Hello!

Sorry if this been asked 1000 times already,
I did try to search but didn't find what I was looking for...

My question is about the shifting light.

I heard it goes red at different rev's.

Why does it do that?

Thanx in advance

The shift light comes on when it is optimum to shift upto the next gear, rather than at a fixed rev count.

I remember someone saying you should actually shift BEFORE the light comes on. Because when the light comes on, it means you were on the perfect shift point, BUT you don't react fast enough when you see the light. My experience tells me you should shift almost always at the same point, the light goes on around the same RPM every time. e.g. When I drive the FZR, I know when the light should go on, so I shift just before that point. And as far as I know, it is faster...

Actually, you should shift a teeny bit AFTER the light comes on, as the revs and speed drop during the change, meaning you'll end up at the optimum time before. The delay is roughly equal (on the slower shifting cars) to an average reaction time. See the light, hit the button = fastest.

I just wish we didn't have this perfect shift light, and instead had more information, such as torque curves and wheel torque curves, in the pits, and the option of configuring shift lights manually. But I guess the auto perfect shift light does save some hassle, and means that for a given set of ratios LFS is a level playing field.

The shift light doesn't nesecarily tell you the perfect time to shift, it tell's you when there is more toruque available in the next gear AFAIK

I always thought they should be rev-limit lights, rather than shift lights, and should be adjustable, the noise of the engine should be enough to tell you when to shift, with the light coming on if you venture into the engines "red-line".

Dan,

Problem is, as far as I know, in a real car you can feel the acceleration, so you know when the car stops pulling... But in the sim you have the rely on the sound completely, and when you're in 5th gear, it's hard to hear sometimes when the right time is there to change to 6th.

thank you, but how can the best place to shift be at different revs?

Quote from Rolle :

thank you, but how can the best place to shift be at different revs?

gearing. the "spacing" inbetween gears isn't uniform, so the drop in rpms in the 1-2 shift will most likely not be the same drop in rpms as in the 4-5 shift. its all about ending up at a good point in the powerband after the shift.

and given that power starts to drop off after a certain rpm on most cars, combined with the gearing issue i explained above, you'll have to shift at a different point in each gear to "land" at the same rpm after the shift.

Close. In fact it's probably right if you squint whilst reading it.

When you apply gearing to the engine torque output (including the gearing of the wheel itself) you end up with tractive effort curves (or wheel torque curves if you ignore the wheel diameter). These curves are road speed vs wheel force.

Most of the time they cross over. i.e. at some magic road speed the line for 1st crosses the line for 2nd and so on for each gear. This is the magic 'ideal shift point'. From that road speed you know the engine rpm in the first gear, which is your shift rpm for the gear. as each gear ratio is spaced differently then the crossover will happen at different engine rpms.

Some engines have gearing/torque curves which DON'T cross, and it's there engines that you have to rev to the maximum possible RPM and shift there (usually the redline unless you're a brave driver who has enough money for engine rebuilds ).

Some cars have gearing that will give a higher top speed in the penultimate gear, using top as an overdrive to keep revs down at cruising speeds. Again, the tractive effort curve can help you visualise this and set it up. Finally, a drag curve (combination of aero and rolling) can be overlayed on the tractive effort curve, and where this crosses top (or whatever gear you are interested in) is the top speed in that gear. If you run out of revs before it crosses a gear then your car is 'rev limited' in top speed, if it manages to cross then the car is 'drag limited'.

There you go - everything you need to know about gearing and performance estimation in one easy to read (*) post.

*May not be easy to read