tcanin00

Welcome to the ownership of the Sprint 2, aelsaid! Glsad you found this thread and have posted in it. It has been a knowledgable read, as I have learned a lot about my car by going through all of the posts.I feel as though I learned more from this thread in the month I spent reading it, than I learned from my car in the two years that I have owned it. Unfortanetly, there doesn't seem to be much interest in this car as it is considered to be old and outdated.
I should update with pics of progress on my version of the car. I had completed the roll cage, only to find the handling was terrible. With the cage in place, it made suspension adjustment nearly impossible. Out of frustration I removed the cage, and ran the car with a 1970 Plymouth 'Cuda body. That in itself made a difference because I removed some of the excess weight, and lowered the center of gravity. This allowed me to dial in the suspension, and move some of the components around in order to improve weight distribution. After several test runs with the car in a parking lot, I feel like I have the car handling much better than it ever has. The biggest problem was that when I first bought the car, I knew nothing about Akerman or D/Radjustments. Instead of turning the knob on my controller to get more through from the servo, I shortened the center link and lengthened the outer tie rods thinking this would increase leverage. In actuality, this induced understeer as I had factored in a lot of slip angle from the different rates of the wheels. As stated earlier, what I learned from this thread help me diagnose this situation and correct it. I still have a bit of on power understeer, so any advice would be appreciated.
On with the pictures.
The soldering of the main cage:



Main in place for to check for clearance:



Rear view as its coming together:



More bracing added for strength:




Main cage on the chassis:



At this point in the project, I wanted to reduce weight. The first plate that I cut from aluminum was exactly the same size as the body of the car, so it was pretty heavy. I ordered a sheet of 1.5mm thick carbon fiber, only to find it was to flimsy to be structual. I cut a new chassis out of aluminum that was much smaller, and I could use the foam front bumper. I will use the carbon as trim peieces, like for a rear diffuser.


All of the new parts I had been waiting for, ball diffs, Boca bearings, a full set of CVD's and new belts:



I also replaced the front steering blocks and c-hubs with aluminum pieces from an eBay seller named RC Dampner:



I decided to try out Xceed foam tires in varying hardnesses:



How the cage looks through the windows:



Nearing completion:



I linked the cage to the bulkheads with plates:



This shows the carbon fiber diffuser plate:



I made a filler plate for the rear window out of carbon fiber:



And a dash panel:



I decided to lighten the aluminum center chassis brace, first by drilling holes:



Then cutting out triagular sections:



This is it installed:



And this is the finished product:







Intial testing showed that I had a lot of body roll, so I modified a set of E10 sway bars to work:



I made end links for the sway bars from old shock absorber shafts:



Rear end link installed:



Top view of the rear suspension with out the cage:



How the car looks complete:



From the rear:



And after testing:



The combination of way too much rear toe in and improper suspension settings shred the first set of foams. I decided to look at weight distribution. Here is the process of moving components around:



Since the battery was much farther forward, I had to deal with belt clearance. I made tensioners out of the original hubs, some bearings that are the same width as the belt, and aluminum:



End result:



I moved the servo back and made a new pitman arm:



New lay out, which moved the CG 12mm forward. Not a perfect 50/50 distribution but very close:



And the 'Cuda body I am using for testing:

t9dragon

My Feedback: (11)

That is one kool looking build.. How much time do you have into it?

tcanin00

Thanks t9dragon! I have about six months of time involved, on and off. All of the metal work is by hand, I don't have a mill or any other precision equipment. I'm putting the roll cage back on tonight since I have the suspension dialed in, and the paint is flaking off the 'Cuda body. Tomorrow I'll see how much of an effect the added weight has.

flnsx

My Feedback: (3)

Can anyone recommend a 3S that will fit in the flux?

tcanin00

It has been awhile since I have been on this site, and I wanted to update the status of my project. First, handling was compromised by the custom roll cage so it was removed and I was able to make progress in getting the car to handle decently. Then after success was made with the chassis set up, I had a catastrophic failure of the electronics due to my choice of battery.
I ordered several different Turnigy LiPo batteries from Hobby King for what I thought was a reasonable price. As it turns out, their batteries are "B" grade by industry standards. I had a lengthy discussion at my LHS about Turnigy batteries, and was told that large orders of batteries placed by the store netted a 15% failure rate. My battery, a 3S 3,000mAh fell within that percentage by dead shorting one of its cells together and destroying my motor and ESC. Luckily, I was able to disconnect the battery from the car before it went up in flames or started smoking. The wires did get hot enough to melt the heat shrink off. Not how I wanted to end the day.
FLNX, I would NOTrecommend ANYTHINGfrom Hobby King. I have had good results with Dynamite, Thunder Power, and Onyx/Duratraxx LiPo batteries. Before I modified my chassis, I could fit a hard case Dynamite 3S 3,200 mAh LiPo. Hope this helps, and DO NOTbuy from Hobby King.

Quattromanta

Hi guys, have you got room for a new member from the UK? I've seen a few UK forums but you lot seem more passionate about the Sprint 2 Flux and you sound like a really good bunch.

I bought my car 2nd hand, it needed a new chassis and upper deck but once I got those sorted I was ready to go. I also joined the local rc racing club at the start of the year and every Thursday evening we meet up for indoor carpet racing. I'm in the beginners group for now and although I'm not particularly good at it I do find it great fun.

I'll post some pics soon if your interested?<br type="_moz" />

tcanin00

Welcome Quattromanta! Its good to hear from other parts of the world who share a common interest, the hobby of r/c cars.
What chassis did you replace yours with, the carbon fiber pieces or stock? Either way, I would like to see your car. It seems interest in this chassis is tapering off with the introduction of the next "latest and greatest" models. To be honest, I'm even considering shelfing my car as a static display and replacing it with something shaft driven like the E10 or TC3/4 since the majority of my racing is in the form of parking lot bashing. Belt driven cars don't like pebbles or debris.

Quattromanta

Hi tcanin00, cheers for the welcome.

I replaced the chassis and upper deck with the standard parts as at the time I didn't know carbon fibre parts existed. I must say how impressed I am with your handywork with your aluminium parts, I'm not good with metal work but I'm ok with wood....not sure about a timber HPI chassis though :-)

My car is standard so nothing exciting but you're more than welcome to take a look. The car originally came with a pre-painted Porsche 911 shell but I always wanted to get my own, so a few weeks ago I bought the Subaru Impreza Type C after pretty much everyone I spoke to told me that aerodynamics was everything when it comes to racing but really I wanted something like your gorgeous E30 shell or the Subaru Impreza rally car.






It would be a shame if you stopped using the Sprint but I understand where you're coming from, in my club there is only me and one other that have Sprint 2 Fluxes, everyone else has cars 2 to 3 times the value of mine, no wonder I can't always keep up with them.

tcanin00

Thanks for checking for checking out my project! I like to work with metal and other materials in order to build custom parts. I do the same thing with real cars.
Your car looks great, there is something to be said for a cleanly assembled stock chassis. That just shows that the original parts work. There is a homemade r/c car section in this forum that I also posted this project in. There is a guy from the U.K. that had to scratch build a car for a school project, and he used thin sheets of wood for his main chassis. Check it out and see if you get any ideas from him.
The Porsche looks nice, I like the 911's. The Subura looks like a sedan version of the new BRZ. Your choice in color suites it. I was origianlly building my chassis to be used with the Plymouth Cuda body, but I bought a 1984 BMW318i while I was building it so I thought it would be cool to have a scale version of my actual car. Your friends told you correctly about aerodynamics. Both the Cuda and M3 bodies needed substancial downforce from a massive wing before they would handle properly.
Like I said early, my main reason for wanting to shelf mine is that it will cost as much if not more to get the parts I need to repair the car. I spent quite a bit on the car during the build on things like front and rear ball diffs, a complete Boca bearing set, new drive belts, two sway bar kits that I combined to retro fit, and aluminum steering knuckles, bell cranks, and C-hubs. After asembling everything, I moved the lower screws for the C-hubs and rear hubs to the front of the A-arms so they couldn't loosen and come out. This allowed the hubs to move around and create slack in the A-arms. So another exstensive parts list would include A-arms and the treated hinge pins, and the bell crank modification posted by Uncle Vinnie earlier in this thread. Not to mention all new electronics from using a cheap Turnigy battery.
I was looking at shaft driven cars to prevent the driveline from being destroyed rocks and othe rdebris from parking lots. To be honest though, I am attached to this car. It was my first "real" r/c car so its hard to put it away. I have some time to think about it, so I'll figure something out.

Quattromanta

I love cars from the 80's so I have a soft spot for the BMW's of that era, rear wheel drive is so much more fun. Not sure if you had them in the US but I used to have an Opel Manta, it was a pretty successful rally car in the UK and Europe, it too was rear wheel drive and I had it for over 10 years, however my wife became pregnant and the car had to go and I had to grow up and get an Audi A4.

I've been to the US a few times, to Mount Plesant in Pittsburgh. My Mum moved over for a few years but she eventually came back to the UK. During my time there I grew quite fond of the Camero, I'm not too clued up on American cars but was a similar to 'Kitt' the Pontiac from 'Knight Rider'.<br type="_moz" />

tcanin00

I know what you mean about old cars. The newest car I own is a 1989 Mazda B2200 that I'm in the process of converting into a track car, once the funding is available. The is something gratifying about a proper rear wheel drive manual transmission car, especially an E30. I swapped the motor for an M50 2.5L straight six out of a 1994 325i and it is phenomenal. I made some short videos of both scale and full size videos. They can be found on youtube, look for Mr.Tcanin00 and you'll find them.
We didn't get many Opels in the US. I remember some late 70's Buick/Opels, and there was a sports car that was similar to a scaled down Corvette. I couldn't tell you the models of either car. I'll look up yours and check it out. Responsibility isn't something I have accepted yet. I am 31 years old and have made it this far without a wife or children, so I basically do whatever I want.
I live in Pennsylvania, the north east corner of the state about about 5 hours from Pittsburgh. I used to own a 1986 Firebird. Since it was white, it was aptly named the "White Rider." My brother and I used it to smash a clothes drier while I was on leave prior to deploying to Iraq with the National Guard.

tcanin00

Quattromanta, I wanted to clear something up. I feel like my lost post was a bit out of hand and very off topic. As stated, I admittedly did something stupid with my real car. I was not  trying to brag about how "out of control" I am. To be honest, I was an alcoholic at the time so my choices were compromised to say the least. I guess your mention of liking 3rd generation, or MK3 Cameros and Firebirds made me think of how poorly I treated my car during that time. I will say that the hobby of r/c cars has helped maintain my sobriety.
All this aside, what kind of suspension settings and tires do you use? I had difficulty tuning out a ridiculous amount of oversteer on both foam and rubber tires. I actually moved the battery forward and relocated the steering servo a bit further back and closer to the centerline of the chassis. I was able to get the weight balance close to 65/35 front to rear before I lost my electronics due to my poor choice in batteries. I was planning on making a new motor mount in order to move it forward, and repositioning the electronics to get the weight balance closer to 50/50. I don't remember my current chassis settings, but if I'm not mistaken I have the front and rear roll centers low, front shocks stood up to reduce initial steering, 40 weight silicone, and stock black springs plus  a light sway bar. The rear shocks are angled inward with 35 weight silicone and blue springs from the RS4 shocks and a heavier sway bar. My front camber is -1.5, and the rear is -1.0. I also shortened the shocks internally with plastic shims by 1.8mm to reduce ride height  without having the droop screws threaded through the A-arms. This seems to work, combined with a high downforce wing on the body of the ///M3, but it isn't optimal. I have to be rather conservative with corner speeds and would like to dial in the car's handling.<br type="_moz"/>

Simulacra53

Sorry if this has been asked before, but I'd like to update/upgrade my still stock Sprint 2 Sport.

I'm more of an off road guy so that's where most of my interest goes and hence experience, on road is something new for me.

I've got a castle SV2 1406-4600 combo that's not being used that might fit the Sport 2, but I am not sure about the gearing on 2S.

It doesn't have to be lightning fast, I'm more interested in control, reliability and perhaps some drifting.

Stock gearing is 23/87, would that be a good starting point?

I've found an old Castle gearing chart which recommends 19-23t, but that might be conservative as the 4 pole 1406 is more powerful than the older CM36 2 pole design.

<span class="Apple-style-span" style="-webkit-tap-highlight-color: rgba(26, 26, 26, 0.296875); -webkit-composition-fill-color: rgba(175, 192, 227, 0.230469); -webkit-composition-frame-color: rgba(77, 128, 180, 0.230469); ">Speeds up to 45-50mph on 2S.</span>

Also any pointers to getting he slop out of the steering?

Again sorry if this has been asked before.<br type="_moz" />

tcanin00

Your Castle should work for the Sprint. Most 540 and 550 size brushless motors have the same bolt pattern, or even two sets of holes and can be used in almost anything. The stock gearing with that motor will get you into the speed range your looking to reach. A smaller pinion will help reduce operating temps and lengthen run times.
There are two very good repairs in this forum. Uncle Vinnie posted something back on page 45 that looked like the best way to address it. His solution involved the use of aluminum RS4 steering components. I think it would cost about $30.00 to buy the parts. There is also another method using the stock parts, close to Uncle Vinnie's post, I can't think of the guy's name ATM. He posted a good write up on how to crimp the tube for servo saver, effectively making it smaller and taking up the play in it. He also recommended shimming up the bearings on the opposite side of the bell crank. I used his method and it worked for me. I also replaced all of the original end links with a combination of Traxxas and heavy duty plastic ones. That is the most common recommendation from this forum. Hope this helps!

MF-DK

You find the other steering repair on page 34. 

Thanks btw. for this helpful thread. I'm new to this place and just learned great things and goodies for my Sprint. Might have go try out those RS4 steering components.

tcanin00

Thanks MF-DK for finding gokemidoro 's repair. He later added a link to the pictures of his write up. His method worked for me. I would like to replace the bell cranks with RS4 parts,  but that will be later once the funds are available.
This thread has been very informative, and I have learned quite a bit about setting up my car.
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Simulacra53

Thanks for the quick response and good pointers.

This thread is filled with valuable information, so I'll just have to take the time to read it all.

Ruy<br type="_moz" />

tcanin00

No problem, Simulacra53
This is a very informative thread, and i have learned a lot about the Sprint 2 from it.
<br type="_moz"/>

jcon

First time loging on this forum GREAT info on the hpi sprint2sport/flux i purchased a sprint2sport just for kicks and quickly thought it would be a great idea to put a bigger motor on it, I put a 6800kv dynamite fuze with a 2c 7.4 lipo,Its crazy fast and hard to control now, i changed the pinion gear from a 23 tooth to a 28 tooth 90 tooth spur gear, recently ordered a 31mm tire has not arived yet, my goal is to see how fast i can get it to go, atm i run neck and neck with a rustler brushles with 11.1 3c lipo, but i cant throtle up to fast or it spins out, i figure its from the slopy stearing, i tryed this mod that was posted on here and came up with something that i think helped me and its simple, i put a rubber band across the 2 centerpost/steering horn/steering crank set (part 85097) seems to have taken alot of the slop out, havnt tryed it out yet ill repost another day as i have to wait for parts from breaking the lower control arm

tcanin00

Welcome to Sprint ownership, jcon
Traction is a big issue with this car because of being relatively light weight. Depending on what type of tires you have coming will determine how much they will help. I currently run foams, and I looking at Sweep racing tires specifically for asphalt once I get my car fixed. Go through this thread and see how other guys have set their suspension up. Small adjustments really help dial these cars in as well.
I had read about putting a rubber band across the center link, and it sounds like it would work. I used gokemidoro 's method on page 34 and it worked for me. I also added an adjustable turnbuckle in the place of the centerlink so that I could adjust ackerman. I found that lengthening the center and reducing the outer tie rod ends helped reduce understeer. I know that's not exactly your issue, but something you can look into if you notice it as a problem.
Positioning the rear shocks on the inside most holes, a lower weight oil in them, and softer rear springs help add grip to the rear of the car. Hopefully your parts come in soon so you can get back to beating that Rustler.

jcon

I think that HPI must have refigured the mainchasis, cause i already have a triangle cutout under both diffs, and it already has a adjustable turnbuckle centerlink, also i am trying a cheep fix to the diff slip... i added a couple of pieces of ziptie to create some friction inside so it has a limited slip instead of free spin, i noticed more wear on the left side tire which is consistant with the direction it spins out we will have to see how it works, parts arrived today so ill be taking it to the track, ill repost later how it works

tcanin00

I had seen pictures of a more recent version of the chassis which had cutouts under the diffs, along with the sections of bulkheads removed that are close to the diffs which trap rocks. I didn't know it had an adjustable ackerman link.
My original diffs were quite loose, and they don't seal well enough to adjust with thicker oil. If you're seeing more wear on the left rear, its definitely spinning through the spider gears. Some people have had good results with clay and putty in the gears to lock the gears. I remember someone posting that the Wheely King spools are a direct fit in the spider gear case.<span style="font-family: Arial,Helvetica,sans-serif; font-size: 16px; font-weight: bold; color: rgb(255, 255, 255);">#88073  DIFFERENTIAL LOCKER (SPOOL DIFF HUB/2pcs)</span>http://www.hpiracing.com/products/en/88073/  Locking front and rear would negatively effect handling, but since your focus is top end it might work for you. I replaced both front and rear with ball diffs and that seems to help with forward traction.

MF-DK

I wonder ifHPI did same recent changes to the Woven Graphite chassis. Never seen it but want one.

tcanin00

No MF-DK ,the new woven chassis does not have the cut outs under the diffs. Here's the link to it on HPI's site: http://www.hpiracing.com/products/en/73829/. The Exotek chassis does have the cut outs, and its cheaper as a complete kit: http://www.exotekracing.com/sprint-spx-pro-chassis-set/. Give these a look ans see if they will work for you.

MF-DK

Well, I can now only ask, why they don't give us cut outs in this case? Someone ever daredcall HPI?

The Exotek sure gonna fix that up, however,it can only be used with saddle packs - not exactly what I've planning to do.

Edit: 31-05-12
<span style="font-size: larger"><span style="font-family: Arial"><font color="#1f497d"><div style="line-height: normal"><span style="color: #000000"><span style="font-size: 9pt">A little interesting update to below and above post. Got reply from HPI telling this little story:</span></span></div><div style="line-height: normal; margin: 0cm 0cm 10pt"><span style="color: #1f497d; font-size: 9pt">
</span><span style="color: #1f497d; font-size: 9pt">"Since the Sprint 2 is an entry level model we found that may users were upgrading to newer chassis such as the HB TCX when they wanted to upgrade their cars rather than fitting option parts to their existing Sprint 2 models. As there was not sufficient demand for the option parts for the Sprint 2 they were discontinued several years ago."</span><span style="color: #1f497d; font-size: 9pt">

</span><span style="color: black; font-size: 9pt">There you go. It was discontinued, Btw Ifound out the HPI one alsomayturn outa problem with stick batteries. Might go "stick" with stock chassis. </span></div><div style="margin: 0cm 0cm 10pt"></div></font></span></span>