"Clutching" to get a better launch?

[Keith Carter]

Probably better known as depressing the clutch and then throttle to get high revs quickly and then dumping the clutch to launch has been a trick for 125cc dirtbikes where power was an issue for getting off of corners. Does anyone use this method for our cars on race starts? I tried it at one of our last regional events at the start, but I'm nowhere near good at it enough for it to be an advantage. Would it be worthwhile to use it or am I not making any sense?

[Steve Demeter]

Keith,

Our engines make a fair amount of torque.

That said, yes it can help.

What it actually does is get the flywheel spinning faster, and the energy stored by doing so is what helps the "launch".

That said, it is also hell on the entire drivetrain and do it at your own risk. I don't do it with the F2000 car, but did it regularly with the Super Vee, cause it didn't have much torque and the starts were normally way too slow for the engine to be on the cam and if I didn't do that, 10 casrs would pass me before the first corned.

[GR]

IMHO. I never thought about it. I am not sure me pressing in on the clutch as we see the green flag will put me in a better position than the guy flooring the throttle at the same instant.

This seems to be counter productive to me.

Interesting topic.... let's see where it goes......

[ckracing]

They say of the golf swing "1 swing thought is all you should have".

May have some merit. I think there are better things to work on.

[EYERACE]

eye had no choice this past weekend at Sebring but to be doing exactly this at the start.....but first let me share with the reader what soon is to be an entry in the "most embarrassing" thread....when you leave the false grid at sebring for practice/qualifying sessions you turn to the right and go down pit road to exit onto the track but for a race start one leaves the false grid and turn left out onto the track where the splitter will assign you your R/L - to begin the first race of the weekend, the first car turns right instead of left and the next two cars follow....fourth goes "thanks for the pole!" and goes out onto the track, P1 thru 3 get no pace lap and are held at pit out and start from the rear after the green is thrown and all go by. anyway the now P1 car slows to the green after the pace car releases the field and all i can do in first to keep the revs up is keep slipping the clutch and feathering the gas pedal. it makes for a bit of a jerky up and back in line waiting for the green but right, the flywheel stores the energy - this also might provide a little launch on a standard speed start too but watch out that the car doesn't try to go a little sideways as one rear tire bites more than the other.

[size="1"][ October 25, 2004, 02:20 PM: Message edited by: EYERACE ][/size]

[Lee Racing 8]

This could happen because both times I did it I was rolling. Don't drop the clutch to fast b/c you will "weld" the pressure plate to the clutch disc. I did it 2 times at Sebring in July, once on a missed gear I finally got it in and just dropped it and did'nt have any clutch after that, and in the final race, where it was a bit wet I spun in the right hander after club pit out. I got it straight and was still in 1st but here came 2nd place, so I put it in gear and dropped the clutch. No clutch after that either. When we took it apart we had to beat the crap outta it to get the 2 apart.

[Dennis Goughary]

Originally posted by Keith Carter:
Does anyone use this method for our cars on race starts? I tried it at one of our last regional events at the start, but I'm nowhere near good at it enough for it to be an advantage. Would it be worthwhile to use it or am I not making any sense?

I’ve never done this of course, but I have a friend who knows a guy who has a cousin that dated the sister of a racecar driver who did. Anyway, his story goes something like this…

“Clutching” works, and can give you a pretty good launch, but it’s not as easy as it sounds. First, you need to find that “sweet spot” which (according to him ) may not be that easy, and is subject to variables outside of the driver’s control (i.e. pace suddenly getting much quicker, slower, etc.). His advice is to “know when to hold ‘em and know when to fold ‘em”. He also refused to answer when quizzed on what some of the other “variable factors” were citing his 5th Amendment rights.

I guess this really comes down to how many of our little “secrets” do we want to reveal in a public forum? I remember a quote from Little Al when he said, “My dad taught me everything I know about racing. Unfortunately, he didn’t teach me everything HE knows!”

[andyllc]

ok guys, i can give away some secrets since i dont race open wheel cars anymore and i dont even dare try it on my stock transmission in the lexus. i do exactly what people are talking about but with the brake, not the clutch. i went through clutches quick enough in the zetec that i didnt want to add anything else to it. if you have seen a zetec start you will know that normally i am able to pick up a spot or so. anyways, as we are forming up two by two i leave a bit of a gap to the car in front. then (just for an example of distance) as we are going up the hill at road atlanta after turn 10 i close that gap to the car in front of me which is basically letting the engine rev up. then so i dont hit the car in front of me i get on the brakes without lifting off of the gas (gas is almost if not totally floored). i have to be on the brakes pretty hard but most importantly keep your revs up, then once you see the green let go of the brake and you will launch pretty hard (that is why if you were at road atlanta for the zetec race in 03 my shock cover was in my face cause i launched so hard i hit the pole man). make sure your revs are up though cause if not you will bog and get blown away. make sense?

[GR]

That makes more sense to me than the topic.

[Tim FF19]

Andy.

I don't understand. How do you keep the revs up with just the brakes on? If you put the brakes on to keep from hitting the car in front either the revs come down or the clutch has to slip. Are you just trying to time when the flag drops?

Inquiring minds want to know.......

[formulasuper]

Ya, I was wondering that same thing myself. That method worked well when I was racing F500 cars with the CVT. Braking with power on causes the CVT to shift to a lower gear ratio, setting you up for the start.

[DaveW]

My method on (slow) starts is not exactly rocket science. A short time before I think the flag will be thrown, I just disengage the clutch and rev the engine to ~5K, engaging the clutch very intermittently just enough to maintain speed. When the flag flies, I dump the clutch and floor the throttle. This seems to give a little extra acceleration over just leaving the clutch engaged and flooring it.

If I'm over ~4K approaching the start I don't do this, I just leave the clutch engaged and floor it.

[mark defer]

however, if dave is on the pole doing his "weitzenhof crawl", you won't be doing anywhere near 4k.

mark d

[Dick R.]

You guys should try an autocross, or better yet a Pro Solo, standing start with warm R25A tires on a grippy surface. With a 45 mph first gear in my FF1600 my launch revs can be as high as 5K or 6K when drop the Tilton clutch. Whew!!! [img]smile.gif[/img] Only one broken part (half shaft due to "pot hole" just after start) in over a decade.

Dick

[Jon Horgas]

Dave describes it perfectly. I used the same method on every start I made in 1600 and FC, and it had great results with minimal wear and tear (given proper preventative maint.) on the clutch. I used a slightly higher rev than Dave does, but this gives you a launch like being shoved from behind. It helps a lot.

[Dennis Goughary]

Originally posted by DaveW:
My method on (slow) starts is not exactly rocket science. A short time before I think the flag will be thrown, I just disengage the clutch and rev the engine to ~5K, engaging the clutch very intermittently just enough to maintain speed. When the flag flies, I dump the clutch and floor the throttle. This seems to give a little extra acceleration over just leaving the clutch engaged and flooring it.

If I'm over ~4K approaching the start I don't do this, I just leave the clutch engaged and floor it.

My friend who knows the guy who has the cousin who dated the sister of the racecar driver previously mentioned also concurs 100% with Dave W.

[andyllc]

How the revs stay up I don't know but they do. You can also hear a definite change in engine pitch from my car to a car that isnt using it although by the end of the season a lot of people had started doing it.
Just try it with the brakes and with the clutch in practice for a couple laps and see how you get on with it.

[Jon Horgas]

[/QUOTE]My friend who knows the guy who has the cousin who dated the sister of the racecar driver previously mentioned also concurs 100% with Dave W.
[/QB][/QUOTE]

This forum is what I thought to be an aid to help others. Someone asked a good question some would not be smart enough to think of on their own. The smug remark to my post will keep my information to myself.

[SStadel]

Jon, That smug remark was a quote from a post way before yours. I used to do the same thing as Dave W, but have been a little easy on the FSCCA drivetrain so I haven't used it on this car.

One "problem" I encountered when using the brake as Andy did, was that I used to quickly stab the clutch on all my upshifts (no longer do with the FSCCA car), and when my brain got in the way at a start and didn't move my foot to the clutch instead of the brake...., well you can imagine what it felt like when I went for second. Luckily the jump I got kept this from being on the "most embarassing" thread!

[Keith Carter]

I don't think Dennis intended his statement to be directed towards anyone, Jon. That's the problem with posting on public forums and instant messaging... Sometimes something very innocent can often be misconstrued and sour posters to the point of not wanting to contribute. We (the moderators of the forums) like to keep a close eye on things like that to ensure that never happens so people never feel that way. The use of smileys kind of helps in that situation, but not always. He was just offering information that his 'friend of a friend' had done in the past . I've learned to give posters the benefit of the doubt cause sometimes even a comma can COMPLETELY change a statement around from being just an ordinary statement or something that appears to attack someone. Thanks for your post Jon, it does indeed help me and the users of this forum and that's why we're all here. Ok, enough of that....


It appears that launching techniques are one of those things that people like to keep in their bag of tricks, but there are also the people who came forward and will tell you anything you want to know (well maybe not anything) for the good of competition. Very interesting responses and I will try them all out to see what works for me.

[Purple Frog]

Andy's technique might work on a fuel injected/ECU car... not sure it would work the same on a "antique" carb car. Need to test it.

Got to love Dave. Tells us all his secrets, then goes out and beats us. [img]smile.gif[/img]

It's sort of like what a very famous engine builder told me one time when he was gladly answering all my questions, "Son, you are not smart enough to ask the questions that I won't answer."

But from this thread we may have learned how Rossella has been blowing Sean's and my sidepods in during starts this year. So... I'm coasting into the green next race at 6200 rpm. I can just imagine the PA speakers at the next race... "There's the green... and it appears car 48 has just snap spun across the start/finish line!" [img]graemlins/skull.gif[/img]

[DaveW]

Back when I ran the "Export A" pro F2000 series up in Canada, we used to have standing starts.

To get the best start possible, we used to run a slightly lower 1st gear than was best for the slowest turn, but even with the engine floored against the rev limiter at 7200 RPM, it would still bog off the line, and you had to dip the clutch a second time to not be a moving chicane.

Very hard on the clutch.

[R John Lye]

Purple Frog wrote:

> Andy's technique might work on a fuel
> injected/ECU car... not sure it would
> work the same on a "antique" carb car.
> Need to test it.

FWIW, this is the technique that my driving
instructor suggested during my very first driving
school at Summit Point. He advocated left foot
braking while keeping the revs up to get a good
launch after the green flag. This was for a FF
1600, which is definitely an "antique" carb car.
It always seemed to me that it would be hard on
the clutch, but I'd like to hear if anyone knows
otherwise.

John

[DaveW]

I must be missing something here!

If the clutch is slipping while your foot is not pressing the clutch pedal, it is shot and won't work at all. If it doesn't slip and you get more revs at the same speed, the rear tires must be spinning somewhat. If neither of those things is happening, the the only benefits you get are having fuel flowing at WOT in steady state plus having the intake manifold pre-cooled by the fuel mixture. This would provide some benefit, but wouldn't change the revs before you launch, unless your car speed is faster than it otherwise would be.

IF the clutch doesn't slip, the only thing this technique would be hard on is the brakes.

[R John Lye]

IF the clutch doesn't slip, the only thing this technique would be hard on is the brakes.

That was what I was thinking, also - that's why
I was wondering if I was the one who was
missing something.

John

[Frank C]

Perhaps there is an explanation. Loading the engine by using the brakes (without slipping the clutch) might be thought of as being the same as having the engine loaded on a dyno. The engine has to be developing more horsepower than it would (at the same RPM) without the extra loading and also would have the throttle butterflies wide open with a higher air flow rate. When the brakes are released, the engine, at least instantaneously, is developing more power than it would without the brakes on, and may provide greater initial acceleration than the case of suddenly flooring the throttle, even without any bogging.
- Frank C

[size="1"][ October 27, 2004, 04:07 PM: Message edited by: Frank C ][/size]

[DaveW]

Frank, I agree completely with what you said. You said basically the same things I said, only you explained it much more clearly.

What was not possible or explained in the original statement was that the RPM was stated to be higher at the same speed without anything slipping.

[Purple Frog]

So... I just ran out to the parking lot and jumped in my trusty 14 year old Honda. (Please note I put a new stock clutch in it this spring.)

I tried both techniques at different speeds and different gears.

My only conclusion is that a 14 year old Honda Civic with 194,000 miles is not the proper test platform.

At 40mph, doing the DaveW method, I got massive clutch slip. It didn't seem to be as quick as just simply jumping on the throttle. Just for grins I tried it at 15mph...neat tire smoke and wonderful FWD torque steer.

There seemed to be a lot of variation depending on the delta between what rpm the car should be in at that speed and the rpm you raised it to before dropping the clutch.

Then I tried Andy's brake/throttle method. I had the sensation it worked a little bit, but only if the speed I held was such that I could hold the rpms in the peak torque range while pulling against the brakes, in the Honda's case about 4200. If I was holding 5000 against the brake, when I released the brake I didn't get any real surge. Same with 3000.

Like i said, see my only conclusion above. [img]smile.gif[/img] [img]tongue.gif[/img]

Now that I'm curious, I definitely have to do some testing with the FC. Or... just go ask Rossella.

It's all about about being in the torque band.

[GR]

I also tried it as I left the office today.

Jumped into the trusty ol' crew cab, extended bed, turbo-diesel F250 and........ Difference... What difference...

Guess something a bit shorter and a bit lighter may work

[Frank C]

In comparing Andy's and Dave's techniques, it seems that Dave's technique may be safer, at least for the lesser skilled among us! Andy mentions his little problem in running up the back of someone, and I would guess that if you have lots of brake on holding back the car, you might not have much brake left to respond to a sudden slowing of the car in front of you.
- Frank C

[carnut169]

we may have learned how Rossella has been blowing Sean's and my sidepods in during starts this year

lol. That is exactly what I thought when this topic first came up.

[fkennette]

Hello all:

I'm new at this (driver's school completed thus far, no races yet, so please excuse me if I'm way off), but -
Considering the non-limited-slip differential in a F2000/F1600 car for Andy's method to work would not one wheel be spinning to provide the higher RPM and the wheel with relatively more brake friction/traction be holding the car back?

Andy, how stable is the car using your method ?

Francis Kennette
Windsor, Ontario
97 Euroswift FF1600

[EYERACE]

though non limited slip, believe it or not, FFs and FCs will leave two black strips on the ground at times when one floors 'em...but the potential is there for a car wanting to have the backend kick a little sideways in the process too [you'll notice that one stripe is a little blacker than the other so one must be careful with rear step out when in a group of cars if playing a "feather the clutch and gas" launch - not as much of a factor in the "one foot on the brake/one foot on the gas" launch [this last idea of a launch is well known to go karters or street light drag racers with automatic transmissions]- this whole thing of step out is more obvious from a standing start than a rolling start so don't worry about it terribly - practice makes perfect.

[Brian]

Back when I rode street bikes, this was called fanning the clutch - basically slipping the clutch to get the motor up on the cam, then modulating the clutch to transfer the maximum power that the rear tire would take from the excess being produced by the engine. Clutch out too fast and the engine either bogged or the front tire came up too far and you had to back off. this is exactly what adjusting the clutch on drag cars does, adjusts the amount of slippage so that the tires aren't over-loaded. Clutches are wear items on drag cars, but major investments for me. Still, I can see where 6800 rpm and judicious slipping of the clutch would get a great start in someone elses car...

Brian

[DaveW]

"Fanning" the clutch sounds like a great idea - except that the sintered metal clutch disk (if that's what you have) would melt and leave you with no clutch engagement at all. It might work on a stock clutch, if it didn't explode.

[Lee Racing 8]

Yea it welds itself together pretty good...so I hear.

The "step out" does'nt seem to be a big problem for me. On the pace lap if you get your tires really good and sticky it should'nt step out too much. On the pace lap I steal a little bit of Fernando Alonso's driving style. Instead of weaving easy I do the weaving motion but when I turn I "jerk" the wheel making a huge push and that gets the fronts good, for the rears I just "nail" the gas when turning (carefully) and the rear really steps out.

[Lee Racing 8]

I was just scolded by my dad for giving advise. Even though I have'nt been in the car very long I have listened to my dad and James Lee talk about this for like 3 years.

[andyllc]

Francis-

The car is always pretty stable when I do it. We could debate it to death and one might work for some and one might work for another.

[Riaanc]

Hi All,

In South Africa (Formula GTi) we use a standing start. My wife's car has a single plate sintered clutch and it can handle about 10 launches then it is gone, clutch slipping so badly that one has to ease the throttle down to prevent slip. In fact, the car is undrivable.

Our power and weights are roughly same as F2000, so is such clutch wear excessive?

My car has a double plate Tilton, that seems to be better. I'd like to upgrade her car but the finances are not there at this time.

Regards
Riaan

[D.T. Benner]

Riaanc. As we don't have standing starts in formula car races here we don't have the clutch wear your wife's car experiences. Pitty as I was very good at them in England! Seems most people here only ues the clutch to get moving and then drive without it. Is your Tilton clutch a dual 7 1/4 inch model or the 5 1/2 inch unit? If you have been around South African Formula car racing for a while you may remember a mate of mine named Paddy Flynn. He was big in FF1600's in the late 1980's and even made it to the Formula Ford festival at Brands Hatch. He's now a very successful businessman in Dallas texas!