rev match downshifting
 

can someone give me the exact steps on how to rev match downshift... i have always just put it in neutral to slow down

Drive .... slow down a bit with brakes .... clutch in, downshift, quick tap the gas to pop rpms to about 5k, slowly let off clutch .... keep doing it that way until you are more comfortable with the engine. Eventually you will be able to "feel" how much you need to rev.

Let off the clutch to fast and you will buck like all hell, too slow and your rpms will drop and the synchro's start to take over.

so say i am going about 35mph in third gear and i need to shift to 2nd to make a turn, to what speed should i slow down to. like when i am in third around what rpm should i brake to before i push the clutch in and revmatch

In our cars it is best to drive between 3 - 4k rpm, if you need to downshift because you intend on slowing down, around 3-3.5 is when you want to perform the operation i mentioned above. Tap the gas to pop the rpms up around 5k-ish and slowly let off the clutch

note eventually you want to get it so you CAN let off the clutch immediately, you are doing it right when the car doesnt buckle forward or back

i just have one more question what exactly would you do when you roll up to a red light

Just pop it in neutral.

For a large downshift for acceleration, like going from 6th to 3rd, it's easiest to double-clutch (the above post is about single-clutch rev-matching). To do this, clutch in and shift to neutral, then let the clutch out and give it gas to rev up, then clutch in and drop it into the lower gear and let the clutch out. When you do it right it will just drop into gear. It's easier and faster than it sounds, with a bit of practice.

It's not simply matching RPM speed, but more about making sure the angular momentum is changing in the same way.

When you step on the clutch and let off the 'gas' to downshift, the flywheel starts to slow down, but when downshifting, the input shaft will speed up. When the slowing down flywheel meets the speeding up input shaft, the drivetrain is shocked because one is slowing down while the other is speeding up.

So you blip the throttle so that when the input shaft meets the flywheel, they are both speeding up, which makes your downshift smooth.

One other method of downshifting is simply to not let off the 'gas' when you depress the clutch to downshift. This is analogous to blipping the throttle.

If you're curious about rev match points, check out this thread:
https://www.rx8club.com/showthread.p...ight=rev+match

depending on the speed and depending on the light condition.
if you know you gonna stop, just keep it in whatever gear you are in now, use the brakes to slow down, then drop into neutral when the rpm is about to dropped to idle.
if the light is going to change, still keep in the current gear, slow down, then downshift into a gear according to the speed using revmatching (clutch in, blip gas and downshift, clutch out).
if you comming up to a corner and you dont have to stop half way, slow down using the brakes, and use heel and toe to downshift (brake, clutch in, move the heel of braking foot towards the gas pedal to blip gas, clutch out).
its all practice, dont use the engine to slow the car down, use the brakes and work around the gearbox to keep the engine in optimum rpm.
http://www.youtube.com/watch?v=G41qs6rXLUc

Why not use the engine? When coming down a mountain, if you use only the brakes you'll feel fade and may even lose the brakes. The same concept comes for any deceleration in a car. The engine will give drag on the wheels without losing grip (unless you do a 5th to 2nd at 90mph) and lower fuel consumption. When an engine is in gear and clutch is out you are not using fuel but you are creating drag, hence you’re breaking without wearing on the pads as much and using less fuel than being in neutral.

It all depends on where you are and what you need to do. Coming down a steep grade I’d use the engine before any breaking. I even do that on level roads mostly, (95KM before I needed to change my escort’s stock pads and the Shinka is still on originals at 40KM). It’s all about learning your car and when/what rpm to shift at. At less than 20mph I’ll coast (in gear, I hate not having the ability to move if needed). More than 20 I’m engine braking unless I need to slow down faster. I’ve never put a ding in a car (other than a roll over in a jeep CJ in a blizzard) and I’ve never replaced a clutch or tranny in the 4 cars I’ve owned in 25 years (still own 3 of them).

P.S. - I've never really used that double clutch technique (other than in a van or straight truck). Learn the rev match and you can single clutch (heal toe or not as needed) very well for most any gear change. Excluding, of course 6th to say 2nd or 1st at high speeds.

This is like classroom learning. You need to practice by doing it and that's how i learned. Practice makes perfect, it works all the time.

Learned it in a day. Very simple. Focus first on Downshift Rev Matching from a higher speed (50-60 mph). Start in 6th gear coasting. When you want to shift down to 5th,

1. Depress the Clutch while simultaneously;
2. Shifting from 6th to 5th while simultaneously
3. Blipping the Throttle (Give it a good amount of gas at least 3-4k RPMS)
4. Let off the Clutch slowly so the car doesn't jerk. (It will jerk most of the time on your first attempts learning)

It's all one motion. Learning to do it at higher gears leaves less room for mistakes. When you're comfortable with downshift rev matching, you can move onto heel-toe, which is a bit more advanced.

For day to day driving, you don't need to downshift rev match unless you want to enjoy the driving experience. Some examples of when i do downshift include passing up other cars and i need the speed and on turns. That's essentially everything. For red lights, just pop it in neutral and then brake when you get there.

Good luck!

not sure about the "true driver" part. Thats a nice way to fry ur clutch.

Good link... I'm still in the learning process but I'm getting better;)

Im not saying not to use engine braking. Im saying not to use engine braking as primary braking force. I have seen some people overly down shift which wears out clutch, transmission, and the engine.

Brakes are cheaper than transmissions/clutches in my opinion. I use rev match when i am passing or any time i need quick acceleration. It really is just getting a feel for the car. Help me if im wrong, but usually what i do when i rev match is just that, i guess iv learned what gears do what speeds at aprox what RPM. So if im driving in 4th or 5th and i want to drop to 3rd and i am doing 45, i know that i have to blip my gas to match aprox 4,500 to 5,000 RPM. I would suggest that from now on pay attention to you speed and RPM in what gear your in. Then it will all come natural.

This may or may not help you, but I have adjusted the pedals slightly so that the gas and brake are more aligned. I also have added in stainless steel lines to firm up the brake pedal. This allows for the brakes to react with less pedal movement. I don't heel to toe, just not comfortable enough to do it with size 12 feet in the 8, I actually drive both brake and accelerator pedal with one foot, just tapping the throttle as needed with one half of the foot while working the brake with the other. Thats only because I have a blind intersection I have to cross where a lot of people like to run the red light, its my way out of a bad situation. I cross 3 blind intersections coming over the tops of small hills and need to be in 2nd gear, its a 45mph intersection.

Next scenario:how to change from 4-3
A
1-press the clutch ,
2-select third gear
3 then rev the engine
4-release the clutch

B
1-press the clutch
2-rev the engine
3-select third gear
4-release the clutch

what is the correct way ?

I'm clumbsy as hell so I can't heel and toe, but that's only kinda necessary racing on track, but downshifting is easier and faster than shifting up gears carefully to not scratch synchros.

Say I'm cruising along in 4th at about 3-4k rpms, and I'm about to pass the car up front so I'm not braking any anyway.

Just clutch in, shift to neutral and let clutch out, blip the gas for a second (don't worry about the rpm's and don't floorboard), then clutch in, shift to 3rd, clutch out, and you should be in power band maybe 5-6k rpm.

After you master the downshift when not needing brakes, then, you can be on brakes into a corner, jump off brakes, and do the throttle blip downshift as above.

Never downshift to slow down unless you're in racing or going fast mode; that'll just ruin your trans and clutch faster, and the brakes are cheap, easy to fix, and very effective on this car.

I can watch traffic and lights and get 100k miles on most cars brakes.

I even tracked my 07 6sps auto (yeah, I don't like throw out bearing noise) 11 times (27k miles), and I don't need pads, yet.

Neither.

1. Press the clutch
2. Neutral
3. Release the clutch
4. Rev the engine
5. Press the clutch
6. 3rd gear
7. Release the clutch while revving to match

Just rev matching while you engage the clutch at the lower gear saves wear on the clutch. Double clutching saves wear on the synchros. It's best to do both.

Ken

Are you pretty much heel-toeing when you're double clutching? Basically the same thing, just with re-disengaging and engaging the clutch, and not going but to N, and then into gear, instead of all in one motion?

they both wrong.
clutch in
shift and rev AT THE SAME TIME
clutch out

If you're braking, then you're heel and toeing. Unless you're that F1 driver from the '60s (forget his name) who had wooden leg and used a hand throttle on his gearshift for downshifts.

When you get adept at it, the steps become somewhat blurred. The clutch does not have to come all the way up when in neutral - just enough to spin the gears up to speed. The last step, to have the revs match on the final clutch engagement, is very important. Otherwise you'll have a jerk either forward or backward. Not good if you're racing, and embarrassing on the street if you have a passenger.

There is a really good quantitative description of double clutching in Piero Taruffi's book "The Technique of Motor Racing."

Ken

why is it better to drive in that rpm range? I like how it feel anywhere above 3000 rpms, but does that affect fuel optimization in every day driving?