Tips & Pointers on Launching the 1M

[DSCPLN]

I've probably been losing up to 2 seconds from having a terrible launch on the 1M.

Any tips from the Autocross or Time Attack pros?

Do you have your CDV removed or a modified variant?

[GAZ 345]

remove it for the win

[nachob]

Originally Posted by DSCPLN

I've probably been losing up to 2 seconds from having a terrible launch on the 1M.

Any tips from the Autocross or Time Attack pros?

Do you have your CDV removed or a modified variant?

The launching problem with 1M is loss of traction. I'm not sure how a slightly faster clutch engagement will help that. It engages quickly enough already and actually a gradual hookup might help reduce wheelspin. It's an art of finding the right throttle and clutch engagement. I remember in 2011 everyone recorded 4.5 0-60 times but motor trend got 4.2 by practicing the launch. Still will keep an open mind but don't think Cdv removal is necessary in 1M like it was in e46s. There is quite a "thump" going through the drivetrain already when speed shifting. Also look up my comments on Dinan tune. I looked up the torque specs on our gearboxes and they were already near their limit. Adding more shock through the drivetrain will probably not help in the long run. I only drive manuals since 1984 and the 1M clutch engagement is really good. I did remove the Cdv on my e46 325i and 330 zhp and did make an improvement but 1M is perfect as is IMHO.

http://www.1addicts.com/forums/showt...amp;amp;page=3

1M gearbox is ZF GS6-45BZ

It is rated by ZF at 470 NM input torque ( 346.61 lb ft)

I removed links because no longer valid. Our motors are already 320 lb feet torque and 369 overboost though overboost is always in a rolling situation there is less shock than in a launch.

Update. Here is current link to ZF:
http://www.zf.com/corporate/en_de/pr....shtml#tabs1-1

[eeghie]

Originally Posted by nachob

... 1M gearbox is ZF GS6-45BZ

It is rated by ZF at 470 NM input torque ( 346.61 lb ft)

I removed links because no longer valid. Our motors are already 320 lb feet torque and 369 overboost though overboost is always in a rolling situation there is less shock than in a launch. ...

Bmw M 1M development lead claimed they internally qualified it at 500Nm to allow for the overboost.

[nachob]

Originally Posted by eeghie

Bmw M 1M development lead claimed they internally qualified it at 500Nm to allow for the overboost.

That's 368.8 lb ft. Which is at the limit of 369 lb ft for 1M. My point is that the gearbox is close to whichever rating you want to believe. ZF or the BMW lead. Adding more jolt through the system is worrisome especially because the Cdv in 1M is pretty well calibrated. If it was as slow as e46 325i then yes change it. I have done it myself but that gearbox and clutch only had to cope with 175-200 lb feet of torque. Now you are sending a shock of possibly double that. Furthermore, the issue with launches is not slow clutch engagement. It's the rear tires breaking loose and slight clutch slip might even help the tires hook up better! It really makes little sense from a technical perspective when you weigh stressing the driveline vs benefit. Even if you worried about clutch longevity it is still a wear item and cheaper to replace than the gearbox. If you were drifting and needed very precise and quick clutch engagement Cdv delete would make sense. If you are in the track also it would make sense because the benefits might outweigh the risks but for launching the car from a standstill is the hardest thing in the car and that is the one place where the Cdv shines in allowing a tiny bit of slip to reduce shock to the driveline. Anyway, OP I understand that you are collecting info and will make your own decision. Just offering my point of view. Cheers.

[DSCPLN]

^ nachob, Appreciate the elaboration on your decision to not removing your CDV.
There are definitely several different schools of thought on that topic depending on who you ask.

I'm more so interested on the method on how people have been launching their 1M's from the start.

Provided that you performance 'racing' and are starting from 0, running through a time circuit of any sort (Autocross, drag racing, etc)..
What is the best way to launch the 1M? With that, obviously keeping tire slip to a minimum is definitely up there in priority.

[nachob]

Originally Posted by DSCPLN

^ nachob, Appreciate the elaboration on your decision to not removing your CDV.
There are definitely several different schools of thought on that topic depending on who you ask.

I'm interested on the method of how people have been launching their 1M's/

Provided that you performance racing and are starting from 0, running through a time circuit of any sort (Autocross), drag racing, etc.. what is the best way to launch the 1M? With that, keeping wheel spin to a minimum is definitely up there in priority.

I'm right there with you and trying to master it myself which is how I got into the thread. It takes a lot discipline to keep balance boost, lag and traction. I was expecting someone to offer an rpm range and other pointers but the Cdv delete threw me off. Anyway back on track. Who is a Master launcher here? The best time recorded was motor trend. I wish we could get that guy to tells us the secret. They recorded 4.2 0-60on PS2s.

[DSCPLN]

Who is the aster launcher here? :P

[Karmic Man]

Originally Posted by DSCPLN

I've probably been losing up to 2 seconds from having a terrible launch on the 1M.

Any tips from the Autocross or Time Attack pros?

Do you have your CDV removed or a modified variant?

I see that you have quite a bit of mod on your car so its making quite a bit more torque in the mid range then stock. You will always have traction problem unless you change to even stickier tyres.

Also you will place a lot of stress on the gearbox if you remove the CDV as others had said. Not worth it.

[DSCPLN]

Originally Posted by Karmic Man

I see that you have quite a bit of mod on your car so its making quite a bit more torque in the mid range then stock. You will always have traction problem unless you change to even stickier tyres.

Also you will place a lot of stress on the gearbox if you remove the CDV as others had said. Not worth it.

Driving my car on stock or with all the performance modifications I've made over the years, I've always modulated my launches from the start so that I get minimal to no tire slip at the launch.. you don't "always have traction problems" or need to "change to stickier tires."

Understanding how to properly launch the 1M provided its high torque is the entire point of this thread.

I'm not looking into starting a debate about the CDV either (there are pages and pages of the ongoing debate if you search the forums) - you either understand its trade-offs, or you don't. I was just curious what high performance drivers were running and their perspective.

I am still looking for relevant 1M launch advice from a competitive performance driver.

[Ric in RVA]

While I don't have a 1M I am sure the CDV is the same.

I think my CDV makes my shifting less precise and leads to clunky drive line loading and unloading..which is probably worse for wear.

Without the CDV I have CONTROL over engagement points. With the CDV it is a crap shoot as to when it will hook up since it is all dependent on how fast the little hole lets the pressure bleed...engaging and disengaging the clutch.

It is there to stop the ham fisted from doing clutch drops.

If you understand how a clutch works and don't dump it you wont have any issues.

[DSCPLN]

From a high performance driver friend:

"BMW is the only brand among performance cars that have a CDV.

The clutch is a wear and tear part. - So if you performance drive all the time, you'll reduce its lifespan by like a year or two. So probably will require replacement every 4 years vs every 6 to 7. Same cost as a new set of tires.

The launch is gonna be different every day based on the conditions and the surface.

You just gotta do it a few times to see where you just chirp the tires for a split second. That's the fastest launch.

I drop the clutch at that optimal RPM (which will vary) upswing then floor the gas, but ease off if you feel any rumble from the tires slipping. If you hear that perfect short chirp, that means you did everything right.

The Optimal Launch RPM will change throughout day.

With the pavement warming up from the sun. In the morning the surface is gonna be cold, so you're not gonna have much grip. And even while it's cool like that, the tires are gonna heat up run after run - that's gonna give you more grip until they get overheated and become greasy.

My E92 M3 (which is 8 years old now) is still on the stock clutch with no CDV. And I launch all the time"

[nachob]

Originally Posted by DSCPLN

From a high performance driver friend:

This is really good and really explains the art that is a good launch. You have to take into account so much. The pavement temp, tire temps, outside temp, silt or road, asphalt or concrete and rpm range and clutch release. It really is an art that can probably only be mastered by practicing with a timer and muscle memory of what worked when and where.

I am still open so some suggestions, for example a driving instructor told me to pretend there was an egg between the throttle pedal and the throttle actuator so that you press delicately. It helped a bit and there are probably tips like that that hopefully will help out.

Now I go off a little bit......

DSCPLN I know the CDV keeps coming back in the discussion so I promise that this is the last mention I make. You said that there are many opinions on this which is one one of the problems with the forums and the Internet. Every opinion is weighed equally. Someone can spend days doing research, posting actual numbers and real data and engineering analysis and someone will just make an off the cuff comment and the forums weigh them equally as just another opinion. I think that is a mistake because there are many that are thorough and are on quest for the truth and try to back it up with data.

For example, I stated that the the transmission in our cars is near the limit of its rated capacity and that is something to consider when increasing the shock of removing the CDV valve. Especially when the bigger issue with our cars is the triple combination of turbo lag, a crazy surge coupled with limited traction and an engine that where output seems to vary quite a bit with temperatures. For example as related to launching the 1M. I find on cool morning the motor makes more power but the tires are colder! Later when the tires are warmer, the car doesn't pull as hard....crazy!

Anyway, our performance buddy is right on on every point but his last statement also goes with what I am speaking about the internet where everything is weighed equally.

The e90 does not make the torque like the 1M.

At 1800 RPM we are speaking about 320 lb ft going through the driveline and mounts. The e90 is more gradual and doesn't even make that much torque at full swing. Furthermore, the transmission in the e90 is much higher rating that the 1M gearbox. So he implies that his experience without CDV and launching all the time is directly related to the twin turbo 1M. If you look at the ZF link I provided the next model up is the M3 gearbox and it is a 53BZ rated at 600 NM (442 lb/ft). You have a higher rated gearbox with less torque. The opposite is true with the 1M. You have a lower rated gearbox handling more torque so driveline jolt is a bigger concern in our cars.

Also the part about BMW only one using CDV valve, I will not speak to because I only speak about things I research and don't know off-hand if that is true. What is true is that BMW uses expensive dual mass flywheels. The dual mass flywheel is a two piece flywheel where both pieces can move respectively with springs to absorb engine vibration. While this design makes for smoother running, it is another piece that is impacted severely by a jolt and they can soften over time, overheat and fail.

You will notice the 1M has a clutch temperature sensor. This piece is expensive and another reason engineers use CDV to reduce the driveline jolt.
https://en.wikipedia.org/wiki/Dual_mass_flywheel


I see a lot of these testimonials all the time. In another thread discussing direct injected turbo oils and 15k oil change intervals, someone chimes in and says my old 328i has 250K miles and I changed the oil every 15K miles totally discounting all the research posted about direct injection spraying cylinder walls and some fuel mixing with oil, etc. Again, everyone just weighs this off the cuff irrelevant statement the same. The 328i is a normally aspirated, port injected motor. The 1M is a twin turbo direct injected motor and the oil is taking a bigger beating than his 328i.

Another poster says on an F80 says I didn't break-in my e46 and 80K miles it doesn't burn any oil. Again, if that's true, lucky for him but his car used iron cylinder walls, the F80 used a new process where metal is welded directly on the aluminum block. Not the same material on the new cars.

So that is all I will say about it anymore and I apologize if your thread went off. I wish the CDV hadn't been the first silver bullet mentioned in it. I assume with your mods that you are OK incurring the additional risk to the driveline but I just want to make sure that people don't just think taking off the CDV is going to give them 2 second faster launches with no impact to the durability of the Dual mass flywheel and gearbox. I hope you understand the spirit of why I posted this.

Humbly.... done.

Thank you.

[DSCPLN]

^ nachob Very well put.

Lots of questions raised regarding the capability of the stock gearbox to support tunes set to higher levels of torque. And the impacts of a removed CDV

[Karmic Man]

I had drag hundreds of time (not on the 1M) and its all trial and error. Same day same road but different tyre temp and clutch temp will require adjustment.

Past cars I drove that had CDV is Lancer Evolution and AP2 S2000 and it never bothers me a bit as I know I can hammer the gearbox harder with the extra cushion from CDV.

If you lost 2 seconds on launching that is some serious traction problem to me. Anyway each to their own.

[CarJunkie]

Originally Posted by Ric in RVA

While I don't have a 1M I am sure the CDV is the same.

I think my CDV makes my shifting less precise and leads to clunky drive line loading and unloading..which is probably worse for wear.

This was my experience in the 1M. The shifting was unnatural, lots of clunking and passenger head-bobs. It made me feel like a newby despite decades of driving stick. Deleted the CDV and the car worked properly. I tend to be easy on my clutch engagement, and like having it do what my foot tells it to do when it tells it to do it. It is rare that I get a clunk.

Maybe others will recall some examples, but I personally only remember hearing of one transmission failure here on the forum and I don't think the guy was running a lot of mods. There are lots of people putting out 450-500 ft-lbs for years now with no transmission issues. . . Clutches, well that's another story.

Now back on the original topic . . . I find that there is no need to rev beyond about 2000-2500 RPMs for a good launch. Slight hold at the friction point, and as it grabs, right foot to the floor. For me, the variation is in the feel for traction while briefly holding at the friction point and how quickly to get it fully engaged. There is not much variation in the starting RPM's. My autocross club usually has about 150' lead in (usually with a gate) prior to the timing start, so perfect launch from the line is less critical then being able to put full power down through the start. My approach to a straight line all out 0-60 run or 1/4 mile may be different, but I don't really do that.

[DSCPLN]

Originally Posted by CarJunkie

This was my experience in the 1M. The shifting was unnatural, lots of clunking and passenger head-bobs. It made me feel like a newby despite decades of driving stick. Deleted the CDV and the car worked properly. I tend to be easy on my clutch engagement, and like having it do what my foot tells it to do when it tells it to do it. It is rare that I get a clunk.

Ditto. No more passenger head-bobs with my modified/free-flow CDV

Originally Posted by CarJunkie

There are lots of people putting out 450-500 ft-lbs for years now with no transmission issues. . .

Very curious on that as well.

Great tips on launching! Very relevant to my needs (Autocross)

[M3 Adjuster]

Originally Posted by CarJunkie

This was my experience in the 1M. The shifting was unnatural, lots of clunking and passenger head-bobs. It made me feel like a newby despite decades of driving stick. Deleted the CDV and the car worked properly. I tend to be easy on my clutch engagement, and like having it do what my foot tells it to do when it tells it to do it. It is rare that I get a clunk.

Maybe others will recall some examples, but I personally only remember hearing of one transmission failure here on the forum and I don't think the guy was running a lot of mods. There are lots of people putting out 450-500 ft-lbs for years now with no transmission issues. . . Clutches, well that's another story.

Now back on the original topic . . . I find that there is no need to rev beyond about 2000-2500 RPMs for a good launch. Slight hold at the friction point, and as it grabs, right foot to the floor. For me, the variation is in the feel for traction while briefly holding at the friction point and how quickly to get it fully engaged. There is not much variation in the starting RPM's. My autocross club usually has about 150' lead in (usually with a gate) prior to the timing start, so perfect launch from the line is less critical then being able to put full power down through the start. My approach to a straight line all out 0-60 run or 1/4 mile may be different, but I don't really do that.

I'll have to consider removing the CDV, I have had it in all this time. I don't consider it a major issue but I do have the occasional clunk in exactly the fashion you mentioned, many times when doing very casual driving.

I agree with your launch technique. It takes quite awhile to realize that you don't need to launch it at high rpm.. And it's really difficult to keep dialing back. Most of the autocross events I do have a 5 foot roll out to the timer so it's pretty much an immediate launch ... a little bit of wheelspin is fine but less is more. Getting into the boost off the line just means you will roast the rear tires.

The best way to improve rear traction is bigger rear tires. I run 10" rear wheels and 285/30/18 really helps and 315/30/18 (on a 10.5) makes you go " wow.. I was roasting the 285s.." ..

[nachob]

Originally Posted by M3 Adjuster

I'll have to consider removing the CDV, I have had it in all this time. I don't consider it a major issue but I do have the occasional clunk in exactly the fashion you mentioned, many times when doing very casual driving.

I agree with your launch technique. It takes quite awhile to realize that you don't need to launch it at high rpm.. And it's really difficult to keep dialing back. Most of the autocross events I do have a 5 foot roll out to the timer so it's pretty much an immediate launch ... a little bit of wheelspin is fine but less is more. Getting into the boost off the line just means you will roast the rear tires.

The best way to improve rear traction is bigger rear tires. I run 10" rear wheels and 285/30/18 really helps and 315/30/18 (on a 10.5) makes you go " wow.. I was roasting the 285s.." ..

The thunk has nothing to do with CDv actually a
Quicker engagement will make it worse. BUT IF it does take it away please report back so I can eat some crow cake. Tjamks

[COChris]

I lean toward nachob's point of view.

And I typically notice the CDV effect more with basic moderated driving and less with spirited driving.

Haven't removed it to see what the difference is.

Also you have to consider that this car's forte wasn't meant to be launching and making a quick 1/4 mile, but to be quick around a track or through twisty roads.

If you learn to anticipate the effects of the CDV, it's not much different than learning to drive a manual in the first place.