R/C Tech Forums

Go Back   R/C Tech Forums > General Forums > Electric On-Road

Reply
 
Thread Tools Search this Thread
Old 06-25-2012, 11:36 PM   #31
Tech Addict
 
Marv's Avatar
 
Join Date: Jul 2011
Location: ORD
Posts: 698
Trader Rating: 2 (100%+)
Default

Quote:
Originally Posted by rramjet View Post
Thanks Marv.

I played with the electronics today including going back to the HPI RX and TX. No real help so put the HPI servo back in; still no improvement. Went back to the Spektrum Rx and Tx setup and changed the Tx frame rate to 16.5 ms the slowest possible and things are normal again. Based on my driving skills the slower servo speed is probably better but still need to figure out whats going on. Think I'll try the capacitor next.
Is it happening after a right turn, left turn or both?

The reason I ask is because mine only did it after a left.

Which esc are you using?
Marv is offline   Reply With Quote
Old 06-26-2012, 07:27 AM   #32
Tech Regular
 
Join Date: May 2012
Location: Somewhere in Tornado Alley
Posts: 308
Trader Rating: 4 (100%+)
Default

With my Sprint 2 Sports, the first thing to change was the steering servo. My friend at the LHS where I bought mine told me that I would want to do that right off the bat. He sold me a Traxxas servo which I'd have to look up the model, seems to me it was a 1075 or 2075, something like that. I put a spektrum in the other one, an S6010 with metal gears. They are both plenty fast and strong for steering now. They sell for around $50 with tax. I did have to trim the mount a bit to get a good fit.

The radio isn't that bad but I would add a glitch cap. Novak and Spektrum sell them for around $10 to $12. They just plug into the bind channel on the receiver.

The ESC isn't the greatest, but will get you started. You will want to replace it if you go brushless. Depending on if you plan to race, you will have class restrictions that may dictate the ESC and motor you can use, such as in USVTA. I think this chassis will make a very do-able VTA car once tuned and modded.

With the info in this thread you can make a Sprint 2 competitive.

Thanks Marv!
nubie-wan is offline   Reply With Quote
Old 06-26-2012, 08:36 AM   #33
Tech Addict
 
Marv's Avatar
 
Join Date: Jul 2011
Location: ORD
Posts: 698
Trader Rating: 2 (100%+)
Default S2 Capacitor Mounting

Capacitor Mounting

Everyone has their own voodoo. This is my voodoo. This is what works for me.

I'm still using the OEM waterproof Rx box on my S2.

I didn't want the capacitor just hanging there.

I notched out the top of the box where I wanted the wires to come out.

Next I cut a 1/2" strip of .020 styrene plastic and made a loop around the cap - punched a hole to accomodate the M3 screw used to hold the Rx box top in place and added several pieces of masking tape to take up the slop in the fit of the strip to the cap.

Click thumbnails for larger picture.

HPI Sprint 2 Mods - Making a silk purse from a sow's ear.-dscn4309.jpgHPI Sprint 2 Mods - Making a silk purse from a sow's ear.-dscn4312.jpg

If you have another or better way to fix, mod or improve the S2 then by all means post it.

All voodoo is welcome here -

Last edited by Marv; 08-06-2012 at 01:27 PM.
Marv is offline   Reply With Quote
Old 06-26-2012, 12:58 PM   #34
Tech Adept
 
rramjet's Avatar
 
Join Date: Apr 2012
Location: Everett WA in the Summer Mesa AZ in the Winter
Posts: 116
Trader Rating: 5 (100%+)
Default

Quote:
Originally Posted by Marv View Post
Is it happening after a right turn, left turn or both?

The reason I ask is because mine only did it after a left.

Which esc are you using?
Now that you mention it the problem is predominately the LH turn. Still has the original HPI ESC. Been suspicious of it's BEC from the beginning.
rramjet is offline   Reply With Quote
Old 06-26-2012, 01:33 PM   #35
Tech Addict
 
Marv's Avatar
 
Join Date: Jul 2011
Location: ORD
Posts: 698
Trader Rating: 2 (100%+)
Default

Quote:
Originally Posted by rramjet View Post
Now that you mention it the problem is predominately the LH turn. Still has the original HPI ESC. Been suspicious of it's BEC from the beginning.



Thanks for the info! That helps narrow down the culprit.

Ditto on the OEM esc - that's what I'm running

Intially, the Savox sorta "chirpped" or hummed (for lack of a better term) in neutral. Like it's binding, but it isn't.

Could have been from the tight RPM ball cups - all seems normal now = no chirps or hums.

The skinny is that digtal servos are noisey...

The OEM servo just twitched / stuttered and hummed when it was trying to return to center from a left.

That esc will get changed when I upgrade to a brushless system later on.
Marv is offline   Reply With Quote
Old 07-02-2012, 08:29 PM   #36
Tech Addict
 
Marv's Avatar
 
Join Date: Jul 2011
Location: ORD
Posts: 698
Trader Rating: 2 (100%+)
Default C hub Steering Radius Mod

Everyone has their own voodoo. This is my voodoo. This is what works for me.

C hub steering radius mod:

For this mod you will need a belt sander, sanding block or file.

Simply remove 50% of the stop material on the C hub.

Click on thumbnails for larger pictures.

HPI Sprint 2 Mods - Making a silk purse from a sow's ear.-c-block-trimmed-copy.jpg

You may also consider going -1 of toe on the front wheels at this time if you haven’t done it yet.

Much more than -1.5 and you may experience handling issues.

Reset your end points using the bottom shock eye as a reference point = rotate your wheel applying slight pressure towards the front with the wheel turned (poor man’s way of simulating the lateral force on the wheel when turning) because there will be high & low spots / close & far from the shock eye.

The wheels are not perfect & there is going to be axle bearing slop and other slop issues that I haven’t addressed yet.

Find the happy spot - - -

HPI Sprint 2 Mods - Making a silk purse from a sow's ear.-too-close.jpgHPI Sprint 2 Mods - Making a silk purse from a sow's ear.-just-right.jpg

Then run the car on a stand turning the wheels to double check that the wheels aren't rubbing the shocks/shock eyes.


Other slop fixes for the C hubs/flange pipes, knuckles & axle bearings are forth coming pending parts.





Last edited by Marv; 07-02-2012 at 08:54 PM.
Marv is offline   Reply With Quote
Old 07-03-2012, 02:42 PM   #37
Tech Addict
 
Join Date: Oct 2009
Location: Cincinnati, OH
Posts: 719
Trader Rating: 5 (100%+)
Default

Hey Marv, where did you get the setup sheet on the first page? It's far more complete than the one in the manual and I'd like to track setup changes.
AMorgan is offline   Reply With Quote
Old 07-03-2012, 03:05 PM   #38
Tech Addict
 
Marv's Avatar
 
Join Date: Jul 2011
Location: ORD
Posts: 698
Trader Rating: 2 (100%+)
Thumbs up Set Up Sheet

Quote:
Originally Posted by AMorgan View Post
Hey Marv, where did you get the setup sheet on the first page? It's far more complete than the one in the manual and I'd like to track setup changes.

More Voodoo = I made it.

There is a blank one in post #14 with just the out of box settings in green.

Right click or double click for larger picture and save to your pc & print.

The rear camber - according to HPI should be hole 2 on the rear knuckle, but was actually hole 1 on my car out of the box = that's why it's marked the way it is.

Makes it easier for me to go back to basics if I get goofy.

Last edited by Marv; 07-06-2012 at 05:20 AM.
Marv is offline   Reply With Quote
Old 07-03-2012, 03:23 PM   #39
Tech Addict
 
Marv's Avatar
 
Join Date: Jul 2011
Location: ORD
Posts: 698
Trader Rating: 2 (100%+)
Thumbs up Chassis Weight Sheet

Here's a chassis weight sheet I made up - more Voodoo.

HPI Sprint 2 Mods - Making a silk purse from a sow's ear.-dressed-chassis-boxes-full-sizecopy.jpg

Right click or double click - save to pc & print.

Last edited by Marv; 07-06-2012 at 05:25 AM.
Marv is offline   Reply With Quote
Old 07-04-2012, 02:19 PM   #40
Tech Addict
 
Marv's Avatar
 
Join Date: Jul 2011
Location: ORD
Posts: 698
Trader Rating: 2 (100%+)
Thumbs up EXCEL Corner Weight / Gross Weight Balance Calculator

This voodoo isn't mine.

But it is good voodoo.

I have no idea where I found it.

I have no idea when I found it.

I have no idea who made it.

However, I did enhance it a bit and write an instruction page on how to use it.

I works quite nicely.

To use it you will need EXCEL (97-2003 or the newer 2010 version) on your PC and 4 small jeweler's type scales to weigh your car similar to these.

The scales have to be level / balanced to the suface you are using.


Corner Weight Balance Calculator.zip
Marv is offline   Reply With Quote
Old 07-07-2012, 05:33 PM   #41
Tech Addict
 
Marv's Avatar
 
Join Date: Jul 2011
Location: ORD
Posts: 698
Trader Rating: 2 (100%+)
Exclamation HPI USA SITE WARNING

Bad voodoo...

HPI Sprint 2 Mods - Making a silk purse from a sow's ear.-hpi-hacked.jpg

I was on this site yesterday & it was ok.

Today, GOOGLE has it flagged.



Malware may knock thousands off Internet on Monday

Tony, The stand alone USA HPI site was removed from the GOOGLE search on 07092012.

Last edited by Marv; 07-20-2012 at 02:20 AM.
Marv is offline   Reply With Quote
Old 07-07-2012, 06:07 PM   #42
Tech Elite
 
TPhalen's Avatar
R/C Tech Charter Subscriber
 
Join Date: Aug 2001
Location: Brookfield, CT
Posts: 2,793
Trader Rating: 2 (100%+)
Default

Quote:
Originally Posted by Marv View Post
Bad voodoo...

Attachment 943937

I was on this site yesterday & it was ok.

Today, GOOGLE has it flagged.



Malware may knock thousands off Internet on Monday
A web site that was host to a ton of pirated software was shut down. Any sites that used it or had users that used it were flagged and told that Monday the servers were going down and formatted.

I'm not 100% sure HPI's site was included in that but a couple hundred thousand sites will be going down Monday. Sucks if you were in on that.
__________________
Tony Phalen
UF1 Team Lotus/Renault
RCDriver.com
CompetitionX.com
R Sector / F1 Paint Labs
TPhalen is offline   Reply With Quote
Old 07-07-2012, 08:26 PM   #43
Tech Regular
 
AlienModified's Avatar
 
Join Date: Mar 2010
Posts: 484
Trader Rating: 6 (100%+)
Default

Got a mod for a thicker battery? I have one Venom 2s 5000mah 30c that fits, and four Sky LiPo 2s 5000mah 40c batteries that don't fit...
AlienModified is offline   Reply With Quote
Old 07-07-2012, 11:41 PM   #44
Tech Addict
 
Marv's Avatar
 
Join Date: Jul 2011
Location: ORD
Posts: 698
Trader Rating: 2 (100%+)
Default Doesn't look good...

Quote:
Originally Posted by AlienModified View Post
Got a mod for a thicker battery? I have one Venom 2s 5000mah 30c that fits, and four Sky LiPo 2s 5000mah 40c batteries that don't fit...
That's odd that the Venom would fit & the Sky wouldn't =

VENOM SPECS = Dimensions: 25 thick x 46.5 wide x 137.5mm long (0.98" x 1.8" x 5.4") This one?

SKY LIPO SPECS = Thickness(mm) 25.14 width (mm) 46.73 Length (mm) 137.96 This one?

Length and width wise it should work.

25.14 / 0.98976378 inches tall / thick


How did you manage to stuff the Venom in there?

The distance between the lower part of the battery holders and the chassis is measuring out to just shy of .90 inches / 22.86mm.

I'm not real good at math, but it looks like you'd have to raise everything / shim up everything that's mounted to the chassis or possibly just the upper deck with washers about 2.28mm = 0.0897637795 inches

It can be done -

However, this raises your center of gravity = It may not make a difference
if you're bashing or drifting...

OR

Relocate the battery holders - I'm working on a fix...




Last edited by Marv; 07-10-2012 at 02:26 PM.
Marv is offline   Reply With Quote
Old 07-08-2012, 08:47 AM   #45
Tech Regular
 
AlienModified's Avatar
 
Join Date: Mar 2010
Posts: 484
Trader Rating: 6 (100%+)
Default

Yes to both batteries, and I loosened it up to stuff the battery in there, then tightened it down.

Guess my best bet would be to start buying smaller batteries?
AlienModified is offline   Reply With Quote
Reply


Tags
hpi, sprint 2


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off



All times are GMT -7. It is currently 03:44 PM.


Powered By: vBulletin v3.9.2.1
Privacy Policy | Terms of Use | Advertise Content © 2001-2011 RCTech.net