Maximum downshift point - 2nd to 1st

[Quicksilver]

Originally posted by geof33
Speeder...

That is somewhat incorrect. Downshifting is nec coming into turns depending on the speed of the turn. F1 guys don't just brake (and slam three of four gears lower) they downshift all the way into the turn. It's a combination of the two. And of course the downshifting is only done coming in on a straight line into the corner in the break zones, not in the turn. If one downshifts in a turn... well say goodbye.
...

There are a few things wrong with this statement on a number of levels as amk pointed out.
At rest your car has a 40/60 weight distribution. When braking you want to get the weight transferred quickly and smoothly to the front of the car so the weight distribution is stable. I would guess the split is about 60/40 depending on the grip of the tires/road cmbination and the skill of the driver. If it is exactly 60/40 then you want exactly 60% of the braking force on the front end and 40% on the rear. This will give maximum braking force. Any change to the split of force will reduce the total braking force.
Engine braking under these conditions will cause the rears to slip and tend to spin the car. Engine braking went away in every form of racing when the cars gained adequate brakes. Heel-toe braking is specifically used to keep the engine braking effect from upsetting the car (and make it easy on the syncros).
The F1 guys don’t engine brake - ever. If you watch them they tend to shift as fast as they can because there is so much braking force that they never spend much time on the brakes. On really fast straights you can see them start braking and at the end of the braking zone they do the flip,flip,flip... shifting bit.
Read Niki Lauda’s book from the 70’s; No engine braking.
Gas and brakes at the same time? A few reasons; -A tap to get the front of the car to bite without lifting on a full throttle corner. -If you want to grab the rears to loosen the car you can use gas and brake. Common in rally and very common (necessary!) in front wheel drive ice racing cars. -A really sharp driver can add some slight rear drag on a car that doesn’t have adjustable brake bias when a track has gone very slippery such as driving rain with a dry setup (tricky).

My advice on all of this is don’t do it. If you ever get to the point where you need this stuff then you will already have learned enough to ignore this thread and decide on your own.

Wayne

[geof33]

I sort of mis-stated what I was saying. I know that the downshift is not for braking, but it is necessary (as AMK stated) to be in the proper gear for the turn exit. (thanks AMK for refreshing my memory on TRAIL braking.) And I am aware of needing a sequential trans for that... I was using it as an illustration.

The post made it sound as if one were never to downshift at all.

And I don't ever downshift into first... l

Since I wrote the post very late... maybe I'll just delete it...

[speeder]

Well, you can delete the post if you want, but it lives in infamy thanks to the "quote" button.

Once again, only terrible drivers use the engine and trans in place of brakes. (To slow down the car). The downshifting that you are hearing in a Formula 1 race is just rapid downshifting trying to keep pace w/ the incredible deceleration that the brakes accomplish on those cars. No way are they using the engine compression to brake the car, straight line or not. So what was your point?

I downshift my car on the track while braking hard before a corner at the end of a straight, my car will shift into any gear that I select, but obviously if a downshift causes over-revving it will blow my motor. Just use common sense, (and your tachometer), and these questions are irrelevent.

And like I said previously, there is no good reason to downshift into 1st above ~15 mph, but a good transmission will go into 1st easily much faster than that. Always match your engine/trans/wheel speeds when downshifting.

[svandamme]

first gear is only designed to get you rolling from dead stop
so unless approaching a red light and you know you will have to come to zero mph : don't downshift.

[svandamme]

Once again, only terrible drivers use the engine and trans in place of brakes. (To slow down the car).

yep , that's why every drivers instructor in Europe teach us stickshifters to use the engine while braking to make sure everybody in Europe would be terrible or worse than terrible at driving...

[geof33]

Originally posted by speeder
Once again, only terrible drivers use the engine and trans in place of brakes. (To slow down the car). The downshifting that you are hearing in a Formula 1 race is just rapid downshifting trying to keep pace w/ the incredible deceleration that the brakes accomplish on those cars. No way are they using the engine compression to brake the car, straight line or not. So what was your point?

Well to banter further... Maybe the ideal scenario is to not engine brake... Fine, I don't really do it, but it's fun to argue!!!

Anyway with the F1 cars... having seen them up close and in person both in practice and in race conditions, they do use that downshift for some slowing. Given the sequential transmissins... every time they pop a gear the car resoponds. Yes, it is true they are keeping up with brake forces, but the cars do spike the RPMs a bit in the downshift which indicates a slowing action taking place by the engine. Is it supposed to be that way... maybe not. But it does happen. When the cars come down the straight at indy they dump five gears into turn one. I must say it is wild seeing a car drop from 180 or so to 30 in about 200 ft... (if even that far!!)

Anyway, no big deal and I agree with everything said about 1st gear. From a shifting perspective, if your trans is good and you push in the clutch you should be able to "put the car into first" at just about any speed. Pop the clutch and watch it BLOW!

[nostatic]

I put my car into first at a dead stop, or maybe if I'm rolling at 5mph...never higher. Never found a reason to. I'm not drag racing anybody, and it'll calmly pull in 2nd at low speed.

Wasn't the dogleg tranny made that way because 1st was only used to get out of the pits and never anywhere else?

[amk]

Originally posted by geof33
Well to banter further... Maybe the ideal scenario is to not engine brake... Fine, I don't really do it, but it's fun to argue!!!

Absolutly, love a bit of banter

Is the spike in RPM you're hearing the throttle being blipped on the down change? In theory even with a sequential box and left foot braking you're still meant to blip the throttle on down change to avoid unbalancing the car (not that I've ever driven a sequential box on the track). Some sequential boxes blip the throttle for you, on others there's a gap between the gears being engaged, if you time it right you can blip the throttle between the change (apparently this is easier than it sounds).

[geof33]

AMK...

Perhaps... since I'm not going to be sitting this big ass into an real F1 anytime soon... I couldn't tell you for sure.
I just know the sound of deceleration along with backfire... which would suggest engine slowing to me.