[hammick]

I have searched these forms and on Google but can't find enough good info to make my own conclusion. I'm talking about braking and boosting from a stop to build boost for a launch. I have a 335d and people that take theirs to the track say it's the only way to get a good run.

What are people's opinions on how hard this is on your tranny? The 335d guys are boosting to 2,100 rpms and releasing the brake, only locking the converter for a couple seconds.

I haven't done this as I'm afraid I'll fry my tranny and the car will record data that I was brake boosting.

Was the launch control that I had in my '03 M3 SMG doing the same thing, just automatically? In other works, does BMW launch control in the SMG and DCT automatically apply the brakes. If so, it would arguably be just as bad for the car.

Looking forward to people's opinions.

[richpike]

My understanding is that when you do a brake torque, the torque converter is *not* locked, which is why you can raise your RPMs (same reason the car doesn't die when you come to a stop in an automatic).

As you brake torque, it creates a lot of heat, which breaks down the transmission fluid - and can eventually plug the small passage ways in the transmission causing failure. Is it going to happen the first time you do it? Probably not, but if you do it a lot, I'd make sure to have your transmission fluid changed regularly.

Having said that, I've also wondered if codes are somehow stored when you brake torque - anyone know?

-Rich

[richpike]

Originally Posted by hammick

Was the launch control that I had in my '03 M3 SMG doing the same thing, just automatically? In other works, does BMW launch control in the SMG and DCT automatically apply the brakes. If so, it would arguably be just as bad for the car.

Forgot to give you my opinion on this question - I believe it is very different from brake torquing an automatic. Since the SMG/DCT transmissions are just automated manuals, there is still a clutch that is not engaged when you use launch control. Basically, it is very similar to dropping the clutch in a manual transmission. The reason you use the brake to do it, is the brake acts like the launch "code" that tells the car when to dump the clutch.

Having said all that, I've never owned a car with launch control so someone can feel free to tell me I'm off in the weeds

-Rich

[VTECaddict]

Rich is correct on both accounts.

[richpike]

Originally Posted by VTECaddict

Rich is correct on both accounts.

Thanks. Any guess if the car stores a code when you brake torque?

-Rich

[hammick]

That makes sense since they are clutches manuals.