Ball Diff on this Car?!?

[Shooterb]

I've read this car has a differential. My ZZ SE has the back end let go around corners. Is this diff available on its own? Would it click into an SE? I'd really welcome a detailed photo of it.

I made one for my SE from a stock axel using a jeweler's lathe and it clicks in like normal, but, I'd love to see how the factory one is built. Can you adjust the plate tension?
Thanks!
Brett

[payaso]

I make jewelry too. What exactly did you make for your SE? Got any pics?

My SE is crazy fast with the modified circuit board in it.



silla

[Shooterb]

Hi Payaso,
The Diff I made has 3 x 1/16th in. steel balls cut into the drive gear (convenient they have 6 holes already for centering: they just need widening for the balls). The drive gear is free on the shaft, with a .03" x .25" gap into the shaft side for the .22 dia. x .025" steel disk that's soldered to the shaft.
The wheel side has a .25" dia x .30" rare earth magnet with a .05" centered hole in it so the .047 drive shaft rotates freely within it. This magnet is cut into the wheel and the steel plate is in the gear so this mod is almost invisible. The magnet causes the tension between the plates. The whole unit clicks in just like a normal ZZ drive axel.
Shoulda patented this before sharing, but there it is.

Web cam on the blink.

How'd you modify your SE circuit board? I've sent mine to uA and I have some LiPo cells on the way (planning to single cell the 3.7V x 145).
Brett

[payaso]

Sounds like some good stuff there. I sent mine to OZ as well so the man micro_Amps could do his magic. He does some outstanding work.


Does your car handle any better with that diff?


silla

[Shooterb]

Yessir,
I'm still futzing with the design. I suspect that there's some slip in it. Good for overspeeded setups but I'd rather deal with that through other means (e.g. tall gears, with SE I can control the speed).
I'd think this car would never 'wheelie' or climb verts ;) with the diff.

That's why I'm interested in the tensioner in use in the Yokomo car.

Do you have a one of these diffs? I'd love to see how they work.
Brett

[Jtskty]

shooterb, would you be intereted in selling these when you get a finished design? Please;)

[Shooterb]

Absolutely love to if I can get a tight design going.
I'm going to experiment with a thicker steel plate for more magnetic tension. Very fun to spin one rear wheel and see the other turn the other way on such a small thing.


I've got another idea I want to try. I'm likely off topic far now, but I us Newbie sorts are called such for a reason. Let me know where to move this kind of thing to if you know.

Working two gear "auto transmission" concept:

Drill and mount a second tranfer gear spindle onto behind the drive gear so a ZZ red and blue gear are mounted, both contacting the drive gear (green for the drive gear will likely mesh with both reasonably).
Cut out the motor mount area and fit the motor onto a pivot so it can go forward and back onto the two gears (only one contacting at a time). Mount a magnet on the pivot, spring it so the motor gear contacts the rear blue gear, mount a "steering coil" such that when activated, the motor and its pivot are pulled forward to the red gear. Put a trim-able timer on the coil so that after the motor is run for X seconds (X being time for attaining top speed with a blue transfer gear on the drive surface) then
the coil kicks in and pulls the motor to the front red gear.
Better if I could figure a way to have the coil kick in using a centrifugal switch... This way pulsing power at top speed would keep it engaged in high gear while the car is going quickly.

This, with the diff, with the Li Poly battery & peak charger, with the king 4.2 & heat sink, with the uA FET Mod, with the cut off and siliconed back on rear motor set (rear 'suspension'), with the ROUND aluminum wheels (wheels out of round drive me nuts...), with the resonant-length guitar string antenna, with the tuned SE Propo steering (sorry, better than 'thumb propo' at high speeds I'm thinking), with the lightened and lowered body/ chassis-lose the lighting gimmick!), bearings on the drive axel, and cool ink jet created decals of Tiny RC, uA, King 4.2, ShooterB Engineering, etc. (this gimmick isn't heavy...) is where I'm headed right now.

Brett

[payaso]

I don't own a "puchi Maru" I was going to get one, but when the SEs came out, I thought I'd see what they were all about.

Turns out they're exactly what I'm looking for.

Did you look around the TTTT forums to see if some of their parts might be of use to you?

Too bad you don't live in FL. Would like to race you.



silla

[Shooterb]

I'll spare you an overly easy victory... I drive these cars with more enthusiasm than skill... Next you're up near Toronto I will demonstrate.

I really enjoy the futzing/developing/building/testing cycle. I'm an engineer so it can't be stopped...

Brett

[dgilpin]

I will try to get some pics of the puchi ball diff next time I get one torn down. Might be a while with Christmas and all.

[Shooterb]

Thanks dgilpin!
I'm most interested in the how the differential holds the friction plates together.

Merry Christmas everyone!
Brett

[payaso]

Originally posted by Shooterb
I really enjoy the futzing/developing/building/testing cycle. I'm an engineer so it can't be stopped...

Brett


That can be as much fun as driving them... I'm getting a 50th anniversery Corvette for Christmas.


My dad picked it up at RS. Can't wait to see how it handles.

30 years old, and still lovin the presents form my pop.

We might have a few ideas over in the hood that might help too.

http://www.bitpimps.lixlink.com/pages/phpForum/index.php


silla

[Shooterb]

Thanks Payaso,
Great link!

I just turned 31.
"Some people outgrow their desire to play, others, their desire to play outgrows them!"

Brett

[Shooterb]

Picture of the ball diff...

[dgilpin]

Puchi ball diff pics...

This is in the car, but with the two sides slightly separated.

[dgilpin]

This is the side with the tension screw. The screw tightens against a ball bearing.

[dgilpin]

With the screw and one half removed, exposing the spur, balls, and one plate.

[dgilpin]

And with the spur removed showing both plates.

[Shooterb]

Thanks dgilpin!
Excellent pictures!

The one I've made soaks up more torque than I'd like and I'm trying to figure away to improve this. Does really improve cornering, but at the cost of serious acceleration. Your pictures have already suggested an improvement: locate 6 balls (instead of 3) farther out, .25" instead of the .17".

Still, I think I need more tension. Perhaps if I could get even the inner plate magnetic...
Thanks,
Brett

[Whatup1049]

ncredible work, how do you make such tiny stuff? What tools do you use? I hope once you get a final prototype you sell those cause I would buy one!

[cheesehead]

I'm a shade confused, but I think I get the general idea.
Why not use a 3-gear differential? With 2 gears with horizontal teeth (facing each other) and a 3rd gear spinning freely between them, it would work great. You spin 3rd gear, which spins the other gears in turn. If one side slows down, the center gear adjusts the other one up. And you would get nearly no loss of torque with gears.
You can see what I mean with the LEGO diff-same idea.
Of course, you would have to be a clockmaker to get the gears to mesh....

[strakka]

your probably rite ... when you get this small a 3 gear diff would probably be better (like a Bit Char-G) but Yokomo made this car based on larger RC cars. thats probably why its a 2 gear diff