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Old 10-16-2012, 09:55 PM   #136
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That's NICE, Vostok!




And your work area is so... so...

I'm gonna cry now...

Last edited by Marv; 10-17-2012 at 07:11 PM.
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Old 10-21-2012, 08:38 PM   #137
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I have done ALL the mods listed here. They make it a much better car for VTA racing. I originally shimmed the stock steering but bought HPI #86005 steering for the Sprint 1. I had to shave .75mm off the lower spacers and install four 8x5x2.5mm bearings but it fits perfectly, it's very tight and all the slop is gone.I put 3x10mm screws on the top of the aluminum steering posts.

Here's link to the steering parts. rcplanet.com has a pic of the steering parts if you do a search. Don't have enough posts to attach URLs.
I had to order them off eBay from Europe and they're not made anymore so good luck.
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Old 10-21-2012, 09:50 PM   #138
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Quote:
Originally Posted by bobbyb323 View Post
I have done ALL the mods listed here. They make it a much better car for VTA racing. I originally shimmed the stock steering but bought HPI #86005 steering for the Sprint 1. I had to shave .75mm off the lower spacers and install four 8x5x2.5mm bearings but it fits perfectly, it's very tight and all the slop is gone.I put 3x10mm screws on the top of the aluminum steering posts.

Here's link to the steering parts. rcplanet.com has a pic of the steering parts if you do a search. Don't have enough posts to attach URLs.
I had to order them off eBay from Europe and they're not made anymore so good luck.


HPI Sprint 2 Mods - Making a silk purse from a sow's ear.-hpi86005-sprint-1.jpg

That's a great fix!

Thanks for posting that.

Glad to hear you're S2 is VTA & working good for you!

Last edited by Marv; 12-27-2012 at 04:43 AM.
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Old 10-22-2012, 06:55 AM   #139
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The Sprint 1 #86005 steering is suppose to be no longer available but if you search around you may be able to find it. I had to order from Europe thru eBay. Also the description says it's uses 8x4x2.5mm, it is wrong. The bushing/bearing center is 5mm not 4mm.
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Old 10-22-2012, 10:38 AM   #140
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Did you use the 'Z' bar?

Or did you go with the ball studs and link from your S2?
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Old 10-23-2012, 12:40 PM   #141
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there is some really awesome stuff in this thread. i love my sprint 2 and its my 2nd one. i have the tt01 and e10 as well but my sprint 2 is by far my favorite. i mainly use it for drift but alot of this stuff is really good general tips. im going to do the rear belt tensioner soon as my rear slips alot when drifting. thanks for all the info
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Old 10-23-2012, 01:25 PM   #142
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New wheels:





Took a lot of work, but seems to be running good now. Only parts I'm waiting for are the threaded shocks (just came) and the rear graphite tower (should be here soon). Probably going to order some 3x8x3 bearings to get rid of the tape when I get a chance.

With the bellcrank mod, a few shims on the front A Arms and C-Hubs to take up slop induced by the aluminum pieces and a proper alignment, seems to be driving good now. No more on/off throttle drastic toe changes, for instance
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HPI Sprint 2 Flux - GPM and OEM hop ups
AE RC10TC6.1FT - partial WC conversion, RSD hop ups
3Racing FGX - IFS, OEM Aluminum, Exotek hop ups
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Old 10-24-2012, 02:06 PM   #143
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that car looks really good. i love it
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Old 10-25-2012, 11:57 AM   #144
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Another tip I use is to replace the wheel nuts with the Traxxas ones. They are cheaper and stay put better as they are serrated on the flat side next to the hub. http://www.amainhobbies.com/product_...Locking-Nuts-8

Doesn't help performance much but it beats seeing a wheel roll off during a race!
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Old 10-31-2012, 11:31 AM   #145
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Hi Marv and friends.

Well my car has several pieces adapted as you can see.

The ball studs, ball caps was from other car that i don't know.

Now this car looks like an original Sprint.







And i put a new rear diff and new belts:



But i have a question about the Sprint 2 Flux combo (motor/ESC): this combo is providede by Castle. It's a Vektor 5900kv motor and a Vapor ESC. But both manuals that came with the car tell us the best gear ratio for this combo. So if i only use this car for drift what is the best gear ratio that i can use with this combo?

Marcelo
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Old 10-31-2012, 11:41 AM   #146
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I almot forgot, this is my new sprint:





I bought this sprint of a friend of mine and the only thing i do was change the rear belt...

Marcelo
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Old 11-01-2012, 12:16 AM   #147
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Quote:
Originally Posted by MARCELO CAMPOS View Post

But i have a question about the Sprint 2 Flux combo (motor/ESC): this combo is providede by Castle. It's a Vektor 5900kv motor and a Vapor ESC. But both manuals that came with the car tell us the best gear ratio for this combo. So if i only use this car for drift what is the best gear ratio that i can use with this combo?

Marcelo

Lookin' good Marcelo!


You'll need some guts in that new diff case - (CLICK FOR LARGER PIC) HPI Sprint 2 Mods - Making a silk purse from a sow's ear.-diff-parts-copy.jpg






From what I'm reading, you'll have to "lock" the rear diff to drift...


I'm a "gripper" = If my S2 "drifts" it's because I didn't use enough tire sauce...


You might also try these drift threads for help with gearing, counter steer mods, D Box info and all that fun stuff for drifting.

DRIFT 1


DRIFT 2


DRIFT 3


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Old 11-01-2012, 05:17 AM   #148
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Hi Marv.

Thanks for everything.

Well, today i have 3 Sprints here with me:

1 - Sprint 2 Sport original. this one is for ride normal, with some vintage cars like my 40 Ford coupe and my Dodge Charger NASCAR and sometimes drift with a brazilian Chevy named Opala. This car i'll never do a modification, it'll be allways original.

2 - Sprint 2 Flux: this one is for only use in drift. I will use a one - way front diff, d-box and some parts that used in drift cars, all HPI parts. Of course i'll do yours modifications, your voodoos is mine too!!!

3 - Sprint 2 RTR: this chassis is all in carbon fiber. Is the one with vintage wheels. I use with a Dodge Charger body (i'll post a pic later). This car was my first rc car. I bought it used and came to me with a lot of damage parts, changed parts and missing parts. I'm overhauling this car, change 95% of parts by new one. The rear diff is only an example! By the way, this diff is complete with new o-rings, gears and lube. Runs free... But i have problem with ball bearings. All bb were worn...I'll change by Acer ceramic bb...
Another problem in this car is missing screws. The old owner build this car but don't use all screws...So i'll have to buy it...

That's it...Thank you again...And let put this cars on the road!!!!

Marcelo
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Old 11-03-2012, 03:48 PM   #149
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Default S2 DIFF SHIMMING VOODOO

S2 DIFF SHIMMING VOODOO

Everyone has there own voodoo.
This is my voodoo.
This is what works for me.
Until I find better voodoo...


There's inherent slop in the diff out drives on the S2
There is lateral movement and side to side wobble/slop

The short side diff out drive is wobblier/sloppier in it's half of the diff housing than the long side

Because diff housing on that side is shorter and doesn't have the support that the long side does

Shimming will help stabilize both of the out drives =
Virtually eliminate all lateral movement and side to side wobble/slop
This means that there will be less trauma transfered to the dog bones & axles or cvd's (aka Universal Dog Bones) - if you use cvd's
Which in turn smoothes out the drive train, cuts down diff case wear and axle bearing wear.


NEEDED
HPI Z694 Shims
HPI Z852 Shims

To make the bushing/bearing shims =
Zip Lock bag for the shim disks
7/16" Hole punch
#7 Hole punch - a kids school type punch may work/the holes may be a tad larger, but this isn't an exact science
X-Acto knife with a sharp #11 blade - to trim the excess bag shim after install

2 - 5x8x2mm Bearings - IF you chose to upgrade the B070 bushings to bearings

NOTE:
If you intend to totally lock your diff, you won't need to upgrade to bearings = Just shim the bushings and the out drive cups

NOTE:
You can replace the E clips - HPI Z241 If you choose...
Or reuse the old ones if you give them a slight squeeze to tighten them up before reinstalling


PROCEDURE
Disassemble the diff(s)

Pop the bushings out

Clean out both halves of the diff housing

Zip Lock bag shim the bushings (or bearings if you're upgrading) as pictured




Shim out drive cups as pictured

This particular diff required two HPI Z852 shims and one HPI Z694 shim on each side to make it right




Reassemble the out drives and gears & check for smooth operation
If everything is smooth then disassemble the gears again, lube the back side of the gears, lightly oil the long diff cup shaft and reassemble
Lube the gear shaft & two smaller gears
Reassemble & reinstall in car

If operation is too loose or to tight =
Adjust with more or less shims depending on your needs



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Old 11-14-2012, 11:11 AM   #150
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Thumbs up Aluminum C Block Upgrade - STEERING SLOP FIX



Everyone has their own voodoo.
This is my voodoo.
This is what works for me.
Until I find better voodoo...



Aluminum C Block Upgrade - STEERING SLOP FIX


NEEDED:
HPI 72111 SHIM SET - $7.00
CLN4734 (Calandra racing Concepts) 4mm Shim Set - $5.99
Dubro 2109 3mm Washers
Associated 31290 - Ball Studs $7.00
Associated 6272 Dusts Covers - $2.00
GPM Aluminum C blocks - $10.70 to $15.40


Replace the OEM C blocks with GPM aluminum C blocks from Asia Tees.
The C blocks are priced from $10.70 To $15.40 (less shipping) depending on your color preference - ASIA TEES
Scroll down the left column for Sprint 2 Parts.

CLICK ON THUMBNAIL FOR LARGER PICTURE
HPI Sprint 2 Mods - Making a silk purse from a sow's ear.-pic_loader.jpg

These C blocks have either a 6°caster (according to the web site description - they have it listed as toe...)
The GMP C blocks are CNC machined.
There is no cant/angle on the upper ear of the C block like on the OEM C blocks.
Therefore, the hubs sit square to the GPM C blocks.

The fit of the OEM flange pipes in the GPM aluminum C blocks is better than the fit in the OEM C blocks, quite acceptable (IMO).

The OEM lower screw that goes through the C block and into the steering hub is an M3.
The fit in the flange pipe is acceptable (IMO).


However, the OEM ball stud, on the other hand, is a 4-40.

This means that the ball stud is way looser in the flange pipe than the lower screw is.
This is not acceptable (IMO).


The fix for this is to replace the OEM 4-40 ball studs with M3X10 Associated Titanium Nitride Balls Studs Part #31290.

NOTE ON RPM BALL CUPS:
RPM states that the same ball cups that fit the HPI 4.3 ball studs will fit The AE 4.3 ball studs.
They do snap on tight, but there's a little perceivable up/down slop =
The HPI ball studs are taller and have a slightly different configuration than the AE ball studs.

You can use the Associated Ball End Cup Dust Covers ASC6272 to take up that slack and keep the dust out.

There will be some slight up/down movement of the flange pipes in the new C blocks and virtually no side to side slop of the flange pipe.

The up/down movement may be reduced significantly by using the CLN4734 4mm shims, one each per flange pipe, between the flange pipes & the C blocks.

To fine tune/shim the hubs you can use HPI 72111 SHIM SET 3x5mm (M3x5x0.1-0.2-0.3mm/10pcs each)
DON'T OVER SHIM!

CLICK ON THUMBNAILS FOR LARGER PICTURES
HPI Sprint 2 Mods - Making a silk purse from a sow's ear.-aluminum-c-block-right.jpgHPI Sprint 2 Mods - Making a silk purse from a sow's ear.-aluminum-c-block-left.jpg



NOTE:
If your OEM C blocks rocked in the control arms, chances are the GPM C blocks will too.
You can shim the C block/control arm pin (screw) with in the control arm with the HPI 72111 SHIM SET.
Ditto for the rear hubs' control arms.

Additionally, I would HIGHLY recommend using a Dubro 2109 3mm washer immediately behind each control arm pin screw heads (front and rear) before reintalling them =
This will prevent the control arm pin screw threads from penetrating & grabbing the C block (which they do).

CLICK ON THUMBNAILS FOR LARGER PICTURES
HPI Sprint 2 Mods - Making a silk purse from a sow's ear.-control-arm-1.jpgHPI Sprint 2 Mods - Making a silk purse from a sow's ear.-control-arm-2.jpg


NOTE ON SHIMS & WASHERS:
Shims & Washers are stamped =
There's a smooth side and the other side has a sharp edge from the stamping process =
I like to put the smooth side towards the aluminum part I'm working with whenever possible (or bearing, if I'm shimming a bearing) and the edged side towards the plastic part.


NOTE ON GPM Aluminum C Blocks:
On the set of C blocks that I got I had to lightly sand out the control arm shaft hole on the right C block on one end - machining burr. No biggie.

I recommend using fresh hubs.
Installing the M3 ball stud into the already 4-40 threaded hole is not a good idea =
You'll more than likely cross cut the existing threads and weaken the assemblies.

If you pre-install the ball stud/screws in the fresh hub, before you assemble the C blocks/hubs, you have a better chance of getting them in straight on final assembly.

Adding a light coating of oil to the threads prior to the pre-install will ease things along.

If you're going to clean/oil, or up grade your front bearings, add CVD's (Universal Dog Bones) or diff cup springs - now is a good time to do that.

All voodoo is welcome here. If you have a fix, mod or upgrade for the HPI Sprints by all means post it.
Including what you did, how you did it and the parts you used (parts numbers) will greatly help other Sprint owners.




CONTENT ADDED 12.09.2012 =
*Having run with these on a fairly tight road course this last Friday night I can state that they held up GREAT!
*Where I would have snapped the OEM C block, from smackin' stuff and riding the rail, now only the camber link ball cup on the C block pops occassionally.

Last edited by Marv; 12-27-2012 at 04:40 AM.
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