Carbon Rear Wing Repair

[yellowss7]

Well, after the little incident with the apex cone on track on Sunday at NJMP during the 7s gathering, I finally took a good hard look at the damage to the wing and the carbon light block.

 

The carbon light block seems to have survived pretty much unscathed with the exception of a very enlarged hole where one of the screws and washer pulled thru. The rear lens was not found and from the twice twisted screw with a small piece of red plastic from the housing, I'd say it's safe to say that it was destroyed.

 

Luckily I had a spare lens and rubber block unit that will work nicely as donors. I had to grind down the metal light backing to fit in the carbon block, but it fits now and all is good. I ordered a spare connector as the one on the light was ripped off. Hopefully my woeful electrical skills will allow me to attach the plug correctly for a good connection.

 

The Wing itself actually was better than I expected after seeing it and hearing it come off. And after watching the video, it's hard to believe that it survived at all after all those laps, although I think someone did hit it at least one more time. The inner section that has the holes in it to attach to the side skin of the car, took the brunt of the damage. Luckily the prior owner Karl, had replaced the original steel bolts with Nylon ones so when the cone hit it, the nylon bolts broke and did not damage the side skin or the rivnuts.

 

That inner section has pretty much separated from the main body of the wing. I've ordered a carbon repair kit of some carbon fabric and epoxy that I hope will allow me to reattach it. There are a couple of other cuts in the carbon on the wing that I think I can put back in place with some epoxy and I will reinforce one area that seems to have taken a good/bad hit.

 

I'm treating this like a fiberglassing job. Any suggestions or advice on the repair process?

 

I know that this won't be show quality but I don't show the car and it is a track focused machine.

 

Tom

[Black Hole]

Good luck on your repair! Since I will be autocrossing my car your experience has convinced me to go the nylon bolt route. Do you know the size of the bolts that secure the wings.

 

Thanks

[yellowss7]

I just ordered, bolts, nuts and washers. I'll send you some. They are M5x20 or 25.

[Croc]

Good luck on your repair! Since I will be autocrossing my car your experience has convinced me to go the nylon bolt route. Do you know the size of the bolts that secure the wings.

 

Thanks

 

Everyone should go that route whether they auto floss, track or not. It just prevents a ton of damage to the ali panels should there ever be a minor rear wing loss for whatever reason.

[fastg]

As for the actual repair. I think you need to keep the wing in it's stock shape while you do the repair, if you just turn it upside down and do the repair work it will spread. I would make a template of the mounting holes, out of a sheet of plywood, bolt the wing to that before you start the repair, then it will stay in shape.

 

Graham

[yellowss7]

Thanks Graham. I'll give that a try. The main body of the wing is pretty much in shape, the inner flange that attaches to the side skin of the car, is separated, but again, pretty much intact. I need to strengthen a section that is cracked and then reattach it to the main section, and then patch up a few areas that are more cosmetic. Unless I find some other damage, I'd say it was amazing that it came thru as well as it did.

 

My fiberglass ones on the yellow car took a few hits autoxing years ago and they were in much worse shape, but came out pretty well after several hours of patching and sanding.

 

My feeling, is it's nice to have a set for track or Autoxing and a spare set for shows or pictures. The Fiberglass ones are cheap enough. Carbon, eh not so much.

 

Nylon bolts, washers and nuts are due in today, Not bad since I ordered them yesterday from McMaster Carr. Epoxy and carbon fiber are due to arrive next week. The Car is still at NJMP in Croc's garage, but I'm stopping over there tomorrow to pick up my SD card to see if I got any usable video of our sessions. I'll make a template of the bolt holes tomorrow, and make the jig over the weekend so I'll be ready once the epoxy arrives.

 

I'll check in on your car when I'm over there. Tom

Edited July 7, 2017 by yellowss7

[xcarguy]

Luckily the prior owner Karl, had replaced the original steel bolts with Nylon ones so when the cone hit it, the nylon bolts broke . . .

 

 

Tom,

 

When I had my accident at TWS, the nylon bolts holding on my rear wings snapped saving the wings from any real damage. Too bad that couldn't have worked for my back.

[yellowss7]

Hi Shane, yeah, it's always the weakest link that breaks. Hopefully you are healing well and will eventually be pain free. If not you can always change careers and become a weather forecaster. :jester:

 

Now get to work on the Storker and get it ready for next year at NJMP. We miss you.

 

Tom

[Croc]

We miss you.

 

 

Truth be told we miss Suave! :jester:

[NVP66S]

I have a lot of experience with woven fiberglass and some with carbon. One feature of the glass is that you can see through the layup and find any dry spots while you are working it. You can't see through the carbon, so use more than the minimum of epoxy. It won't affect the strength much, it'll just add a few grams of weight. The other thing is to make the layers of cloth different sizes. If they are all the same, there'll be a spot where the patch makes the area stiff, then suddenly less stiff outside the area. When building an airplane structure, the advice is 1 inch overlap per ply, but you can lower that to about 3/8 inch for a repair job. Also, make sure to sand the broken surface before starting the layup, so that the cloth will lay flat without being held off the surface by broken fibers. Good luck!

[NVP66S]

Oh, and if the job looks like it may leak the resin through and drip off the bottom, duct tape over the area to prevent leakage.

[yellowss7]

Thanks for the tips. Keep em Coming!

 

Tom

[Black Hole]

I just ordered, bolts, nuts and washers. I'll send you some. They are M5x20 or 25.

 

Thanks for the kind offer, now that I know what the correct bolt is it will be very easy to get some.

[Klasik-69]

As an experienced rear carbon fiber wing ripper upper, I can relate. I ripped mine off at Talladega TGPR track after thinking cones were like fun targets. My wing flew up about 20 feet in the air and was in about 4 pieces (separate pieces). W never found the taillight. No big deal, I thought, I'll call Caterham and have them ship me a new one....until I saw the price of around $650 + Freight. I've had a ton of experience with fiberglass so I figured I'll repair the wing with the West Epoxy system and glass material. I put the pieces together with duct tape from the outside. Amazingly the shape stayed true enough to be almost original. Using the Epoxy two part material and adding micro-glass bead filler I made a filler paste to apply to the inside at the cracks to make the parts smooth. Then using 6 oz glass cloth, I laid in a layer over the entire wing interior. At this point, the wing became incredibly rigid and strong. I placed the wing up against the car body to see if I had maintained the shape. It was within 1/8" at the worst spot.

 

i had to re-construct a part of the receiving wing flange (the area where the bolts attach the wing to the body) since about a third of it was beyond use. No problem. I placed the wing against a Formica table which I had waxed with mold release wax first and proceeded to glass in a new flange where needed. The epoxy doesn't shrink like polyester resin so war page is limited. I leaned the wing around 8 degrees from a true 90 degree to accommodate a little shrinkage.

 

After that I applied balsa wood core reinforcement to the inside of the wing while applying a layer of 1.5 oz fiberglass mat inside first, lay the balsa core on it and glass that in with an overlapping layer of mat and epoxy. It worked great.

 

since I race at some tracks that have a lot of loose gravel and small rocks, and since I race super sticky Hoosiers, these rocks slam the inside of the wings with such force as to damage the exterior surface. Having a 1/4" thick layer of balsa wood absorb the impact eliminates exterior damage. So I took off the right wing and applied the balsa core to it as well.

 

Ok, some are going to say I have negated the benefit of light carbon fiber by adding all thus weight. Maybe. But if you go eat a big meal at one of your favorite Italian restaurants, your butt weight gain might well be more than what I did.

[yellowss7]

Thanks Mike. I've done my yellow fiber glass ones before and figured this would be a similar process. I just made a couple paper templates of several patches for inside the flange to reinforce and repair some cracks. Using parchment paper to soak the piece of carbon fiber and press it into place. then brushed in more epoxy mixture to saturate. Initial small patches seem to be setting up nicely.

 

Once these are done, then I'm going to work on the rest of the flange before I epoxy that back into place. Then I will work on the larger cracks and dings that the exterior of the wing incurred.

 

It won't win any awards for it's shininess like Crocs wings. But it should hold up ok.

 

When are you going to come back up to NJMP and run with us again? Tom

[Klasik-69]

You'll be surprised how good the wings will turn out. From the outside, if you do a little body work with fillers and some elbow grease sanding, a good paint job and even an expert like Croc won't know it's history. I avoid cones now like they're the plague. Ikei, our local champion racer in Atlanta, made some triangular guides just in front of the rear wings to force the cones away from the rear wheels. His car with about 385 HP at the rear wheels coukd likely fly over the cones.

 

I really enjoyed being being up at NJMSP, and you're a great bunch of guys to hang with. I only wish it wasn't 1100 miles away or I'd be up there more often. Back surgery fused L3 thru L5-S1 slowed me down, then a blown right shoulder needed mending. Getting old sucks. I'm racing this year in SCCA SEDIV TT events and doing well. Maybe next year I'll come up. You guys were awesome and I do miss the group.

[yellowss7]

F unny, I've been sanding away all last night and some this morning. It won't be show quality like Croc's wings which are real purty.

 

But structurally it is coming along nicely. I ordered some 14 inch wide 1x1 carbon to match and the biggest exterior crack, while reinforced from the inside, looks ugly on the outside. I think I'm going to try to cover from the rear light position down to the bottom edge with a sheet of the wide stuff. Only downside is that the epoxy is really clear and shiny and the original wing is pretty dull. I guess I could just take some 1000 grit sandpaper and take the shine off so it somewhat matches.

 

For the track it should be fine. I still need to make a set of the wider front wings and extend the wing stays like you did to be able to fit the big hoosiers on.

 

Yeah it does suck getting older, but considering the alternative, eh not so much. Key is to keep having fun. We would love to see you again next year. Start making plans with your wife. Croc is talking about changing the date to get us on Thunderbolt. We have to wait and see what next year's member dates and track assignments are before we can say for sure. But I'm betting that we will get close to or exceed 30 cars next year. Hope to see you and your wife again. Tom

[yellowss7]

I've been filling and sanding for the last few days. I reattached the inner flange which gave it back it's structural rigidity. I've filled all of the external cracks and have sanded them down and other than one more attempt to fill in a few low spots, which I'll do tonight, I'm pretty happy with how it's turning out.

 

After I fill the low spots I'll sand again and then sand with progressively finer grit down to 2000. After that I plan to hit it with a light coat of clear just to bring back a little gloss.

 

I'll post some pictures once I finish it. Again, any other suggestions let me know. Tom

[Klasik-69]

If you want to use the same kind of wide front cycle wings like my crude fiberglass ones, I could ship you the mold so you can pull some pieces off. As you know, they ain't "purty" but they keep some of the crap on the track from flying back at you. To make them right, the back sides of the wings need to have an area about 6" wide and 8" long cut out to let air pressure bleed off. Ideally, a stainless steel wire screen should be glassed in to prevent debris from flying out thru there.

 

The other way is to fabricate them from 0.095 aluminum which may even be lighter. 0.062 might be too thin and too easily damaged.

 

By the way, I went back to the original Caterham spun aluminum wheels, 13" X 6.5" front, 13" X 8.8" rear with Hoosier bias ply tires and found I coukd shave 1.5 to 2 seconds off my lap times. At Carolina Motorsports Park I ran Saturday with the wide steel wheels (13" diameter) and only managed 1:52.634 as my best lap time. On Sunday I ran the Caterham wheels and on the first session got it down to 1:51.06. Next time out I ran 1:49.543 and managed to beat every formula car but one. Faster hole shot with less wheel mass is my best guess. I lost some grip in tight turns but I found the 7 coukd drift with comfort and not lose too much time. Actually it really became fun.

[yellowss7]

Thx Mike, I'll pay for the shipping if you are willing to send them. I'm planning on getting the car recornerweighted and set up to see if I can get it to handle more like my yellow car.