[Chrisred]

hwta u guys think?? i usually rev up to 3000-3200rpm and drop the clutch but isn't this harmful for our tranny's??? if u let of clutch slowly at that rpm isn't that bad on your clutch?? so which way to go????

[Tortfeasor 335xi]

Launching an AWD car involves some pretty extreme RPM and a clutch drop. The problem with this is it subjects the entire drivetrain to some pretty extreme forces. This can lead to broken axles, sheered gears in the transmission and lots of other failures.

The other option is to run lower RPM and slip the clutch a little to avoid bogging the engine. While this does result in slower times and worn clutches, it results in a lot less broken expensive bits.

Just compare the replacement cost with labor of your transmission versus you clutch, and you will see why it is better to stress the clutch.

That said, if you like your warranty, consider doing regular street starts on your car. Because if you break something in your car, and the car shows signs of abuse, i.e. launching, you better believe there will be discussions about not honoring your warranty among the service department.

[Babydragon]

Originally Posted by Chrisred

hwta u guys think?? i usually rev up to 3000-3200rpm and drop the clutch but isn't this harmful for our tranny's??? if u let of clutch slowly at that rpm isn't that bad on your clutch?? so which way to go????

Just rev it up and dump the clutch.
It maybe the stupidest thing you can do next to going 90mph and dropping it into first gear. But that's how it's done.

[fdriller9]

Or you can pull fuse #26 (at your own risk) and disable the AWD system so you can burn the rear wheels.

There are some down sides though. Like the wipers never stop, speedo doesn't work, wheel angel sensor, ABS, DTC, DSC, EBD, don't work, gauge cluster lights up with multiple lights and the gas gauge fluctuates.

I'm sure there's more but that's all I can think of. Go check out the thread in the AWD section.

Also there a ton of hidden fault codes that get stored.

[BRAISKI]

Quarter miles is very harmful to your car. In my previous car I went once well (one day) and that was enough. But then again I am more of a Auto-X, Circuit track kind of guy. Which doesnt do as much damage as the quarter mile.

[fdriller9]

^do realize how much flex your chassis undergoes on an auto x track?

I would agree launching repeatedly is bad but so is taking turns at 80 mph.

Launching is bad for your transmission, axle/s, and drivetrain in general.

Auto x is bad for your chassis.

[BRAISKI]

Originally Posted by *********

^do realize how much flex your chassis undergoes on an auto x track?

I would agree launching repeatedly is bad but so is taking turns at 80 mph.

Launching is bad for your transmission, axle/s, and drivetrain in general.

Auto x is bad for your chassis.

I do, had some pics when my car was cornering.

The thing is that some "sport cars" are design for cornering thus better/reinforced chassis. No car is designed to ride the clutch...

[pits200]

My xi is an auto and I launch from about 2500 rpms and it never seems like it is stressing the car at all.

I obviously probably only do this once a week but still it feels like its at home with the awd and launches.

[fdriller9]

Originally Posted by BRAISKI

I do, had some pics when my car was cornering.

The thing is that some "sport cars" are design for cornering thus better/reinforced chassis. No car is designed to ride the clutch...

Touche

[AWD Addict]

You want to practice "slipping" the clutch (not riding, and not dumping). There's an optimal point in between that will minimize stress on the drivetrain, but will also toss you back into the seat on the hole shot pretty good.

Turn on DTC as well, otherwise the car will cut throttle on you when you slip.

[Down_Shift]

Wouldn't dumping the clutch at a rev shock the drivetrain? A rear and fwd car fine the power just grandees to smokey tires. But a awd, it would put all the shock into the drivetrain right?