Cheap screen fix

[paulc]

This has been reposted!

OK , I know a little about how air currents work and how to bend air,now lets throw the cat among the pigeons and tell you why you get that buffeting at speed when there is a cross wind of ANY strength.
For all that air the screen pushes out of the way it causes a void of air behind the screen a vacuum of a sort,when there is no cross wind a certain amount of air will fill the void to a degree, as you go faster the air presure builds up in front and the vacuum behind the screen increases dramatically.
If you treat water as a fluid ''which most tecs do'' you will get the same response, if you put a saucer into water and let it sink it will go from side to side ''turbulance'' much like the air is doing going around the screen but much slower.
The trick is to combat the vacuum by finding a way to fill that vacuum, you Will stop the buffeting but will notice an amount of moving air behind the screen.
Now try this it,s very very cheap and gets very very good results.
Get yourself some perspex or plastic or even aliminuim with a thickness of 8 to 10mm and make four spacers 25mm square will do,drill 5.5 to 6mm holes and fit them behind the screen ''up the screws to M5x40''.
The idea behind this is to let certain amount of forced air from the presure zone in front to travel behind the screen and relieve the vacuum and stop the turbulance.''you can change the thickness to suit''
Doing this simple thing will reduce drag ,increase speed and save on fuel,,,,,,,,guaranteed ,try it what have you got to lose?
I must say sorry to the makers of screen gadgets who make their living form other peoples lack of air/fluids dianamics knowledge.
SORRY

[Wigan Chris]

for the more technically inept and those lacking the imagination to picture what youve described (yes, i mean me) do you have any piccies?

[Snaphappy]

The MRA Vario has holes to allow that, I found it better to increase the distance between screen and fairing by an Inch and half and close the holes on the screen, its also a couple of inches higher. When it rains I can watch the drops go over my head that peal off the screen but I cant ride with open viser so I am somewhere in the middle of quiet air and no screen with no turbulance

[davsato]

because of the curve of the front of the bike, bringing the screen out will put the holes out of alignment? they dont go in straight, i had trouble lining them up when i made my gps mount, and thats only 3mm thick.

you could try it with a load of washers before going to the trouble of making spacers, but i think it will put a lot of strain on the four screen screw mounts. ive never had it apart but i think they are only those rubber wellnuts, not the most robust fasteners in the world.

[paulc]

View image in gallery

Ok pics, screen is at at it's lowest setting with 10mm spacers

View image in gallery

The holes line up with no bending of screen or stressing anything and is just as strong as if it was the standard fixing

[Snaphappy]

Good point Dave
I had a go at making my own bracket similar to the Madsted but didn't like the look, so I binned half of it just keeping the mount with no adjusters.
Making the mount was hard enough because of alignment issues and well nuts are

...well, nuts

[davsato]

hmm conflicting views then. im going to have a play in the garage, i have a load of 1" delrin spacers i pinched from some packing cases because they looked bling and might come in handy one day, i must be prescient. shame they are white but that may look ok, if it works i can sort that out.

[paulc]

Please report on your thoughts about how it works.
You will find a bit more air rush noise but will get none of the wobble at high speed.
I'll keep on it until I have the perfect thickness of spacer.
In theory the spacer for the high screen setting should be 6-7mm thick (not comfired yet) .
Dont forget to increase the length of screw incrementally
Oh and i've JUST read what the guy who makes the Laminer flow said about his product and it,s basicaly the same as that which I posted about the vacuum being the problem

[davsato]

ah, theres another problem right there, in that we are all different height, weight, wear different helmets etc..... i dont experience any wobble at all unless the starship dave gets up to warp factor stupid, but its the wind noise i dont like!
so modifications that eliminate a non existent wobble while increasing annoying wind drone seems a bit silly to me. but i will still have a play, its only four screws and an excuse for a blat about tomorrow.

on a tangent but similar theme, does anyone else notice that if you have a pillion or a big bag filling the gap between you and the topbox, the noise and buffet is much less? disrupting that big swirl of negative pressure again, i guess

[paulc]

As I said ,I'm still playing with it......................................






should've grown out of it by now