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Old 01-21-2013, 08:59 PM   #1
mutt2jeff OP
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Building a better windscreen

So, it winter, and I am bored. The bike is sitting in storage on its battery tender, so this is the perfect time to tinker, right?

Anyway, we all know the stock windshield/fairing sucks. The constant buffeting drove me completely up the wall commuting last summer, and I think I can do a better job. Its also been a long time since I have spent much time on ADVrider, so I think a build thread is in order.

The premise is this. I want to build a shorter screen, with a nice little lip. It will be made of carbon fiber, and preferably a little bit lighter than stock. This is sort of an experiment for building more complex parts for different bikes later on, so I choose the 950 windscreen because

1. Its an extremely simple part to make a mold of and experiment with
2. I have one, and am intimately familiar with the issues


So, where do we start? First thing to do is get the damn windshield off. Its 15 degrees out, and two of the screws are frozen into two of the stupid rubber grommit mounts. So I have to pry those out and use plyers on them, f*ing brilliant!

Anyways, next up is clean the part up, and mount it to our laminate board! The very first step of this process is simply to make a casting of the outside using fiberglass. So, we tape it down to the board so it cant move around.


Now, I would prefer not to ruin my perfect good windshield during this process, so it is going to need a couple coats of mold release, PVA. This is sprayed on with a paint gun, and left to dry.


My buddy, who has a decade of experience building carbon fiber performance parts for airplanes, giving me a hand.


Next up, fill the holes with clay, cut out some squares of fiberglass that are big enough, and start loading them up with resin!


We can really load it up, remember that right now, we are just copying the part so that we can make an actual mold to lay CF in. So we don't care if there is too much resin, or even much about how it looks. Here you can see the screen before we roll the air out.


And here it is mid rolling. You gently roll the air bubbles and creases out of the fiberglass, and set it to dry. It needs about 24 hours at this point, So tomorrow I will look at it and see if there is a need for a second layer, depending on how rigid it is. If it does, it will be another 24 hours. This is a very boring part of the build, basically just waiting for things to dry. Half and hour of work, 24 hours to dry, lol


More tomorrow!
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Old 01-22-2013, 04:30 PM   #2
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Wow, look at all this interest! Thats ok, things will get more interesting here over the next couple days. The goal is to have the part completed this week barring any holdups.

So, I dropped by today to work on the splash some more. Unfortunately, 1 layer of fiberglass was not stiff enough, so I added another as well as to bracing strips that run horizontally. Not much in the way of pictures, when I am working with the fiberglass and resin, I don't want to touch my phone for fear of getting it all sticky and hairy.

So, here is the splash this morning, before I did any work. You can see the the windshield released in a couple places. This is good, means that I am probably going to get it back in tact, lol.


And after the second layer has been applied, along with the bracing strips. Pre-rolling though, so you can see lots of air trapped in between the layers. Its important to really soak the material with resin at this point, it needs to be completely saturated. Excess gets rolled out, but the layers need to really become one.
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Old 01-22-2013, 04:34 PM   #3
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Wow, look at all this interest!
I subscribed. I was waiting for something to happen
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Old 01-22-2013, 04:44 PM   #4
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I should point out the importance of letting the resin do the work for you. Depending on how hot you mix it, you usually have a good half hour of working time. For me this is forever compared to the stuff I usually work with, which can go from a water like thickness to completely solid and burning hot in 5 minutes.

So you really want to saturate the fiberglass. Then, step away for 5 or 10 minutes, let it soften up and absorb every bit it can. Then, you can roll out air and wrinkles without a thought. If you have a little spot that seems to have air or a foam type layer that you cant get out, more resin! That spot is just too dry.
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Old 01-22-2013, 04:46 PM   #5
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I'm watching too. Interesting process.

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Old 01-22-2013, 10:20 PM   #6
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I'm in. Hell knows we need a better screen (and a lesson on fibreglassing can't hurt)
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Old 01-22-2013, 10:25 PM   #7
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Old 01-22-2013, 10:25 PM   #8
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I always laugh because i have an aftermarket screen on my 950 that works great for me (1.5" Taller and wider than stock) But I am enjoying the lesson.
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Old 01-22-2013, 11:54 PM   #9
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Yeah, there is quite an aftermarket for these things. I personally don't want a bigger screen. I find the line in the middle of my vision distracting on stock size, and hate looking though cheap acrylic of full-size windscreens. I have bigger plans than this (can you say Rally Fairings?) but this is a good way to brush up my skills and get an idea of things that need to change before investing a lot of time in a bigger project. I looked around on the aftermarket and didn't really find what I envisioned (or it cost more than was reasonable) so I decided to do it myself
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Old 01-23-2013, 09:20 AM   #10
MotoTex
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As long as you are handy with fabrication you may want to try making something like this:



This is a photo of Aeroflow's Aeroguard for the 950/990. I've been running the stock screen with these and never experience buffeting. For reference I'm about 6'2" and have Seat Concepts stepped seat that drops me down and inch or so. I wear a Shoei RF-1000 helmet. Height and distance behind the screen will be a factor to where the airflow hits the helmet, if at all. This is what makes troubleshooting this buffeting issue so confounding.

I think the Aeroguards keep wind from coming up behind the stock screen and creating that oscillation that we feel as buffeting.

Anyway, after doing an exhaustive evaluation of several of the Aeroflow screens that fit over the OEM windshield, both with and without the Aeroguards, in the long run I've been most satisfied running the stock screen and Aeroguards for everything other than long-distance highway touring where the larger screen offers a slight benefit by getting more wind off of me and being less fatiguing on those 400+ mile days.

If you like the looks of the OEM screen, I'd suggest building something to block that troublesome airflow at the point shown in the photo and see if it eliminates the problem for you. Changing the screen size and shape only may not be the best answer.

For those who don't want the hassle of fabricating, just get the Aeroguards from Aeroflow and avoid the time and effort.

Either way, I think this is a solution that will directly address the airflow problem in a way nearly all the myriad versions of screens don't.

I hope this helps and best of luck with the project!
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Old 01-23-2013, 07:13 PM   #11
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Hmm, that's an interesting product. Don't care much for the looks, or the price, yikes . But the idea has merit.

Anyways, today's update. The splash is complete! Unfortunately, it claimed a victim, the windshield is pitted and damaged. Some sort of chemical reaction. This was always a possibility so I am not upset about it or anything, but really, the purpose of building the splash was to save the shield. Oh well.

The inside of the splash, post windshield removal.




Damaged windshield


Run the splash over to the bandsaw and trim off the excess fiberglass.


So the next step is to release the inside of the mold, and set about making a new, modifiable screen. I did this right away, and was not good about taking pictures. Once the release was cured, I cut two more layers out and applied them to the inside of the splash. Some process as before. I was able to apply two layers consecutively this time now that I have a nice, rigid splash to work from, instead of the super flexible windshield. Pictured are two layers of fiberglass, plus two reinforcing strips along the bottom to help fill that section out. It all blends into one nice layer as the starch is broken down.


I am also using a new resin which sets up faster, but does not do nearly as good a job at breaking down the starch in the fiberglass, making it more difficult to work with. Unfortunately, we used the very last of the old resin up yesterday, and it can no longer be obtained.

Tomorrow, I will pull my new replica windshield, and cut it down/create the lip. This will involve lots of sanding and bondo. If I have time, I will also make the actual mold. Probably not though.
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Old 01-23-2013, 07:15 PM   #12
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+1 on the Aerogaurds from aeroflow with the stock screen. I was really impressed.
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Old 01-23-2013, 07:39 PM   #13
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Hmm, that's an interesting product. Don't care much for the looks
+1, eye disinfectant, stat
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Old 01-23-2013, 07:46 PM   #14
mutt2jeff OP
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+1, eye disinfectant, stat
Agreed. I am usually a big function over form guy, but I cant stand tacked on stuff like that.
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Old 01-24-2013, 08:04 AM   #15
MotoTex
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Agreed. I am usually a big function over form guy, but I cant stand tacked on stuff like that.
I know what you mean. But for me the ride quality improvement, and the fact that the clear Aeroguards kinda disappear from my view with the tank bag on, easily made function win over form.

Nonetheless, the function that they perform is still what has to happen to reduce the buffeting. The low pressure area that is created behind the screen in motion will want to draw air in to balance the pressures. This is what creates the oscillation felt as buffeting.

A bigger shield, with no design to either/both reduce the low pressure and restrict the airflow into that area may not make the difference you want.

Keep this aspect of the aerodynamics in mind while finalizing your design. The problem to solve is the dead air space behind the shield, rather than how the shield parts the wind.

If you can design a shield that has laminar flow on both the front and the back of the shield, that would be optimal in balancing the pressures and forcing the wind up over the rider's head. The front and back airstreams converging together at the top would prevent airflow from trying to roll into the low pressure zone above the dash.

One way to achieve this might be a two-layer design where the back layer has a 1" space between it and the front layer. Then the front layer would have a cutout the width of the shield and an inch or two tall just above the headlight to channel the air into the space between the front and back layers. Sort of a smaller version of what the Aeroflow windshield does.

Anyway, that's just an opinion based on studying windshield designs going back to a 1988 BMW K75S shield that was designed something like this. The only tweak I had to make to eliminate buffeting was to install vortex generators on the top back side of the windscreen to clean up the airflow just before it recombined with that from the front side. It was a eureka! moment for me and helped me better understand just what was going on and how to address it.

Those who have used the brute force method of trying to push more air out of the way haven't met with much success because they often create a greater low pressure zone, thus making the problem worse.

I know you have a lot of enthusiasm and will be putting much effort into the design. Hopefully this might help you visualize what needs to happen to clean up the airflow as it leave the top of the screen.

The Aeroguards change the flow pattern, so the wind doesn't have a direct path into the low pressure zone. Instead it has to come in from farther behind and this helps eliminate an upflow that amplifies the buffeting. It was easier for me to do this than to commit to a fabrication project.

Again, best wishes on the project.
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