Newbie - Advice needed on Spoiler/Wing mount project please


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robjohnson
robjohnson
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Hi there, this is my first post - I am 33 years old Car enthusiast from South London, the car is a Mazda RX7 and my challenge is to fit the rear Spoiler. 

The mount needs to be exceptionally stiff and strong, the wing is 1710mm and I estimate it will create extreme forces at higher speeds, therefore its essential that the mounts are extremely sturdy.

I have been thinking and researching about how to fit this wing for over a year looking at examples on pro time attack cars and competition vehicles, most of the solutions I saw were either beyond my engineering skill or ability (CNC/cad etc) or just looked inferior, unprofessional or just plain ineffective. 

I decided on composite layup because of the uneven working surface and awkward angles involves, my plan is to lay up carbon by hand - in the photos the Carbon is represented by the Cardboard template I have made up. 

I will then release the structure from the car and trim to shape before attaching to the car in final form with bolts, as you can see in the pictures I have the wing uprights (these will be scrapped as the dragon design is a bit lame imo) positioned pretty much where I want them to be - I will use the alloy uprights in the pic as a mold effectively to get the shape of the mount - I plan to make new uprights in Carbon sheet as you can see on the picture of the white car. 

I need you guys to help me out with any tips please, I am anticipating a lot of overlap/mechanical locking problems which might stop me releasing the mount, I have no power at the Garage.

I also need some help with the shopping list please, this mount will be subject to downforce of maybe 200kilos but also twisting and tearing forces, my concern is that the resin will crack because of the constant flexing forces. 

I am not so bothered about finish as it will be hidden by the boot hatch and the wing upright which will be a carbon sheet made by Carbon mods so will look perfect from the outside - my main concern is strength so what is the shopping list please - do I need Kevlar? what type of CF sheet do I need please. 

I also need to move the carbon riveted mounts from the underside of the wing outwards as it was originally designed to mount to a steel boot hatch - my hatch is GRP skin so not at option, my concern is that these mounts are resin infused and therefore much stronger than the hand lay up techniques I have available (no power at the garage) - I dont want to make new mounts with hand lay up and have them shear off at high speed which could cause a hideous accident - tempted to bolt through from the very top of the wing which would be unsightly but possibly the strongest and safest option.  

Please review the pics and video and give me some tips, I fixed a bumper with fibreglass from Easy Composites once but that is the only experience I have and I might a right mess of it. 

ajb100
ajb100
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You're facing a very similar problem to us with mounting the wing on the xf. I can't help much but thought is throw out our solution in case it works for you.

The CFD work had showed we were going to have circa 150kg at 100mph so needed a strong solid mounting. It couldn't be mounted to the boot as that needed to be easily removable for damper changes/adjustments. In reality when we went in the wind tunnel we'd removed the second element of the wing we were only around 100kg so the mount is more than strong enough. As you can see in some of the pics, we had a mishap at nurburgring and the mounts bent in the middle instead of at the car

The solution was to channel out the side of the boot opening and mount to the frame work around the edge of the boot. Due to the size if the opening in an rx7, the metal work around it will be very strong and should be able to hold it.




ajb100
ajb100
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Apologies for the poor pics, I don't have many pics of it on my ipad.

If you continue with the composite route, I don't think you'll have any release issue as there doesn't look to be any undercuts, all the panels are made from press moulds anyway so the have to be able to come out of them easily so there rarely is on vehicle exteriors. I would however question doing it just a wet lay method. I'd at least want to vac bag it on the car. If there's no way get power to the car (generator?) then you could mould the section, make a copy of the section of car in grp, then form the carbon to that at home.

Alternatively, cut those sections out of a scrapped car and form at home again.
robjohnson
robjohnson
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Thank you so much for your answer and expertise, really appreciate the help. 

As you say the area of the car body around the boot hatch/1/4 panel gap is very stiff and strong, no chance of denting or flexing that area - I can put my whole weight on it and it compresses the shocks which are sprung for the track so pretty solid. 

I am not sure what you mean by channel out the side of the boot opening, the only issue I can see with that is the fact that on the RX7 the outer lines of the boot hatch actually angle outwards from the center line of the car, the wing mounts are normally fitted facing directly forwards as you can see from the angle created between bodywork gap and actual wing mount as seen in this pic - 

http://s1144.photobucket.com/user/orangefd3s/media/photo4_zpsc70fceeb.jpg.html?sort=3&o=19

So I could mount to the channel but if I did the wing mounts would effectively splay outwards by a few degrees rather than facing directly forwards, I do not wish to do this - 1, because it just looks odd and 2 because I intend to have solid plate uprights rather than machined frames, the reason for this is that I understand that plate wing mounts not only have less drag than frames but also have a stabilizing advantage compared to frames like the dorsal fin of a fish or the tail fin of plane - they are both solid and facing directly forwards for the purpose of straight line stability, this is an effect I wish to achieve the wing mounts - so aesthetically and dynamically I feel its important they face directly forward rather than splay outwards as they would do if I mounted to the boot hatch/ quarter panel channel. 

Solid wing mounts - http://s1144.photobucket.com/user/orangefd3s/media/CRAFTCO_zps7feae669.jpg.html?sort=3&o=6

Regarding the vac back suggestion, thank you for this - I could easily hand lay up one sheet of CF, release the cured units and return home for further layers and if I did this I would have access to power so I could vac bag - but what would be the advantage of this please? - less resin/mess = more strength?  I might need to take it home anyway because it might be too cold for the resin to cure in the garage. 

Really appreciate your helpful suggestions thank you 
Edited 11 Years Ago by robjohnson
Warren (Staff)
Warren (Staff)
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The way you are looking to place the mount, you will be relying on a wide panel gap so there is enough room for the mount to go through.  If not, you will need to recess as above, or trim the boot edge so it clears as the boot opens.

In an ideal world, id made a copy of the section or use panels from a scrappy car as the moulds so you can at least vacuum bag or resin infuse as the parts will be a bit stronger that way, but wet lay will still work if you are careful.

You will need as a minimum:

Yellow Filleting Wax

Easy-Lease Chemical Release Agent

EL2 Epoxy Laminating Resin

200g 2/2 Twill 3k Carbon Fibre

300g 2/2 twill Kevlar

 In essence the process is to lay on the wax in areas where you have sharp edges, holes, undercuts etc to smooth them out to get a good release.  Then wetlay the carbon onto the car in the shape you want.  I recommend you include some kevlar layers.  Not for specific strength, the carbon if done right will be strong enough, but for crash reasons.  The mount may well break and crack in an accident but its more likely to stay in one piece with some kevlar in there.

The biggest problem you are going to have is working on a car outside with epoxy resins. Much below 20C and the cure times go up rapidly. Much below 15C and you will get several days cure time if it cures at all as moisture absorption over the extended cure time can become significant and ruin the part.



Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant
Edited 11 Years Ago by Warren (Staff)
robjohnson
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Thanks Warren, so it looks like the temperature will be a major issue here - ideally by Springtime I want to be on the track not still tinkering. 

Looks like I need to mold and work on a mock up mold back at Home, I am confident in making a mold of the car - wax, gelcoat, GRP, release, repeat to get a copy of the working area on the Car in portable form - probably less hassle for me to make the mold than source and chop up a scrap shell right now. 

So I need a resin infusion kit too, this intimidates me a little but I need this done and I need it done well - if the item turns out poorly I will get upset and feel negative about the Car in general.

So what do I do then? - get the mold, wax it, lay up CF by hand (tacked in with spots of resin to hold it in place?) stick it all in a seal bag and pump resin through it? 

So i need to buy the resin infusion starter kit too right? I geuss its worth doing just for me but also when other people see these mounts they are going to want them too if I do them right so once I have a mold I can knock out a few sets for others ££ pay back the infusion kit maybe. 

Thanks 
wojtepanik
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Hi!
 Last winter it was so cold in my garage so I had to move to my house with stinky resins and so on. So if you really want you can do this Smile here i attach some link to gallery where is shown I think the most famous polish drift car which is gt 86 with 1000 horsepower. look closer to the spoiler how it is mounted! it looks really mad! i think that such a mounting point could be easily adapt and reproduced at your purpose with carbon fibre.
http://moto.onet.pl/aktualnosci/toyota-gt-86-orlen-teamu-1000-km-mocy/y9d3s

~~~Everytime I hear sound of demoulding part I have eargasm~~~
robjohnson
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lol - you dont want to put "vacuum pump" into Ebay
Warren (Staff)
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You dont have to infuse it, but you will likely get a better result. Especially if you are making moulds of the car panels to work from which will obviously be airtight.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant
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