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Will this mount onto the short stoc polyurethane spoiler? Or would the short one be removed and as this extension put in its place?
It mounts to the stock small spoiler. I had that one on my car before the Pace Car type spoiler:
The fiberglass Pace Car type spoiler did more for stability than this rubber one did, in my opinion.
The clincher for me to change to the Pace Car spoiler was when I had a buddy look at the rubber one for me from his car while I driving at about 90mph.....he told me that it was being significantly bent back by the air pressure!!!
Of course, if your front end mechanical parts are not in good shape or if you do not have a proper alignment, a spoiler isn't going to overcome that.
How does it handle with the pace car (indy) spoiler compared to the stock.
Originally Posted by 7t2vette
It mounts to the stock small spoiler. I had that one on my car before the Pace Car type spoiler:
The fiberglass Pace Car type spoiler did more for stability than this rubber one did, in my opinion.
The clincher for me to change to the Pace Car spoiler was when I had a buddy look at the rubber one for me from his car while I driving at about 90mph.....he told me that it was being significantly bent back by the air pressure!!!
Of course, if your front end mechanical parts are not in good shape or if you do not have a proper alignment, a spoiler isn't going to overcome that.
You are sure the "floating" isn't caused by an alignment issue or excessive steering box play?
Agreed. Even after alignment, my 1970 was floaty in the front and would drift to the right without hands on the wheel. It ended up being the power steering bias. Once adjusted, the front is now firmly planted and feels completely different through the steering wheel.
Agreed. Even after alignment, my 1970 was floaty in the front and would drift to the right without hands on the wheel. It ended up being the power steering bias. Once adjusted, the front is now firmly planted and feels completely different through the steering wheel.
the power steering VALVE has a screw adjustment in the end of it, and can be out of balance/bias by directing more assist toward the right or the left. To check it:
Jack up the front of the car, start the car with front wheels off the ground, rev the motor a bit, and see if your steering wheel and wheels turn magically to the right, or left. If they do drift either way, bias is out of adjustment.
Pull the front left wheel, pop the end cap off the steering valve with a screwdriver. Use a 7/16" (1/4" drive to fit between the lines) socket with extension, re-center and mark the top of the steering wheel with painters tape so you can see it turn, start the car and let idle, and adjust the bias. I turn it both directions until I find the two points where the pump will turn the wheels one way or the other (about 5/8 of a turn apart) and turn it back just over a 1/4 turn to the "middle". I never knew about this adjustment until someone on the forum pointed it out.
After adjustment, mine drove like a different car. Tracks straight down the road and when I turn it no longer "dives" or darts one way or the other. The steering is heavier and the front wheels feel well planted. I absolutely cannot believe how nice it is to drive.
Last edited by JoeMinnesota; 03-13-2018 at 08:54 PM.
Awesome, thank you. Guess i have a project this weekend.
Originally Posted by JoeMinnesota
the power steering VALVE has a screw adjustment in the end of it, and can be out of balance/bias by directing more assist toward the right or the left. To check it:
Jack up the front of the car, start the car with front wheels off the ground, rev the motor a bit, and see if your steering wheel and wheels turn magically to the right, or left. If they do drift either way, bias is out of adjustment.
Pull the front left wheel, pop the end cap off the steering valve with a screwdriver. Use a 7/16" (1/4" drive to fit between the lines) socket with extension, re-center and mark the top of the steering wheel with painters tape so you can see it turn, start the car and let idle, and adjust the bias. I turn it both directions until I find the two points where the pump will turn the wheels one way or the other (about 5/8 of a turn apart) and turn it back just over a 1/4 turn to the "middle". I never knew about this adjustment until someone on the forum pointed it out.
After adjustment, mine drove like a different car. Tracks straight down the road and when I turn it no longer "dives" or darts one way or the other. The steering is heavier and the front wheels feel well planted. I absolutely cannot believe how nice it is to drive.
You are sure the "floating" isn't caused by an alignment issue or excessive steering box play?
C3's are known to have a lot of lift at speed. Wind tunnel tests show it as well as just driving one really fast. You will feel it. Anything you can do to reduce lift will help these cars feel more stable at speed. Of course if there is any play in the suspension or steering it amplifies the effect and they really feel squirrely going fast.
In a wind tunnel a C3 produced 160lbs of front end lift at 100mph and more than 400lbs at 160mph.
But, even little bigger/better front spoiler can help a lot.
For example:
Original state, no spoiler - severe front end lift at speed:
Then factory made a tiny change and introduced a small front spoiler reducing lift by 40%:
BTW. I went with the spoiler in post #1. Haven't installed it yet though. Planning to make a kevlar reinforced version of it to myself to make it last a long time.
I have read and understand that the C3's have lift at higher speeds, so no argument there. In my experience, though, the front was light, darty and almost scary at anything above 70mph ... it didn't even feel great around town. The front felt light, with no play in the steering box, and it didn't improve with an alignment as I'd hoped.
After adjusting the bias it now feels well-planted at 100mph+ and really much heavier and more stable around town driving as well. I couldn't pull my hands from the wheel before the bias adjustment without the car drifting.
Last edited by JoeMinnesota; 03-14-2018 at 08:35 AM.
Even the wheelwells you are getting turbulences and by reducing the distance of the tire to the fender you limit quantity of air. Therefore if you lower, you should limit suspension travel, thus not as advisable for street operation. Lowering in a lot of instances, lowers DC, but then the spoiler could put that right back to a higher Drag Coefficient by adding one. Naturally if you plan to go fast, maybe consider putting a rake on your set up.
So does the car produce enough pressure to car weight to lift the nose into take off? Depends on set up! I definitely don't like a bouncy bouncy suspension letting unpredictable air under the chassis to lift it, so I like heavy springs and married shocks. If I am going to flip, I would rather at least had good handling up to the point of lift off!
Last edited by TCracingCA; 03-14-2018 at 04:25 PM.
this is what i am working with On my 69. It has about a 3 inch lip.
I cant believe that NO aftermarked Corvette fiberglass parts supplier ever rebuild this exact 68 - 72 chin lip as an Extended to the ground (like the rubber lip you have to Pop rived on) fiberglass Version with the original mounting brackets so you could Exchange the lips... The Pop rived lip doesnt look right (factory) to me. Even tho i am Aware it was on the late L82`s...
I bought mine from a GM dealer in 1990 after noticing the spoiler extension on a 79 in 1989 while at a car show. I went to a local Chevy dealer parts department and ordered mine (which is still the GM one that I ordered today on the car), waited a week or so for it to come in, and went and picked it up. The parts guy told me at the time that the L-82's with Heavy Duty cooling only got the spoiler extension from the factory and years went by before I ever saw the spoiler extension on a non 79 C3. I originally was chasing a cooling issue with my L-82 and the reason I purchased the spoiler extension......It solved the heat issue at speed with my L-82. The 79 Only with this spoiler extension with the heavy duty GM cooling package also came from the factory with an electric fan mounted inside the lower mechanical fan shroud area inside the hood in the engine bay that came on only periodically for additional airflow when the car was not at speed. I recall paying $20 for the piece from GM in 1990! The spoiler extension was mounted by me in 1990 with aluminum bolts/nuts that I bought from a local hardware store and has never been touched by me since then...stainless screws and nuts were hard to come by in 1990 and I was looking for a light weight fastner that would not rust. You can see in this picture from 2017 that my diligence paid off...no rust!
This is a GM spoiler^^^^^^^^^^^^^^^
As shown on my picture above and in the Willcox renditions previously, the GM extension has a split midline to allow for this rubber piece to flex if it encountered any contact with road obstacles. It was never intended to be a "spoiler" in the true definition of the word reducing drag and lift. Remember that this piece was a 1 year ONLY option, 1979 L-82's with heavy duty cooling ONLY, that also came with the factory auxiliary electric cooling fan inside the mechanical fan shroud, for additional cooling for the L82's that ran right from the factory, very high coolant temps...normal temp for a 4 speed L-82 was 225 and with AC on a hot day, 1978 and 1979's without HD cooling could run 240 degrees. The 1978 L-82s heat issues were the reason for the 1979 only option of the rubber spoiler extension. Since this extension was used only in 1979 AND was NOT installed on many L-82's was probably the reason that it was pop riveted on as an afterthought...................there were very few 1979 L-82's that had this spoiler extension whose sole purpose was to increase the airflow directed to the radiator to reduce the coolant temps at normal highway speeds, not uber high speeds. This factory piece extension's objective ^^^^^^^^was to aid with cooling at speed, nothing more. Of course making it much more rigid can change its effect at speed but it really is not practical for street driving since you can see that the bottom of the extension is VERY close to the roadway and needs to be flexible.
Note-I have not once bottomed it while driving, just an occasional slight scrap with some driveways on my 78 that is about 2-3 inches lower in the front versus the factory ride height.........with the spoiler extension. Also, the GM spoiler extension on my car does NOT flex visually at 80-90 MPH...can't say above those speeds which I do not drive at with this car on the highway....
I have the 3 piece pace car spoiler on mine, I did a flat bottom on it to protect it from road rash but maybe it helps with lift also, I don't know but I like the look
I have the 3 piece pace car spoiler on mine, I did a flat bottom on it to protect it from road rash but maybe it helps with lift also, I don't know but I like the look
Thanks for posting that. I need to do something along the lines of that or what beejay has done with his splitter - my car is low, and I've scuffed my pacecar spoiler badly since fitting it only 6 months ago! I'm glad I went with urethane instead of fibreglass...
What did you use for the bottom surface?
Last edited by Metalhead140; 03-15-2018 at 07:47 PM.
I agree with lowering the front. Mine has a definite rake and is way more planted at high speeds than it was.
I'd be curious how those lift figures would be affected by a rake.
Thanks for posting that. I need to do something along the lines of that or what beejay has done with his splitter - my car is low, and I've scuffed my pacecar spoiler badly since fitting it only 6 months ago! I'm glad I went with urethane instead of fibreglass...
What did you use for the bottom surface?
I made a one like BeeJay but out of hdpe plastic I bought from Menards, hardware and spacers to keep from over tightening it, I havent found the right splitter supports for it though.
BTW. I went with the spoiler in post #1. Haven't installed it yet though. Planning to make a kevlar reinforced version of it to myself to make it last a long time.
Thanks for posting that. I need to do something along the lines of that or what beejay has done with his splitter - my car is low, and I've scuffed my pacecar spoiler badly since fitting it only 6 months ago! I'm glad I went with urethane instead of fibreglass...
What did you use for the bottom surface?
It's a 5mm plastic, got it from work, it's used on the tractor for protection from rocks and such so it's very sturdy
All i wish for is something like the early Camaro or VW Rabbit MK1 had (had one of These pocket rockets ) These were made of ABS Plastik and worked great for downforce and cooling... It would have to use the OEM mounting Points of the chin "Spoiler" lip, so it could be a clean replacement. VW also offered from the factory a short lip for the base "Rabbit" and the Extended Version for the "GTI". Both had the same mounting Points to the cars Body! That would be perdect to me and look well... Cant anybody build one like that?
03-13-2018, 04:32 PM
) These were made of ABS Plastik and worked great for downforce and cooling... It would have to use the OEM mounting Points of the chin "Spoiler" lip, so it could be a clean replacement. VW also offered from the factory a short lip for the base "Rabbit" and the Extended Version for the "GTI". Both had the same mounting Points to the cars Body! That would be perdect to me and look well... Cant anybody build one like that?