Is the sheet clear? If it's Lexan (polycarbonate) you can bend it almost like aluminum. If it's Plexiglas (acrylic) it will break.
Aero improvement, or roadhugging weight?
- Thread starter 69427
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69427
The Artist formerly known as Turbo84
The stuff is smoked (I haven't tried to scratch it to see if it's more than just skin deep). I'll try to bend a small section later to see what happens, but it appears to have been part of a display case so I'm guessing it's just plexiglass.
I'll also heat and bend a small section to see if that works out.
69427
The Artist formerly known as Turbo84
Made a little progress today. Got the splitter/forward pan roughed in. It's 52" wide by 48 inches long. The angle of the photo doesn't show how far forward the PC spoiler front lip is. It's amazing how much area I had to cut away to clear the tires at full lock.
Still have some clearance cuts to make around the LCA pivots. Also, it looks pretty straightforward to find several areas to position hanger brackets to support the sheet. I'm mulling over riveting some side fences around the thing to discourage the top and bottom air from mixing easily.
I hope this thing earns its keep. While it's only 7 pounds, I hate adding weight to the car, especially when it's centered over the front axle.
phantomjock
Well-known member
It looks great from this angle.
It would be so kind of you to share a sketch with dimensions in the downloads section - or here before you mount it more or less permanently.
The Notch for the oil pan may be a bit different - but the wheel clearance, etc would be close I'd wager.
Cheers - Jim
It would be so kind of you to share a sketch with dimensions in the downloads section - or here before you mount it more or less permanently.
The Notch for the oil pan may be a bit different - but the wheel clearance, etc would be close I'd wager.
Cheers - Jim
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69427
The Artist formerly known as Turbo84
No problem with posting up the dimensions of this when I get it finished. Please remember that the dimensions are for mounting under an aftermarket PC spoiler (early C3), and that my front crossmember lower surface is very different shape (flat, versus round) which allows the tray to extend back to the oil pan.
turtlevette
The Turdle
It will be very interesting to test that. Do you have a place where there is a decently long straight where you get up to 150+? That may trap air underneath the front and make it want to take off.
I took off the lower valance with spoiler opening up the underside of the front nose and surprisingly enough the high speed stability got better. I'm guessing 135 achieved by my wimpy motor on the Mosport straight.
I took off the lower valance with spoiler opening up the underside of the front nose and surprisingly enough the high speed stability got better. I'm guessing 135 achieved by my wimpy motor on the Mosport straight.
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Twin_Turbo
Der Maulwurf
- Joined
- Mar 5, 2008
- Messages
- 7,579
To stop it from doing that you will need to fab a splitter up front to direct air away from the car, easiest done by extending the lower air dam with something like a garage door sealer strip.
69427
The Artist formerly known as Turbo84
Well, 130-140 (indicated) is all I've seen at the tracks I've been to (I make no claims to the accuracy of my speedo at track speeds).
I don't see where trapped air is going to be a worse issue than before. Given the rough underbody shape of the (stock) volume just prior to the front crossmember, this flat tray ought to reduce the amount of air that gets trapped in there.
Here's an old picture of when I was swapping the body onto the modified frame. This gives a little better view of the front of the spoiler. Note that it has about a 4-5" horizontal section that acts like a modest splitter. The tray I'm putting in just helps improve the function of the splitter.
While I've been messing with the tray installation I've been kicking around putting a couple vanes/fences underneath it to direct a little more air to the rotors. If I can get it right it ought to help brake cooling a touch, and also reduce the volume of air that eventually reaches the underfloor area.
68/70Vette
Well-known member
What about the rear of the car? It's like a cookie cutter upside down for aerodynamics. I'd don't have spare tire carrier. I've thought about an aluminum floor pan extending from the rear axles back to the end of the car.
Looks like you've a Richmond tranny or maybe the Doug Nash predecessor. Five speed or six speed?
Thanks
Looks like you've a Richmond tranny or maybe the Doug Nash predecessor. Five speed or six speed?
Thanks
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69427
The Artist formerly known as Turbo84
Nash 5spd. Swapped out the original 3.70 rear and have been bouncing back and forth between 3.08s and 2.73s.
I'm still trying to figure out what can be done at the rear. Most of the airflow at that point is probably going to be pretty turbulent. Right now I'm just concentrating on trying to minimize the quantity of air that makes it back that far.
69427
The Artist formerly known as Turbo84
Got the undertray and brackets pretty much done. Just need to get some correct length bolts to tidy things up a touch. I'd like to put some end-fences on it, but I think I'll make a few pressure measurements on it first. Had a few minutes to kill today so I cut out a replacement rocker panel out of the scrap plastic sheet to see what it would look like. It's two inches deeper than the stock rocker.
If it doesn't look too out of place once the car is back on the wheels I'll sand the panels down and put a coat of black paint on them. I like to keep the mods unnoticeable if possible but I don't know if this one will be.
If it doesn't look too out of place once the car is back on the wheels I'll sand the panels down and put a coat of black paint on them. I like to keep the mods unnoticeable if possible but I don't know if this one will be.
69427
The Artist formerly known as Turbo84
Got a couple more things done. The tray is installed other than three bolts through the leading edge to secure it to the spoiler. While I was fastening things I thought I'd try diverting a little of the air to help cool the brakes, and reduce the amount of air that goes under the car. The front wheels do get noticeably dirty with brake dust under hard use, so I'm assuming that the front spoiler kicks out enough side air to cause a low pressure area outside the wheels. Hopefully this will allow an increase in the volume of air exiting the wheel well area. I just took a couple pieces of scrap aluminum angle stock (1 1/2 x 1 1/2) and bolted it to the bottom of the tray. I painted them black so they wouldn't be noticable from the front view (when the car is on the ground).
I also quick sanded the rocker material and put a coat of semi-gloss black on it. It doesn't look too out of place, so I think I'll cut one out for the passenger side. (Please pardon the mess.)
The two pieces of aluminum angle at the back of the wheelwell are for a small air dam to inhibit air from being trapped in the area between the frame and the rocker.
I'm also playing around with a flat panel under the transmission. Right now it's just clamped up there, and I still need to get some of the shape figured out.
I'm trying to get this finished so I can do another track day in the next couple weeks.
I also quick sanded the rocker material and put a coat of semi-gloss black on it. It doesn't look too out of place, so I think I'll cut one out for the passenger side. (Please pardon the mess.)
The two pieces of aluminum angle at the back of the wheelwell are for a small air dam to inhibit air from being trapped in the area between the frame and the rocker.
I'm also playing around with a flat panel under the transmission. Right now it's just clamped up there, and I still need to get some of the shape figured out.
I'm trying to get this finished so I can do another track day in the next couple weeks.
mrvette
Phantom of the Opera
MESS,? I don't see any MESS, I DO see evidence of work being done.....
rtj
Well-known member
- Joined
- Nov 5, 2011
- Messages
- 2,972
Greenwood's Spirit of 76 car had a nicely done front end and air dam. He used the rubber strips to get the spoiler as low as possible.
I think my car would overheat in FL with that aluminum panel under the front end. But, if it works for you that is all that matters.
I found the rubber/vinyl baseboard trim works really well for side skirts and front air dams. It comes in long rolls, many colors, and is pretty tough. You only have to trim off the rolled edge that is intended to blend to the floor when used as a baseboard trim.
I think my car would overheat in FL with that aluminum panel under the front end. But, if it works for you that is all that matters.
I found the rubber/vinyl baseboard trim works really well for side skirts and front air dams. It comes in long rolls, many colors, and is pretty tough. You only have to trim off the rolled edge that is intended to blend to the floor when used as a baseboard trim.
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69427
The Artist formerly known as Turbo84
MESS,? I don't see any MESS, I DO see evidence of work being done.....
I appreciate it Gene.
(I keep telling myself that when I get caught up I'm going to do a major cleanup/sweepup of the shop, but I never seem to get caught up.
)68/70Vette
Well-known member
Couple of comments: I've heard that the Doug Nash 5 speed is much stronger than the Richmond 5 speed. (For people that don't know, Nash went bankrupt and his tranny design and patents were bought out by Richmond Gear. One patent they particularly wanted, or so I've been told, is the split case design of the Nash. Richmond now sells this tranny under their own name.) However the story goes, that in order to keep the price of the "Nash now know as Richmond" tranny down, they downgraded the gear strength quality. I was able to read some internet blogs saying the Richmond wouldn't withstand high horsepower Big Blocks. The owners manual for the Richmond states that its torque limits are 450 ft-lbs. This seems to substantiate a claim that the Nash has been downgraded. It's marketing was targeted to competition cars. For my 70, I was going to use a Richmond 5 speed and a 3.08:1 rear end. As a result of the realization that the Richmond was only a 450 foot pound tranny, I bought a TKO600 5 speed, 650 foot pounds rated, and also switched to a 3.73:1 differential ratio. The TKO's 5th gear is a 0.64 overdrive so I won't have to be spinning the engine excessively on the freeway. The TKO 600 is THE perfect tranny for a C3 in that it's first four gear ratios closely mimic the Muncie 4 speed. What's not so great for the TKO 600 is that in kit form for a C3, it's got a price tag of $3500. I've never shifted the Richmond 5 speed under power. I have a lot of experience shifting the Doug Nash. A new Doug Nash (circa 1975) is an absolute bear to shift , mine loosened up a little as I drove it. The TKO 600, now in my 68, is just so nice to shift. Very short throws, almost just wrist motion, and the gear patterns, repeat.. are nice for me. A 3.55:1 in my 68 means stock Muncie response in the lower four gears, and then at highway cruising ...5th gear..bam. 2.27:1 cruise.
second comment: I have the spare tire tubs out of my 68 and 70. I'm driving the 68 with a giant upside down cookie cutter in the rear for aerodynamics. (The 70 is not drivable). I'm thinking a flat surface would be great for aerodynamics.
I read you're concerned with turbulent airflow under the front of the car. I'd think the turbulent airflow under the rear might be just as important. Also, if achieve some nice laminar airflow under the front of the car, will that aerodynamically unstabilize the front end? Seems like turbulent airflow under the nose of the car would help prevent the nose lifting.
Sometime around 1980, Gale Banks set a Bonneville speed record for a stock bodied automobile. (Gale Banks is alive and well today selling turbo kits for trucks). The stock bodied automobile was a 1968 Corvette Convertible with a hard top. The body was pristinely stock. What was underneath was not. He had a twin turbo charged 427 engine producing 1200 hp. The front radiator was removed an in it's place was a 50 gallon water ballast tank (400 pounds). The front end of the car was dropped to about an inch (2 inches?) above the pavement (i.e. salt). I forget, but he went something like 240 mph. I saw the car and talked to Gale about it. I have always been impressed about the 400 pounds of weight up front. Keeps the nose down, and the center of gravity of the car way in front of the aerodynamic center of pressure.
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denpo
Carburated Nihilist
That was good reading thank you.
FIY there's one NASH 4+1 for sale on Ebay
All the replacement part I see are straight cut gears, was the NASH like the M22?
FIY there's one NASH 4+1 for sale on Ebay
All the replacement part I see are straight cut gears, was the NASH like the M22?
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69427
The Artist formerly known as Turbo84
Couple of comments: I've heard that the Doug Nash 5 speed is much stronger than the Richmond 5 speed. ........................
Here's a picture of the Nash when I had it apart. I mismatched the RPM during a 4-3 downshift with sticky tires and sheared a few teeth off the third gear set when the rear tires chirped.
I don't know anything concrete about the strength issue. All I can offer is that this transmission shifts like a truck tranny, while my Richmond 6spd in my '84 is much smoother. Can't really explain the reasons.
second comment: I have the spare tire tubs out of my 68 and 70. I'm driving the 68 with a giant upside down cookie cutter in the rear for aerodynamics. (The 70 is not drivable). I'm thinking a flat surface would be great for aerodynamics.
I read you're concerned with turbulent airflow under the front of the car. I'd think the turbulent airflow under the rear might be just as important. It is. It's just harder to eliminate the turbulence after the air has traveled 12 feet under the car on its way to the rear axle area. Also, if achieve some nice laminar airflow under the front of the car, will that aerodynamically unstabilize the front end? Seems like turbulent airflow under the nose of the car would help prevent the nose lifting. I would believe it would be the opposite.
..........................................
I would love to clean up the rear underdeck area (volume), but that would take a ton of work. Right now the biggest (and easiest) improvements I think I can make in back is cleaning up the front area (thereby reducing some of the negative effects downstream) and reducing the amount of air that actually ends up entering the rear underdeck area.
denpo
Carburated Nihilist
Thanks, tranny case closed.
I'm truly curious about the result of your aero experiment.
Excellent thread.
I'm truly curious about the result of your aero experiment.
Excellent thread.
redvetracr
Well-known member
I`m curious about one thing...how do you plan on sliding a jack under the car at the race track in case you have to bleed a caliper or change a tire?