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      02-23-2009, 08:15 AM   #23
BarryC
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Quote:
Originally Posted by mixja View Post
Probably the same protection that prevents you from downshifting from 2nd to 1st at 50mph...

Did you ever try the kick down at say 70mph with the stock FD? Did it go to 2nd then?
Didn't try 70 but every time I tried it at 60 it would always go to third so I assumed the same for 70.

BC
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      02-23-2009, 07:41 PM   #24
carbonbmw
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How much did the actual diff cost you? Did they just rebuild one with different gears or did u get one reassembled. I got quoted more the 2k just for the diff.
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      02-23-2009, 10:23 PM   #25
BarryC
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This was a ring and pinion change only to my existing diff. So the cost covered removal and reinstall of the diff, r&p change and the cost of the gears.

Thx,
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      02-23-2009, 10:44 PM   #26
mixja
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Quote:
Originally Posted by BarryC View Post
Didn't try 70 but every time I tried it at 60 it would always go to third so I assumed the same for 70.

BC
What was the start gear before kickdown?
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      02-27-2009, 01:40 AM   #27
mixja
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Quote:
Originally Posted by BarryC View Post
Didn't try 70 but every time I tried it at 60 it would always go to third so I assumed the same for 70.

BC
Strange - so with the stock FD it would kick down to 3rd gear at 60MPH?

Doesn't make sense to me - with the 3.62 FD the RPMs in any higher gear will be higher at 60MPH therefore the computer should never be attempting to kick down to a lower gear than what it would with the stock FD...
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      02-27-2009, 08:20 AM   #28
BarryC
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Quote:
Originally Posted by mixja View Post
Strange - so with the stock FD it would kick down to 3rd gear at 60MPH?

Doesn't make sense to me - with the 3.62 FD the RPMs in any higher gear will be higher at 60MPH therefore the computer should never be attempting to kick down to a lower gear than what it would with the stock FD...
Don't know either but I'm assuming there are preset actions for a given speed in the software. I would be impressed if the car is programmed to calculate the rpm result of multiple downshift scenarios and then pick the one that would present the least risk for overrev and do it instantaneously....

BC
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      02-27-2009, 03:43 PM   #29
mixja
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Quote:
Originally Posted by BarryC View Post
Don't know either but I'm assuming there are preset actions for a given speed in the software. I would be impressed if the car is programmed to calculate the rpm result of multiple downshift scenarios and then pick the one that would present the least risk for overrev and do it instantaneously....

BC
Doing based upon RPM would be the most ideal obviously, it's not really that difficult for a computer to work out. It just needs to know the gear ratios and current gear and current RPM, based upon that information it can come up with a list of potential gears and resulting engine RPMs it can downshift to and choose the highest that is below a threshold (say 6500RPM).

Even if it is done based upon speed, it still doesn't make sense why it would downshift to 2nd instead of 3rd after the increase in FD - it should downshift to the same gear as the stock FD at a given speed.
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