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If your wing only attaches to the stock wing area mount points that's definitely not enough. Here's my Kognition trunk plates. The use the stock holes and add one more towards the middle.
https://cimg0.ibsrv.net/gimg/www.evo...1a06d5a52.jpeg Also my trunk is solidly mounted using threaded spacers and elevator bolts. The bolts that go through the base plate have threaded female spacers on the inside and elevator bolts threaded into the other end which give a larger contact patch to transfer the force into the chassis. My trunk doesn't sag or bend at all if people sit on it, once the elevator bolts are set to the right length the only way the trunk latches is if you slam it pretty good. https://cimg1.ibsrv.net/gimg/www.evo...3c6451526.jpeg |
Originally Posted by ayoustin
(Post 11881974)
That pic looks like it's just your suspension compressing...
Chassis mounts are nice for a few reasons but trunk mounts work a lot better than you guys make it out to be. The key is to solid mount the trunk. I've had my Kognition solid trunk mounted for over 3 years now, ran it as high as 25* AOA and it's never once moved the trunk metal. The only time I ever tell people that a chassis mount is mecessary is when they're running a thin/light carbon trunk. Otherwise, just brace the trunk properly and save yourself the hassle of having to chop **** up for a chassis mount. Oh, and the Spage stuff is very nice. Seen a couple wings in person and the quality is awesome, but do realize that doesn't come with mounts or uprights so plan to spend another $3-500 for those as well. Compare the sticker and the wing end plates to the shape of the top of the guard. i tried to find a stationary picture to compare with but basically the wing is twisting backwards on the bootlid by about 15deg |
Originally Posted by deeman101
(Post 11881979)
I can buy the trunk bending issue but not the "absorbs down force" reasoning unless the wing's angle of attack changes as the trunk is bending or the wing element is bending due to trunk skin flex. I'm not an aerodynamics or auto engineer but I have to assume the classical physics that I know for my job works the same in all situations. Transient response forces aside (which is likely much shorter time scales than your car accelerates up to speed and your wing builds downforce), once steady state is reached the force on trunk mounted wing is the same as chassis mount UNLESS the place where you chose to direct your wing's force through your chassis is different. That is where you can get more perceived downforce but also have to worry about pitching up the front. I'd assume trunk mount wings average out into putting most of the downforce directly through the rear coilovers down. If you chassis mounted to the rear bumper beam area, then the effective force through the rear coilovers will be more for the same amount of downforce, but will also tend to pitch up your front end (assymmetrical see-saw basically). In essence trading away front downforce for the rear at speed. If you chassis mount to the shock towers in the rear then I wouldn't expect any actually downforce advantage over the rear.
Why this matters to me is basically I don't want to cut into the body/trunk to do a chassis mount over looking at reinforcing the trunk mount. Also shows that companies like voltex were not out to lunch with their trunk wing mounts. Which method is right depends on the context but with people trying to design their own aero here it needs to be clear what are the pros and cons of chassis mount and how to do it best. Pretty much the wing twists which changes the angle of attack. Its also basic energy physics. all ur boot seals and the flex in ur panels etc will absorb some of this energy being applied in a downwards direction in the form of downforce. On a trunk-mounted wing, you might lose one or two degrees of AOA if the trunk lid exhibits any sign of travel or distortion. In some cases, this distortion may be permanent and will not only set your wing at an improper angle or height but may also continue to distort the trunk until the surface fails and the wing, lid or both fly off. Even in less extreme cases, the 1⁄4 to 1⁄2 inch of travel that your trunk can migrate effectively induces a time delay that causes you to lose critical downforce when it is needed. If personal preference or class rules require you to run a trunk-mounted wing, be sure to add some type of damping or filler to the rain gutters to minimize the amount of travel. You also save weight in ur bootlid by being able to run a very light weight lid vs having a reinforced to africa lid to prevent the above ^ BTW you dont need to cut anything really to chassis mount. We made some towers up that mount to the chassis rails at the bottom and then theres 2 bolts per side which go through the trunk lid and screw down into these towers Couple little WTAC nuggets of spoilers failing including the voltex one you mentioned. the cyber evo was the real deal voltex built car and its trunk mounted wing failed at WTAC. Both wings were voltex, Cybers was the real deal voltex not sure about the second clip. both appear to fail at the bootlid area. I was there the year that the Cyber one failed and it literally tore the mounts out of the skin of the bootlid. granted it was a carbon lid but still if it was bolted to the chassis i doubt this would have happened. All in all if ur doing auto X or just a fast street car dabbling in a lil bit of track stuff its probably not worth bothering about but it will scare the **** out of you if it does fail one day. and could potentially put ya in a wall if u get a big enough aero inbalance. |
No wing, unless you're running something insane like a triple element making upwards of 800lbs of downforce will cause a catastrophic failure of a steel trunk. Trunk mounts are easy and work, they just need to be done right.
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Ciro actually has a provision on the front of the mount to install a hood pin into the drip rail to stop the wing from pulling up on the trunk. I eventually plan to use that hood pin mount and something more along the lines of Austin's adjustable rear mount to solidify the back of the trunk. I can understand not liking the AOA changes that come from the rubber flexing but the forces are still being transferred to the car.
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Originally Posted by ayoustin
(Post 11882037)
No wing, unless you're running something insane like a triple element making upwards of 800lbs of downforce will cause a catastrophic failure of a steel trunk. Trunk mounts are easy and work, they just need to be done right.
Originally Posted by terror rising
(Post 11882040)
Ciro actually has a provision on the front of the mount to install a hood pin into the drip rail to stop the wing from pulling up on the trunk. I eventually plan to use that hood pin mount and something more along the lines of Austin's adjustable rear mount to solidify the back of the trunk. I can understand not liking the AOA changes that come from the rubber flexing but the forces are still being transferred to the car.
Youd be surprised how much force is actually applied, we used a small quik latch style latch originally and it tore the guts out of the latch after a round of competition. The load still transfers but theres still losses compared to if it was directly mounted. think of it as if your pushing something heavy directly vs putting a spring in between yourself and the thing your pushing. sure u can still push it but first youve got to overcome that spring. essentially the same thing happens with the rubbers and the rest of the flex which you must overcome before the rest of the load transfers into the chassis. |
Maybe your evos are different but in the US the stock trunk is steel
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When I use to run Voltex trunk mont wing I had a go pro camera facing the rear and there was at least 1/2 to 3/4" deflection on the trunk around 115 mph, It was crazy.
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Originally Posted by Kidloco51
(Post 11882057)
When I use to run Voltex trunk mont wing I had a go pro camera facing the rear and there was at least 1/2 to 3/4" deflection on the trunk around 115 mph, It was crazy.
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Originally Posted by bee-raddd
(Post 11882043)
The load still transfers but theres still losses compared to if it was directly mounted. think of it as if your pushing something heavy directly vs putting a spring in between yourself and the thing your pushing. sure u can still push it but first youve got to overcome that spring. essentially the same thing happens with the rubbers and the rest of the flex which you must overcome before the rest of the load transfers into the chassis. Hearing the trunk skin issues people have been having though is interesting. Initially I was thinking of using 3D printed blocks to put into the rain gutters for extra trunk support. But maybe more needs to be done to reinforce the middle too. I would also agree that running a wide wing base if trunk mounting is a must. |
I have warpage around my APR mounts. Stock trunk. I was at the top of 4th and a bit into 5th gear on a 6spd, so however fast that was. So, the damage is real. Looks like the front of the mounts have pulled the metal up a bit.
After adding the splitter, I'm definitely going to find a way to brace the wing since I'll be upping the AOA. Hopefully while still being able to open the trunk, seeing how I still use it. |
I'm curious what other people are using for baseplates. I've not heard of bent trunk lids, I've seen plenty of carbon ones fail but the factory ones are stout, just need to distribute the load across as much area as possible.
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Originally Posted by ayoustin
(Post 11882094)
I'm curious what other people are using for baseplates. I've not heard of bent trunk lids, I've seen plenty of carbon ones fail but the factory ones are stout, just need to distribute the load across as much area as possible.
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Originally Posted by Kidloco51
(Post 11882057)
When I use to run Voltex trunk mont wing I had a go pro camera facing the rear and there was at least 1/2 to 3/4" deflection on the trunk around 115 mph, It was crazy.
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