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-   -   Spool vs Ball Diff (https://www.rctech.net/forum/electric-road/749784-spool-vs-ball-diff.html)

hyujmn 08-07-2013 08:13 PM

The reason for running a front gear diff with 2.5million cst (I don't like putty because its inconsistent) is for increased entry steering and a generally smoother feel overall. I started my car with a spool and ran it that way for nearly a year before trying a gear diff up front with thick oil. With the spool, the car was under steering into a corner. With the gear diff, entry steering increased greatly and the car was more predictable overall.

It's more of a tuning thing i suppose. I know that I probably won't run a spool up front with my 17.5 ever again though. Conversely, I have a spool in both my VTA and mod car because I like how they're set up already.

hyujmn 08-07-2013 08:14 PM


Originally Posted by dirtybirk (Post 12425246)
Thanks for all of the feedback. A lot of good information. It seems as though not much has changed over the years accept going back in time to gear diffs. I will try one with front oneway and one standard ball diffs and adjust from there.

James

One ways are also pretty obsolete.

F. Mendoza 08-07-2013 08:20 PM


Originally Posted by mkiiina (Post 12424059)
.... Don't quite understand the rational behind running putty/jb weld/ anything else that makes a gear diff essentially a spool....

Me either, just makes the gear diff much heavier.


Originally Posted by Skiddins (Post 12424144)
Don't know about HPI, but Xray's gear diff is 10g lighter than their ball diff!

Also, if rotating mass is everything, surely you're better off using a spool as they weigh even less again.

Thanks because I was about to weigh both my gear diff and ball diff. :)

Shawn68z 08-07-2013 08:33 PM

One more point. A spool is harder on the drive line, and you will need to replace parts more often (Thinking of those small clips on the drive shafts). Esp if you hit a board, you will probably break and outdrive.

With running a diff (of any type), you are less likely to break a component if you tap a board, and the wear and tear on the drive line tends to be less.

I run a spool outdoors for the extra power coming out of the corner, but on carpet I quickly switched back to a diff (ball) for the extra steering. I have not had the opportunity to run a gear diff in electric, but do play with them in nitro (120K front, 30K rear). Works really well.


Shawn.

nsgland 08-08-2013 07:00 AM


Originally Posted by hyujmn (Post 12425280)
The reason for running a front gear diff with 2.5million cst (I don't like putty because its inconsistent) is for increased entry steering and a generally smoother feel overall. I started my car with a spool and ran it that way for nearly a year before trying a gear diff up front with thick oil. With the spool, the car was under steering into a corner. With the gear diff, entry steering increased greatly and the car was more predictable overall.

It's more of a tuning thing i suppose. I know that I probably won't run a spool up front with my 17.5 ever again though. Conversely, I have a spool in both my VTA and mod car because I like how they're set up already.

Where can I find 1.5 or 2.5 million cst. I have 500K but haven't found anything thicker.

ByteStream 08-08-2013 07:31 AM


Originally Posted by nsgland (Post 12426373)
Where can I find 1.5 or 2.5 million cst. I have 500K but haven't found anything thicker.

Gravity RC .. also available at online at many shops

http://www.teamgravityrc.com/dealers.html

oceanhighz 08-08-2013 07:33 AM

Gravity RC
http://www.teamgravityrc.com/products.html


beat me to it...........bytestream, haha!

hyujmn 08-08-2013 07:44 AM

That stuff is super thick. It doesn't flow so you basically have to just scoop it into the diff. They provide a little syringe to try and load it in but it doesn't work. I decided to just use an old spec r gear diff I had instead of using a $60 one from xray. Does the same thing (weighs more but my car is under weight anyway) and was a lot more cost effective.

Skiddins 08-08-2013 08:49 AM


Originally Posted by mkiiina (Post 12424059)
..Don't quite understand the rational behind running putty/jb weld/ anything else that makes a gear diff essentially a spool....

I have a gear diff with 2.5million in it, I only use it when running Mod and it does still have some diff action.

You can turn the wheel by hand and make the opposite wheel rotate in the opposite direction. It's stiff (obviously :p) but does help.

Tried it in stock and all it did was reduce drive out of corners so I took it out.
In Mod you have to be so much more progressive with the power anyway that this doesn't show up as much (also adds stability in Mod over a spool)

Skiddins

F. Mendoza 08-08-2013 11:13 AM


Originally Posted by Skiddins (Post 12426723)
I have a gear diff with 2.5million in it, I only use it when running Mod and it does still have some diff action.

You can turn the wheel by hand and make the opposite wheel rotate in the opposite direction. It's stiff (obviously :p) but does help.

Tried it in stock and all it did was reduce drive out of corners so I took it out.
In Mod you have to be so much more progressive with the power anyway that this doesn't show up as much (also adds stability in Mod over a spool)

Skiddins

That info helps a lot. I used a gear diff up front with 50, 000 diff oil and point both outdrives in the same direction. It felt the same as the spool. After the run I notice no change of direction on the outdrives with 17.5. Will have to test it in Mod. It's been so long since I touched Mod. Thanks for your input.

hyujmn 08-08-2013 11:22 AM


Originally Posted by Skiddins (Post 12426723)
I have a gear diff with 2.5million in it, I only use it when running Mod and it does still have some diff action.

You can turn the wheel by hand and make the opposite wheel rotate in the opposite direction. It's stiff (obviously :p) but does help.

Tried it in stock and all it did was reduce drive out of corners so I took it out.
In Mod you have to be so much more progressive with the power anyway that this doesn't show up as much (also adds stability in Mod over a spool)

Skiddins

Yea you had the same experience I did with a gear diff. Reduced drive outta corner but increased entry. I always felt like my car oversteered a bit outta corner and understeered into it so the gear diff seemed like the perfect fix and it was exactly what I was hoping for.

F. Mendoza 08-08-2013 11:30 AM


Originally Posted by hyujmn (Post 12427211)
Yea you had the same experience I did with a gear diff. Reduced drive outta corner but increased entry. I always felt like my car oversteered a bit outta corner and understeered into it so the gear diff seemed like the perfect fix and it was exactly what I was hoping for.

Good, someone we lse who can substantiate the test. Nice! :)

grippgoat 08-08-2013 12:50 PM


Originally Posted by Stratus Racer (Post 12427236)
Good, someone we lse who can substantiate the test. Nice! :)

I found the same thing, too.

Interestingly, I found that DCJ's with a spool had a similar feel to 500k gear diff without DCJs, in terms of turning into the corner better and being smoother through the middle. But it of course kept the corner exit pull that the gear diff was lacking.

-Mike

hyujmn 08-08-2013 01:01 PM

Hmm that's something I didn't notice. I always run xray ECS driveshafts up front

F. Mendoza 08-08-2013 01:08 PM

Question, are DCJs from what manufacture the same as Xray's ECSs? :confused:


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