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Dusterbd13-michael
Dusterbd13-michael MegaDork
6/24/19 6:39 p.m.

im sure someone makes this, and theres probably a $2 chinese version on ebay, but i dont even know what its called. so ill make it instead! 

seriously, if theres a stupid cheap readily available version, ill just buy it instead. 

 

anyway, i want to temporarily mount something to the edge of a trunk lid. think the short sides, parallel to the sides of the car. it needs to be a sturdy mount, but i don't want to drill holes in the car, or make it permanent. 

my mind goes to something like a C channel, with a setscrew and rubber feet. maybe somehow made with angle iron? im really not sure here. needs to hold up to a couple hundred pounds of force (think like a CSP miata spoiler, only bigger forces!)

as this is an experiment, im looking to do it cheap and easy. pretty can come after proof of concept, as in if it works, and works well enough, id be willing to drill holes. probably. 

but anuway, how do i make this, or better yet, where can i buy a pair for a couple of bucks?

EvanB
EvanB MegaDork
6/24/19 6:44 p.m.

I initially thought beam clamp but that is probably too thick.

californiamilleghia
californiamilleghia HalfDork
6/24/19 6:57 p.m.

Does it need to fit in the gap so the trunk lid closes ?

RossD
RossD MegaDork
6/24/19 6:59 p.m.

I am not sure about how you plan on doing a mount without holes, but are you familar with UniStrut?

Dusterbd13-michael
Dusterbd13-michael MegaDork
6/24/19 7:08 p.m.
RossD said:

I am not sure about how you plan on doing a mount without holes, but are you familar with UniStrut?

nope!

Dusterbd13-michael
Dusterbd13-michael MegaDork
6/24/19 7:09 p.m.
californiamilleghia said:

Does it need to fit in the gap so the trunk lid closes ?

yes. roughly 1/4 inch panel gap there, with about 1/2 inch depth between the li and the rain gutter around the opening

No Time
No Time Dork
6/24/19 7:11 p.m.

Depending on what you want to do, it may be best to search CL for cheap bike racks to use as a starting point and build from there.  

 

Dusterbd13-michael
Dusterbd13-michael MegaDork
6/24/19 7:16 p.m.

what im doing is seeing how my car reacts to a big autocross style spoiler. with all the power, its tail happy. i want to quickly and easily test back to back between runs. if it works, ill make a nice one. if it doesnt, i havent hurt fresh paint. 

No Time
No Time Dork
6/24/19 7:24 p.m.
Dusterbd13-michael said:

what im doing is seeing how my car reacts to a big autocross style spoiler. with all the power, its tail happy. i want to quickly and easily test back to back between runs. if it works, ill make a nice one. if it doesnt, i havent hurt fresh paint. 

I’d take a look at bike rack for ideas on how to support the load. The loading from bicycles on a rack apply load similar to the moment your wing will apply to the mounting. 

Even if you don’t go that route, you may get some ideas. Many of the trunk mount rack have adjustable arms, so you may be able use those ideas to make an adjustable mount so you can experiment with different angles of attack easily  

 

ProDarwin
ProDarwin UltimaDork
6/24/19 7:27 p.m.

Are spare trunk lids difficult to come by?

wlkelley3
wlkelley3 UltraDork
6/24/19 7:42 p.m.

I thought of old style CB radio antenna clamp mounts but none that I found clamps like you want. Maybe can adapt one?

Nate90LX
Nate90LX Reader
6/24/19 8:22 p.m.

I second the modified bike rack idea. You might only need the clips from it that mount to the body. You can use straps (try lashing straps) to set and adjust the angle of attack. You talk about wanting to protect fresh paint, but anything you put on fresh (soft?) risks leaving marks. 

Also, is this only a high(er) speed corner issue, because that is where the spoiler will be most effective. I assume you have tried all the normal oversteer reduction tricks (disconnect/remove rear bar, spring rates, damper adjustments, tire pressure)?

Stampie
Stampie PowerDork
6/24/19 8:25 p.m.
No Time said:

Depending on what you want to do, it may be best to search CL for cheap bike racks to use as a starting point and build from there.  

 

Don't know about Michael but I'm on CL searching for bike racks now. 

dculberson
dculberson MegaDork
6/24/19 8:33 p.m.

I have had that style of bike rack mess up my paint something fierce. I’d be afraid to use it on fresh paint. 

HotNotch
HotNotch New Reader
6/24/19 9:28 p.m.
Dusterbd13-michael
Dusterbd13-michael MegaDork
6/25/19 2:09 a.m.

In reply to HotNotch :

Exactly! Those aren't cheap but are almost exactly what i need.

Nate: haven't ha d a better driver check it out yet, but it seems to be the higher speed corners 

Knurled.
Knurled. MegaDork
6/25/19 6:07 a.m.
californiamilleghia said:

Does it need to fit in the gap so the trunk lid closes ?

If it does, an old CB antenna clamp would work.  Might be still common in the ham radio world.

DeadSkunk  (Warren)
DeadSkunk (Warren) PowerDork
6/25/19 6:46 a.m.

Remove the trunk lid altogether and mount the wing to the trunk floor where it won't screw up the paint.

Edit: At the 2017 Challenge my Miata had a 10" high spoiler like the CSP Miatas usually do. For the drags I had a second trunk lid with no spoiler. 

Dusterbd13-michael
Dusterbd13-michael MegaDork
6/25/19 7:22 a.m.

Part of the quick removal idea is to remove for the drags and replace with a drag oriented piece. 

Also, the trunk still needs to operate as such without tools. 

Im liking the antenna mounts. Should be able to recreate that pretty easily out of angle iron and a welder.

AngryCorvair
AngryCorvair MegaDork
6/25/19 7:35 a.m.

I’d prep and paint a second trunk lid to accommodate the wing mounts.

wawazat
wawazat HalfDork
6/25/19 7:49 a.m.

Search for beam clamp.  Cheap, malleable iron, and threaded holes already in place.  Not attractive but paint is cheap.

cmcgregor
cmcgregor Dork
6/25/19 5:41 p.m.

I'd either do a second trunk lid, or a blackbird fabworx style adjustable rear spoiler. 

Dusterbd13-michael
Dusterbd13-michael MegaDork
6/25/19 6:47 p.m.

Im going to look at the beam clamps first, then fabricated stuff second. If those fail, ill drill the decklid. 

AWSX1686
AWSX1686 SuperDork
6/26/19 10:58 a.m.
ProDarwin said:

Are spare trunk lids difficult to come by?

I have an extra trunk lid. It's probably worth something, but I'd donate it to the build. You're like 6 hours away though IIRC.

 

Edit: I would agree that having a second trunk lid would be ideal anyway so you can have one for autocross and one for drags.

ProDarwin
ProDarwin UltimaDork
6/26/19 1:45 p.m.

Additionally, if this is a challenge car, why not put the holes in the lid with threaded inserts/brackets/whatever in place on the bottom.  If you use them, great.  If not, put a plug in there.  

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