexchen86,

I'll post it again, as being in many places, those who "stumble" across it, may help them.

Take out both bellcranks. Place a .005-.008 (depending on how much slop you have) shim under the E-clip on the left bellcrank. Set it aside, as that one's done. Take the right side bellcrank apart. You will see the base pin, made of steel, and the aluminum sleeve that goes over it, that is part of the servo saver (the lower part of the servo saver is attached to it). Take a Dykes (side-cutters) and CAREFULLY dent the sleeve about halfway up, at 12:00, 3:00, 6:00 and 9:00 o'clock positions around the sleeve. Don't use too much pressure, as you only want to tighten it up, not make it bind. I made that mistake, and had to:
If the sleeve is too tight on the base pin, it will not rotate freely, which is what you want. Put a small drop of oil between the base pin and sleeve, chuck the pin in a hand drill, and SLOWLY spin the pin in the sleeve until it turns freely by hand (you'll have to take the pin out of the drill to check, and may have to do it several times, depending on how tight you made the dents).
Check for up and down play, because if you don't, that may loosen the sleeve up again, and the slop will return. Shim it like the left side.
Assemble it back together. You may have to readjust your steering settings, I did.
I also replaced the center and steering links with 10th scale off-road ones. I used the same turnbuckle, but replaced the rod-ends (I absolutely hate ball cups). The camber links I left alone, as they won't be adjusted anytime soon.

So give the fix a shot, and let me know how it turns out! Best part of the fix is, if you have the shims, it doesn't cost a dime more!

alexchen86

gokemidoro I am a retard haha do you have pics of this mod. We can have the forum moderators move it over to the Sprint 2/Sprint 2 Flux Official Thread later.

I think I kinda understand but show me some areas where the shims go and everything if possible. Thanks bud!

gokemidoro

alexchen86,

Unfortunately, I don't have the capability to post pics yet, butI can "walk" you through the procedure, if you like.

If you've got the bellcranks removed, look at the left bellcrank. At the top, you'll see the E-clip. That needs to come off, and the shim (whatever thickness you need, will be trial and error) placed underneath it, and the E-clip re-installed (Be careful not to lose that E-clip!). Make sure the bellcrank can spin on the pin easy. Set the left bellcrank aside, as it is done.

Now for the right bellcrank. Take the servo-saver adjustment wheel and spring off. The arm that connects the right steering arm and center links is next. Now you are left with the base pin, made of steel, and the aluminum sleeve. The aluminum sleeve has the arm that connects to the servo link. THIS is the part you'll need to dent with the Dykes. From top to bottom, measure about halfway down, then dent the sleeve with the Dykes, at 12:00, 3:00, 6:00 and 9:00 O'clock positions, as you look at the top of the sleeve (like looking through a tube). Remember to keep the base pin INSIDEthe sleeve when you dent it. You don't need too much pressure, just enough so the sleeve contacts the pin.
If the sleeve doesn't rotate on the pin easy, that's why the drill. Chuck the pin (the side that sticks up into the upper chassis plate, when it's installed) into the drill. You can do it finger tight, as it won't take much to damage the pin if you use a key to tighten it. Add a drop of oil between the pin and sleeve, then spin the pin inside the sleeve SLOWLY, until the sleeve turns easy on the pin. You need to do this, or risk taxingand trashingthe servo, once everything's together.
O.K., now assemble the parts in reverse order that you disassembled them. Hold the bellcrank in your hand upright, the way it will be in the chassis. Look at the top of the bellcrank. See where the pin goes through the sleeve, with the hexagon shape? A shim needs to go there. disassemble it again (no worries, if you have to take it apart for any other reason, you'll know how everything goes), and remove the pin from the sleeve. Put the shim on the pin, then slide the sleeve into place. Reassemble as before.

Now, you can put everything together, and if you decide to go with the off-road rod-ends, do it now, and save a LOT of trouble later. Of course, you don't HAVE to do this part, but like I said, I HATE ballcups! And I think off-road rod endsstay tighter for a longer period. Axial makes the same length rod ends that will take the turnbuckles. So does AE and Traxxas (which are the ones I'm using, they come from the electric 4-Tec).</p>

If you still need pictures, I have E-mailed Extreme RC Cars to tell them about pics, if they publish the fix, which I'm sure they will! If you can get next month's issue, they say it will be in that one. Do you get XRC Cars magazine, where you live?
I'm sorry if what I wrote isn't clear, as words don't really do as much as pictures can, and I really want this fix to get out there, because it's worked for me for sure! There are so many Sprint 2 owners with sloppy steering, and this is the best fix I could find.

If you need help with it, I check my E-mail every morning, Pacific time, and in the afternoons. I think the time difference is you're two hours ahead of me. It's almost 8:00 PM here, so you should be 10:00 PM. E-mail me anytime, and I'll get back to you ASAP! If you see I'm online, keep checking back. We'll get this done, hook or crook! </p>