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      08-04-2015, 07:53 PM   #1
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McLaren 675LT, open diff

Just watched Chris Harris' review of the car and couldn't believe it has an open diff and brake steers the way I imagine the 335 does with electronics but I'm sure it's more advanced.

Makes you wonder if the 335 does need an LSD upgrade. I am really keen to get one myself eventually.

Even the P1 and 12C are open diffs!
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      08-05-2015, 04:16 AM   #2
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The active suspension means it can't "cock a leg" so the inside wheel should never loose grip. It will be an extremely complicated set up.

WM
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      08-05-2015, 10:08 AM   #3
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Quote:
Originally Posted by windymissile View Post
The active suspension means it can't "cock a leg" so the inside wheel should never loose grip. It will be an extremely complicated set up.

WM
Yes the 4 wheels with their own active hydraulic suspension is awesome.
I still wouldn't expect the P1 to drift in as a controlled state as it does. I'd have expected a bit of a snap back when straightening up but maybe the wheel braking is taming that.

The design of that car is just going to be so good. Light weight, lots of down force to boot.
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      08-05-2015, 01:09 PM   #4
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This is a good read:

http://www.mclarenlife.com/forums/mc...tml#post184626

I wish someone would update the 335i DME, DSC to be as good at brake cornering as the McLarens. Then I can spend my diff money on suspension!
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      08-05-2015, 01:29 PM   #5
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The mclaren also has a hydraulically controlled Z bar or heave spring
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      08-05-2015, 02:55 PM   #6
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Just because the car doesn't have an LSD doesn't mean no car should have one, the car is built around the fact it doesn't need one.
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      08-05-2015, 06:49 PM   #7
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Just basically from what I'm reading mechanical diffs are too old tech and imprecise. An electronic controlled diff is the way to go. It can be controlled any time. On or off throttle and far more quickly and precisely.
If the stability control program on the 335i could be updated\hacked\enhanced to act during cornering it would be beneficial to handling.

Plus there's the weight and cost saving. I'm sold personally and I never thought I would be!
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      08-06-2015, 04:29 AM   #8
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Quote:
Originally Posted by Digitalize View Post
Just because the car doesn't have an LSD doesn't mean no car should have one, the car is built around the fact it doesn't need one.
It kinda does have one. Just not in the common sense that we know.
It will allow a limited amount of slip before braking the unloaded wheel and transferring drive to the other wheel *while keeping power on*
* this is the major difference as a regular car will cut power to regain control.
E-diff now available on option is a similar set up. The main difference is the hydraulic suspension, as it means the car will stay planted in all but the most extreme situations, so never really losing grip in the first place. As you said, it's built around this principle.

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      08-06-2015, 05:38 AM   #9
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How does it work in the wet, or slippy conditions where its not just about cornering load?
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      08-07-2015, 09:48 AM   #10
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Quote:
Originally Posted by djgandy View Post
How does it work in the wet, or slippy conditions where its not just about cornering load?
Well the car is stiffening and softening the suspension on the 4 points of the car in response to cornering etc and balancing power to wheels with use of the brakes just like ESP.

Weight of an LSD which can only function under power anyway is out. Wheels brake to get the car around corners and can be done thousands of times a second. I'm really impressed because I thought I'd never be convinced.

I'm trying to read more and more on the subject.
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      08-07-2015, 10:52 AM   #11
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Before whenever I wanted to do some donuts I'd always turn DTC and DSC fully off. I get that the open diff would cause the inside wheel to spin up faster (losing traction) and that when that traction comes back that it can cause the car to really snap back.

I'm wondering now if I leave the car in DTC mode if I can drift it?

Just got new tyres so I can't test this for a while. Unless I can find some grass.

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      08-11-2015, 05:27 AM   #12
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An interesting exert from the manual.

My car is 2009. Appears that the electronics will emulate a diff even with all nannies off. So a 335i, 330i, 330d, 335d can probably drift like the 135i above.

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      08-14-2015, 03:55 PM   #13
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Quote:
Originally Posted by optigrab View Post
The mclaren also has a hydraulically controlled Z bar or heave spring
The z bar isn't hydraulically controlled its in essence an anti roll bar.
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      08-21-2015, 09:18 AM   #14
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Found a car park with a spot where I could put one rear wheel on loose gravel and one on asphalt.

Put the car in DSC off mode and I can only assume the car is using the brake on the wheel on gravel to redirect Torque to the wheel on the grippy surface.

It's pretty cool. You can't feel it happen so it doesn't pulse. The car goes straight.

If you repeat the same and put the car in DTC mode, you can feel the traction control kicking in after the wheel spins enough. Then stop when it's got traction again and repeating the process.

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