APR wing mount question
 

So I am looking at upgrading my current extruded aluminum dual-element APR wing to something with a better profile. There are a lot of used carbon skin APR wings available out there for not much money.

My wing mounts are already built on the car, not a trunk mount. Problem is, they are not at the usual upright attachment spacing that APR uses on their wings. So, if I get an APR wing I'll have to add new attachment points on the wing for the uprights.

I did this on the aluminum wing I have now and it was pretty straightforward, just a matter of rivets and skins. But I have not done this on a composite wing. Based on what I have seen the composite wing skins are really thin, and there is usually a foam core to contend with. So I am thinking it will require something different, like bonded-in hard points for hardware attachment.

Anyone ever done this? I'm looking for suggestions. Note that valid responses do not include "Just buy Emilio's GTC wing and be done with it."

Are you looking for Miata specific wing or the universal one ?

Wondering if 42,5" can fit at the edge of trunk/quarter.

Any pictures of your current setup?

Universal

It is a rear panel mount with the wing mount pillars about 12" apart.

Only thing that is important here is how to relocate the mount points on a composite skin APR wing.

Make it happen, Mr. Engineer. I know you do a lot of aero work, lolol.
https://www.miataturbo.net/attachmen...ine=1329094130

Ok, so what I'm guessing you're referring to, is the threaded inserts the upright's attach to. This particular GTC-300 has two sets of upright mounts seen here:

https://www.miataturbo.net/attachmen...ine=1329157487

I take it, you want to place your own upright mounting points on the wing/airfoil itself in a spot that lines up with your existing mounts on the body?

I think you would have to drill through the airfoil and do a nut and bolt attachment to do it securely, but I doubt you want to hack up the wing like that.

Or, I think you'll need to drill the airfoil to a particular depth, and epoxy a threaded insert/bung into the spot you need it to be. I imagine the original threaded inserts in the APR wings are installed this way, but who knows how exactly. This goes without saying, but whatever way you decide to affix them to the wing though, has to leave you 100% certain and confident, that wing won't separate at those insane loads it surely sees.

Yep you got it, that is what I am after

Yes, exactly.

Yes not good for aerodynamics. More importantly though that would crush the core and screw up the wing profile unless the hole was sleeved.

Yes I am looking for someone who has done this. Threaded inserts are common practice for honeycomb core composites, not sure if that works here or not. But yes depending on the AOA and the speed the loads can be huge, hundreds of lbf. so it needs to be a strong connection.

Maybe I should just call APR tech support.

Yea give them a call and see what they say.

I was in a similar boat; wanted to grab one of the many cheap used GTC wings out there for sale, but most of them have a mounting base width greater than the 41" miata trunk span. Contemplated epoxying in some custom inserts, maybe even adding a layer of carbon over it and then drilling it out again, but after all said and done, figured it would be a safer move to just buy the right wing to begin with. GL!

It would be way easier to modify the mount as it come up to the wing, think L bracket.

Where are these inexpensive APR wings you guys speak of and how can I get my hands on them?

I had called APR and got a price on putting new threaded inserts in a new location on my wing and they quoted me $70 plus shipping. They are more than happy to put the inserts in the correct location witch will make it easier to mount to your current bracket. I will assume there will still be some sort of adapter needed. From your mount to the wing.

It would be a really big L-bracket I think.

OK thanks for the info.

You know, looking at that picture of the APR GTC wing above, the inserts look kind of like rivnuts. That is what APR used on the aluminum wing I have now.

Really good info there I wasn't aware of... gonna give them a call tomorrow myself...

Called APR today... rep said GTC-300 wing's have their uprights permanently rivet'd and epoxied to the airfoil itself... The GTC-200's have threaded inserts that can be redone for about $40...

Could swear the GTC-300's have threaded inserts too... the pic I posted of an APR wings underside with the threaded inserts I thought for sure was a GTC-300...

Tex post pics of your rear :) seriously the rear of your car.

I just got off of the phone with them as well. I called them during lunch. The rep told me that on the older GT wings they just used rivnuts riveted to the skin. I asked about the GTC series and he said they do the same thing there, although I did not specify a 200 or a 300. So it could be different between those two like they told you.

He cautioned that when installing the rivnuts it has to be done very carefully to keep from overstressing the carbon material. Good advice. A carbon composite is more fragile than an aluminum skin of course. I would probably also bond the insert to the core for good measure regardless.

If rivnuts work I would rather DIY than hassle with the shipping.

I'll show you my rear anytime you sexy man you.

https://www.miataturbo.net/attachmen...1&d=1329246425

You can see that the wing mounts are just a bit wider than a US license plate. This mount was a lot of work to fabricate and install. Plus it is very strong and stiff (by design) so I am not going to toss it just to accommodate someone's wing mount points.

Ok, so i just called APR again and spoke with someone a bit more knowledgeable.

According to him, on the 300 series wings, they can remove the riveted bracket and upright assembly from the airfoil. They can then move it further inboard or outboard, but not ANYWHERE along the width; the bottom of the apr wing is such that they can only place the upright/bracket in a few spots.

Furthermore, they recommend you buy new brackets and/or new uprights, to rivet back into the new location. Not completely necessary. This extra hardware was in the $150 range I think. Labour is about $40.

Furthermore, if you're buying an old or worn wing, they say they cannot guarantee successful overhaul of the mounts. Wing might be too 'worn out' and fragile to successfully transfer brackets around.

Tex, I'm curious why your not going for the Nascar wing?

Those wings are really nice but they are expensive ~$600 IIRC. I am not concerned about the weight difference (NASCAR wing is super light). Something with a more efficient L/D ratio than what I have now would be good.

I've been shopping for used GTC-200s and 300s as well.