Wait wait wait wait.

"TexasEdition" (TexasEdition) 11/22/2013 at 00:33 • Filed to: None

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The consumer market 12C has an open diff?

MtrRider Just Wants Doritos > TexasEdition 11/22/2013 at 00:38

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It's probably an electronic diff that's mechanically open. There's no way in hell it has a regular open diff.

All Motor Is Best Motor > TexasEdition 11/22/2013 at 00:42

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I too was all "double you tee eff, mate?" when I watched that part.

TexasEdition > MtrRider Just Wants Doritos 11/22/2013 at 00:44

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That's what I was thinking, otherwise it would be doing the ol' one wheeler peeler up there with the best of them.

Simplify, then add beer > TexasEdition 11/22/2013 at 00:44

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What? Bullshit.

*googles a bit*

Wait, you're right.

McLaren opted for braking the inside wheel and a "Proactive Chassis Control system" instead.

Not going to argue with them, they seem to know what they are doing.

Interesting read here.

TexasEdition > TexasEdition 11/22/2013 at 00:45

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Also, this is one of the best On Cars I've seen yet, as far as how it was shot and edited. I loved the absence of music and being able to ride in car with Chris and watch everything that was going on, with the occasional in-car commentary.

TexasEdition > Simplify, then add beer 11/22/2013 at 00:48

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So there's not even an electronic locking system or anything?

Based on my Ph.D in performance differentials and all the experience I have designing and building them (none, I'm lying), I can't say I agree with that reasoning.

But seriously, it sounds like a real diff would work better and put much, much less wear on the brakes.

MtrRider Just Wants Doritos > TexasEdition 11/22/2013 at 00:55

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Yeah, I doubt a 600+ hp supercar would be very fun to drive with a peg leg. It would lay a fucking black line for miles though.

Simplify, then add beer > TexasEdition 11/22/2013 at 00:56

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It's surprising at first, but makes a lot of sense when you think about it.

Locking a differential - even an LSD - would not give you as much control as adjusting the wheel speeds and correcting the suspension system. Once you have these devices in place, locking the diff would seem redundant.

They can still get sideways, so it does the job:

lonestranger > TexasEdition 11/22/2013 at 00:58

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It doesn't have anti-roll bars or conventional dampers, either. Everything is electronically controlled.

TexasEdition > Simplify, then add beer 11/22/2013 at 01:04

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I suppose you're right.

But it still seems to me that having both or just the proper diff would be a better bet. Again, I'm mostly pulling this out of my ass, but I do have a decent understanding of it all.

Anyway my thinking is that, say you're accelerating pretty hard out of a corner, and a wheel unloads while you're still in rotation. The computer senses it and counteracts by grabbing a brake, slowing the wheel and balancing torque delivery. It seems like you would lose out on potential acceleration during that process as opposed to mechanically managing torque delivering within the differential itself, not requiring the wasted energy caused by grabbing a brake.

It seems to me that may be why a real diff is the setup they use in GT3.

A sideways 12C is certainly a pretty sight though.

TexasEdition > lonestranger 11/22/2013 at 01:19

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That's crazy, and the engineering behind each one of those systems is truly remarkable, but I can't help thinking it would end up feeling artificial and less connected when tested against an excellent mechanical equivalent.

That and I'm firmly in the if it ain't broke don't fix it camp. And somewhat irrationally annoyed by electrogizmos replacing good mechanical systems. A great driver is a great driver, and no amount of electronic wizardry can combat that!

Simplify, then add beer > TexasEdition 11/22/2013 at 01:27

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The GT3 diff was changed not for performance reasons, but to keep it in line with the rules and regs.

The wheel braking only affects the wheel that is not generating any traction, so you're not losing any speed. It's just allowing the wheel to slow down and therefore gain speed. With a diff that is locked (even temporarily) it's still going to be spinning too fast to be of any use.

*Source - me talking out of my arse

TexasEdition > Simplify, then add beer 11/22/2013 at 01:33

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Well by that I meant it might have been the reason behind IMSA going with that particular regulation.

Anyway, I can definitely see how both of these setups make sense, but if one is better than the other remains difficult to determine.

This subject deserves more thought and discussion, I'll contact my posterior and get back to you.

Simplify, then add beer > TexasEdition 11/22/2013 at 01:36

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Good idea. I might go lock my rear differential and make some 'thought circles' on the road.

TexasEdition > Simplify, then add beer 11/22/2013 at 01:40

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Oh man. Can I call them 'thought circles' now?

Where do I make out the royalty check?

TexasEdition > TexasEdition 11/22/2013 at 01:41

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In the meantime I'll be out laying down some 'pondering lines.'

lonestranger > TexasEdition 11/22/2013 at 01:58

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Normally, I'd agree with you. And from what I've heard and read, the MP4-12C, especially the early ones*, are somewhat sterile to drive. And although I've never driven one, I think McLaren have used electronics and computers to the best use here. Anti-roll bars are only useful in cornering. In a straight line, they only harm both the performance and comfort. By controlling the roll stiffness electro-hydraulically, the car can make it stiffer in corners than even a very stiff anti-roll bar can, and more compliant in a straight line than if it had very soft anti-roll bars, and do it all in the blink of an eye.

Since we're watching Monkey in a Macca, here he is describing how easy the car is to live with, due to all the techno-wizardry:

*An advantage of such extensive computer control is that things can be tweaked after production, via firmware upgrades.

lepie > TexasEdition 11/22/2013 at 02:10

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It's an open diff. They do all of their torque vectoring magic using the brakes. They've gone the full electronics route, and an LSD would only work against them in this situation. I don't necessarily agree with this strategy, but it sure seems to be working.

Simplify, then add beer > TexasEdition 11/22/2013 at 03:26

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May I also recommend some Sideways Contemplation

Manuél Ferrari > TexasEdition 11/22/2013 at 04:09

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Don't worry, no amount of electrogizmos can stop a bad driver from being bad. I was at a local track to see a guy I knew run his ZR1. He told me that there was a dude with a 12C who totaled his car at the track. He said poor driving was to blame.

And get this - the car wasn't even his, it was the loaner car that the dealership gave him when his was in for service!

Manuél Ferrari > Simplify, then add beer 11/22/2013 at 04:09

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Mind is blown right now...

Manuél Ferrari > lonestranger 11/22/2013 at 04:13

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The problem is that in the end the computers will win, whether we want them to or not. The advantages you brought up are real. And at the end of the day supercars are all about performance. We might prefer our supercars with gated shifters but 99% of buyers want DCTs, so MTs died. Same will happen with other mechanical systems that were not computer controlled in the end...

Just wait until our cars become aware and turn on us...

lonestranger > Manuél Ferrari 11/22/2013 at 04:23

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LOL, as soon as I saw in my notifications: rusto replied to you "The problem is that in the end the computers will win...", I was already planning on responding with this pic:

BKRM3 > TexasEdition 11/22/2013 at 07:16

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Brits, man. I was shocked when I first learned this about the Elise and, like you, did some reading. Fourth post down expresses the philosophy: http://www.lotustalk.com/forums/f25/lsd… but I am sure the 12C goes way beyond the Lotus approach because of its fancy computer smartness.

You can tell a Finn but you can't tell him much > TexasEdition 11/22/2013 at 08:57

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I'm guessing that IMSA hasn't mandated LSD's, but more likely they have banned traction control. This would be done in an attempt to limit costs and prevent teams with more resources from running away from the field. Things like TC, active suspensions and active aero are very computer intensive to get them to work correctly. A team with more resources will be able to throw a lot of money at the computer guys to get it working while a privateer team wouldn't be able to spend the time and money on it. This is the reason that traction control, active suspensions and active aero are banned in F1.

Manuél Ferrari > lonestranger 11/22/2013 at 15:50

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That's hilarious!

We both know it will eventually happen. Google cars will be forced on us to alleviate traffic jams. Then the NSA will hack them to be prepared to quell any potential revolutions. Then the military's AI will take control of the cars and crash them all into each other to eliminate as many humans as possible.

Hopefully I'll be dead before this happens.