DIFFERENT differentials - do you beg to differ?

[sparrow.2]

Originally Posted by bigred5765

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

Works exactly the same though... What would a "proper" LSD do differently apart from maybe different states of lock depending on load???

[bigred5765]

whats a atd diff please
as fare as im aware theres nothing that even comes close to a lsd diff

[SHY]

Originally Posted by elvo

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

LOL! You can have them in a jar for Christmas if you like!

Originally Posted by elvo

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.

I'm not THAT stupid! But why does the ball diffs not bind as much as gear diffs at speed? And put more drive to the wheel with less traction compared to a gear diff? And what does that Schuey logo actually try to illustrate? With that "askew line"???

TC have more traction, is that why geared diffs work good for them? And for 1:10 OR you would still prefer a ball diff?

[Zedman]

Next issue looks like it will be brake balence, how do u channel more brake force to the front wheels in an electric setup ?

On a side note are u allowed to run rear wheels on the front in competition ?

[bigred5765]

Originally Posted by Zedman

Next issue looks like it will be brake balence, how do u channel more brake force to the front wheels in an electric setup ?

On a side note are u allowed to run rear wheels on the front in competition ?

i would say like the schueys of old with a double sided slipper tcs system i think they called it
im sure someone will correct me if i got it wrong

[SHY]

Originally Posted by Zedman

Next issue looks like it will be brake balence, how do u channel more brake force to the front wheels in an electric setup ?

On a side note are u allowed to run rear wheels on the front in competition ?

I think the XX4 "clicker" allows you to adjust brake balance front/rear

[mole2k]

The schumacher TCS system was a slipper clutch to the rear wheels and then an adjustable one way so you could adjust the amount of braking to the front wheels from full to none and any step inbetween. The slipper clutch to the rear wheels meant you could have it mostly fwd accelerating out of the corners, I never had one in my cat but I did have the adjustable braking to the front wheels which I quite miss in other cars.

[Jonny_H]

I did once see a picture of a 'proper' plate-and-ramp diff for a model car, probably a 1/8th. It only appeared to have one plate each side though, so it had ridiculously shallow ramps angles - maybe 15-20°.

In theory, a ball diff provides more torque-dependent locking than a gear diff, because for the ball to rotate it has to slide inside the hole in the 'cage', whereas a gear diff's planets rotate on small pins.

In practice, I once measured a pan car ball diff at about 1.4:1 torque bias ratio (changing how tight it was only affected the initial 'preload' torque, and made almost no difference to the TBR under load) - but 1:1 'open' gear diffs also produce about 1.4:1, so it would be interesting to measure a typical model gear diff the same way I did on the pan car.

Having sealed diffs so you can fill them with thick oil/grease seems like an excellent solution to me - that way you get some speed-dependent locking, exactly the same as a 1:1 viscous coupling (VC) diff.

Torsen diffs provide torque-dependent locking (not speed dependent, Sparrow) and 1:1 ones can do 4:1, maybe a bit more. Presumably a Torsen with thick grease then also adds some speed-dependent locking...

As mentioned though, it's difficult to design something effective in 1/10th size, which is probably why we use spools and one-ways a lot - basically a spool is a diff with infinite TBR, and a one-way is the same but only in one direction (a bit like different drive and coast ramps in a plate-and-ramp diff).

I haven't seen the ATD but it sounds like it effectively gives adjustable preload - but it would be nice be use actual TBR as a setup tool as well.

Careful now, you've got me started on diffs...

[SHY]

Very good!

[sparrow.2]

Originally Posted by Jonny_H

Torsen diffs provide torque-dependent locking (not speed dependent, Sparrow) and 1:1 ones can do 4:1, maybe a bit more. Presumably a Torsen with thick grease then also adds some speed-dependent locking...

I meant the relative difference in output speed (left-right). But then I had a nosebleed already when my friend got to that part of the explanation

Originally Posted by Jonny_H

I haven't seen the ATD but it sounds like it effectively gives adjustable preload - but it would be nice be use actual TBR as a setup tool as well.

The ATD diff has a ring in the middle made of the same material as slipper pads. This pad touches the diff rings slightly before the balls and gets compressed, giving a very stiff feeling diff. Somewhere between a straight axle and a diff.

Here is a pic where you can see the bits.

[Lee]

One thing i tried whilst racing on road was a spool up front with a centre one way on the layshaft and a ball diff at the back, i found this gave a smoother entry and more steering where the spools tend to wash out mid corner and on power it was just like a spool again, it was quite quick for me


I cant see it being great with bumps though in off road

[Lee]

Originally Posted by sparrow.2

I meant the relative difference in output speed (left-right). But then I had a nosebleed already when my friend got to that part of the explanation



The ATD diff has a ring in the middle made of the same material as slipper pads. This pad touches the diff rings slightly before the balls and gets compressed, giving a very stiff feeling diff. Somewhere between a straight axle and a diff.

Here is a pic where you can see the bits.

Thats what comes with the aero, i didnt like it so filed the centre spacer down, now i have a ball diff

[elvo]

Originally Posted by Jonny_H

Careful now, you've got me started on diffs...

Hi J! Have you seen XRay's Ramp-ish locking-ish front diff for their XB8? Comes with 2 ... ramp things.

http://www.teamxray.com/teamxray/new...a=1305&catName=

[Gayo]

How do they work ? I don't get it.

[sparrow.2]

Originally Posted by Lee

Thats what comes with the aero, i didnt like it so filed the centre spacer down, now i have a ball diff

Did you try running it like that first? I've seen one with that diff on carpet and astroturf and it went like poo off a shovel

[bender]

What about this one then:

[Lee]

Originally Posted by sparrow.2

Did you try running it like that first? I've seen one with that diff on carpet and astroturf and it went like poo off a shovel

Yes i did try, it for a few meetings like that, whilst the grip was high it was very good but it made it difficult to get the power down on a low grip surface, the car is much more predictable on our multi surface tracks with a ball diff.

It may work on a smooth blue groove track

[jimmy]

what is this badboy then, does it stiffen the action without crushing the balls to death? is that the idea?

[Lee]

Jim, from what i can gather, it is to stop the car diffing out when one wheel goes light, but it does also hinder the diff action to a degree.

[SHY]

Originally Posted by bender

What about this one then:

Where's that from?