How can an oped diff'd car drift?
How can an oped diff'd car drift?
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Synchromesh

Original Poster:

2,428 posts

189 months

Sunday 4th March 2012
quotequote all
What I don't understand is how a car with an open diff can drift. Surely when torque exceeds traction under a lateral load, only the inside wheel would spin up as it has less weight on it than the outside wheel.

Therefore the outside wheel (which given that is has the majority of the grip is holding the car laterally) would not loose traction, thus the car wouldn't oversteer.

Excuse my poor explanation and terminology - I'm clearly no vehicle dynamicist.

foz01

773 posts

286 months

Sunday 4th March 2012
quotequote all
Yes!

I can't be bothered to give the long answer wink

m44kts

801 posts

223 months

Sunday 4th March 2012
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[Clarkson] Power, maximum power[/Clarkson]

???

Synchromesh

Original Poster:

2,428 posts

189 months

Sunday 4th March 2012
quotequote all
foz01 said:
Yes!

I can't be bothered to give the long answer wink
I realise they can, but the question was how, so it's the long answer I'm after.

sheps

741 posts

220 months

Sunday 4th March 2012
quotequote all
Heh.

It works, but is not easy.
Maximum attack.

Ozzie Osmond

21,189 posts

269 months

Sunday 4th March 2012
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If you jab the throttle hard enough both rear wheels will lose traction at the same time. Once both are spinning they will stay spinning unless and until something (for instance a change of road surface on one side of the car) causes one to grip at which point it will stop and the other wheel will spin away all or nearly all the power.

cptsideways

13,826 posts

275 months

Sunday 4th March 2012
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Excessive speed can help, as will some additional torque enough to reach the tyre slip limits

rallycross

13,686 posts

260 months

Sunday 4th March 2012
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Without the handbrake drifters would not be able to drift -'it's all a bit of a con based on hand brake induced oversteer.

anonymous-user

77 months

Sunday 4th March 2012
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Friction my dear boy, friction..........


(in the cross gears mostly)

Synchromesh

Original Poster:

2,428 posts

189 months

Sunday 4th March 2012
quotequote all
Ozzie Osmond said:
If you jab the throttle hard enough both rear wheels will lose traction at the same time. Once both are spinning they will stay spinning unless and until something (for instance a change of road surface on one side of the car) causes one to grip at which point it will stop and the other wheel will spin away all or nearly all the power.
But surely only the wheel with the least grip will spin, and one wheel will always have more grip than the other, even if it's just by 0.01%. Unless it was a special circumstance (e.g. different surfaces between wheels, or standing water just under one side) then it would always be the inside wheel that would have less grip, thus the inside wheel would spin, hence no drifty.

Synchromesh

Original Poster:

2,428 posts

189 months

Sunday 4th March 2012
quotequote all
Max_Torque said:
Friction my dear boy, friction..........

(in the cross gears mostly)
So are you trying to say that an 'open' diff isn't truly open due to the inherent friction in the diff?

wackojacko

8,581 posts

213 months

Sunday 4th March 2012
quotequote all
Weight transfer.


Simple.

Ozzie Osmond

21,189 posts

269 months

Sunday 4th March 2012
quotequote all
Synchromesh said:
But surely only the wheel with the least grip will spin, and one wheel will always have more grip than the other, even if it's just by 0.01%. Unless it was a special circumstance (e.g. different surfaces between wheels, or standing water just under one side) then it would always be the inside wheel that would have less grip, thus the inside wheel would spin, hence no drifty.
The theory you describe is indeed what makes open diff cars not much use/fun for drifting - typically needing a wet road or other low grip surface. However, it can be done if the car has the right characteristics in terms of engine power, gearing, low grip and lack of weight over the back wheels. Owners of 6-cylinder E30 BMW 3-series should be able to confirm....

Papa Hotel

12,760 posts

205 months

Sunday 4th March 2012
quotequote all
rallycross said:
Without the handbrake drifters would not be able to drift -'it's all a bit of a con based on hand brake induced oversteer.
I'm no expert. Neither are you.

cptsideways

13,826 posts

275 months

Sunday 4th March 2012
quotequote all
rallycross said:
Without the handbrake drifters would not be able to drift -'it's all a bit of a con based on hand brake induced oversteer.
Not quite true

This is at Brands Hatch, no handbrake just a big flick on full throttle before the clearways corners just past the back of the pits. And a good example of how an open diffed car "could" do similar.

Its even possible in a fwd car wink



Synchromesh

Original Poster:

2,428 posts

189 months

Sunday 4th March 2012
quotequote all
wackojacko said:
Weight transfer.

Simple.
So am I, so explain...

Frances The Mute

1,816 posts

264 months

Sunday 4th March 2012
quotequote all
Ozzie Osmond said:
However, it can be done if the car has the right characteristics in terms of engine power, gearing, low grip and lack of weight over the back wheels. Owners of 6-cylinder E30 BMW 3-series should be able to confirm....
Yup. My old 325i track car had no problem in this department. It was quite easy to control in a slide, too, providing you kept the power on.

There was no weight over the rear end and had sufficient power to overcome the tyres in 1st and 2nd gear in the dry. In the wet, it was hilarity personified.

Dave Dax builder

662 posts

282 months

Sunday 4th March 2012
quotequote all
In the "Sport" of Drifting they have to use the handbrake.
The actual "art" of drifting is actually Power sliding.
The term "Drifting" has been stolen by the loud logo'd ricers.

Give a car enough lateral force and the back end will step out. Ford focus's do it and they're front wheel drive.

cptsideways

13,826 posts

275 months

Sunday 4th March 2012
quotequote all
Synchromesh said:
wackojacko said:
Weight transfer.

Simple.
So am I, so explain...
Weight transfer is inducing yaw angles using the momentum in vehicle, based around the polar moments & execessive yaw overcoming tyre traction

Captain Muppet

8,540 posts

288 months

Monday 5th March 2012
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Dave Dax builder said:
In the "Sport" of Drifting they have to use the handbrake.
The actual "art" of drifting is actually Power sliding.
The term "Drifting" has been stolen by the loud logo'd ricers.

Give a car enough lateral force and the back end will step out. Ford focus's do it and they're front wheel drive.
I competed in the "sport" of drifting for 4 years. For two of those years I didn't have a handbrake capable of locking the rear wheels. For the two years I had a decent handbrake I only used it when I'd cocked up - on a good lap of a track I wouldn't use the handbrake at all.

As for "power sliding" - I compteted in a 115bhp MX5. This does not have the power to spin the wheels just by flooring the throttle at 70mph, you need to use the other controls too.

It's a fun way to pass time in a car. I can see why you'd look down on it though.