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Old 02-20-2013, 03:55 PM   #376
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Hi for those of you who runs on asphault circuits with the sprint 2, how do you have your differential setup? Does anyone mess with it or just keeps it in stock form. Or does anyone have a writeup on running thicker weight oils or grease or whatever it is. Sorry I have the RTR version and Im trying my best to be able to keep up with the big boys. I figured this would be the best place for me to ask for setup tips.
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Old 02-20-2013, 05:08 PM   #377
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Originally Posted by ninjlao View Post
Hi for those of you who runs on asphault circuits with the sprint 2, how do you have your differential setup? Does anyone mess with it or just keeps it in stock form. Or does anyone have a writeup on running thicker weight oils or grease or whatever it is. Sorry I have the RTR version and Im trying my best to be able to keep up with the big boys. I figured this would be the best place for me to ask for setup tips.

All of my diffs (except the last purchase) have been rebuilt and shimmed per
HPI Sprint 2 Mods - Making a silk purse from a sow's ear.

I'm currently running on textured and cushioned vinyl flooring
Soon to be on carpet for the Scale Nats
Asphalt won't be until the weather breaks around the end of April most likely, unless we have another false spring like last year

Mr Whiteside from the Track @ Harbor Hobbies and I discussed diff oils briefly a few months back
I believe he mentioned that some drivers use 300,000 to 500,000 wt oil in the fronts
I don't recall what he said for the rears

My S2 =
I have a silver diff tuning spring in the front to stiffen it up a bit
The rear is stock

I tried a one way diff for one night (2 qualifiers + 5 races) =
On a small track with an uber technical course - not a lot of free running room =
I didn't care for it =
I took it out
Maybe at a larger track it might have a purpose, but for now =
Not for me at my current skill level

Here's a good read = http://radiocontrolzone.com/showthread.php?t=267694

Set up Tips For Asphalt...:
Balance the car - This is going to be a challenge because the S2 is ass heavy
The battery needs to be moved forward =

This is a mod I am currently working on (more to come soon)
My car pushes big time - lacking decent front traction...

Balance the shocks - all equal lengths
Chassis protector - or a chassis that you don't mind getting scratched to hell

The OEM chassis are CRAP out of the box =
All warped =
If you want to be competitive =
(IMAO) Go carbon fiber or aluminum for accuracy

Or just stick with the OEM POS chassis

Not sure which upgrades or fixes you have done yet - if any - now's the time to tackle the ones you like that will work for you

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Old 02-21-2013, 04:57 AM   #378
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i noticed on mine the other day after a parking lot run my rear diff spins super free when you spin the tire by hand and my front diff does'nt spin free, it feels tight when you spin the tire by hand

Diffs are stock and i am wondering which is the one with the problem? loose or stiff?
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Old 02-21-2013, 08:35 AM   #379
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Originally Posted by MaxThrottle View Post
i noticed on mine the other day after a parking lot run my rear diff spins super free when you spin the tire by hand and my front diff does'nt spin free, it feels tight when you spin the tire by hand

Diffs are stock and i am wondering which is the one with the problem? loose or stiff?
With a brand new S2 both diffs will be a bit stiff =
The grease that HPI uses is covering the gears
As you use the car the grease displaces some and the diff spins easier

HOLDING THE SPUR SO IT DOESN'T TURN

My front is stiffer because I have a tuning spring in it -

Possibly, your front had more grease than the rear (?)


Someone else with more knowledge can chime in at any time...


Last edited by Marv; 02-23-2013 at 09:02 PM.
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Old 02-21-2013, 11:20 AM   #380
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Quote:
Originally Posted by Marv View Post
With a brand new S2 both diff will be a bit stiff =
The grease that HPI uses is covering the gears
As you use the car the grease displaces some and the diff spins easier

HOLDING THE SPUR SO IT DOESN'T TURN

My front is stiffer because I have a tuning spring in it -

Possibly, your front had more grease than the rear (?)


Someone else with more knowledge can chime in at any time...

Do you have a picture or a part number of this spring? And what is the difference between tightening up the diff with the spring and tightening it up with the oil?
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Old 02-21-2013, 03:31 PM   #381
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Sad day... as I watched the background graphics change =
No Sprint 2 Sport...
Sad day indeed...

http://www.hpiracing.com/news/2013021501/

Or maybe they just forgot...
Attached Thumbnails
HPI Sprint 2 Mods - Making a silk purse from a sow's ear.-untitled-2-copy.jpg  
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Old 02-21-2013, 05:10 PM   #382
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MT, do they make funny noises or anything?

Quote:
Originally Posted by ninjlao View Post
Do you have a picture or a part number of this spring? And what is the difference between tightening up the diff with the spring and tightening it up with the oil?
He posted it like 3 posts up.
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Old 02-21-2013, 06:04 PM   #383
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I have both types - But this one is very hard to find =

HPI72215 =
This came as a diff tuning kit for the RS4 Nitro line (same diff back them as electric)
I back the spring ends with HPI72111 SHIM(S) =
This increasesspring preload

Brit Site has a bunch in stock = http://www.hpirchobby.com/hpi-gear-d...15-p-5004.html

HPI Sprint 2 Mods - Making a silk purse from a sow's ear.-hpi72215-2t.jpg


This one is available on the net
The spring itself is different in wire thickness an overall length
I think I have a diff with one of these in it as well
I have a number of diffs....

HPI87023

HPI Sprint 2 Mods - Making a silk purse from a sow's ear.-hpi87023.jpg

I'm not the expert -

For now, I prefer using the spring method =
Less mess...
The spring is constant = won't be affected by heat/cold as much a diff oil is (IMAO)




Last edited by Marv; 02-21-2013 at 06:19 PM.
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Old 02-21-2013, 06:25 PM   #384
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Just a headzup =
Swapping out a diff on the S2 is not a walk in the park

Carefull planning and keen attention to shit that flies that ain't suppose to fly and then the follow up noises = sproing ---zoooom---clack and more...

And if you don't intend on buying replacement E clips then
A)Don't lose any and
B) Give each a squeeze to snug it up some before you reinstall it...

Last edited by Marv; 02-23-2013 at 09:03 PM.
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Old 02-23-2013, 05:44 PM   #385
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Quote:
Originally Posted by Marv View Post
Just a headzup =
Swapping out a diff on the S2 is not a walk in the park

Carefull planning and keen attention to shit that flies that ain't suppose to fly and then the follow up noises = sproing ---zoooom---clack and more...

And if don't intend on buying replacement E clips then
A)Don't lose any and
B) Give each a squeeze to snug it up some before you reinstall it...
Excellent work on the noises Marv! I adjusted the settings on my hearing aid....just in case. lol
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Old 02-24-2013, 12:44 AM   #386
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Gotta love taking things apart.....then while you're not looking...SPROINGO!
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Old 02-24-2013, 12:49 AM   #387
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Originally Posted by Nitro Ace View Post
Gotta love taking things apart.....then while you're not looking...SPROINGO!

Yeah and if you have a cat it gets even better...
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Old 02-24-2013, 05:50 AM   #388
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Quote:
Originally Posted by Slobalt7 View Post
MT, do they make funny noises or anything?


He posted it like 3 posts up.
No noises just that the rear spins super easy, may have to take it apart and check the lube in it i guess.
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Old 02-24-2013, 05:54 AM   #389
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Quote:
Originally Posted by Marv View Post
Sad day... as I watched the background graphics change =
No Sprint 2 Sport...
Sad day indeed...

http://www.hpiracing.com/news/2013021501/

Or maybe they just forgot...
i only saw the E-10 Drift
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Old 02-24-2013, 09:52 AM   #390
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Quote:
Originally Posted by MaxThrottle View Post
No noises just that the rear spins super easy, may have to take it apart and check the lube in it i guess.

Are you spinning wheels with the diff stationery?
Some lube will STICK to the gears even when displaced by rotational forces, some will stick..
The stuff they use (green in my diffs) is sticky....
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