Anyone Master Downshift Rev-Matching

[san rensho]

Originally Posted by shadrach74

If the goal is smooth and quick shifts, than yes that extra step does take time and smoothness away from the process. The whole point of a heel and toe when driving is to match the engine speed to transmission speed for the gear I'm moving into. The clutch must be released at the precise moment the engine reaches that speed. What you are talking about is double clutching. It is necessary in older non-syncro crash boxes to blip the throttle in neutral. Today in a modern car, it's not needed, nor will it trash a gear box, it may be easier on the syncros, but it's not necessary...nor is it a recipe for quick/smooth shifts...

I'm not recommending double clutching, my method uses the clutch just once, just blip as you are going through neutral. Its no slower than putting it in the lower gear first, then blipping, it actually faster, you are doing two things at once, blipping the throttle and moving the gear shift.

And blipping while going through neutral does save a modern synchro mesh tranny. Even with the clutch depressed, there is some drag in the clutch and blipping the throttle while in neutral will spin up the input shaft some, which means the synchro has to do less work.

[pothole]

Originally Posted by san rensho

I'm not recommending double clutching, my method uses the clutch just once, just blip as you are going through neutral. Its no slower than putting it in the lower gear first, then blipping, it actually faster, you are doing two things at once, blipping the throttle and moving the gear shift.

And blipping while going through neutral does save a modern synchro mesh tranny. Even with the clutch depressed, there is some drag in the clutch and blipping the throttle while in neutral will spin up the input shaft some, which means the synchro has to do less work.

The problem with your position is that gearbox failures are pretty rare on modern cars. So it's simply not necessary to shift using your method.

I'd also dispute whether it's faster using your method or even if it's practical as you describe to blip literally within that tiny window as the box goes through neutral on a fast downshift. I'd have to see some video or preferable a first hand demo to really gauge what I thought.

[shadrach74]

Originally Posted by san rensho

I'm not recommending double clutching, my method uses the clutch just once, just blip as you are going through neutral. Its no slower than putting it in the lower gear first, then blipping, it actually faster, you are doing two things at once, blipping the throttle and moving the gear shift.

And blipping while going through neutral does save a modern synchro mesh tranny. Even with the clutch depressed, there is some drag in the clutch and blipping the throttle while in neutral will spin up the input shaft some, which means the synchro has to do less work.

Got it, I misunderstood what you were suggesting. It's likely that I am on the gas as the shifter goes into neutral... It's one fluid motion from one sift gate to the next. I get absolutely no resistance going into the lower gear when it's done correctly. I think that we're both recommending same method, it's just that you were more detailed in your explanation.

I thought that you were suggesting that one needed to release the clutch during the neutral blip and then re-engage it for the shift...

[sb01box]

at what rpm are you downshifting?
for me, in normal daily drive, it's when the RPM is about 3000 so that the engine rev is kept in the 3500+ region. When I'm having fun, the downshift rpm is about 1000 higher.. which keeps the engine rpm above 4000 and ready to provide torque once my foot is off the brake and back on the throttle.
since I'm on the brake for most of my downshifts, downshift does not have to be fast, but make sure I don't $$$$ shift.

[shadrach74]

Originally Posted by sb01box

at what rpm are you downshifting?
for me, in normal daily drive, it's when the RPM is about 3000 so that the engine rev is kept in the 3500+ region. When I'm having fun, the downshift rpm is about 1000 higher.. which keeps the engine rpm above 4000 and ready to provide torque once my foot is off the brake and back on the throttle.
since I'm on the brake for most of my downshifts, downshift does not have to be fast, but make sure I don't $$$$ shift.

It depend on what gear I'm changing into and from where. The ratios on my 02 S are not evenly spaced. There is no "one size fits all" rpm difference with the 6 speed box. The five speed may be different.

[Frodo]

Originally Posted by san rensho

I'm not recommending double clutching, my method uses the clutch just once, just blip as you are going through neutral. Its no slower than putting it in the lower gear first, then blipping, it actually faster, you are doing two things at once, blipping the throttle and moving the gear shift.

And blipping while going through neutral does save a modern synchro mesh tranny. Even with the clutch depressed, there is some drag in the clutch and blipping the throttle while in neutral will spin up the input shaft some, which means the synchro has to do less work.

I'm pretty much positive I'm over-thinking this...but I have to ask: When you're doing this your way (blipping as you are going through neutral---presumably you're talking about the instant before down-shifting), do you again blip as you release the clutch? Or is it just one longish blip that both meshes the synchros (as you down-shift) and makes for a smooth transition as the clutch is released in the lower gear?

[san rensho]

Originally Posted by Frodo

I'm pretty much positive I'm over-thinking this...but I have to ask: When you're doing this your way (blipping as you are going through neutral---presumably you're talking about the instant before down-shifting), do you again blip as you release the clutch? Or is it just one longish blip that both meshes the synchros (as you down-shift) and makes for a smooth transition as the clutch is released in the lower gear?

Its just one blip. Essentially, I'm doing two things at once, blipping and shifting. As soon as I put the clutch in I blip, at the same time, I'm also moving the gearshift to downshift.

[Frodo]

Gotcha. Thanks.

[shadrach74]

Frodo,

You will get a feel for it. On occasion, I will blip the throttle a second time if the situation warrants it.

[jaykay]

Originally Posted by san rensho

Its just one blip. Essentially, I'm doing two things at once, blipping and shifting. As soon as I put the clutch in I blip, at the same time, I'm also moving the gearshift to downshift.

Yep if you can blip to cover the synchro and clutch engagement everytime you have got it down.....when I am on the track under pressure in heavy work zones and am worried about balky shifts I blip coming through neutral to make sure the lever moves into gear and another for the clutch...this is usually for 2nd. The revs stay up nicely but I am likely slower for it

I will start trying a longer blip to cover both a bit more in those cases

[grubinski]

I find it helpful to make sure the throttle is at least cracked open a bit (not fully closed, even if you are still braking) as you let the clutch out. That way, if you have missed slightly low on the revs when you blipped, you don't upset the car with engine braking due to a closed throttle in the lower gear.