fg23knight

Hi Guys, can any one give me some proper downshifting techniques? I have already done a search but still had bunch of question in mind still. I really don't want to screw up my new car hopefully someone can enlighten me

Althought I have never done any of the below yet but this is what I think:

1) double clutching is done when you want to downshift by 2 gears, say you are going form 4th to 2nd, you clutch in to neutral and rev it up high so engine speed will match up when you clutch in again and shift to 2nd. My question here is that, by reving high at neutral, what do u gain when u clutch to 2nd? do you end up at a lower rev at 2nd or higher? what happen if you didn't, is this how u can over rev ur engine?

2) in Toe heal clutching, is it the same concept as, clutch in, break, rev up, clutch out, and accel?? except you are doing it slower. if so, what's the difference between this and double clutching?

3) when wanting to speed up during a race or something. Say you are in 3rd gear going at about 5000 rpm. How do you get the best boost? when should you downshift?

4) Lastly? I am having trouble understanding downshifting. When slowing down, I have been told to downshift so as to use my engine to help breaking, thus preventing wear on the brake pads. Is this a good practice? would this not wear out your clutch instead?
I notice when i try downshifting, my car would suddenly rev up and suddenly slow down.
What would be the proper way to downshift? should I down shift at the right speed? cause inorder for me to do a smooth downshift, I would actually have to apply a little acceleration. That's contradicting the fact that I am trying to slow down. When downshifting to slow down, are we suppose to use the accelerator at all? or just down shift at the right speed and keep using the break to slow down until almost a full stop, then clutch in?



Thanks for your input

boiler

The idea is to match the engine's rev's to the lower gear's rpm requirements. In other words, if the difference between the gears is 1500 rpm, you would need to speed the engine up by 1500 rpm to get a smooth shift when you let the clutch out in the lower gear. Doing this will minimize the wear on the transmission/drivetrain parts. I prefer to declutch, then rev the engine, then downshift. Doing this in this order does a similiar thing as double clutching in that it matches the speed of the transmission's parts and maximizes the parts life (synchro's). I can perform this downshift very quickly and smoothly. You only notice that the engine speed has increased. Doing this, I am able to shift into first at 30mph with no problem. I usually don't do this, but I can if I want to. I needed to do this at the autocross driver's school on one section, to make a 180 degree turn.

I practice this everytime that I need to slow down or downshift. In this car, that's a lot. I didn't tell you that I love this six speed and love to shift it. After a bit of practice, it's second nature and I don't even look at the tach or speedo. There's no need to, listen to the engine. All you need to do is to blip the gas pedal before downshifting.

You might want to practice rev matching a bit before moving on to more exotic things like double clutching and heel/toe downshifting.

Good luck. When you make your first smooth downshift, it will all have been worth it.
Bob

Destiny2002

Brake pads are cheaper than clutch discs.

Unless you are practicing to race or racing, your car will give you better service life by not downshifting for engine braking.

A cool way to understand how to heel-toe downshift is to catch the Extreme Machines episode on the CART series/McLaren F1. They show the actual feet motion (with in-car cameras) required for downshifting on the racetrack.

fg23knight

First of all, Thanks Bob for the clear explaination. I just have one more question in mind. What is the best way to practice rev matching? Thanks

Destiny2002

When you let the clutch out on a downshift, the car will do one of three things:

(1) The car will slow suddenly because you didn't have the engine speed high enough to match,

(2) The engine will suddenly slow because you had the engine speed too high to match,

(3) The downshift will be smooth with not much of (1) or (2). You've got it down

Practice makes perfect. This is what makes driving stick shift so rewarding!

StwoK

boiler hit questions 1 & 2. I'll take a shot at 3 & 4.

If you are in a race you want to win ... right ? So your in 3rd at 5000 rpm, you want to get the engine into its VTEC range, 6000 to 9000 rpms. That is where our engine makes the most power. A quick down shift to 2nd will jump your rpms about 600 or so, your now just 400 rpms away from VTEC and power. Keep it in VTEC.

Down shifting to brake puts additional wear on the synchros. It is always cheaper to replace brake pads.
There are time when the additional breaking effect from a down shift will help, but that is only on occassion.

Just remeber there is a rev limiter that keeps you from accelerating beyond 9000 rpms. But when you down shift the rev limiter does not keep you from going beyond 9000 rpms. Several engines have been blown by down shifting and Honda's warranty does not cover that.

xviper

So as to not repeat myself, see this thread:
https://www.s2ki.com/forums/showthread.php?...2&highlight=rev

FormerH22a4

There seems to be two schools of thought on downshifting vs braking. One is better for avoiding wear and the other is just plain cool if done properly. I'd say at least know how to do both

fg23knight

okay, that was the 2nd time I have read that other thread. and something new just popped up.

<just went for an 1hour drive practicing downshifting outside>

StwoK mention that downshifting put additional wear on the syncro, but from what I know, the syncro is that thing that allows the "dogteeth" to engage the gears properly. So assuming I rev it up properly to the right speed for the next lower gear, would that still put wear on my syncro? that's Destiny2002's item (3)

Also I am wondering how many pplz actually practice this additional engine breaking techniques, I figure either a) I practice doing it all the time, or b) i don't do it at all. Since If I don't practice it all the time, when I really need the extra breaking, it'll probably not just kick in.

fg23knight

and one more note to xviper:

I was reading your other thread, you mention the following:

you would have more control and be more "under" control if you went through each gear as you slowed down, engaging the clutch (carefully so you don't lurch) for each gear, etc. Under "normal" driving conditions, you should be able to anticipate your stop so that you would have the time to do this. If you are not rev matching, then you should ease up on the brake slightly at the moment of clutch engagement so you lessen the "lurch".

Can you explain what lurch is in some more detail? so if I decide that I'll go through the gears as I slow down (with the clutch depressed) I'd be better off If I were to lighten the break, as I downshift? So is this suppose to help lessen the loan on the syncro again?

and one more one more
It's my 1st standard car, I stalled a lot during the first few days, I was wondering if stalling is bad for the engine? I can understand that stalling is probably bad for the clutch, but would it do harm to the engine?

Once again, thanks everyone : )