DIFFERENT differentials - do you beg to differ?

[sparrow.2]

Originally Posted by Lee

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

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...

[mark christopher]

Originally Posted by sparrow.2

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!!!

[SHY]

Originally Posted by Lee

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


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

The actual car that had this had a ventilated brake disk as part of the outdrive:

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???

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...

Originally Posted by sparrow.2

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...

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...

[mark christopher]

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

[sparrow.2]

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


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???

[SHY]

LSD? What's that?

I wanna get high...

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

Originally Posted by sparrow.2

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.

Now that does ring a bell yes...

[Zedman]

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

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

[SHY]

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?

[sparrow.2]

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....

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...

[SHY]

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



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

[sparrow.2]

Frick! That's ace!

[Lee]

Amazing

tulibudibu douchooo

[showtime]

another good diff page for those that like reading the theory

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

[SHY]

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"...

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...

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

[mark christopher]

Originally Posted by SHY

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"...

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...

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

[SHY]

Originally Posted by mark christopher

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?

[bigred5765]

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

[sparrow.2]

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...

[elvo]

Originally Posted by SHY

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

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

Originally Posted by SHY

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

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.

[bigred5765]

Originally Posted by sparrow.2

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...

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