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1956 at 80mph for 2 hours. Good or bad?

Started by Hillbillycat, August 17, 2020, 02:40:44 AM

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Hillbillycat

Hi,

probably opening up a can of worms, but my 1956 Sedan Deville likes to run.....took her on a weekend trip at 80mph for a two hour drive. Car ran fantastic. I get the impression the car is getting better and better.
However, almost every other classic car owner seems to be shocked when I tell them I run our Cadillac this fast for this long. Seems like they all baby their cars. Or am I the one who´s doing wrong? Am I hurting the engine when doing these speeds on our Autobahn here in Germany?

I´m not discussing safety - I know this speed is unsafe with bias ply, no belts, drum brakes etc.


The Tassie Devil(le)

Sounds good to me.

Heck, these cars were designed to run all day when they were new, so there is no reason why they shouldn't continue to run nicely out on the open road.   Plus, they had bias ply tyres, drum brakes and no belts.

Some people just like to baby their old cars, but there are old cars, and strong old cars.

A babied car shouldn't be run at high speeds suddenly, and the same goes or a car that is run hard.   They shouldn't be idled for hours on end.

All being well, there is nothing wrong with running at the posted Speed Limits, but one has to drive to the conditions as well.

Back in the day, I used to run my '50's cars as fast as I could drive them, but then, everyone else around had drum brakes, no belts and bias ply tyres.

Bruce. >:D

PS.  I'll bet you were being passed many times on the Autobahn.

PPS.   Was it 80 Mph on the Speedo, or GPS.  There is a big difference.
'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

Hillbillycat

Hi Bruce,

thanks. That is exactly what I think, too. They were built to be driven, not babied.

It was 80mph on the speedo. GPS showed something around 120km/h, so it is pretty close.

And yes, I got passed a lot :-) But earned a lot of smiles, of course.

Oliver Betker

Hello,
I had last year a long trip (400 ml) with a lot of Autobahn from Germany to Denmark.
And I felt like I was getting faster and faster every 50ml.
In the end, I overtook Dutch caravan convoys with 72 ml / h (GPS), and I had a very light and small caravan even on my own trailer hitch.

By the way, with an old flathead and model year from 1946.
It was a little much in the sommerheat and cost my a set spark plugs, but it was quite funny.

This Weekend we start the same tour and I promise I will stay at 60ml Maximum.
The old Girl shouldn't work such hard.
Regards
1946 Cadillac Series 61 Coupe
1958 Chevrolet Bel Air 4door Sedan
1958 Wartburg 311 4door Sedan 900
1961 Wartburg 311 4door Sedan 1000
1963 Trabant 500 2door Sedan
1989 Trabant 601 2door Sedan
1966 Bulldozer T 100 MGP
1968 Bulldozer T 100 MGP
1998 Nissan Pickup Navara
2015 Ford Ranger Pickup
1978 MZ T 250/1
1992 Harley Davidson Fat boy

James Landi

#4
A few observations, owned two (daily drivers  during the 70's), parents brought a used  one back in '58

1. I have noted that the '56 engines run significantly better after they've "exercised" on the turnpike for extended runs.  (The gas pedal is far more responsive to a light touch!)

2. Around town, stop and go, seems to cause a deterioration in engine performance over time. 

3. I learned over  tens of thousand of miles of daily driving, that the cooling system needs to be perfect to stave off exhaust valve leaks--viz: running a hot '56 engine on hot days with a crusty radiator is asking for problems with the standard valves that came with the engine, in spite of what the temp gauge is reading.

4.  I was convinced that I could judge the "internal health" of the engine by looking at the color shades of the exhaust carbon on the bumper "stacks."

5. Because there's no pvc with this engine, short trips and long periods of idling creates sludge, especially in the oil pan... an easy "work around" might help get the condensation out of the engine... this work around also keeps the noxious blow by from under the car and out of the passenger cabin.

So by way of summary, yes, run you '56, stay off the accelerator( i.e. flooring it) and let her run.  I vividly recall my mother driving the turnpike at nearly 100 mph, chatting with my father, and being oblivious to her speed.  We never experienced such luxury and quietude  in an automobile.   Hope this experiential observation helps. James

The Tassie Devil(le)

Quote from: Hillbillycat on August 17, 2020, 04:47:51 AM
It was 80mph on the speedo. GPS showed something around 120km/h, so it is pretty close.
And yes, I got passed a lot :-) But earned a lot of smiles, of course. 
120 Kph only equates to 74.5 Mph.

Factory Speedos always read up to 10% faster.   It is a built-in factor back in the day.

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

scotth3886

#6
Quote from: Hillbillycat on August 17, 2020, 02:40:44 AM
Hi,

probably opening up a can of worms, but my 1956 Sedan Deville likes to run.....took her on a weekend trip at 80mph for a two hour drive. Car ran fantastic. I get the impression the car is getting better and better.
However, almost every other classic car owner seems to be shocked when I tell them I run our Cadillac this fast for this long. Seems like they all baby their cars. Or am I the one who´s doing wrong? Am I hurting the engine when doing these speeds on our Autobahn here in Germany?

I´m not discussing safety - I know this speed is unsafe with bias ply, no belts, drum brakes etc.

I'm still working on a harmonic noise/vibration issue or I'd be running my 66 at those speeds.  Hell, peeps used to get in their Caddy, Pimperial, Lincoln in LA and be in Las Vegas a little over three hours later for the 300 mile drive.  Of course, far less traffic than today so you could run 100 mph.  If you have what they used to call 'highway gears', you could do it.  Only danger was a blow-out costing you time (or worse).  Back in those days, most western states had at least a 75 mph speed limit with Kansas 80 on the turnpike plus Nevada, no limit and Montana no daytime limit. 

My 63 GP that I built 21 years ago was built with an .7 to 1 overdrive 700r, so its 40 mph per 1000 in 4th.  It's been run at a pretty good rate of speed since I built it and will easily cruise at 100 mph.  Top speed, it won't upshift into 4th at WOT so its wound tighter than Dick's hat band, but 21 years later, the car still runs great.  In fact it was 18 years before I bought the car that the engine had been rebuilt so 39 years on the rebuild. 

If you have good tires, brakes and the car is happy, run it. 

Lexi

That sounds fantastic. James is correct that the cooling system has to be perfect in these cars. I don't think I could ever run my '56 like that. It is the Limo model so it has the different rear end, as well as a split drive shaft. Even with my rebuilt engine she seems happiest around 60 mph, though had her up to 85 once. Seems like Cadillac wanted to better move the Series 75s from a dead stop rather than to give them more performance at the top end. Clay/Lexi

fishnjim

So long as you can stop it, I see no issue.  (seat belts?)
Mickey Thompson set the land speed record, 406 mph, back in the day('60) on bias ply tires, so if they're sound and within age limits, they'll take it.   I used to run much faster (3 digits) on them in the '60s.
That motor was probably only turning around ~2.5K rpms.   We dyno'ed mine to 5K.
I'd stay out of the over 4K for wear issues.   These don't have the oil filtration, etc.

bcroe

I drove my 62 at 80 mph for much of an hour every day, that is actual since
I always correct the speedometer.  Wore out a lot of tires.  Bruce Roe

quadfins

#10
I drive my '61 to the Grand Nationals, which often takes a couple of days of steady highway driving. Usually 70 - 75, depending on the speed limits and road conditions.

Original Cruise Control holds steady, and the car floats along at those speeds for hours. No problems, much enjoyment.

Jim
Jim Eccleston
1961 Coupe de Ville
BATILAC
Senior Crown
DeCou Driving Award x 4

cadman56

I have owned 5 56s in my life, numbers 2, 3, & 4, my Sonic Blue convertible, were all driven at speeds of 75 mph plus.  when measuring time between mile markers my wife and I would consistently see 40 - 45 sec on the clock.
I really loved number 3 car because I had glass packs on it.  The sound was pure heaven with both feet flat on the floor when the trans would shift into high.
Drive it, 80 is fine.

Now you know why I love the 56.  In my estimation it is the very BEST Cadillac ever builtt, even to present builds.
1956 Cadillac Coupe deVille (sold)
1956 Cadillac Convertible (sold)
1956 Cadillac Eldorado Seville (sold)
1967 Cadillac Eldorado (sold)
1968 Cadillac Convertible (Sold)
1991 Cadillac Fleetwood Brougham dElegance
Larry Blanchard CLC #5820

cadillacmike68

Quote from: fishnjim on August 17, 2020, 10:18:45 AM
So long as you can stop it, I see no issue.  (seat belts?)
Mickey Thompson set the land speed record, 406 mph, back in the day('60) on bias ply tires, so if they're sound and within age limits, they'll take it.   I used to run much faster (3 digits) on them in the '60s.
That motor was probably only turning around ~2.5K rpms.   We dyno'ed mine to 5K.
I'd stay out of the over 4K for wear issues.   These don't have the oil filtration, etc.

Yeah, but he only ran them for a minute max. Not several hours on the interstate highways.

I run the 68 DVC at those speeds all the time.  I don't let it drone at a constant speed, but it stays up there if there's a distance to be traveled.
Regards,
"Cadillac" Mike

Hillbillycat

Thank you very much for all the interesting replies/stories and confirmation I´m doing right.

Well, to sum things up the coolant system is the vital part here. If it´s top notch no worries.

Jay Friedman

I've driven my '49 on many long trips at highway speeds.  It has a 3.36 differential and bias ply 8.20 x 15 tires.  I don't like to drive as fast as 80 mph for safety reasons, but I do cruise on the interstate at 65-70 mph.   
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."

bcroe

Quote from: Jay Friedman
I've driven my '49 on many long trips at highway speeds.  It has a 3.36 differential and bias ply 8.20 x 15 tires.  I don't like to drive as fast as 80 mph for safety reasons, but I do cruise on the interstate at 65-70 mph.   

The cars much before 1964 tended to have 3 something axle ratios,
to get good acceleration, but they were not geared ideally for high
speed cruising.  Once we had transmissions with torque converters
(that is a TH400 for Cadillac), axles ratios in the 2s could be used
which were well suited high speed freeway cruising.  Bruce Roe

cadillacmike68

Quote from: Jay Friedman on August 18, 2020, 06:05:12 PM
I've driven my '49 on many long trips at highway speeds.  It has a 3.36 differential and bias ply 8.20 x 15 tires.  I don't like to drive as fast as 80 mph for safety reasons, but I do cruise on the interstate at 65-70 mph.   

Below 80 and you can get rear-ended on some parts of I-75 and I-4 here.  :o
Regards,
"Cadillac" Mike