CC reader Donny B sent the following question:
I recently discovered that luxury vehicles from the 1970’s had “drum” style thermometers on the driver-side mirror. When did these disappear? I’d like to know because having one made late enough to use Celsius would be really cool, if such a thing exists. I don’t know where else I’d ask a question like this. Sometimes being a Canadian in half-Metric half-Imperial limbo is hard.
I’m sure the CC Cognoscenti will be able to help you out.
For Cadillac the 1982 model year is when they had electronic climate control and displayed the outside temperature on the climate control module. I do not recall ever seeing a drum thermometer on a GM car.
My Dad’s ’76 Park Avenue had one. Car was black so it always read too high.
Yes, my 1980 Eldorado has the Electronic Climate control, but still has the drum thermometer.
I remember the drum thermometer on my Mom’s ’78 Fleetwood. You can see the drum in this photo of a doppelganger of her car:
https://barnfinds.com/wp-content/uploads/2017/02/cadlm4-e1488258987408.jpg
Here’s an ebay listing from an Eldorado:
https://www.ebay.ca/itm/1977-1978-Cadillac-Eldorado-LH-Door-Mirror-w-Thermometer/112713224416?hash=item1a3e3b50e0:g:7akAAOSw5cNYhkv2&vxp=mtr
Not sure of the exact years but I’m guessing that Canada went to the metric system around the same time that these were starting to phase out. They may not exist in Celcius. However, if you could find the guts, I’m sure that someone could 3D print a new drum for it and label it correctly.
“someone could 3D print a new drum for it and label it correctly”
Or perhaps just print a label strip that could be affixed to the existing drum?
Bingo, no need for a new drum just need to figure out the proper scale for a new label to put on the existing drum.
Sure, take the easy way out. 🙂
I remember Buick and Olds offering these as options in the ’70’s as well.
Bob
Wow, I had forgotten all about these. I wonder if the Canadian, European or Australian divisions of the US companies used these same parts but with metric readings? This is just idle guessing, because I have no idea.
Never seen one out this way metrics arrived in 73/4
In the late 60’s – early 70’s, I worked at a busy service station in a tony neighborhood. I do remember seeing these. Few and far between. Seems that the trouble was not being accurate due to the location of the unit. My wife had a ’91 Riviera with an outside ambient air temperature sensor and digital gauge on the dash. The readings were transmitted by algorithm to the optional digital instrument panel. Way off sometimes! 40 degrees F or even more! I think the ones on later cars are much better than the one on her Riviera – even so, I ‘d give my eyeteeth to have this car back. It was a beauty with “White Diamond Pearl ” paint. Those older ones probably aren’t much more than toys.
Depending on how old the Canadian he may only need the “cold part” of the drum in metric. 32F and lower. If you are old enough to remember pre-metric it is more dramatic to say it’s 88 degrees outside or Grab your coat it’s -5 out. It’s only recently that I’ve been using 28 and 32 degrees to say it’s hot outside.
As someone else has pointed out these were out of fashion before the metric switch. At least I have never seen one.
I remember these; they were on big American luxury cars in the ’70s but I can’t remember exactly which ones. Did they light up at night?
I assume they disappeared once electronic dashboard displays came along and did the job better.
The engine computer needs to know the outside temperature anyway, so once there’s a display it’s literally zero cost to add the thermometer.
No the engine control computer does not need to know the outside temp. What they do need to know is the temp of the air in the intake tract and depending on the current conditions the two can vary dramatically. Even when the temps are in the 30’s and 40’s you can see intake air temps exceed 100 if the vehicle is moving slow enough or has been under a significant load.
However technically they don’t truly need that to run for years there was no intake air temp sensor on the GM EFI cars. So the fact is that many cars that display a external temp are using the information from an different sensor than the one that the engine uses, even though in some cases it is the exact same part, just snapped into a clip under the front bumper instead of threaded into the intake tract.
They were illuminated at some point, not sure about the first ones.
It sounds like 81 was the last year they were available on Caddilacs so I guess you need to track down some 80-81 Caddys for sale in Canada to see if theirs are in Celsius or not. Then if they are track down one for sale.
Or as mentioned above find one of the Fahrenheit units and figure out the proper scale and print a sticker to put on the old drum. Of course that isn’t the most trivial thing to do properly, not that they were that precise in the first place.
Still cool to have and one of those little features that was only available on a company’s most expensive brand.
My Edmunds price guides show that they were first available some time in the mid 1970’s and for Cadillac were available through 1981, except after that the limo’s (Fleetwood 75’s) still offered them for a while. Buick still offered them for 1982, and probably till they had electronic climate control.
With the sun shining on them the accuracy of the temperature would be in doubt. Even cruising along at highway speeds I would question how accurately they would be.
I seem to remember them being on Buicks and Oldsmobiles at least up to the mid-80s as well.
I have a unit on my ’73 Eldo and ’81 CDV. The Eldo might have been originally a US car, but the ’81 was sold in Canada, Both are non-metric and non-functional. From what I recall, they didn’t really work too well, and were soon supplanted by in-car digital read-outs.
81 CDV
’73 Eldo
The late presidents Urho Kekkonen and Mauno Koivisto of Finland had 1979 Cadillac Fleetwood Limousine with a drum thermometer…but I remember reading about it in a local car magazine article which stated it was with imperial scale, not metric. The car still exists and is preserved in a museum in Espoo, Finland. And, one can just about make the shape beneath the mirror.
The Lincoln Town Car featured a drum-style external thermometer through the 1989 model year, as seen in photos at this listing:
http://www.mjcclassiccars.com/1989-lincoln-town-car.shtml
Can we find a Canadian ’89 Lincoln? By that time Celsius temperature readings were in the mainstream.
Yep. Dad had a 1969 Town Car with one of these. Not very accurate, but it looked cool, especially when illuminated at night.
I remember these as one of the features that seemed especially cool on late 70s Cadillacs. Not something you’d find on our family’s Beetle or Corona.
Thanks Curbside Classic, I had no idea these existed!
Since I’m posting I’ll add my data point. My ’94 Fleetwood has both an intake air sensor on the engine and an outside air temp sensor in front of the radiator. It is still pretty accurate; the only time it’s significantly off is when the car is parked hot for a while. Probably pretty common.
I have the same experience with my 96 Roadmaster wagon. The digital climate control thermometer is surprisingly quite accurate. Wish I could say the same for the radio clock. It keeps terrible time.
First car I’ve had with automatic climate control and I have to say I love it. Didn’t think I would. I’m only about 20 years behind.
Yes, Harry, similar experience with the one on my former ’87 Brougham, although I’m not sure where the sensors were located on the older “box” model. It would definitely read like 130 F though when turned on after the car was parked in the sun.
My 1979 Buick Estate Wagon has this kind of thermometer on the driver’s mirror. It seems like it reads the temperature o.k. until it gets close to freezing- then it won’t drop any lower. Guess the car is just longing for spring….
I figured it was an option on the Estate Wagons. You can barely make it out on this buick press photo of a 77 Estate Wagon.
Love to see a photo of your Estate Wagon!
Fascinating, but I have never heard of these or have seen one.
Just goes to show just how informative CC really is!
+1
Really nice and weird tidbit. Never knew of them, nor how.widespread they were.
I reckon one of the few pre-electronics European cars with an outside temp gauge as standard was the Panhard 24 BT / CT, though the gauge was on the glove compartment, so it measured the temperature of the car’s interior, rather that it’s exterior.
Canada went metric in ’77, but it took awhile to be fully implemented/accepted. I recall seeing these and don’t think any were metric. It’s still common to hear people refer to inches or pounds in some situations. Celcius temperatures seemed to catch on faster than say, distance measurements. I was in high school at the time and the only real problems that arose involved disputes over ounces to grams…..
Seems to me the US was considering a switchover at around the same time and decided against it for some reason.
As for the thermometers, the comments of others mirror mine-they weren’t very accurate when exposed to sunlight.
I had an 88 Lincoln Town Car with a drum thermometer built into the rear view mirror. It read 58 degrees year round. Converted to Celsius it was still broken.
here’s doug demuro showing one of these on a 77 eldorado
https://youtu.be/HxHfrc60k8M?t=2m10s
Dad’s 78 eldorado had the drum thermometer in imperial and the speedo and mileage in metric.
My 85 Fleetwood had an internal digital thermometer that could be set to read either.
I believe you could get one on a ’71 Toronado. I remember seeing one in the dealership when we were shopping for a new family car.
Interesting, never seen these before.
Seems like this might be the sort of thing that, like old radios and clocks, could be updated with modern internals to be made to work much better than the original versions.
OTOH, how, exactly, do these work? If there’s no power source involved, well, maybe they can’t be upgraded.
If I recall correctly, these thermometers were offered on GM’s Electra, 98, and Sedan Deville/Fleetwood, ElDorado, Tornado, Riviera, and Seville. A quck check of OldCarBrochures.com shows the outside temp on the mirror starting in 1973. I haven’t checked, but I don’t think it was available as an option on the Impala/Caprice, Bonneville,Lesabre, Eighty-Eight …but please DO research that out. And going by memory, the temp indicator was available through the early 80’s on those cars.
Lincoln had it later on the Town Car, Mark, and Versaille (lousy spelling!) starting around 1976 and continuing through the early 80’s.
My fading memory seems to remember reading about these–there was an internal spiral “clockspring” made of a temp-sensitive material that expanded/contracted based on temp. The base of the clockspring attached to a point on the interior of the mirror housing; the other end of the spiral to the internal side of the drum. But, that’s based on my memory of having read an article somewhere. As a convenience, they also had a small light inside to illuminate the drum when headlights were on.
As several have mentioned, these weren’t terribly accurate and were largely replaced as displays for climate control went digital.
(BTW, OldCarBrochures has some of the brochures available for Canadian models–so it might be a good source simply to start researching availability.)
My 1977 Edmunds price guide shows that Chevrolets and Pontiacs did not offer it as an option. However all full size Buick and Oldsmobiles did offer it including the LeSabre and Delta 88’s. Not sure about other years.
Correct, these were primarily offered on GM C&E bodies. My brother-in-laws parents had one on their 75 98 Regency. The mirror was vandalized in the early 80s and a replacement was not available. They had to settle for a normal unit.
BTW speaking of electronic readouts, the one on my Cruze consistently overestimates the temp by 3 degrees, winter or summer, as measured against the gov’t meteorology site here in Korea.
There is one on my ’76 De Ville (private import from the US, bought in Belgium). I first noticed it on the day I picked up the car. I had no idea what it was until the seller told me just before I drove off.
It’s in Fahrenheit units and kind of useless to me (I never drive the car in bad weather anyway) but I’m happy to have it. I find it really cool, among the many cool features only a malaise-era luxo-barge like that one can offer. Never seen one of those on a European car.
In the end, conversion of such a device to Centigrade would be counter to the design ethos of the car and its period. Preserve the unique original features!
Just remember 32F = 0C, 100C=212F, the two scales meet at -40 (as in
Montreal, winter, 1976, I think?), and it’s beautiful weather at 25C or 77F!
I had one on my 74 Coupe de Ville. It was pretty accurate on a cloudy day.
What is the purpose of the tiny 3 on the right side of the -30 degree on the drum thermometer?