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What is double clutching?

Started by Tom Boehm, October 13, 2019, 12:41:36 PM

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Tom Boehm

My 1940 Lasalle has a synchronized transmission. I understand a non synchronized transmission is more difficult to shift (double clutching). How is a non synchro transmission shifted?

LaSalle5019

Your first gear is not synchronized so if you ever want to down shift, you’ll want to learn to double clutch. It is used to synchronize the the input shaft and output shaft for the gear selected. Basically you depress the clutch to shift out of gear, then release the clutch. Now you need to determine the approximate input shaft speed you want. If you are up shifting you want to allow the engine to slow a bit before clutching again and shifting. If you are downshifting you will need to rev the engine a bit before clutching and shifting. It takes some practice to determine the approximate engine speed you want based on gear selection and current vehicle speed. You also want to slowly shift and “feel” your way into gear.
Scott

Tom Boehm

Thanks Scott for your explanation. I understand it now. I figured out that it is not synchronized if you downshift. I also "feel" my way into reverse so as not to grind the gears. My everyday car is a 4 cylinder 5 speed manual Ford Escort. I have come to realize habits I picked up driving and shifting the Escort do not work at all on the Lasalle. The range of speed on each gear on the Escort is narrow so I shift and downshift a lot. I can't do that on the Lasalle. It is not designed to do that. I need to shift up to third gear and leave it there. The car is designed such that you can come to almost a complete stop in third gear and speed up again without a shudder. The only time I really need to shift is when I come to a complete stop and start up again.

Jay Friedman

#3
Quote from: Tom Boehm on October 13, 2019, 10:05:53 PM
Thanks Scott for your explanation. I understand it now. I figured out that it is not synchronized if you downshift. I also "feel" my way into reverse so as not to grind the gears. My everyday car is a 4 cylinder 5 speed manual Ford Escort. I have come to realize habits I picked up driving and shifting the Escort do not work at all on the Lasalle. The range of speed on each gear on the Escort is narrow so I shift and downshift a lot. I can't do that on the Lasalle. It is not designed to do that. I need to shift up to third gear and leave it there. The car is designed such that you can come to almost a complete stop in third gear and speed up again without a shudder. The only time I really need to shift is when I come to a complete stop and start up again.

I wouldn't go that slow in 3rd gear.  The motor may not shudder, but it does strain the main and connecting rod bearings.  I suggest you downshift to second at speeds below 20-25 mph or so. 

I think double clutching is a a skill best learned by practice.  As Scott wrote, pause in neutral with your foot off the gas when upshifting and briefly give it some gas when in neutral before downshifting.  Depending on the make of the car, until the late '20s or early '30s, all transmissions except planetary transmissions like Model Ts were completely unsynchronized and required double clutching in all gears.  I believe Cadillac/LaSalle had the first transmissions synchronized in 2nd and 3rd. 
1949 Cadillac 6107 Club Coupe
1932 Ford V8 Phaeton (restored, not a rod).  Sold
Decatur, Georgia
CLC # 3210, since 1984
"If it won't work, get a bigger hammer."

The Tassie Devil(le)

The difference between the Escort and your LaSalle is in the amount of Torque that the engines generate.   And the "Band" at which that Torque shows itself.

The difference between short stroke and long stroke.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

Barry M Wheeler #2189

Gay and I had taken Toby and Lynn Bergstrom on a ride one evening to show them Berlin. (He had just been transferred in.)  We had gone to the Brandenburg Gate and were heading home on Unter den Linden and coming up to the "Ring" around the Victory Monument. I was "just driving" our 1952 VW and all at once, Toby asked, "Where did you drive?"  I was somewhat confused and replied, "Oh, Indiana, mostly." He repeated, "No, I meant what track did you drive on?"

Evidently, he was impressed with my shifting of our crash box VW up and down. Kinda made my evening.
Barry M. Wheeler #2189


1981 Cadillac Seville
1991 Cadillac Seville

DaveZ

#6
Cadillac came out with Syncro in '29.  Double clutch prior to that you would have to push the clutch in let off gas take it out of 1st let clutch up when in Neutral, push clutch in again and shift to 2nd. Same operation from 2nd to 3rd. Sometimes when in Neutral quick pump on gas pedal to change rpm up and release to lower then shift up. Reverse and 1st from dead stop only even with the syncro's. One other thing to note is that even with the syncro transmission, unlike modern cars, you have to wait for the rpms to drop before shifting. If you don't you will get the "If you can't find them grind them":-)
Regards,
David Zitzmann
1932 345B

DaveZ

And to what Jay said you don't want to lug the engine. You are basically hammering the bearings and wristpins.
Regards,
David Zitzmann
1932 345B

z3skybolt

Tom,

For ease(non-crunching) of selecting 1st gear or reverse when stopped or even first from reverse when just barely rolling backward....first shift into 2nd gear and then right into first or reverse.
Old technique from my youth.  Works fine in my LaSalle.

Bob
1940 LaSalle 5227 Coupe(purchased May 2016)
1985 Lincoln Town Car Signature Series. Bought New.

Tom Boehm

Thanks everyone, I learned a lot from this thread.    Another question:  Jay you mentioned a model T planetary transmission is different. How is a model T shifted?

The Tassie Devil(le)

That is one for the Ford crowd.

Bruce. >:D
'72 Eldorado Convertible (LHD)
'70 Ranchero Squire (RHD)
'74 Chris Craft Gull Wing (SH)
'02 VX Series II Holden Commodore SS Sedan
(Past President Modified Chapter)

Past Cars of significance - to me
1935 Ford 3 Window Coupe
1936 Ford 5 Window Coupe
1937 Chevrolet Sports Coupe
1955 Chevrolet Convertible
1959 Ford Fairlane Ranch Wagon
1960 Cadillac CDV
1972 Cadillac Eldorado Coupe

Jay Friedman

#11
Quote from: Tom Boehm on October 14, 2019, 08:44:21 PM
Thanks everyone, I learned a lot from this thread.    Another question:  Jay you mentioned a model T planetary transmission is different. How is a model T shifted?

Tom, a Model T planetary transmission has 2 forward speeds, low and high, and reverse.  Without going into too much detail, as I agree with Bruce that it's for the Ford folks, gears are shifted with foot pedals and the gas is worked with your right hand.  Shifting between low and high is done with the left-most pedal worked by your left foot and reverse with a middle pedal also worked by your left foot.  (A 3rd pedal worked by your right foot is for the brakes.)  Needless to say you have to learn how to drive all over again to drive a Model T, including how to start it if it doesn't have an electric starter as well as setting the spark advance, etc. 
1949 Cadillac 6107 Club Coupe
1932 Ford V8 Phaeton (restored, not a rod).  Sold
Decatur, Georgia
CLC # 3210, since 1984
"If it won't work, get a bigger hammer."

Glen

Here is a good video on planetary gear operation. 
http://zork.info/planetarygear
Glen Houlton CLC #727 
CLCMRC benefactor #104

Jay Friedman

#13
And here is one on driving a Model T:

https://www.youtube.com/watch?v=n0hQh_Ej_34

Thankfully, in 1928 Ford introduced the Model A, which has a conventional 3-speed transmission and clutch. 

A point of interest to us Cadillac folks about planetary transmissions is that the GM Hydramatic, introduced on Cadillacs in 1941, has 2 planetary gear sets, one behind the other, providing 4 forward speeds.  Along with lots of other parts, including a fluid coupling, bands, pumps, etc., it was the first fully automatic transmission.  Nonetheless, it could be described as merely being an updated version of the Model T planetary transmission.
1949 Cadillac 6107 Club Coupe
1932 Ford V8 Phaeton (restored, not a rod).  Sold
Decatur, Georgia
CLC # 3210, since 1984
"If it won't work, get a bigger hammer."

INTMD8

Uh oh, deleted in 3....2...1...... :-X :-X :-X :-X :-X

>:D

veesixteen

Quote from: Jay Friedman on October 13, 2019, 11:00:55 PM
I wouldn't go that slow in 3rd gear.  The motor may not shudder, but it does strain the main and connecting rod bearings.  I suggest you downshift to second at speeds below 20-25 mph or so. 

I think double clutching is a a skill best learned by practice.  As Scott wrote, pause in neutral without your foot off the gas when upshifting and briefly give it some gas when in neutral before downshifting.  Depending on the make of the car, until the late '20s or early '30s, all transmissions except planetary transmissions like Model Ts were completely unsynchronized and required double clutching in all gears.  I believe Cadillac/LaSalle had the first transmissions synchronized in 2nd and 3rd.

"Old geezers", like me, started double-clutching, with regular European cars, well into the 50s. I got proficient in Scotland and France 'cos I did not think to get a drivert's license until 1963 ... when I was already 24
!
Yann Saunders, CLC #12588
Compiler and former keeper of "The Cadillac Database"
aka "MrCadillac", aka "Veesixteen"

dochawk

Quote from: Tom Boehm on October 13, 2019, 10:05:53 PM
The car is designed such that you can come to almost a complete stop in third gear and speed up again without a shudder.

The minimum speed for high gear was an advertised feature at the time--and Cadillac was a leader (gee, surprise!).

I want to say they reached some silly number like 2-1/4 MPH :o

I don't have the link (maybe the 70s Cadillac history book?), but there was a report of some event (new car show?) where  Cadillac basically taunted a competitor (Packard?) by looping around the other car in circles at a speed that it couldn't match, forcing it to pass the Cadillac . . .  ;D

Quote from: Tom Boehm on October 14, 2019, 08:44:21 PM
Thanks everyone, I learned a lot from this thread.    Another question:  Jay you mentioned a model T planetary transmission is different. How is a model T shifted?

In a most psychotic manner . . .

And Jay left out that the hand brake is part of this all . . . pulled all the way back is braking, middle is (another ) neutral, like depressing the left pedal half way, and full forward engages the transmission.  Also, the right "brake" pedal doesn't actually engage the brakes; it clamps bands down on the engine, with the handbrake applying the regular brakes . . .

Did I mention that they're psychotic?

I'm kind of the go-to driver for old and odd stuff at the local auction . . . .but I'd like to drive a T for once that works properly.  Last year, it wouldn't fully disengage from drive (which is why it had to be driven where they normally push for exhaust reasons), and it hopped a few feet at a time in reverse (both trying to engage), and didn't brake properly and overshot (again, forward still engaged).  This year, one had a v6 mustang engine and an automatic ( :o >:( (and bad brakes), while another couldn't be started again due to the battery . . .

Quote from: veesixteen on October 16, 2019, 10:56:19 AM
"Old geezers", like me, started double-clutching, with regular European cars, well into the 50s.

I picked up on a poorly maintained U-haul!   It occurred to me that I'd used the clutch twice, and I aid attention the next time--it was sticking leaving neutral, and I double clutched instinctively . . .

Quote from: Jay Friedman on October 15, 2019, 07:47:58 AM

A point of interest to us Cadillac folks about planetary transmissions is that the GM Hydramatic, introduced on Cadillacs in 1941,

If memory serves, it was effectively developed by Cadillac, but GM stuck it in Oldsmobile for a year first--not wanting Cadillac to get the backsplash if it didn't pan out as expected . . .
1972 Eldorado convertible,  1997 Eldorado ETC (now awaiting parts swap from '95 donor), 1993 Fleetwood but no 1926 (yet)

R.Miller

Get an  old truck driver to teach you. Basically you have to learn to feel and hear , the RPM s . Going into and out of gears . Shifting use the clutch to go from any gear  into neutral , and again going in any higher  gear.  Downsizing is the opposite out of Higher gears to neutral then snowblower gear . It's easy and you will really learn to feel the vehicle.