Rear Window Blowout!!

[guy incognito]

Was driving along some weeks ago with roof ON and rear screen in, but drivers window fully wound down.
Accelerated up to motorway speed, before hearing a sudden whooshing noise.
Look in the mirror and see my rear screen floating through the air landing in a bush at the side of the road. Luckily no damage done to other cars/pedestrians/screen itself.

Has this happened to anyone before? I know theres a risk if you drive roof OFF and window in, but i thought roof on was pretty safe

At the time there was a problem with my boot in that it didnt lock securely, and one of the retaining clips had become a bit loose on closer inspection (both now resolved), but am still apprehensive driving at speed with the rear screen in.

Has anyone fitted their window more securly, dont want to permanently bond the thing in, but was considering maybe some sort of leash system in case it happens again!

[Laser Sag]

Had the same happen with the roof on in my Mark II, Raceproved do a revised clip which is much more secure or if you dont want to have to use an allen key to fit and remove the screen you could superglue a small piece of plastic on to the existing clips to act as a ledge so the window can not slide downwards and out.

[jcpgasoline]

Raceproved replacement clips solve the problem.

[guy incognito]

I saw those clips, thought £70 seemed a tad steep. But if they really do the job will probably take the hit.

[TheGroves]

I think the rooy cause may have been the not fully closed boot. If thats closed tight, their really isnt anywhere for the screen to go.

My Mk1 still has the old plastic clips and while they hold the screen tight, its the boot that does most of the work.

[so called]

With roof on, window down you get more pressure inside the car which is what blows the rear screen out.
Roof off actually reduces the pressure.

(Stands back waiting)

[G20RG B]

I wouldn,t advise travelling at speed with side windows down and rear screen in place UNLESS you are very sure that the rear screen is held tightly in place or it will disapear.

I always found rear screen out and side window down to be better , kept you nice and cool in the summer time if you didn't have the roof of. But of course the roof off is always the first option

[s6boy]

so called said:

With roof on, window down you get more pressure inside the car which is what blows the rear screen out.
Roof off actually reduces the pressure.

(Stands back waiting)

I think the individual cars may be different - can't see how though, mine was fine on the motorway (a'hem Autostrada m'lord) at 120 with the windows down, but when coming back from Devon last week 75/80 was as fast as the back window wanted to go with the roof off windows up, after that loads of booming as the perspex flexed to let the air out of the sides.
Still not sure after 5 years whether or not I have the larger updated screen which apparently makes a difference.

Still it doesn't matter this weekend as the roof will be off and the window out all the time anyway. If anybody spots a Tuscan between Bishops Stortford and Hemel Hempstead with the roof on it wont be me.

[Robertjp]

so called said:

With roof on, window down you get more pressure inside the car which is what blows the rear screen out.
Roof off actually reduces the pressure.

(Stands back waiting)

Thinking about it, with windows UP that may be right, because you will have low pressure in the cab compared to the higher pressure flowing over the top,

But then again, you will have the same flow over the screen, i.e low pressure underneath and high pressure on the outside, dpends how much the pressure increases as it slows over the targa bar, im not an aerodynamicist (or however you spell it!)

I think the solutuon is screen out, roof off, buy a wooly hat.
Simples