E46 Fanatics Forum banner
  • Hey everyone! Enter your ride HERE to be a part of October's Ride of the Month Challenge!
1 - 20 of 28 Posts

·
1.888.JLEVISW
Joined
·
29,082 Posts
Discussion Starter · #1 ·
I have seen a lot of people with step tranny's saying they turned DSC off to launch and torque braked to get the best times. Is torque braking bad for the car? Also, I have a 325i, and from a standstill, if I floor it, the car does not spin it's tires. So to get the best straight times, without torque braking, would it be best to turn of DSC or just leave it on as the 2.5l doesn't have enough power to break the wheels loose?:dunno:
 

·
P.I.M.P.
Joined
·
2,369 Posts
the reason why you can't break the wheels loose is because you cannot launch it with an auto tranny...I think torque braking can be considered a poor mans launch...and i would assume to get the best times you would need to turn off dsc, hold the brakes, get the revs to the engines peak torque(3000rpm) and drop the brakes....

PS. yes torque braking is bad for the car.
 

·
99% Stock
Joined
·
862 Posts
For sure turn the DSC off if youre torque braking, made a difference of 0.6 sec in my 0-60 time. Not kidding. It's probably really bad for your car, so i only did it a few times to record gtech times.

If youre not torque breaking i doubt the 325i will spin its tires in the dry (ive tried many times) but its probably better to leave DSC off anyways.
 

·
99% Stock
Joined
·
862 Posts
xS3x said:
why do u guys torque braked till 3000rpm?

the max i've tried is 2500RPM, and i was smoking my rears:D
Haha, cause we're talking about 325i's here not 330s!!! Especially nicely modded 330s!!! :flipoff: :lmao: :lmao:

The first time i launched my 330ci manual at 3000 i got such a fat peel out i almost **** my pants. I guess manual + 330's hp makes a noticeable difference.
 

·
Registered
Joined
·
426 Posts
the point of torque braking is to get the engine torque matched to the stall speed of the torque convertor to enable a hard launch, but doing so will cause damage to the transmission or more specifically the torque convertor.

as the outer shell of the convertor spins the vanes pick up the fluid and start to spin the stator (iner vanes attached to output shaft to transmission) as the speed increases the torque or force on the stator does also, however if you are holding the drive end still the stator can not turn so the fluid will spin past the stator vanes and creat friction/heat and stress on the convertor. all this will in time grenade the convertor. not a happy prospect on the BMW trans let alone a step.

think of it this way, would you put your manual into first and floor it while stepping on the brakes?

just a thought:eek:
 

·
Registered
Joined
·
426 Posts
the convertor multiplies the force applied to it from the engine to the transmission, the convertor also allows you to stay in gear while stopped. with out a direct connection like a clutch plate on a manual the auto trans needs a way to get the engine torque to the transmission; with out multipling the applied torque the transmission couldn't move the car. the convertor also applies hydrolic force to the servos and that causes the gear shifts at speed. -basic auto- electric servos and other technology can do this too i.e. steptronic

autotransmissions are very complex and this is why they allways cost more. gives you an idea of the technology needed for the SMG:yikes:

also with the right combination of convertor/trans an auto can put out more torque than a manual and be faster.
 

·
Registered
Joined
·
207 Posts
smg said:
the convertor multiplies the force applied to it from the engine to the transmission, the convertor also allows you to stay in gear while stopped. with out a direct connection like a clutch plate on a manual the auto trans needs a way to get the engine torque to the transmission; with out multipling the applied torque the transmission couldn't move the car. the convertor also applies hydrolic force to the servos and that causes the gear shifts at speed. -basic auto- electric servos and other technology can do this too i.e. steptronic

autotransmissions are very complex and this is why they allways cost more. gives you an idea of the technology needed for the SMG:yikes:

also with the right combination of convertor/trans an auto can put out more torque than a manual and be faster.
Good point. In drag racing we use somthing very similar because of the torque factor on the manual transmission clutch, gears and slider materials. It has a much higher strength withstanding than manual and eliminates the dreaded misshift from over-revving or from worn parts not performing i.e gears. When u shift a gear u are litterally forcing a rod into a rivot to catch the gear. When these parts are worn u will lose races. Meaning that on most transmissions there is a dead point where when reaching a high rpm level the gear is unable to handle the increased power to lock into place and will pop-out or not link at all. In our case tho these auto-transmissions are built for a specific drag purpose and are very expensive. It would not be very well adapt to street use.
But in many cars like Supra's, Skyline and other high HP engines the auto transmission is preferred.
 

·
Registered
Joined
·
26 Posts
Which is the wright combination of convertor/trans for a 328Ci steptronic?
SMG can you please advice?
:confused: :confused: :confused:
 

·
TX Dinan 3
Joined
·
796 Posts
lol even with my mods my 330ci cant spin the tires without power braking from a dead stop, now a 3k drop sets it free...damn step
 

·
Registered
Joined
·
426 Posts
I'm currently looking into a custom built convertor for the GM steptronic trans, but before I go ahead i need to get more info on the electronics. most of the builders stopped working on the BMW trans when the E36 came out becouse the electronics didn't like the higher stall speed convertor and would throw a fault thus locking the trans into 3rd gear.:banghead:

the stock stall speed is fine if you haven't done any internal engine work, but if you have like me then the stock convertor works against you. there are times when the electronic gods are happy and the fault codes are off, then I can induce wheel spin from a stop, but this is very rare. however all turns with the DSC off will cause excessive wheel spin:D

the Dragster i'm building sports a B&M C6 trans with vacum shifting, HOT DAMN!!! does this thing hook up, the hole shot convertor is nice too...
 

·
Registered
Joined
·
3,060 Posts
I can break the tires loose in my 325!

Check for my post on electonic throttle adaptation reset. After you reset the throttle adaptation, you get some peddle and throttle response back and with torque braking you can. I actually did this and posted my comments in that thread as well. Lets say I won't be trying it again, scary. I've done U-turn spins but torque braking launch with DSC off was spin-city, had some smoke going and let off. The smoke got sucked into the car and gave me a headache. :D BTW I only torque braked to 1500 RPM and got a spin and the second time was waiting to make a left turn at 1200 RPM and I was at a stand-still spinning and it slowly moved through the turn spinning until the wheels caught. Not something I would suggest trying.

K-DOG said:
the reason why you can't break the wheels loose is because you cannot launch it with an auto tranny...I think torque braking can be considered a poor mans launch...and i would assume to get the best times you would need to turn off dsc, hold the brakes, get the revs to the engines peak torque(3000rpm) and drop the brakes....

PS. yes torque braking is bad for the car.
 

·
Registered
Joined
·
288 Posts
Hum.. so what effect does the multiplication of torque have on our cars? Can we see any of it to the wheels? What about people with the ZF Trannys instead of GM? Anyway I just wonder in stock form does any increase in torque go to the wheels? Or is the mulitplication of torque just like when you change your gearing?
 

·
Registered
Joined
·
426 Posts
the multipling of the torque is for the transmission gears, the auto trans has different gearing than a manual - the net effect is the same output between the manual/auto however with the right racing automatic the auto can put better torque to the ground. the one BIG advantage of the manual is the putting the power band on the gear where you want. if you're big into drags then the auto is the way to go becouse after the launch the auto will be very consistant and pulling more torque, but if there is a need for constant gear changes then the field advantage goes back to the manual.

see the only connection between the engine and the trans is fluid and that fluid needs to apply force on the 'turbine' stator of the output shaft, similar in concept to the turbo. this is why the convertor ups the torque. also a reason why you'll get latent shifting.:thumbup:
 

·
Registered
Joined
·
288 Posts
Yea I know like a 330 auto has 3.38 gears and a manual has 2.93 but how come like bmw states that the auto 330 is a full second slower? That just doesn't make sense yet the 5 series and z4 etc the auto and manual are 99 percent identical in times? I think it's bs that only the 3 series is that much slower. Okay but does any of that multiplied torque get to the wheels?
 

·
Registered
Joined
·
426 Posts
those gear numbers are for the differential in the rear that drive the wheels, the internal gearing to the transmission is what I'm refering to, and no the increased torque is just in the convertor then applied to the gears in the trans to move you. the only time the convertor is not multipling the torque is when it is in lock, or locked to the trans and engine when cruising you can sometimes feel this when you have covered about 5miles at the some rate of speed and then gently tap the brakes you'll feel a shift as the convertor unlocks.
 
1 - 20 of 28 Posts
Top