What’s with the rear spoiler?

[Moparfiend]

So what’s the deal with the rear spoiler on the 70 Roadrunner? Was that a Chrysler dealer option or just an aftermarket thing? Is there any history on this? I wouldn’t think it provided much functionality. So purely aesthetic.?.

 

[Photon440]

It was an option, but wasn't available right at the start of the 1970 model year. It was introduced after a few months, and the trunk lid stampings were changed to reflect this; besides the outer skin mounting holes, the later inner bracing has the holes meant to secure the inner wing brackets while the early lid braces are smooth. My road runner came with the wing, I have trunk lids in both versions.

I don't know for sure but it may have been option code A45.

(edit) moes pointed out that the correct code for the rear spoiler is J81. A45 is a different package; the factory rear spoiler plus added dealer installed front spoiler.

The actual factory name for it in 1970 was "Rear Spoiler", and for 1971 it was called "Aerodynamic Rear Spoiler", with the same code.

 

[TorRed]

Mine had been added on when I bought it in 74. The reason I know is mine didn't have the correct mounting hardware under the lid but since I had to replace the trunk lid it will have the correct mounting going forward. And definitely mostly for looks. I guess it could be tilted in such a way that at 100+ mph it could make a difference but in my experience anything that pushes the back down raises the front end at speed. After an impromptu 155+ ride in a 1969 Super Bee it got really creepy when the car began 'floating' in the air with everything getting too smooth like the wheels weren't running on the pavement so much. Too much air running under the front of the car makes for bad things likely to happen. The only thing that saved me (I was a passenger, not the driver) was right about the time the speedometer pegged, the engine backfired, blowing flames out of I don't know where so he let off the gas. I worried it might be the engine blowing and locking up sending the car tumbling down the road. I thank the Lord that I made it through high school alive and with all my parts.

 

[Moparfiend]

Mine had been added on when I bought it in 74. The reason I know is mine didn't have the correct mounting hardware under the lid but since I had to replace the trunk lid it will have the correct mounting going forward. And definitely mostly for looks. I guess it could be tilted in such a way that at 100+ mph it could make a difference but in my experience anything that pushes the back down raises the front end at speed. After an impromptu 155+ ride in a 1969 Super Bee it got really creepy when the car began 'floating' in the air with everything getting too smooth like the wheels weren't running on the pavement so much. Too much air running under the front of the car makes for bad things likely to happen. The only thing that saved me (I was a passenger, not the driver) was right about the time the speedometer pegged, the engine backfired, blowing flames out of I don't know where so he let off the gas. I worried it might be the engine blowing and locking up sending the car tumbling down the road. I thank the Lord that I made it through high school alive and with all my parts.

I had a similar experience except much worse 25 years ago now in my Corvette. I had a 1971 LS five 454 that I just purchased in Montana. I changed the oil before I left to drive back to Chicago. I slowly rolled on the accelerator to 155 mph. I watched oil pressure and temp the whole time which was fine. The front end got really light and the headlights came up, which are vacuum controlled not long after that, the engine quit. I pulled over to the side of the road and it spewed out all it’s coolant. I blew the engine. Spun the main bearings.

 

[R413]

Quite ugly and not doing much from aerodynamic side.
Yes optional

 

[moes]

it was an option available J81 from the factory. No functionality, it was added for looks only. Some people like it and some don't.

 

[j-c-c-62]

To keep us all on the same page, that is not a spoiler. A spoiler does exactly what its name implies, it "spoils' air flow, and creates a relatively high-pressure zone wake upstream of the spoiler, causing in most cases downforce on any nearly horizontal nearby surface. It's main downside is an increase in drag. In some certain circumstances an angled rear lip "spoiler" can also reduce some overall drag by helping air reattach after flowing over the spoiler. The rear window optimized almost flat recent SUV lips are not spoilers but reduce drag. Otherwise, air only flows and acts on one surface of a true "spoiler".

Marketing types will call anything that helps sell their product anything, accurate or not. Don't fall for that hype.

A wing, pictured, effects air on two sides and by its shape, size, and angle of attack, generates different air speeds on opposite sides and resulting in a pressure differential which generates a force that the "wing" generates. In a plane its lift, in a car its intent is downforce. It must have air movement on both sides. It's design efficiency is often qualified by the wings lift/DF vs drag ratio.

 

[dadsbee]

It was to keep the back draft dust out of the recessed tail lights! LOL DON'T DO IT !!!!

 

[RemCharger]

An aerofoil ( airfoil).

 

[mmissile]

Fugly. generic looking thing. I don't like bolt-on spoilers, but the 71 was better.

 

[Photon440]

1970 Roadrunner Factory Go wing production