"Do not downshift into first when ... moving faster than 15 mph"

[Norm Peterson]

I'm having trouble wrapping my head around how double clutching would make a difference.

The rev-kick you give it in neutral brings everything ahead of the 1-2 synchronizers up to the rpms that 1st needs to see.

Just a guess, but I have a feeling that Ford figures that most people have little or no understanding of rev matching.


Norm

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[Sivi70980]

The rev-kick you give it in neutral brings everything ahead of the 1-2 synchronizers up to the rpms that 1st needs to see.

Just a guess, but I have a feeling that Ford figures that most people have little or no understanding of rev matching.


Norm

But you can rev match without double clutching. Did it all the time in my last car and even sometimes actually matched revs. So double clutching gives you more time? I have yet to drive a vehicle that needed double clutching. So in my experiences, the thought of it is a waste of leg energy.

 

[vanquishvzla]

But you can rev match without double clutching. Did it all the time in my last car and even sometimes actually matched revs. So double clutching gives you more time? I have yet to drive a vehicle that needed double clutching. So in my experiences, the thought of it is a waste of leg energy.

 

[shogun32]

But you can rev match without double clutching.

technically you didn't rev match. you were still using synchros to harmonize shaft speeds.

So double clutching gives you more time?

double-clutching is required on MT without syncros - OTR trucks for instance. I was going to include Main Battle Tanks and half-trucks in that list but the Army went all soft on that front.

You can double-clutch new trans, you're just lessening the work/wear on the synchros.

 

[Sivi70980]

technically you didn't rev match. you were still using synchros to harmonize shaft speeds.
double-clutching is required on MT without syncros - OTR trucks for instance. I was going to include Main Battle Tanks and half-trucks in that list but the Army went all soft on that front.

You can double-clutch new trans, you're just lessening the work/wear on the synchros.

Thank you. I think I might be starting to kind of grasp this now...maybe lol.

Can confirm the Army vehicles being super user friendly now. I work with Strykers every day and those things are super easy to drive. I've seen a few Abrams too and they also drive like a car now. The LHS (pictured below due to many different names) also drives super easy with an auto transmission.

 

[Norm Peterson]

a single blip of the gas while changing down does the same job rather than two stabs of the clutch plus a single blip of the gas.

Not quite. A single blip (clutch pedal down) only revs up the engine, flywheel, and pressure plate. The clutch disc and transmission shafts are still running at rpms consistent with the higher gear that you're going away from. Which still means a little more work for the synchros and a bit more resistance at the shift lever (if you're sensitive to that sort of thing; not everybody is).

When you're downshifting quickly as you might at the track, double-clutch can morph part of the way back toward single-clutch operation, where you'd be taking advantage of less than full clutch release to speed the clutch disc and tranny bits up via friction and clutch slip.


Norm

 

[Norm Peterson]

But you can rev match without double clutching. Did it all the time in my last car and even sometimes actually matched revs. So double clutching gives you more time? I have yet to drive a vehicle that needed double clutching. So in my experiences, the thought of it is a waste of leg energy.

You're rev matching some of the drivetrain elements. Just not all of them.


Norm

 

[Norm Peterson]

double-clutching is required on MT without syncros - OTR trucks for instance.

Not sure I should even bring this up yet . . . but even non-synchronized gearboxes can be shifted without using the clutch pedal at all. OTR drivers (like my son and son-in-law) call this technique "floating gears".

In that case, it's on the driver 100% to get the revs matched as you move the shift lever to gear down.

It's a neat trick to have in your own MT driving toolkit, if, say the clutch linkage/hydraulics took a dump. There is definitely a lot of "feel" involved, and some risk as well, but it is in fact possible.


Norm

 

[Dave2013M3]

I shift into 1st, just blip the throttle to rev match. I have been doing it for years as long as you do it right. I wouldn't do it without revmatching though.

 

[Zooks527]

Not sure I should even bring this up yet . . . but even non-synchronized gearboxes can be shifted without using the clutch pedal at all. OTR drivers (like my son and son-in-law) call this technique "floating gears".

In that case, it's on the driver 100% to get the revs matched as you move the shift lever to gear down.

It's a neat trick to have in your own MT driving toolkit, if, say the clutch linkage/hydraulics took a dump. There is definitely a lot of "feel" involved, and some risk as well, but it is in fact possible.

1978, in the hills west of Worcester, driving my Mach 1 when the clutch coughed up it's skull. Drove that way for +/- 20 miles until I got back to the city, then the same the following morning to get it to the garage. Stop lights once I was back in the city were the worst part of it, as I had to lurch start the car in gear with the starter motor, which I'm sure did it no benefit.

 

[boB]

Not sure I should even bring this up yet . . . but even non-synchronized gearboxes can be shifted without using the clutch pedal at all. OTR drivers (like my son and son-in-law) call this technique "floating gears".

In that case, it's on the driver 100% to get the revs matched as you move the shift lever to gear down.

It's a neat trick to have in your own MT driving toolkit, if, say the clutch linkage/hydraulics took a dump. There is definitely a lot of "feel" involved, and some risk as well, but it is in fact possible.


Norm

F1 drivers in the 70's did this all the time, it appears that NASCAR on road courses still does.

 

[Farkel]

1978, in the hills west of Worcester, driving my Mach 1 when the clutch coughed up it's skull. Drove that way for +/- 20 miles until I got back to the city, then the same the following morning to get it to the garage. Stop lights once I was back in the city were the worst part of it, as I had to lurch start the car in gear with the starter motor, which I'm sure did it no benefit.

Same here, and also around 1978. Clutch cable broke on my '56 Porsche 356 Speedster, and I had to drive it from Pasadena back to my house in the San Fernando Valley. No fun at red lights, but a good learning experience.

For the record - I left L.A. for northern Nevada in 1980. It got too peopley for me back then, and it's only gotten worse in the years since.

 

[raptor17GT]

rev hang is for emissions apparently, I read that somewhere but could be talking rubbish lol

if you let the clutch out and the engine spins up to 2400 using the gearbox to pull it up versus blipping the throttle to pull the revs to 2400 then let the clutch out to match at 2400 then its the same result. Engine at 2400 rpm.
Shifting the gearbox into first with the clutch in whether double or single dip i just don't see how it makes a difference if the road speed doesn't change during the transition. I mean it will change a bit unless you're on a perfectly matched downslope in which case I'd wonder why shifting down in those circumstances. That hairpin i described above is the only time I'd ever considering changing down into first from any gear while still going forward at anything other than a crawl and with the 5.0 i'm sure second will be more than enough to keep driving on a slight uphill. Not done this down change in the Mustang but a previous car did it (needed a good shove mind) just fine for multiple years with no crunch and no snatch with just a single bigish blip at that Applecross hairpin. 3 of them in fact. Good times.

Anyhow, we all agree it's not a likely gearshift we're gonna do (bar hairpin as above) so lets put it down the Ford Drivers manual filling in some pages.

Not quite. A single blip (clutch pedal down) only revs up the engine, flywheel, and pressure plate. The clutch disc and transmission shafts are still running at rpms consistent with the higher gear that you're going away from. Which still means a little more work for the synchros and a bit more resistance at the shift lever (if you're sensitive to that sort of thing; not everybody is).

When you're downshifting quickly as you might at the track, double-clutch can morph part of the way back toward single-clutch operation, where you'd be taking advantage of less than full clutch release to speed the clutch disc and tranny bits up via friction and clutch slip.


Norm

yeah man, i noticed it at the as stated previously at the Applecross and as stated above, needed a good shove with a big blip of the gas to get it into first. JDM 4 pot turbo engine with bullet proof gearbox, bullet proof as long as you didn't crunch it obv. As stated above, very particular circumstances for those 3 corners and i can't think of any other time I've used first not second. Hairpins, 20% incline and a single track road. Unique over here as it turns out.

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