DIFFERENT differentials - do you beg to differ?
 

Back in the 80s we had the gear diffs. Those were quite smooth I thought back then, and practically maintenance free.

Then the ball diffs came (I now know that Cecil Schumacher invented it, and that their logo illustrates just that, thx)... They cost more than the whole car and were much better it was claimed.

Can someone do a short story about why this is better?

I'm quite sure I read that Serpent is making a gear diff for their S400 (TC), that would be adjustable? Anyone got more on this? Will they try it also in the S500?

Personally I think the ball diffs work fine, but they don't last very long. For 1:12 it sucks big time! One single run and it's not smooth anymore... Not far as troublesome in 1:10 OR, but still I find it too much work (I'm lazy by nature).

1:8 OR cars use gear diffs because of the abuse right?

Give your thoughts and ideas! Can the ball diff be improved? Can gear diffs be just as good? New and even better solutions?

1:8 TR has a solid rear axle and a front one-way... now that's easy for ya! :thumbsup:

SMP tried with a one-way in the rear axle many years ago... why? To stop the WHOLE transmission when coasting... :woot: Has this been tried in 1:10 OR?

How would 1/10th OR perform with two one ways, and brakes via servo and disk?

Id like to cut out the maintenance of ball diffs, when they are good they feel great but when they go they're a pain at times. Plus the quality of the chinese AE and Losi stuff is far lower than what the Losi and AE stuff were like back in the early days of the B4 and Losi xxx/xx4.

Chris

How would you slow the car down with one ways at either end? :confused:

http://www.ymr.no/bilder/SMP/FASTBAK.jpg

The Slide had a brake disk directly on the rear axle ;)

They gave it up for 1:8 TR though, too much power so they never got it to be reliable...

@Chris: I'd love to try an RC car with a dedicated servo for the brakes! (not legal) You'd operate this with your foot, so you could brake and give throttle at the same time, to keep the momentum through the corner - just like when racing 1:1 scale :cool:

LOL, Disk brakes via a servo dude :thumbsup:

SHY guy, that'd be cool - proper toe and heal racing with a buggy.

Serpent HAVE made a geared diff for the S400, most of the team drivers are using it and think its great. Its adjustable by changing the thickness of oil in it (same as 1/8th OR diffs). Its only 5g heavier than the ball diff (are there light!) and the people using it much prefer it due to the reduced maintence and much more reliable tuning (its the same everytime you use it whereas with building a ball diff every 3 or 4 races its difficult to get it exactly the same every rebuild).

If I have 5 new ball diffs to build, all 5 will be identical once built. its easy.

Your comment is only valid if talking about rebuilding a ball diff with used parts. What tends to happen then is it'll be smooth until the grease is run in, then it'll just be dog rough again.

unless you are using a vernier torque meter, it is hard to get a diff exactly the same each time, even using new parts each time, plus the diff has to settle too, which adds to the work, whereas a geared diff, once built, will operate right away, and if rebuilt, with the same oil, will operate exactly the same way.

The only down side of the geared diff, is it removes any 'give' in transmission if you are not running a slipper, hence why the rallyx stuff is well over engineered.

When i rebuild my serpent diff i cant afford to use brand new balls and plates everytime, its opne so it needs a rebuild every 7 or 8 races. And how long have you been racing Chris? meaning how long have you had practice at rebuilding diffs? it does take some skill to get a ball diff identical every time, i can feel 1/16th of a turn difference in my S400, it takes a few runs to get it back to the same as it was.

Also, the comment was made about Serpent cars and Serpent diffs.

also a geared diff ie 1/8th style, can be run much looser than a ball diff with zero slip
and can also be run much stiffer than a ball diff and 100% smoother win win

I understand it would need a disc brake but you would have to have them in the drive shafts if you wanted each wheel to be independent:confused:


Also, i have never rebuilt diffs every few races, i raced open diff cars for years and i only ever rebuilt them after a wet race, a lot of it is down to the grease you use;)

I've often thought with a servo brake it would be quite good to have an xbox style controller with a seperate throttle and brake as triggers then normal steering stick.

Then left-foot braking comes into the equasion!

I used the Serpent stuff that came with it, then i moved onto the schumacher stuff and its ALOT better, would highly recommend it.

I have raced it twice now on one build, its getting raced again then rebuilt, i like to keep on top f the maintenance, would hate to loose and think its because the diff wasnt up to scrath ect.

AE green slime;)

For diffs? :o never knew that.

its very good, i also use it on the bevel gears in shaft driven cars;)

AWESOME!!:thumbsup::thumbsup:

I'll give it a try sometime.

Craig drescher told me about it years ago when we first ran the tc3`s;)

put my name down for a geared diff,

I always have problems with my 501's diff :(

yup and all five will be different once run so unless you use em for one run and fit another the performance will change on each unit

(oh and im not picking on you :p)

the best bit off gear diffs, run em in my S400 and all my ic cars bar the 835 which is a mans car with a front one way and solid rear axle. turn,power,go, hang on :thumbsup:

You could make it work with center one-ways and brake discs on the gearbox input shafts.

You would be adding a lot of weight though for a very questionable advantage.

You can achieve a si,ilar effect by turning off autobrake altogether on brushless setups. I tried this and basically found that the car tends to understeer more than if you have autobrake dialled higher since it doesn't transfer as much weight to the front when you let off the power.

Hope that made sense...

then you would still be running diffs!!!

The actual car that had this had a ventilated brake disk as part of the outdrive:
http://www.ymr.no/bilder/SMP/gml_brems.jpg
The oneway sat inside the rear pulley. So this worked just fine, except for the 1:8 power being too brutal for the one-way. Keep in mind that the driving force applied to the front wheels are a joke compared to what's going on in the rear!

Anyways, for electric we would need a small brake servo in addition to the ESC to be able to brake and give throttle simultaneously... not legal but I've always wanted to try this! Electric motors respond quickly, but for a gas engine you could keep the clutch engaged and the revs up... and for all classes you'd keep the car more stable going through fast sections!

I've been doing RC all my life, and I've learned to hate a few things:
-radio interference
-cleaning bearings
-maintaining brushed motors
-rebuilding diffs

I find it very difficult to build two identical diffs. Not to mention that they should be broken in after each rebuild (incl. sanding down the plates and so on), and gradually tightened. Takes a lot of time! I'd LOVE to just be able to tune a gear diff, and note down my setup... Btw I seem to recall that Serpent had on its Impact some years ago a special diff. I think the diff itself was always the same. And there was an adjustment of some friction plastes in addition... think it worked very well! (don't recall if that was a ball or gear diff though)

Is it really as good as a ball diff??? Why did we then get ball diffs in the first place??? :confused:

And more: if we go back to gear diffs... we can then have torsen diffs, tactyl diffs... or would that not be as suitable as for 1:8 OR? Keep in mind that with LiPos next year we can add some weight back on the cars...

I just make these presumtions, I'm not quite sure:
-the tranny should be as free moving as possible. When coasting I'd wish it was "gone". And no motor brake / drag whatsoever
-the only thing slowing the car down (except when braking) should be the friction between the wheels and the ground

I feel this caters for smoother, more consistent & faster cornering. And in many cases it's faster not to use brakes at all...

710 and impact 835 had ball diffs with adjustable friction collers


gear diffs have seen alot of development in quality and weight reduction, a true LSD is the way to go, when some one masters that, they will make a fortune

As far as I know the touring car guys went for ball diffs because of the reliability over a ball diff and the fact they couldn't put down the power as well with the stupid fast brushless motors they are using now. The newer delta winds put out massive amount of torque and revs their nuts off at something silly like 11000-12000RPM per Volt. That makes 66000-72000 RPM at the shaft at 6V :wtf:


Back in the day of old geared diffs the major problem was the binding at speed and the fact that they channeled the most power to the wheel with the least traction. Ball diffs operate smoother under power. I suppose materials and tolerances have improved to the point where you can make a small gear diff wirk reliably.

Has anyone tried running the ATD diffs in Associated or Jconcept cars. It's the one with the ring in the middle of the diff gear made out of slipper pad material. Gives you a much stiffer ball diff. What would it do to the cars handling???

LSD? What's that?

I wanna get high... :cool:

Edit: Limited Slip Differential?... How does it work?

Now that does ring a bell yes...

Read this explanation
 

Seams ther is no perfect solution, espesialy considering we are talking tiny scale model engineering (

http://auto.howstuffworks.com/differential7.htm

Can someone please explain the physics behind the ball diff? Which I guess can be partially seen in the Schuey logo...

Has this ever been used in real cars???

And can someone who knows about torsen and tactyl diff etc have a say?

Torsen diffs get progressively stiffer the higher the difference in output speeds gets. (at least full-size ones one big cars)

A mate of mine who builds them for Porsches explained it to me once and I got a nosebleed halfway through the explanation....:wtf:

Not actually sure you could build a torsen diff small enough to go into a 1/10 scale buggy without making it too big/thick, which would entail bigger drawbacks than could be compensated by the advantage.

Geared diffs would get a right kicking in a buggy...

This is for anyone on here named Lee:
http://www.youtube.com/watch?v=_RgL2MKfWTo

:lol:

Special bonus: MJ...
http://www.youtube.com/watch?v=jvzfjPQ0WiE

Frick! That's ace! :woot:

Amazing:woot:

tulibudibu douchooo:thumbsup:

another good diff page for those that like reading the theory

http://www.houseofthud.com/differentials.htm

Great link Showtime! Very interesting!!! I didn't know that full scale cars had "spider gears" in the diffs, and not bevel gears in the centre like in model car diffs. Why? Same with the "input shaft"...
http://www.houseofthud.com/images/vc3.gif
1:8 OR diffs are more like real car diffs right?

OK, let's get down to business! Can anyone check if the Serpent gear diffs will fit in any buggy on the market? Maybe with some modifications?

Part numbers? Webshop?

I'd be glad to get rid of my balls... :lol:

Imagine having several sets of complete diffs, with different hardnesses... and no fuss! :drool: Me want!

Has center diffs ever been uses in 1:10 OR?

I'd also like to know how a center one-way is like to drive compared to a front one-way, is it like something inbetween a front diff and a front one-way?

And I'd still really really like to know the physical explanation behind the ball diff! Understandig a gear diff seems quite straightforward.

your pic shows a centre diff not a front or rear diff
most car diffs (1:1) have sun plannet gears which are bevel gears as in the pic, spider gears i believe are just multiple bevel gears


for starters the serpent diffs are belt drive only, so that limits most id say closest would be a tamiya as tamiya diffs can fit in the s400

Yeah, I know. The other illustration was very crude, I wanted to show how the gears looked (as opposed to RC diffs with gear diffs "inside" the gear (centre).

But the XX4 and X-5 are belt drive, are the teeth the same mesh? What's the number of teeth?

the nice thing about the new geared diffs is
as you use thicker oil in the sealed diff you get more of a LSD action to them just as you would in 1/8th cars, the only down side to this is in 1/10th we have no centre diff

We do have limited slip diffs in BJ4's. The ATD diff does just that.

There was a guy on here who had rigged his D4 or BJ4WE with a diff in the middle and it was rubbish because he had no way of hardening the action. I'm not actually sure an adjustable middle diff would actually be much of an advantage in a 1/10 over a slipper clutch...

Don't worry. A few more months....
(SHY gets married this summer)


How can you understand one and not the other? The explanation is the same. Except it's balls and plates instead of gears and gears.

thats a atd diff
im pretty sure theres no propper lsd diff for any toy cars as of yet