center diff in Open cars?

If you don't know which type of Sadev is in the VTSC cars, that's cool, but insulting us for not knowing which that you're talking about comes across (to me, at least) as a sign that you might not actually know the answer. It's a simple question: do they have a Sadev with a diff and a cut-off or do they have a Sadev with a spool and a cut-off?

Maybe this is one of those cases where folks use the name of the company instead of the label for the device because the device is so closely linked in people's minds with the company. I've seen that before. Some folks call a mechanical (plate- or Salisbury-type) diff a "Kaaz" for this reason. But, in this case, using the name of the company isn't getting the point across.

As to the question of punching the clutch in a car with an actual differential, here's the reasoning (which I am here just repeating, not endorsing): when one output from a 50/50 diff is suddenly forced to stop turning, then the other output must start turning at exactly twice the speed as the input. Therefore, to the extent that the tranny, flywheel, and engine will resist suddenly changing to turning at half the speed that they were before you pulled the handbrake, the front wheels must suddenly start turning faster.

Whether the engine suddenly slowing down is possible or whether having the front wheels suddenly speed up isn't a problem is a tad beyond me. But the above is the reason that is given for punching the clutch. My own experience is that it helps a bit - in that it makes the induced slide more predictable - but I would take reports of my experience with copious salt.

I don't punch the clutch nor do I yank the handbrake so hard that it locks up the wheels. In a slide on gravel to get the car around all you need to do is upset the balance. So in the case of the rear wheels you aren't trying to lock them up, you just upset it so now the wheel speed difference changes and the car starts to slide. I hardly pull on the handbrake and it'll come around.

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Iowa999
Therefore, to the extent that the tranny, flywheel, and engine will resist suddenly changing to turning at half the speed that they were before you pulled the handbrake, the front wheels must suddenly start turning faster.

Given that you'll almost certainly be off the throttle when yanking... ask yourself which will resist change more easily, wheels, and driveline, that are connected to the ground, or an engine that is already in 'engine breaking' mode.

Like Matthew says, you're really just trying to upset the balance or the car - particularly in an AWD application - not locking up the rear to slide it around. (I used LFB a lot in the rally car which is why I didn't need to handbrake much.)

At the end of the day I firmly believe people focus on yanking the big stick way too much. It is a truly blunt tool in a game that rewards finesse. Were I building a car today, I wouldn't be bothered with the work and expense of plumbing in a hydro handbrake.

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First Rally: 2001
Driver (7), Co-Driver (44)
Drivers (16)
Clerk (10), Official (7), Volunteer (4)
Cars Built (1), Engines Built (0) Cages Built (0)
Last Updated, January 4, 2015

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john vanlandingham
Blame is for idiots. losers.

I agree with both of you, but we're now two steps away from the original question. As a reminder, the question was whether any Open-class cars in North American rally are using a center spool with a Haldex or cut-off on the rear output, or do they all still have a center differential (plus some other fancy bits).

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Iowa999
I agree with both of you, but we're now two steps away from the original question. As a reminder, the question was whether any Open-class cars in North American rally are using a center spool with a Haldex or cut-off on the rear output, or do they all still have a center differential (plus some other fancy bits).

Probably 80% of open class cars in North America are using the stock Subaru gearbox the cars came with... meaning a centre diff with a DCCD and some fancy mapping to manage the tightness of the diff.

The top open class monsters... only a few on here would have any real idea what's in them for sure.

---

First Rally: 2001
Driver (7), Co-Driver (44)
Drivers (16)
Clerk (10), Official (7), Volunteer (4)
Cars Built (1), Engines Built (0) Cages Built (0)
Last Updated, January 4, 2015

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john vanlandingham
Blame is for idiots. losers.

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Morison
At the end of the day I firmly believe people focus on yanking the big stick way too much.

Hey man, what I do in the privacy of my own home is no business of yours!

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KF7RWG
http://www.utahrallygroup.com

At least he said "big" stick....

Who cares what VSC or Block is using? If you don't already know what they use and how it works, you don't need it and can't afford it.

99.99% of Open class guys with electric center diffs use a simple momentary switch on the handbrake to inactivate the center diff when the handbrake is pulled...it's elementary (says the guy that configured the momentary switch setting incorrectly in his GEMS and couldn't figure out why the center diff wasn't locking and was racing in 2wd for a several events)

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urr
Who cares what VSC or Block is using?

Who doesn't care?

It's an interesting question, with (obviously, as seen in this thread), an interesting answer.

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HiTempguy

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urr
Who cares what VSC or Block is using?

Who doesn't care?

It's an interesting question, with (obviously, as seen in this thread), an interesting answer.

It's actually not an interesting question because the answer(s) is obvious and easily figured out, with a little searching on the inter-web. The question exhibits laziness and doesn't provide any value to the actual ralliest on this forum. It's like asking the Spec Miata forum members how F1 ERS works....

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urr

It's actually not an interesting question

Your opinion, which (my opinion), IDGAF. Have a nice day prick

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urr
It's actually not an interesting question because the answer(s) is obvious and easily figured out, with a little searching on the inter-web.

Ah, now that's a different brush-off than the previous. Your web-skills and inferential abilities are quite impressive.

Too bad you didn't take the ten seconds required to type out the answer. Oh, well.

And I'm sure that it was impatience, boredom, or a desire to not encourage stupid questions instead of a lack of confidence in your answer.

That goes without saying.

ps. Hey, Grant. This sarcasm thing rocks!



Edited 2 time(s). Last edit at 04/02/2014 07:58PM by Iowa999.

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Iowa999

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urr
It's actually not an interesting question because the answer(s) is obvious and easily figured out, with a little searching on the inter-web.

Ah, now that's a different brush-off than the previous. Your web-skills and inferential abilities are quite impressive.

Too bad you didn't take the ten seconds required to type out the answer. Oh, well.

And I'm sure that it was impatience, boredom, or a desire to not encourage stupid questions instead of a lack of confidence in your answer.

That goes without saying.

ps. Hey, Grant. This sarcasm thing rocks!

So are you insulting him for criticizing your inability to simply look it up on the internet… or nah?

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Foard Cleveland
Blue Branch Rally Team
http://www.performancefriction.com

Actually, I was trying to demonstrate that teaching and/or extracting information from folks via sarcasm doesn't work very well. But I normally use sarcasm to be an asshole and piss people off, instead, so I'm not very good at it yet. Can I practice (again) on you? This does seem to be one of the best sites for this.

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Iowa999
Actually, I was trying to demonstrate that teaching and/or extracting information from folks via sarcasm doesn't work very well. But I normally use sarcasm to be an asshole and piss people off, instead, so I'm not very good at it yet. Can I practice (again) on you? This does seem to be one of the best sites for this.

Is this directed towards me? If so yes feel free to, I can be a great cynical asshole.

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Foard Cleveland
Blue Branch Rally Team
http://www.performancefriction.com