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Old 01-05-2012, 10:04 AM
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r15suk
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Default C4 Diff Lock

Can anyone help me with a question regarding the diff lock on my new 964?

When i 'lock' the diif on the car by turning the diff lock switch, am i locking the back from side to side (i.e. now having a lock diif) or locking the front to back, or both?

Also when the diff is in normal position is it a slip diff, or a limited slip diff?

Cheers
Simon
Old 01-05-2012, 10:24 AM
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Rocket Rob
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When you lock the diffs, you are locking the center (front to back) and the rear diffs. When its in normal position, the computer locks the diffs as it deems necessary using the accelerometers as inputs.
Old 01-05-2012, 10:57 AM
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r15suk
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Originally Posted by Rocket Rob
When you lock the diffs, you are locking the center (front to back) and the rear diffs. When its in normal position, the computer locks the diffs as it deems necessary using the accelerometers as inputs.
Thanks for the quick response :-)

Another question - if i lock the diifs do they unlock when i chang to a certain gear or reach a certain speed etc?
Old 01-05-2012, 12:16 PM
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FeralComprehension
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They'll revert to normal behavior above (I believe) 40km/h.

The new secret is that if you hold the lock switch in the 'lock' position for longer than 10s the automatic differential adjustment is deactivated; it won't reactivate until you turn the car off.

Use care.
Old 01-05-2012, 07:02 PM
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tbennett017
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^+1... Not sure if you're new to the 911/964 platform, but I'd get used to the car a bit first before going too far disabling the C4 system. Do it where you have some space like an empty parking lot. The purists will tell you that throttle-off oversteer is awesome, but it's best under controlled circumstances...

I have driven my car for years in the normal C4 mode, and it really never needs manual intervention. I only used the locks once in sand to try it... otherwise when locked the car is the same as a Jeep in 4WD.... all wheels locked together. Otherwise the PDAS system works very well, kicking in when necessary, keeping novices like me out of the weeds.
Old 01-05-2012, 08:04 PM
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RicardoD
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I installed the Green PDAS light in car so I can see when it turns on. I've never driven my car hard enough to see it come on during cornering but do so it come on over bumps sometimes. Looking forward to tracking my car one day to see the PDAS in action.
Old 01-05-2012, 09:48 PM
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kboustani
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so if i hold the lock switch in lock mode for 10 seconds i will have a c2?
Old 01-06-2012, 12:24 AM
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FeralComprehension
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No, you'll have a passivated C4 where the traction control/anti-spin is deactivated.
Old 01-06-2012, 08:50 AM
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r15suk
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Originally Posted by FeralComprehension
They'll revert to normal behavior above (I believe) 40km/h.

The new secret is that if you hold the lock switch in the 'lock' position for longer than 10s the automatic differential adjustment is deactivated; it won't reactivate until you turn the car off.

Use care.
Thanks again for the info. Is there any indication that this has happened (i.e. a sound)? The reason i ask is that when I select the lock position i hear a 'clunk' and then when i 'unlock' i hear a short whirring noise.

I'm new to the 964 and i'm just trying to find out more about it really. I don't necessarily intend to try these things yet. I am doing a session with an advanced instructor in the spring though on a closed track

Cheers
Simon
Old 01-06-2012, 11:16 AM
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FeralComprehension
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Yeah, an alarm sounds and the red AWD light lights up. IIRC the light stays on but the alarm stops after a couple seconds.
Old 01-07-2012, 04:33 PM
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nvrlft
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Everything you need to know...
Attached Images
File Type: pdf
PDAS Technical overviewR2.pdf (142.0 KB, 793 views)
Old 01-09-2012, 05:42 AM
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r15suk
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Originally Posted by nvrlft
Everything you need to know...
Thanks for posting, but i appear to have a problem opening. I have tried on 2 PC?

cheers
Simon
Old 01-09-2012, 11:08 AM
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FeralComprehension
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Bad link for me, too.

Simon, PM me, I have a PDF.
Old 01-09-2012, 01:08 PM
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Laker
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Can y'all access this?
Attached Images
File Type: pdf
PDAS Technical overviewR2.pdf (170.3 KB, 1272 views)
Old 01-09-2012, 01:35 PM
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Rocket Rob
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Laker - It works for me. Thanks



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