Rear end failure using Launch Control at Drag Strip!
09-04-2016, 06:48 PM
#41
Launch control on my 2016 A8 is great.
09-04-2016, 06:53 PM
#42
Le Mans Master
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St. Jude Donor '15
That sucks!
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Mobil 1 (09-05-2016)
09-04-2016, 11:55 PM
#45
Burning Brakes
Thread Starter
09-05-2016, 12:00 AM
#46
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Best of luck with the repair. Heck of a bad ending to a track day.
09-05-2016, 08:54 AM
#47
Burning Brakes
Thread Starter
09-05-2016, 03:06 PM
#48
Burning Brakes
Do you know what actually broke?
09-05-2016, 07:40 PM
#49
Burning Brakes
Thread Starter
09-05-2016, 08:21 PM
#51
Burning Brakes
Your car is bone stock and you broke the ring & pinion. I hope it's not a common problem. Have you had any wheel hop with your C7? I tried launch control at the track one time and had bad wheel hop, I took my foot off the throttle immediately. I'll never use LC again.
09-05-2016, 08:22 PM
#52
Burning Brakes
09-05-2016, 08:44 PM
#53
Racer
Do you have an M7 or A8?
09-05-2016, 09:03 PM
#54
Burning Brakes
09-05-2016, 09:18 PM
#55
Team Owner
the more I think about it, the less I want to take my car to the track or strip again, way too much abuse.
09-05-2016, 10:18 PM
#56
Burning Brakes
Thread Starter
No not the ring & pinion, the spider gears in carrier. I do have wheel hop but when it broke it did instantly before any wheel hop.
09-05-2016, 10:37 PM
#57
Burning Brakes
Oh, Is there a way you can get the parts and post pics? My guess is that the wheel hop caused the damage prior to braking the spider gears. The wheel hop probably fractured or twisted and stretched the gears and finally broke after you launch and hooked.
09-06-2016, 07:44 AM
#58
Burning Brakes
Thread Starter
https://www.youtube.com/c/CarGuy11C7
09-06-2016, 08:27 AM
#59
Launching the M7 can easily stress the driveline too much unless the procedure is done correctly, the A8 with its shock absorbing torque converter is more forgiving of improper technique.
With the M7 you must give the launch control sufficient time to stabilize engine RPM before releasing the clutch; otherwise launch control isn't active. You still need to do this with the A8 but you are less likely to break something with the A8 if you do it wrong but it is still HIGHLY INADVISABLE to do a high power launch incorrectly.
The other key (for the M7) is as the manual states, use a "smooth, quick release of the clutch". This is not the same as "popping" the clutch which creates a horrible shock load from the driven rotating mass of the engine through the driveline. The key is a quick transition from slight slippage which begins the launch process to full clutch engagement. In addition to shock loading the driveline immediate full clutch engagement makes wheel hop and excessive spin more likely causing the launch control to overcompensate increasing elapsed time. Even with launch control active the better driver will still have a better elapsed time, technique still matters.
Probably the next iteration of launch control will include an automatic clutch engagement function for the M7 (or M12 or whatever range of gears the future holds)
With the M7 you must give the launch control sufficient time to stabilize engine RPM before releasing the clutch; otherwise launch control isn't active. You still need to do this with the A8 but you are less likely to break something with the A8 if you do it wrong but it is still HIGHLY INADVISABLE to do a high power launch incorrectly.
The other key (for the M7) is as the manual states, use a "smooth, quick release of the clutch". This is not the same as "popping" the clutch which creates a horrible shock load from the driven rotating mass of the engine through the driveline. The key is a quick transition from slight slippage which begins the launch process to full clutch engagement. In addition to shock loading the driveline immediate full clutch engagement makes wheel hop and excessive spin more likely causing the launch control to overcompensate increasing elapsed time. Even with launch control active the better driver will still have a better elapsed time, technique still matters.
Probably the next iteration of launch control will include an automatic clutch engagement function for the M7 (or M12 or whatever range of gears the future holds)
Last edited by NSC5; 09-06-2016 at 08:51 AM.
09-06-2016, 10:50 AM
#60
Drifting
Member Since: Oct 2013
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I've never had a good launch control. Tires always spin whether its on the street or on the strip. I always get a much better launch doing it myself. LC gives me a 0-60 of mid 5s usually.