Why did GM develop vacuum actuated headlights?
Thread Starter
Racer
Joined: Sep 2016
Posts: 307
Likes: 66
From: Louisville, KY
Why did GM develop vacuum actuated headlights?
Does anyone have any insight to why GM engineers developed the vacuum system in the C3? Weight savings? Cost savings? Reliability? Cool factor??
Me and a buddy have been discussing and cant find anything on the internet helping solve the mystery....
Me and a buddy have been discussing and cant find anything on the internet helping solve the mystery....
Popular Reply
Sep 2, 2023, 09:22 PM
Burning Brakes
Joined: Jun 2013
Posts: 1,076
Likes: 148
From: Hunterdon Cty NJ
Opel GT headlights do not use electric motors they are manually operated with a lever and linkage.
Melting Slicks
Joined: Nov 2006
Posts: 3,394
Likes: 1,812
From: Apple Valley, MN
Interesting question.
TRICO began supplying GM vacuum operated wipers in 1928 and in the 40’s and early 50’s, almost all of GM cars had vacuum operated wipers but were eventually replaced by electrics. We know the C3s’s wipers are driven by an electric motor, but the wiper door is vacuum operated (as, of course, are the headlights).
Given that vacuum wipers were phased out in the 50s in favor of electric power, my suspicion leans to the belief that the reason the General chose vacuum headlights (and a vacuum wiper door (until 73) and fiber optics (until 72)) was, as you say, for the “cool factor”.
Just my 2 cents.
TRICO began supplying GM vacuum operated wipers in 1928 and in the 40’s and early 50’s, almost all of GM cars had vacuum operated wipers but were eventually replaced by electrics. We know the C3s’s wipers are driven by an electric motor, but the wiper door is vacuum operated (as, of course, are the headlights).
Given that vacuum wipers were phased out in the 50s in favor of electric power, my suspicion leans to the belief that the reason the General chose vacuum headlights (and a vacuum wiper door (until 73) and fiber optics (until 72)) was, as you say, for the “cool factor”.
Just my 2 cents.
Safety Car
Joined: Dec 2012
Posts: 3,800
Likes: 1,712
From: Summerville SC
My $.02, adjusted for inflation is MONEY. C2's had electric opening lights with virtually no issues. At least I never had any with mine. SO someone decided that all those rubber hoses could be run off of FREE vacuum power. Rubber hoses were cheaper than an 2 electric motors. Funny how they went back to electric for C4's. I will never forget the first time I opened the hood on a C3 and saw all of those hoses. OMG, no wonder we needed diagrams of where they all went. 
Just another Corvette guy
Joined: Feb 1999
Posts: 8,518
Likes: 3,865
From: Palm Springs, CA.
Yep, a free power source.
And they actually work pretty good when maintained and leak free. Of course once they're 30, 40 or 50 years old, they will need some servicing, but it's worth doing and they'll work like new again.
And they actually work pretty good when maintained and leak free. Of course once they're 30, 40 or 50 years old, they will need some servicing, but it's worth doing and they'll work like new again.
Thread Starter
Racer
Joined: Sep 2016
Posts: 307
Likes: 66
From: Louisville, KY
Makes total sense. ‘Free’ power sounds enticing and carries the cutting edge cool factor Chevy tries with the Vette historically.
Clearly it wasn’t the champ and electric reigned supreme after all. Another reason why the C3 is such a cool car.
Clearly it wasn’t the champ and electric reigned supreme after all. Another reason why the C3 is such a cool car.
Burning Brakes
Joined: Dec 2005
Posts: 1,153
Likes: 341
Vacuum powered wipers may have been popular in great grandpa's day because when wipers froze to the windshield, an expensive electric motor didn't burn up.
I guess the suppliers to GM/Chevy figured out how to prevent that at some point, but stuck with vacuum actuation for popup headlights and those oh-so-wicked wiper doors.
The most LIKELY 1960's alternative was the rotating,motor-driven headlights used on the Opel GT and the cool Pontiac-flavored Corvette. (Banshee, XP833)
Probably came down to a styling decision.
Deciding whether to replace my headlight actuators with electrics I came across this comment:
>I installed a set of these [electric headlight motors] years go. Back then, they were over $800.00. They use Mazda Miata headlight motors. The problem is they won't last, and the gears will strip out. These motors have plastic gears and are not designed to lift the heavy C3 Corvette headlights. I went through two sets of motors already. None of the people selling kits offer replacement motors. You either have to buy Mazda motors, which are not cheap, or you buy another kit and throw the brackets away.
There are 10 follow-up comments to that comment on this highly-rated Youtube about how to convert a C3 to electric openers:
In comparison, many 50 year old vacuum-operated systems, with minor maintenance (new hoses) are still working fine, at worst needing a couple of cheap actuators (vacuum motors).
If you take the time to truly understand how the vacuum system is SUPPOSED to work, it's rather easy to diagnose & repair -- Despite all the evidence to the contrary - mile long CF threads!
So...reliability. And lower cost.
I guess the suppliers to GM/Chevy figured out how to prevent that at some point, but stuck with vacuum actuation for popup headlights and those oh-so-wicked wiper doors.
The most LIKELY 1960's alternative was the rotating,
Probably came down to a styling decision.
Deciding whether to replace my headlight actuators with electrics I came across this comment:
>I installed a set of these [electric headlight motors] years go. Back then, they were over $800.00. They use Mazda Miata headlight motors. The problem is they won't last, and the gears will strip out. These motors have plastic gears and are not designed to lift the heavy C3 Corvette headlights. I went through two sets of motors already. None of the people selling kits offer replacement motors. You either have to buy Mazda motors, which are not cheap, or you buy another kit and throw the brackets away.
There are 10 follow-up comments to that comment on this highly-rated Youtube about how to convert a C3 to electric openers:
In comparison, many 50 year old vacuum-operated systems, with minor maintenance (new hoses) are still working fine, at worst needing a couple of cheap actuators (vacuum motors).
If you take the time to truly understand how the vacuum system is SUPPOSED to work, it's rather easy to diagnose & repair -- Despite all the evidence to the contrary - mile long CF threads!
So...reliability. And lower cost.
Last edited by wadenelson; Sep 4, 2023 at 05:44 AM.
Drifting
Joined: Jul 2022
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From: Wisconsin
2024 C3 of the Year Finalist- Modified
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Vacuum is a free power source, vacuum hoses were cheaper and easier to run than electrical wiring, Also I think the fact that c3s were more "production line" than c2s or c1s , it helped streamline production.
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Pro
Joined: Nov 2014
Posts: 728
Likes: 346
From: Smyrna, TN
I have no problem with the vacuum operated wiper door.
But I really want to know the name of the engineer that came up with that linkage!
Seems like a "Rube Goldberg" design when a simple four link would work...
But I really want to know the name of the engineer that came up with that linkage!
Seems like a "Rube Goldberg" design when a simple four link would work...
Thread Starter
Racer
Joined: Sep 2016
Posts: 307
Likes: 66
From: Louisville, KY
Understanding these plastic geared motors won’t last many cycles, I had a go at it and bought a set last night. $219 shipped after tax.
Thinking I’ll drive so little at night it was worth the chance .
Thinking I’ll drive so little at night it was worth the chance .
Vacuum powered wipers may have been popular in great grandpa's day because when wipers froze to the windshield, an expensive electric motor didn't burn up.
I guess the suppliers to GM/Chevy figured out how to prevent that at some point, but stuck with vacuum actuation for popup headlights and those oh-so-wicked wiper doors.
The 1960's alternative was the rotating,motor-driven headlights used on the Opel GT and the cool Pontiac-flavored Corvette. (Banshee, XP833)
Probably came down to a styling decision.
Deciding whether to diagnose the vacuum system on mine or replace the headlight actuators with electrics I came across this comment:
>I installed a set of these [electric headlight motors] years go. Back then, they were over $800.00. They use Mazda Miata headlight motors. The problem is they won't last, and the gears will strip out. These motors have plastic gears and are not designed to lift the heavy C3 Corvette headlights. I went through two sets of motors already. None of the people selling kits offer replacement motors. You either have to buy Mazda motors, which are not cheap, or you buy another kit and throw the brackets away.
There are 10 follow-up comments to that comment on this highly-rated Youtube about how to convert a C3 to electric openers:
https://www.youtube.com/watch?v=H5ERoiV64Bk
In comparison, many 50 year old vacuum-operated systems, with minor maintenance (new hoses) are still working fine, at worst needing a couple of cheap actuators (vacuum motors).
If you take the time to truly understand how the vacuum system is SUPPOSED to work, it's rather easy to diagnose & repair -- Despite all the evidence to the contrary - mile long CF threads!
So...reliability. And lower cost.
Electric conversions can be had for $300 all day long now, Google shopping. e.g. https://www.google.com/shopping/prod...41898228572624
Cheers!
I guess the suppliers to GM/Chevy figured out how to prevent that at some point, but stuck with vacuum actuation for popup headlights and those oh-so-wicked wiper doors.
The 1960's alternative was the rotating,
Probably came down to a styling decision.
Deciding whether to diagnose the vacuum system on mine or replace the headlight actuators with electrics I came across this comment:
>I installed a set of these [electric headlight motors] years go. Back then, they were over $800.00. They use Mazda Miata headlight motors. The problem is they won't last, and the gears will strip out. These motors have plastic gears and are not designed to lift the heavy C3 Corvette headlights. I went through two sets of motors already. None of the people selling kits offer replacement motors. You either have to buy Mazda motors, which are not cheap, or you buy another kit and throw the brackets away.
There are 10 follow-up comments to that comment on this highly-rated Youtube about how to convert a C3 to electric openers:
https://www.youtube.com/watch?v=H5ERoiV64Bk
In comparison, many 50 year old vacuum-operated systems, with minor maintenance (new hoses) are still working fine, at worst needing a couple of cheap actuators (vacuum motors).
If you take the time to truly understand how the vacuum system is SUPPOSED to work, it's rather easy to diagnose & repair -- Despite all the evidence to the contrary - mile long CF threads!
So...reliability. And lower cost.
Electric conversions can be had for $300 all day long now, Google shopping. e.g. https://www.google.com/shopping/prod...41898228572624
Cheers!
Burning Brakes
Joined: Dec 2005
Posts: 1,153
Likes: 341
Let's compare apples to apples. 12AWG wire is probably about the same price per foot as 1/4" vacuum line
A vacuum "motor" like on the headlights is probably 5x cheaper than an electric motor. Ditto the wiper door motor/actuator
"Vacuum" is no more "free" than electricity in a car. That's nonsense. Both require burning fuel to create.
A vacuum "motor" like on the headlights is probably 5x cheaper than an electric motor. Ditto the wiper door motor/actuator
"Vacuum" is no more "free" than electricity in a car. That's nonsense. Both require burning fuel to create.
Last edited by wadenelson; Sep 4, 2023 at 05:49 AM.
Race Director
Joined: Mar 2017
Posts: 11,927
Likes: 4,497
From: Virginia
There's not a lot of vacuum stuff left in my car. But more than 50 years after these cars were designed, there have been a LOT of advancements in electronics. I'm sure GM saved a few pennies using vacuum hoses for everything, especially the actuators. That's no longer the case today.
BTW, vacuums are much better now, too, but mostly thanks to lithium batteries, better engineering, CFD, plastic manufacturing, etc. Nearly anything that previously required a cord, or an air hose, can be easily replaced with a superior electronic equivalent.
If you are looking for a headlight kit, this is the one to get. Made in USA!
https://www.ebay.com/itm/155261365162
BTW, vacuums are much better now, too, but mostly thanks to lithium batteries, better engineering, CFD, plastic manufacturing, etc. Nearly anything that previously required a cord, or an air hose, can be easily replaced with a superior electronic equivalent.
If you are looking for a headlight kit, this is the one to get. Made in USA!
https://www.ebay.com/itm/155261365162
Burning Brakes
Joined: Feb 2020
Posts: 904
Likes: 569
From: Central NJ
They could have done both lights with one motor mounted in the center driven by shafts. I don't see that being any harder or more expensive than two actuators, two valves, the coffee can and all the stuff under the hood and dash to make them work. Plus the assembly costs of workers running all that stuff.
Nobody has mentioned the heat/cooling controls, they were designed by a few engineers after a Pot party. There are very few engineers who will listen to reason when it will negatively effect a\their pet project and this had to be somebody's bright Idea...
Of course it's also easy to be a monday morning quarterback...
60
Nobody has mentioned the heat/cooling controls, they were designed by a few engineers after a Pot party. There are very few engineers who will listen to reason when it will negatively effect a\their pet project and this had to be somebody's bright Idea...
Of course it's also easy to be a monday morning quarterback...
60
Burning Brakes
Joined: Jan 2022
Posts: 1,069
Likes: 42
I have a 68 eldo that has the same system, so probably not a weight issue, all the hoses and actuators probably don't weigh much less. Never thought a lot about it other than assuming there was a problem with electric motors so they went vacuum, discovered that was even worse than electric and eventually went back to electric.
With the few and far between improvements for the 70's C3, I figured they were too cheap to change it.
With the few and far between improvements for the 70's C3, I figured they were too cheap to change it.
