Useful data yes like speed at exit. Used for determining brake points is not such a good idea.
Huckleberry wrote: My track shorts are Nike but Speedo does make an excellent product it's just that in the US they are not quite as fashionably acceptable as in the EU. What you want is called a predictive lap timer. The AIM Solo is a good example.
The speedo in the Tunachuckers LTD is hilarious, because it's old and crusty and obviously wasn't meant to be all that useful at higher speeds, so at 110 or whatever, it's bouncing wildly between 95 and 120. It looks really excited. So I guess, only for comic relief.
The speedometer is only useful for bragging rights (which admittedly has some value). It's not helpful for improving or really even evaluating our technique.
Your braking point should be a specific spot on the track. Start with a conservative one and then work on being consistent. Once you're consistent then you can work on different lines and moving the braking point. If you find that you're letting off the pedal after the initial application then you can move your point a little closer. If you can't hold your line then you need to move it back. If you end up having a conversation with a corner worker shortly after corner entry they you need to move it back quite a bit.
The tach is useful as you learn a track for figuring out what gear you should be in and where you should be shifting but once you figure that out and get consistent you'll find that you shift in the same place every time.
I don't use the speedo, but in Spec Miata we do use the tach pretty frequently. Its the best way to under stand your velocity mid-corner, at the apex and at exit. Sure, you look at Traqmate or AIM data after each session, but you also need this real-time information to adjust braking, turn in points etc. to track condition and the condition of your tires. Does one braking or turn in point get you more rpm at track out? Then that's the faster way to do it. This isn't something you necesarilly do while actively racing someone wheel to wheel, but absolutely in practice and qualifying as you're trying out setup etc., as well as during segments of races when you've got a gap ahead or behind and you are trying to optimize lap times. If you're following someone closely, and they are pulling a gap on you, its also useful to see whether they make their time at entry, apex speed or exit, so you might also check in that circumstance. Ross Bentley is 100% right that speed sensing is something every track driver needs to work on, but there is probably a very small % of people who can accurately and consistently judge speed down to 1 or 1/2 mph... which can translate to 5mph at the end of the back straight at Sebring. Everyone else uses the tach.
All that said, the tach/speedo isn't something to worry about for the first several track days, where you focus is better placed elsewhere. The consensus is that its more important to learn to control the car, safely, first, then optimize speed.
Edited to Add: 100% agree that the speedo or tach is the wrong thing to use to figure out if you're at a braking or turn in point.
I always say, you can't learn to drive track cars reading the internet. But it is fair game to pass on tips that I got from in-car instructors when I was learning. Might not help any particular student, though.
Early on every instructor told me to visualize my way through the corners. It worked well, but I wasn't growing as confident with my braking. Then an instructor told me to visualize the brake zones too, and it all clicked.
I don't have a functioning speedo in my track car, but I do have a sequential shift light that I can see without glancing down.
my one and only time on a real track I checked the speedo about 3 times to see where we were top speed on thefront straight. Since 3rd tops at 90, and I was in 4th I was curious where we were. Sadly, under 110. In all fairness I was short shifting 3rd a little around 6500 instead of 7400.
JBasham wrote: I always say, you can't learn to drive track cars reading the internet. But it is fair game to pass on tips that I got from in-car instructors when I was learning. Might not help any particular student, though. Early on every instructor told me to visualize my way through the corners. It worked well, but I wasn't growing as confident with my braking. Then an instructor told me to visualize the brake zones too, and it all clicked.
THIS!!!!!!
I almost am not "thinking" about the corner I am coming to because I have already thought about it and I am then thinking about the next corner. So with respect to the corner I am coming to I have already thought about it and driven it in my mind (or visualized it) so I have already done it in my mind. This free's you up to deal with traffic, farm animals and whatever else can appear on track that you will have to make adjustments for.
What I am really doing is not having to think about the mechanics of actually driving the corner that is done with the aid of previously visualizing the corner (or driving it in your mind). That way you can concentrate on what is happening in the corner and how you can do it better instead of having all your focus on just getting through the corner.
Another way of thinking about it is you only have so much brain power if you are using all of it to just get through the corner you don't have anything left to use to improve or make adjustments in the corner. You are driving in reactionary mode as I call it. By visualizing it and driving it in your head ahead of time you will do things more on instinct and mucel memory. This free's up your "consciousness" to deal with refining you driving through a corner and now you are what I call proactive driving. You are thinking forward of the car instead of reacting to the car.
Not sure if this makes any sense to anyone but it is how I describe on track driving.
I haven't been on a track in ten years but neither of my old track cars even had speedometers. I could see where you could use it to see an in and out speed for certain sections of track but I think you could easily get hung up on that.
First I say this, and it's not aimed at intermediate and novice drivers, if a driver can't notice the tach, the colored blob in your mirrors (car behind) and drive three corners ahead I'd be worried about them as a racer. This is especially true in peddle cars like my Datsun, a Spec Miata or IT car.
I use the Tach everywhere as JG said it's the Redneck Motec; I can tell you what the revs are mid corner, exit and at my brake point. A practical example is this, look across the room while at the same time hold your index finger near your chest and move it back and forth like a tach needle you can see both things at once if you don't target fix on either one. It does take some time to train yourself to open up your vision. Again a good driver with a few seasons of experience should be able to do this without issue.
With that said, Dean is correct, as a new driver focus on visualization I.E. being well ahead of the car. The Keith Code's motorcycle book Twist of The Wrist is probably the best book ever written on visualization.
An example of using the tach or speedo is on my home track in turn two I have a goal RPM at turn in, the first 1/3, the middle 1/3 where I feather the throttle to rotate the car into the second apex, approaching that apex, at the apex, leaving the apex half way to the exit curb and the point I fully unwind the wheel at the exit curb. This approach nets 150 extra RPM which equates near 2 mph at the exit and 4 mph at the end of the the long straight after turn two.
Now in a car that actually has enough power to spin the tires in a 75 mph corner, like our old D-Sports Racer, I was not nearly as obsessive as you only needed to know the RPMs mid corner and exits.
Also getting a basic data acquisition system is a very good idea if you're a racer. For track days I'd likely save the money for something else as the Redneck Motec is good enough.
As always my .02
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