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-   -   Genius $3 fix for windshield buffeting (https://www.hdforums.com/forum/2018-softail-models/1314858-genius-3-fix-for-windshield-buffeting.html)

FatBob2018 01-23-2020 06:51 PM

Genius $3 fix for windshield buffeting
 
I'm not taking credit for this idea; I found it in the "What Did You Do To Your 18+ Softail Thread Today". However, I tried it, and it's frickin' genius, and It's too good of a hack to have just disappear in that monster thread.

So, for reference, here's the original post:
https://www.hdforums.com/forum/2018-...l#post18775751

Here's the deal -- if you have a 2018+ Softail, and you have the Harley Detachable windshield, and you're experiencing buffeting, this may very well fix it. Buffeting is evil, it is the Great Satan of riding with a windshield, and I despise and hate it. We chase after it with taller windscreens, shorter screens, fork lowers, everything... and that's all expensive. Oz Gary's fix has totally vaporized the buffeting for me, and the total spend was about $3.

Here's Oz Gary's original post:

This may not appeal to everyone but tried this today and has reduced buffeting by 99%😊
I am 6’2 and use the 19” screen on a Fatboy and have suffered with buffering and intense vibration to the helmet varying depending if riding into the wind direction etc
Using a small extension to the lower attach point and putting a slight layback on the screen there is now a clean pass of wind over the helmet as apposed to the barn door effect with the screen straight up and down
Used similar on a dyna screen before to great success and thought would give it a go on the Fatboy
https://cimg1.ibsrv.net/gimg/www.hdf...99cd1f6b34.jpg

So, as background, I despise helmet buffeting (as said); buffeting is described here as the windscreen creating turbulent air that batters your helmet and bounces your head around like you're riding an old wooden rollercoaster, and it sucks. The general problem is that if you have a windscreen, it's displacing air, which creates a vacuum behind the windshield. And nature (like dogs) abhors a vacuum, so air will rush in to fill in that vacuum. Frequently it comes up from below the tank, or it rushes around the shield's sides, or over the top, or it can result in pressure from behind as the air tries to fill in that vacuum. And that turbulence leads to buffeting.

If you change the airflow, you might move where the turbulent air gathers. That's the goal behind trying lowers, or a bigger windshield; you're trying to change the airflow so that the turbulent air collides behind you (or, if you have a passenger, then you want it to collide behind them).

The Harley screen is fairly vertical, and has that lip on the top of it, so yeah, it's a big barn door and it is fairly un-aerodynamic, creating a big vacuum and lots of air rushing around it. Lowers can redirect the airflow so that not so much comes rushing over the tank and batters you from below, for example. If they work, great. But in my case, I had just installed the JES lowers (modified from the Fat Boy to fit the Fat Bob) and -- the buffeting was still awful.

By angling the screen, two things happen -- the overall amount of air displacement is less, so there's less turbulence created because there's less vacuum to fill. But secondly, the angle of the screen, by pushing the bottom of the screen out, creates a gap below the windscreen, where some of the air can rush in and directly fill the vacuum, meaning that nowhere near as much air needs to come at you from above, the sides, or below. This is the same basic technique used by Madstad windshields to great effect.

For the extensions, I went to Home Depot and picked up some "mending plates".

https://cimg6.ibsrv.net/gimg/www.hdf...59cabba11d.jpg
A 4-pack was just $3. I had to drill the holes out a little bit, they're just a hair too small, so I used a 1/4" drill bit to widen the holes. After that, just bolt 'em on, and enjoy a blissfully buffet-free ride. (Note, as Oz Gary said, this may or may not work for you, it worked for us, but you may need a taller or shorter screen, or more or less angle, to get rid of the buffeting.)

Big thanks to Oz Gary for posting this simple, but brilliantly effective, modification!

Oz Gary 01-23-2020 08:06 PM

FatBob 2018 you really know how to make a blokes head swell, thank you for the kind words. It really did surprise me how well it worked. As you said it smooths the air flow out. Thanks again
Gary

sire86 01-23-2020 09:16 PM

A 4-pack was just $3. I had to drill the holes out a little bit, they're just a hair too small, so I used a 1/4" drill bit to widen the holes. After that, just bolt 'em on, and enjoy a blissfully buffet-free ride. (Note, as Oz Gary said, this may or may not work for you, it worked for us, but you may need a taller or shorter screen, or more or less angle, to get rid of the buffeting.)

Thanks for the post .
Looks like another set of the nylon bushings will be needed ? I might be trying this set up too looks simply enough, I’m done with that head buffeting

Oz Gary 01-23-2020 09:36 PM


Originally Posted by sire86 (Post 18824050)
A 4-pack was just $3. I had to drill the holes out a little bit, they're just a hair too small, so I used a 1/4" drill bit to widen the holes. After that, just bolt 'em on, and enjoy a blissfully buffet-free ride. (Note, as Oz Gary said, this may or may not work for you, it worked for us, but you may need a taller or shorter screen, or more or less angle, to get rid of the buffeting.)

Thanks for the post .
Looks like another set of the nylon bushings will be needed ? I might be trying this set up too looks simply enough, I’m done with that head buffeting

I used a strip of stainless and purchased 2 of the rubber grommets, these can be purchased through HD Part No 12100110 (Grommet Windshield) $6 each here in Australia, probably get 2 in the States for that.

FatBob2018 01-23-2020 10:44 PM

I guess it may depend on the bike. On my Fat Bob, I just fastened the mending plate directly with a 1/4-20 bolt. I moved the bushing out to the end of the mending plate. So, the total parts list was 2 mending plates, 2 1/4-20 bolts, and two acorn nuts.

adm 03-07-2020 02:31 PM

Nifty.

I'm going to try this. Right now I occasionally use the 19" screen on my FatBob, with a little MRA screen extender. It works well, but I'd prefer not to need it. So I shall have play with this.

I have a choice fo 2" or 3" pieces to order - looks like 2" would be the better choice? (MMMV of course...)

T^2 03-07-2020 07:30 PM

Or you can just do a vent to equalize the pressure differential. See Clearview Shields. Similar to what you get with the stock glides...

leftyjm 03-07-2020 08:50 PM


Originally Posted by T^2 (Post 18930415)
Or you can just do a vent to equalize the pressure differential. See Clearview Shields. Similar to what you get with the stock glides...

Hmmm Let’s see $3 or $4 for trying the Quick fix or $200+ for a clearview windshield with an ugly vent.
I’ll give the “quick fix” a try first

T^2 03-07-2020 09:18 PM


Originally Posted by leftyjm (Post 18930581)
Hmmm Let’s see $3 or $4 for trying the Quick fix or $200+ for a clearview windshield with an ugly vent.
I’ll give the “quick fix” a try first

Depends one how much of a Kludge the solution looks like or becomes. I can say the vent both works (particularly with the recurve) and looks fine making the trades acceptable.

leftyjm 03-07-2020 09:35 PM


Originally Posted by T^2 (Post 18930644)
Depends one how much of a Kludge the solution looks like or becomes. I can say the vent both works (particularly with the recurve) and looks fine making the trades acceptable.

Like I said I’ll try the fix first for $3 or $4 and go from there.
I did however talk to someone at Clearview and he admitted to me that they would sell a lot more of the windshields with the vent if people could get past the look of them.
In so many words he admitted they are kind of fugly. I have to agree.


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