Marchev
10+ Year Contributor
- 390
- 74
- Jan 31, 2009
-
Niles,
Illinois
Here is something I've been working on over the last week, I did not see much covering this topic so figured I would share.
Little background:
This car has been a dedicated road race and some autox machine. I compete in the midwest SCCA time attack/time trial and constantly working to improve the car as there are lots of very fast cars in my class. Beginning of this year I installed custom valved Ohlins suspension built by Muellerized and after some seat time and playing with the settings on the suspension, some problems started becoming very apparent.
Issues with handling:
The rear end of the car is very light compared to the front. When I got the car corner balanced it showed how light the rear was. Total weight was 2650 with half a tank. On track that resulted in the rear being unstable in high speed corners, and especially in quick transitions. Racing in rain only over exaggerated the problem and made the car difficult to drive.
Part 2 of the problem was braking and tire wear. Since the rear was so light, I could only apply little rear brake bias otherwise the rear tires would just lock up. That makes my braking distance longer as 90% of my braking was done with the fronts, which translated into changing the front Wilwood pads every 3 events, yet the rear pads would last me 3 years. My idea was to keep the car as leveled as possible during hard braking so I can put more brake pressure to the rear, which would make my braking distance shorter. So somehow I had to add more weight to the back, without actually putting weight in the trunk.
Tire wear confirmed the same theory as even with just -1.7* camber in the back, the pyrometer showed that the inner tire edge was significantly hotter than the outer.
My solution:
Put a functional wing that would add a few hundred pounds of downforce at speed, and also a front splitter so we keep the car balanced. I chose to go with APR GTC-300 adjustable wing for an Evo 8-9. It was the right size and surface area to be legal in my class. I liked it because the mounts were wide enough to be mounted to the quarter panels of the car (as close to chassis mount as I was going to get) and also it felt way sturdier than one that had the mounts closer together. It is also a 3D Airfoil design, which is way more efficient when mounted approximately same height as the roofline. It also made my rear hatch only able to open about a foot, which I didn't use anyway.
Here is the progress:
After removal of the side spoiler trim pieces, I started by grinding the paint off so I can weld reinforcements. That area is sturdy close to the edges, but flimsy in the middle due to thin metal, and all the holes that are drilled for the side spoiler mount, and antenna hole. It is a good area to mount a wing to because it is welded to the rest of the chassis\body of the car.
Next TIG weld a thicker plate on top
After welding it complete I was surprised how sturdy the area became. I was able to put my hole body weight on one fist at any point of the plate with no noticeable fluctuation. Exactly what I was looking for.
Next comes the hard part. Since the body there is at a slight angle, about 10 degrees sideways, and 8 degrees backwards, I had to make a wedge that was multi angled. The wedge had to keep the wing at proper height as well as give it a proper angle of attack (AOA). Onto the bridgeport I went:
Notice how the wedge has a 10 degree sideways angle as well as an 8 degree forward angle in order to give an approximately straight mounting surface to the wing base. I was aiming to make the wing have more of a forward angle since it had plenty of adjustability leaning backwards.
This picture makes the angle look extreme but it was actually almost perfectly in line with the middle spoiler when looked at directly from the side. I was really happy how these came out, they sat almost 100% flat. I had to take a grinding wheel to a couple of areas in order to achieve complete contact. The welded plates underneath weren't 100% flat, as they contoured to the curves of the body in that area.
Next a quick layer of paint, and ready for mounting!
Next I had to cut holes into the side spoiler pieces, these did not come out the prettiest and I will work on making some kind of a cover for the holes. Shoot me some ideas!
It was difficult to measure exactly where the wing will sit, but I did the best I can
I had to bolt the side spoiler pieces to a different location since the original mounting spots were now welded over.
And final mounting!
I had drilled holes through the mounting plates and wedges, and had it bolted down with studs and large fender washers on the bottom side. It is surprisingly sturdy. I can rock the car left to right by pulling on one mount with little to no deviation from the mount itself. Great success! Ha
Now onto the front of the car!
I started with a sheet of 4'x8' of .5" thick alumalite sheet. Its very sturdy and light material with 2 thin aluminum sheets on each side with plastic weaved like cardboard pattern in between. In my class I am allowed to have a splitter up to the middle of the centerline of the front wheels. Also it can not stick out more than 3" from the front of the car. So I went under and started taking measurements. After having the rough shape moched up, I cut it up. Then I used multiple rivnuts aka threaded inserts, on the subframe to give me a rigid mounting points.
Then I traced 3" around the bumper, tapering down at the ends and went to work.
This is the final shape:
Next I worked on attaching my flimsy bumper onto the splitter. This added rigidity to the bumper as well as eliminated gaps between the bumper and splitter. Rivnuts came in super handy
I used some thin aluminum diamond plate to curve around the edges of the bumper. The plate is riveted to the bumper itself, and bolted to the splitter with the rivnuts for easy removal of either piece.
I also utilized the front threaded rods to hold the splitter in the front. Those rods are threaded into the front bumper support and held the air duct that allows cool air to go under the intercooler and directly to the radiator.
And all done!
I'm expecting to even see some help in the cooling department with this splitter because it traps the air in front of the intercooler and not allowing it to go under the car. Up next I'll be working on making air dams with ducting through the fog light holes leading to the front brakes. As well as some more ducting from the intercooler to the bumper.
I will keep this thread updated as the next time attack event is coming up in a week at the same track as before. So that will give me direct comparison since nothing else was changed on the car.
Anything else you guys think I can improve on?
Little background:
This car has been a dedicated road race and some autox machine. I compete in the midwest SCCA time attack/time trial and constantly working to improve the car as there are lots of very fast cars in my class. Beginning of this year I installed custom valved Ohlins suspension built by Muellerized and after some seat time and playing with the settings on the suspension, some problems started becoming very apparent.
Issues with handling:
The rear end of the car is very light compared to the front. When I got the car corner balanced it showed how light the rear was. Total weight was 2650 with half a tank. On track that resulted in the rear being unstable in high speed corners, and especially in quick transitions. Racing in rain only over exaggerated the problem and made the car difficult to drive.
Part 2 of the problem was braking and tire wear. Since the rear was so light, I could only apply little rear brake bias otherwise the rear tires would just lock up. That makes my braking distance longer as 90% of my braking was done with the fronts, which translated into changing the front Wilwood pads every 3 events, yet the rear pads would last me 3 years. My idea was to keep the car as leveled as possible during hard braking so I can put more brake pressure to the rear, which would make my braking distance shorter. So somehow I had to add more weight to the back, without actually putting weight in the trunk.
Tire wear confirmed the same theory as even with just -1.7* camber in the back, the pyrometer showed that the inner tire edge was significantly hotter than the outer.
My solution:
Put a functional wing that would add a few hundred pounds of downforce at speed, and also a front splitter so we keep the car balanced. I chose to go with APR GTC-300 adjustable wing for an Evo 8-9. It was the right size and surface area to be legal in my class. I liked it because the mounts were wide enough to be mounted to the quarter panels of the car (as close to chassis mount as I was going to get) and also it felt way sturdier than one that had the mounts closer together. It is also a 3D Airfoil design, which is way more efficient when mounted approximately same height as the roofline. It also made my rear hatch only able to open about a foot, which I didn't use anyway.
Here is the progress:
After removal of the side spoiler trim pieces, I started by grinding the paint off so I can weld reinforcements. That area is sturdy close to the edges, but flimsy in the middle due to thin metal, and all the holes that are drilled for the side spoiler mount, and antenna hole. It is a good area to mount a wing to because it is welded to the rest of the chassis\body of the car.
You must be logged in to view this image or video.
Next TIG weld a thicker plate on top
You must be logged in to view this image or video.
You must be logged in to view this image or video.
After welding it complete I was surprised how sturdy the area became. I was able to put my hole body weight on one fist at any point of the plate with no noticeable fluctuation. Exactly what I was looking for.
Next comes the hard part. Since the body there is at a slight angle, about 10 degrees sideways, and 8 degrees backwards, I had to make a wedge that was multi angled. The wedge had to keep the wing at proper height as well as give it a proper angle of attack (AOA). Onto the bridgeport I went:
You must be logged in to view this image or video.
You must be logged in to view this image or video.
You must be logged in to view this image or video.
Notice how the wedge has a 10 degree sideways angle as well as an 8 degree forward angle in order to give an approximately straight mounting surface to the wing base. I was aiming to make the wing have more of a forward angle since it had plenty of adjustability leaning backwards.
You must be logged in to view this image or video.
This picture makes the angle look extreme but it was actually almost perfectly in line with the middle spoiler when looked at directly from the side. I was really happy how these came out, they sat almost 100% flat. I had to take a grinding wheel to a couple of areas in order to achieve complete contact. The welded plates underneath weren't 100% flat, as they contoured to the curves of the body in that area.
Next a quick layer of paint, and ready for mounting!
You must be logged in to view this image or video.
Next I had to cut holes into the side spoiler pieces, these did not come out the prettiest and I will work on making some kind of a cover for the holes. Shoot me some ideas!
It was difficult to measure exactly where the wing will sit, but I did the best I can
You must be logged in to view this image or video.
I had to bolt the side spoiler pieces to a different location since the original mounting spots were now welded over.
And final mounting!
You must be logged in to view this image or video.
You must be logged in to view this image or video.
I had drilled holes through the mounting plates and wedges, and had it bolted down with studs and large fender washers on the bottom side. It is surprisingly sturdy. I can rock the car left to right by pulling on one mount with little to no deviation from the mount itself. Great success! Ha
Now onto the front of the car!
I started with a sheet of 4'x8' of .5" thick alumalite sheet. Its very sturdy and light material with 2 thin aluminum sheets on each side with plastic weaved like cardboard pattern in between. In my class I am allowed to have a splitter up to the middle of the centerline of the front wheels. Also it can not stick out more than 3" from the front of the car. So I went under and started taking measurements. After having the rough shape moched up, I cut it up. Then I used multiple rivnuts aka threaded inserts, on the subframe to give me a rigid mounting points.
You must be logged in to view this image or video.
Then I traced 3" around the bumper, tapering down at the ends and went to work.
This is the final shape:
You must be logged in to view this image or video.
Next I worked on attaching my flimsy bumper onto the splitter. This added rigidity to the bumper as well as eliminated gaps between the bumper and splitter. Rivnuts came in super handy
You must be logged in to view this image or video.
I used some thin aluminum diamond plate to curve around the edges of the bumper. The plate is riveted to the bumper itself, and bolted to the splitter with the rivnuts for easy removal of either piece.
You must be logged in to view this image or video.
I also utilized the front threaded rods to hold the splitter in the front. Those rods are threaded into the front bumper support and held the air duct that allows cool air to go under the intercooler and directly to the radiator.
You must be logged in to view this image or video.
And all done!
You must be logged in to view this image or video.
I'm expecting to even see some help in the cooling department with this splitter because it traps the air in front of the intercooler and not allowing it to go under the car. Up next I'll be working on making air dams with ducting through the fog light holes leading to the front brakes. As well as some more ducting from the intercooler to the bumper.
I will keep this thread updated as the next time attack event is coming up in a week at the same track as before. So that will give me direct comparison since nothing else was changed on the car.
Anything else you guys think I can improve on?
Last edited: