Seeking help from you manual pros!

[Wilsonv]

Hey all!
I drive a 2011 sdrive30i Manual

This might sound really stupid, but i am new to manual driving. Well to launching the car fast to be exact.

I am trying to find whats the optimum rev point for my the dump the clutch. (Or should i be slipping it instead?).

I was told to dump it at it's torque peak, which is 2700-3000 according to the BMW SPEC.

So please help me out and i hope i made it clear, Please don't bash me if i did anything wrong. Just seeking help from members

Cheers

[mstevens]

If you simply dump the clutch, you're going to damage something.

With practice, you'll learn how to launch without relying on the tach.

[ManiacGT]

Dumping the clutch at peak torque will do a few things, spin wheels (for a while if you turn off traction control), make smoke and squeal sounds, cost you quite a lot in tyre rubber and probably make you look silly to those around you who you might think are looking at you going 'cool'. It will also mean that you will place full load on every bearing, cog and shaft leading to premature wear or worse still breakage. These are not cheap cars to fix, so consider that.

The fastest take offs require no wheel spin. So its best to get the right revs and offer in the power smoothly. That will give you smoother clutch wear and reduce shock to the transmission. Indeed BMW place a CDV to reduce (but not eliminate) shock to the transmission on manual cars.

As with anything, its all about practice. You'll get the hang of it, just don't go mad.

Just my 'two cents'

[vasmir]

Concur with what's said above.

If by "dumping the clutch" (popping the clutch) you mean literally releasing the pedal in a sudden, jerky motion while your other foot is already at a constant high rpm, then it's going to be rough on your car, and you'll probably get your tires to spin... but that's not the proper way to accelerate fast.

Just like starting from any other stop, what you want is to progressively engage the clutch while providing more throttle to the engine.

The more you drive a manual, the better and faster you'll get. Driving a standard with skill is just like everything else that requires years of practice and experience.

[Wilsonv]

Thank you all for the insightful responses! Would anyone have a step by step?
I hate dumping the clutch as i know it's harmful to the car, though at time to time. Id like to have a bit of fun at the red light with my friends, though i could not seem to start the car quick enough. Ending up always cruising on 2nd gear before doing anything.

Cheers again for great reponses

[rking117]

Originally Posted by Wilsonv

I was told to dump it at it's torque peak, which is 2700-3000 according to the BMW SPEC.

Not to be confused with the technology, in racing I do what is called double clutching. This allows me to launch with minimal wheel spin and maintian high torque.

Think of it like this I sort of dump the clutch for until it grabs and you feel the wheel spin begin, then I push the clutch back in partly and then dump it fully. By the time you do this if done properly you are already launched and going about 10 miles per hour or more if you get good at it.

After learnign this technique I can say my 60 ft times have increased a lot.

[ManiacGT]

That's an interesting technique your 'double clutching'... but in fact double clutching or double declutching as its also known is where you declutch/clutch from a gear to neutral to spin up the transmission to match the ratio of the gear you're shifting to next, making for much quicker shifts. Its not the same technique as the double hit that you're doing on a launch.

As I say though, interesting approach, I can see that working, but your clutch might be a bit unhappy after a while.

[nicknaz]

I try to engage the clutch as fast as possible to minimize how much it is slipped and modulate the wheelspin using throttle. Holding rpm at 3000 seems reasonable for that engine.

[rking117]

Originally Posted by ManiacGT

That's an interesting technique your 'double clutching'... but in fact double clutching or double declutching as its also known is where you declutch/clutch from a gear to neutral to spin up the transmission to match the ratio of the gear you're shifting to next, making for much quicker shifts. Its not the same technique as the double hit that you're doing on a launch.

As I say though, interesting approach, I can see that working, but your clutch might be a bit unhappy after a while.

Certainly i didnt say there couldnt be side affects. And also like i said you shouldnt confuse that with the DCT tranny. IT does something similar when launching to minimize wheel spin but it also uses a combination of traction control methods (brakes) to assist with ECS on. But when off most of that is defeated allowing the person inside to simply burn there tires completey off if that is what they choose. A $5 line lock will assist in that matter. I was just offering the techinique to try if they choose. Really though a true racer isnt gong to care about a clutch too much because they are tearing down and rebuilding parts like that regularly. NOT THAT that is me or anything. I am getting too old for that kind of work.

[nicknaz]

Originally Posted by rking117

the DCT tranny. IT does something similar when launching to minimize wheel spin but it also uses a combination of traction control methods (brakes) to assist with ECS on. .

DCT in my Z4 35i Doesn't seem to do anything of that sort.. When I tried launch control it seemed like a 4000 rpm clutch dump. tons of wheelspin. not that useful

Porsche PDK in a 987.2 cayman s on the other hand pulled timing to maximing traction (great exhaust popping sounds too!) after a 7000rpm launch

[teagueAMX]

Originally Posted by rking117

Not to be confused with the technology, in racing I do what is called double clutching. This allows me to launch with minimal wheel spin and maintian high torque.

Think of it like this I sort of dump the clutch for until it grabs and you feel the wheel spin begin, then I push the clutch back in partly and then dump it fully. By the time you do this if done properly you are already launched and going about 10 miles per hour or more if you get good at it.

After learnign this technique I can say my 60 ft times have increased a lot.

ROFLOL

That's definitely "old school" drag racing. Brings back a few memories. My cars always had large CID engines with tons of torque so double clutching wasn't necessary - my problem was smoking the tires too much. But for those guys with smaller, but higher rev'ing engines and numerically high rear end gears (somewhere between highway and tractor pulling) they used this technique to maintain a higher level of RPM. Not really a good thing for a street car if you want you clutch and drive train to last more than a few thousand miles.

But back on topic, one question I would ask the OP is how good are you using a manual transmission? Have you really mastered the clutch in everyday driving? A firm recommendation: Do Not slip your clutch!

Mastering the clutch first, then think about impressing your friends.

[vasmir]

Originally Posted by rking117

Not to be confused with the technology, in racing I do what is called double clutching. This allows me to launch with minimal wheel spin and maintian high torque.

Think of it like this I sort of dump the clutch for until it grabs and you feel the wheel spin begin, then I push the clutch back in partly and then dump it fully. By the time you do this if done properly you are already launched and going about 10 miles per hour or more if you get good at it.

After learnign this technique I can say my 60 ft times have increased a lot.

Yeah... that's not double clutching. That's slipping a clutch.

Originally Posted by nicknaz

DCT in my Z4 35i Doesn't seem to do anything of that sort.. When I tried launch control it seemed like a 4000 rpm clutch dump. tons of wheelspin. not that useful

So when you use launch control on a DCT equipped Z4, one of the steps to select "Sport+" from Dynamic Driving Control. This partially (not completely) disengages DSC, allowing your wheels to slip a bit. To lessen the slip, lessen the throttle you give the engine.

Originally Posted by Wilsonv

Thank you all for the insightful responses! Would anyone have a step by step?
I hate dumping the clutch as i know it's harmful to the car, though at time to time. Id like to have a bit of fun at the red light with my friends, though i could not seem to start the car quick enough. Ending up always cruising on 2nd gear before doing anything.

Like mentioned above: what you want is to progressively engage the clutch while providing more throttle to the engine. Adding power before you feel the friction point can help; how much power depends on how fast you're bringing your left foot up.
There is no secret to this. Practice and experience are the answers you seek.

[rking117]

Originally Posted by vasmir

Yeah... that's not double clutching. That's slipping a clutch.

I dont mean to be frank but isnt that the job of a clutch, to allow the transmisson plate to slip so that you can get started or change gears? And dont go there, Yes i know you can change gears without a clutch. both upshift and downshift. So really you only need it to stop if you shift right, but that is another subject all together.

I was mearly giving another method of launchng a manual.

As teagueAMX said that is old school for sure. My racing days started in the days of Poison, Aerosmith and Van Halen maybe a little Floyd for your english guys and gals. lol

[nicknaz]

Originally Posted by vasmir

So when you use launch control on a DCT equipped Z4, one of the steps to select "Sport+" from Dynamic Driving Control. This partially (not completely) disengages DSC, allowing your wheels to slip a bit. To lessen the slip, lessen the throttle you give the engine.

With the LC it doesn't just allow wheels to slip "a bit". The rear of the car will step out from all the wheelspin the feature allows.

The fact that I need to take over and modulate the throttle is exactly why I mentioned that it is a "clutch dump" as opposed to a "launch control", in my opinion.

As an aside, I think the best way to start quickly with the DCT is to just floor the throttle past the kick down point without activating the LC. Engine will rev up a little and the car takes off with no wheel spin.

[Wilsonv]

Originally Posted by teagueAMX

ROFLOL

That's definitely "old school" drag racing. Brings back a few memories. My cars always had large CID engines with tons of torque so double clutching wasn't necessary - my problem was smoking the tires too much. But for those guys with smaller, but higher rev'ing engines and numerically high rear end gears (somewhere between highway and tractor pulling) they used this technique to maintain a higher level of RPM. Not really a good thing for a street car if you want you clutch and drive train to last more than a few thousand miles.

But back on topic, one question I would ask the OP is how good are you using a manual transmission? Have you really mastered the clutch in everyday driving? A firm recommendation: Do Not slip your clutch!

Mastering the clutch first, then think about impressing your friends.

Hey,

I don't really know how well i drive with manual, but i'd think i am comfortable with it, but no where near master. I've been on it for around 9 months now.
I am completely fine with everything, perhaps i slip the clutch a tiny bit on a hill start. Generally i am fine, e.g downshifting to overtake etc.

To be honest i am not trying to impress my friends, i just really want to have fun with the car. so i would appreciate if you could perhaps teach me step by step or a general idea of what to do.
I mean everyone have to start somewhere right

Cheers again
Wilson

[teagueAMX]

Originally Posted by Wilsonv

Hey,

I don't really know how well i drive with manual, but i'd think i am comfortable with it, but no where near master. I've been on it for around 9 months now.

I am completely fine with everything, perhaps i slip the clutch a tiny bit on a hill start. Generally i am fine, e.g downshifting to overtake etc.

To be honest i am not trying to impress my friends, i just really want to have fun with the car. so i would appreciate if you could perhaps teach me step by step or a general idea of what to do.
I mean everyone have to start somewhere right

Cheers again
Wilson

That’s fine. I thought maybe you were completely new to the MT.

Even the best of drivers slip a clutch a little bit regardless. I was concerned about slipping the clutch as a practice which is very detrimental to clutch disk and flywheel clutch mating surfaces.

Dumping the clutch, or as we sometimes say it in the States “Popping the clutch” (sounds stupid, right?) is pretty simple, and again not recommended. However, it you’re going to do it anyway:

As noted, rev you engine to around 2600 – 3000 rpm and hold it for a second or two. Be prepared to floor the gas pedal the moment you release the clutch pedal. With a quick sideways motion, slide your clutch pedal foot off the pedal. This minimizes clutch slippage and is better for a quick release rather than moving your foot backwards in the normal manner. It’s important to keep you RPMs no less than the 2600 – 3000 range for acceleration, even after the car is moving. A certain amount of wheel spin is needed, otherwise your engine speed will drop. Keep your eye on the tach because you’ll need to shift to 2nd gear quickly, as noted below.

Here’s a couple of points on shifting. There is a common misunderstanding about when you shift up to the next gear – you don’t have to “red line” the engine. Based on the 2009, Euro spec for the 30i 3.0 l engine it appears you reach 190 kW max power at 6600 RPM. So, there’s no need for your engine to exceed this RPM. In fact exceeding this RPM could slow you down, not mention damage to your engine! The exception is to match the next gear power level for acceleration. Sometimes it's good to shift a little sooner than the peak kW. You have to practice different point and they are not always the same for each gear. The MT's gear ratios at spaced evenly to keep your engine within the broad bower band during normal acceleration. When you race you want to experiment with your shift points so your engine is within its broad power band but at higher RPM points so it pulls you to the next shift point as quickly as possible.

Likewise, you may or may not want traction control on which depends on the amount of wheel spin you’re getting at take off.

This has been my method from years ago, FWIW. Others may have suggestions as well.

Cheers

[nicknaz]

One thing to keep in mind is that the BMWs have a clutch delay valve (CDV) so even if you are "dumping" or "popping" the clutch the car is slipping it for you a little bit.

I used to have an E90 328 (similar drivetrain as your car) and I would hold the rpm at 3000rpm with the traction control in the DTC mode and then floor the throttle while simultaneously "dumping" the clutch. I would get a little chirp at launch and that seemed like the best way to go. minimal clutch slip, a little bit of wheelspin, engine right at the torque peak at launch. traction control full off sometimes required me to modulate the throttle to avoid wheelspin, which resulted in less consistent launches.

[rking117]

you know i would also recommend that you get some racing lessons. Find a track that offers track days or something equivalent near you and book some time with an instructor. We can all give you written advice but there is simply no substitute for an in person session.

Note though that this will hurt the wallet a little but it is so totally worth it. The instructors usually teach newbies as well as seasoned veterans like myself. You will be glad you did it. most tracks do require helmets, fire extinguisher, tow hooks and usually no top down driving. I am sure there are other threads on track days which have all of this info for you.

If you do a track day take a friend to take photos and video. So totally worth it!!!!