Double clutching the downshift.

Zeldman said:
Yeah, I have had to do that a few times as well...:lol:
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I've never had to do it, but I have seen it done. Clutch cable snapped in the car we were driving. Learned something new that day.
 
genna said:
I've never had to do it, but I have seen it done. Clutch cable snapped in the car we were driving. Learned something new that day.
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Once upon a time I had an old MkI Jetta as a winter beater. The button on the pressure plate that the clutch rod pushes against to disengage the pressure plate from the clutch pushed thru, and I had to drive the car the rest of the week until the weekend when I had time drop the transmission and replace the pressure plate. Rev matched shifts, when I had to stop for a light or stop sign, stop the car in neutral, turn off the engine, put it in first. When the light turned green, start the engine in gear and chug away. Fun times. I drove that old piece o'junk in the winters to keep the salt from eating up my nice Nissan 300ZX Turbo summer car.
 
genna said:
I've never had to do it, but I have seen it done. Clutch cable snapped in the car we were driving. Learned something new that day.
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Had a '68 MG Midget. The slave cylinder for the hydraulic clutch was inaccessible without pulling the motor and transmission. The second time it sprung a leak I quit using the clutch. :p
 
Bill Jennings said:
Once upon a time I had an old MkI Jetta as a winter beater. The button on the pressure plate that the clutch rod pushes against to disengage the pressure plate from the clutch pushed thru, and I had to drive the car the rest of the week until the weekend when I had time drop the transmission and replace the pressure plate. Rev matched shifts, when I had to stop for a light or stop sign, stop the car in neutral, turn off the engine, put it in first. When the light turned green, start the engine in gear and chug away. Fun times. I drove that old piece o'junk in the winters to keep the salt from eating up my nice Nissan 300ZX Turbo summer car.
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Lol, I had an '88 300ZX Turbo for my first car. Unfortunately it was the auto-tranny variant though, so not quite as fun. Not much salt down South, so it was driven year-round. The '95 300ZX TT we had later was much sportier with the 5-spd and 400HP vs the 205HP '88 model. Amazing that the displacement remained at 3.0L for both cars, but they increased the HP 50% in the 1990-model, and a quick tune/boost increase brought it to a full 100% increase in HP over the '88.
 
SoonerAviator said:
Don't even need a starter if you parked on a hill or can get it pushed fast enough!
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I had a '47 Chevy pickup that still had the 6 volt system. (and foot pedal starter) I would park at the far end of the parking lot because it had a slight slope for drainage. If the battery did not have enough juice to start the engine, I would put it in second gear, let it roll about 10 feet, let out the clutch and away we go.!!
 
asicer said:
I take it this before the advent of the clutch interlock safety switch.
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kinda. All you need is the pedal, it doesn’t have to be connected to anything, just the switch. Or I suppose hot wire switch.
 
Zeldman said:
I had a '47 Chevy pickup that still had the 6 volt system. (and foot pedal starter) I would park at the far end of the parking lot because it had a slight slope for drainage. If the battery did not have enough juice to start the engine, I would put it in second gear, let it roll about 10 feet, let out the clutch and away we go.!!
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I can still do that with my 2016 pickup. Really doesn't need much to fire up in 2nd gear.
 
I had a clutch cable break in Winslow, Arizona and I replaced it in California. Started in first gear at the lights and rev matched all the way.
 
In My 1985 Honda Civic 5 speed the clutch plate had 4 springs to smooth the engagement. One day one of them popped out and with nowhere else to go lodged between the pressure plate and the clutch. With that spring jammed in there it wouldn’t disengage. [repeat all that stuff about starting the engine in first gear, etc, etc]

when the battery got weak, I drove it for another 2-3 months. 1) it was light enough to push start by myself, 2) it would hold enough charge to start after an 8 hour work day, 3) my driveway at home had a nice slope to it so the fact that it wouldn’t hold enough charge overnight to start wasn’t a hardship.

Ah, old cars when we were poor. What great stories to look _back_ on.
 
jsstevens said:
when the battery got weak, I drove it for another 2-3 months.
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Reminds me of my brother's 66 Ford Galaxie when the voltage regulator went bad. He realized he could drive it a few days if he didn't use anything electrical i.e. headlights or heater fan. He then rigged a string out to the points on the regulator so that he could pull the string and close the points to charge the battery.

He would pull it tight and wind it around the heater/defroster pull knob to charge the battery and loosen it when the battery was charged. I wondered how he knew when the battery was fully charged. He said, "when the headlights get really bright!" :rofl:
 
I was at Ft Irwin/NTC driving one of battalion ops' jeeps (yes, everybody else had Humvees) when the clutch cable snapped. It took a couple days before they could get a replacement part (go figure, spare parts for jeeps were a rare commodity.) I drove it without the clutch the whole time. Sometimes when the convoy stopped, I'd have to pull off the road and circle in the sand until the convoy started moving again.
 
20201015_100100.jpg I've been driving semi trucks for 18 years, 2 million + miles with mostly an 18 speed non-synchronous transmission, I have never double clutched. I don't even know how. Just float shift the thing.

And coincidentally I'll be dropping a PLS truck off at Ft Irwin Monday morning.
 
Capt. Geoffrey Thorpe said:
Except when they have a non-syncromesh transmission.
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All the more reason to never use the clutch at all. Use the accelerator pedal. Get the rpm right and it'll just drop right into gear.

Matter of fact, at the company I drove for, you would get fired if they saw you using the clutch to shift. It serves no purpose, and adds extra wear on parts difficult to service/replace.
 
bluerooster said:
All the more reason to never use the clutch at all. Use the accelerator pedal. Get the rpm right and it'll just drop right into gear.

Matter of fact, at the company I drove for, you would get fired if they saw you using the clutch to shift. It serves no purpose, and adds extra wear on parts difficult to service/replace.
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You stand a greater change of not getting the gear not fully engaged and stripping/ blowing the trans.
 
bluerooster said:
All the more reason to never use the clutch at all. Use the accelerator pedal. Get the rpm right and it'll just drop right into gear.

Matter of fact, at the company I drove for, you would get fired if they saw you using the clutch to shift. It serves no purpose, and adds extra wear on parts difficult to service/replace.
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"Wow. Sounds like a very fun and fulfilling place to work." said nobody, ever.
 
Marky_24 said:
View attachment 91133 I've been driving semi trucks for 18 years, 2 million + miles with mostly an 18 speed non-synchronous transmission, I have never double clutched. I don't even know how. Just float shift the thing.

And coincidentally I'll be dropping a PLS truck off at Ft Irwin Monday morning.
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I agree with you about using the clutch. When Covid-19 slowed the pilot jobs I took a job driving truck. I really enjoy it. I drive 3,000 miles a week & have weekends off.
 
Yes, every down shift, every car I have ever owned Even though modern transmissions have syncro-mesh and don't really need a double clutch anymore, it's how I learned back in the day..
 
Sac Arrow said:
Nobody double clutches on a downshift.
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I did it quite frequently when I still had a manual transmission car.

Zeldman said:
The clutch is only needed for starting from a stop, not for shifting up or down.

And yeah, the first few flight lessons I would stomp the left rudder pedal before starting the engine....
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For a non-synchromesh transmission, yes. If you have a synchro box, it will last longer if you use the clutch to shift.

Tantalum said:
I had a mini I downshifted for 120K miles and never had a problem with the clutch. The clutch should slip very minimally. The deceleration comes from the compression in the engine
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Provided you bring the engine up to speed before you let the clutch out, you won't be creating much clutch wear.

Sac Arrow said:
The only time you're wearing the clutch significantly is when you are starting out in first gear. Constant mesh motorcycle transmissions don't even need to be shifted with the clutch, if you know what you're doing. Well, that goes for large truck transmissions too I guess.
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I think you'd be hard pressed to find a motorcyclist who has never accidentally shifted without the clutch.

genna said:
In a modernish(anything with synchro-mesh transmission ) street car, on the street, I can't think of a good reason to double-clutch. Maybe it will extend the life of your synchros/transmission from 250Kmi to 300Kmi(made up numbers). Maybe. In reality, you won't even know if you are doing it correctly as synchros will mask any mistakes. It certainly not going to have any affect on your clutch's life(actually may shorten it somewhat as you are making more "slipping" moves). It's far more likely that you will will get rid of the car well before any conceivable benefit from it. Of course some cars have weak synchros, but that's a different problem.

Also, downshifting to slow down is not going to do anything to your clutch if you are remotely competent with it(rev-match, quick release). Clutch has exactly the same role in engine braking as it does in acceleration. None, there is no movement! Unless it is used up and slipping or you are dumb enough to slip it.

Now, race cars, semis, old cars, etc. are different types of animals.
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If you're in a hurry to get the car into a lower gear, try double clutching, it's faster. The downside of synchronizer equipped transmissions is that the shifts happen slowly, compared to a non-synchro manual or dual clutch.

weilke said:
Outside of a total brake failure, I don't see a reason to ever shift from 2nd to 1st. Other than that, if I slow down gradually, I will shift down through the gears as required. If I come down a hill under load and use the engine for braking, I will double clutch/blip as the transmission doesn't seem to like having to sync the gears at those higher rpms.
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In a street car, probably never. Racing cars on road courses quite often have a first gear ratio appropriate for the slowest turn on the track.

flyingron said:
I learned double clutching on a 1980 Seagrave pumper.

The amusing thing for me is my Chevy Volt has a PRNDL which really is just a digital input to the computer (other than the mechanical PARK lock). Reverse just tells the controller to flip the motor polarity. N applies a very small hold current. D is just R in the opposite direction. L is the same as D if your foot is on the "gas" but applies a more aggressive regenerative braking if you take your foot off.
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I have a PHEV Fusion that's set up the same way. It also has a hill holder button for going down grades. Just flip the button and the car holds its current speed.
 
genna said:
Nonsense! All you need is a starter :cool:;):D
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Yep , Cable to clutch broke on my old Pete Cabover . The help had left it in the field. It had a 8V92 Detroit That needed good warm up so it would start pulling a 50,000 lb load in low low. Once running and warmed up it started right up in gear with the fully loaded trailer . Easy clutch less shifting to get it home 5 miles to the shop.
 
Tom-D said:
I learned to drive on a 1954, Brockway 4 under a 4 speed, Yep, I knew how to double clutch.
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I learned on a 5&4 no need for clutch. just gotta do it right and with finess.
 
steingar said:
My first bike had a kickstarter. I'll never know how those guys kickstarted the early Harleys and Indians. I could barely do it for a 400cc parallel twin.
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Low compression, and technique, more so than brute force. Sportster OTOH, was reletively high compression. It required proper technique, more than anything. (if you value your knee. ;) )
 
smv said:
"Wow. Sounds like a very fun and fulfilling place to work." said nobody, ever.
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Actually they were a pretty decent bunch to work for. They just had rules, and you were expected to follow them. Their attitude was "the clutch is there for starting off, and stopping, That's it." When done properly, there is no wear on any parts.
 
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