Custom made perplex wind-blockers between Twin Hoop rollbar

[davekmoore]

BARMY has a BD rollbar which initially ruled out refitting the windblocker. I found one solution was to have some custom brackets made so I could refit it, albeit with some juggling. It still works great and still has the advantages of being foldable and having the storage pockets. Don't count the speakers as being an advantage though as they're a waste of space and weight.

[nick viner]

Sorry Dale. I am a computer idiot and don't seem to have the nouse to get the pics out of my camera onto the screen like you smart guys do.
Mind you I wouldn't mind driving up to let you see it.
I used to live at Cabbage Tree Point and still cant believe I sold my waterfront home to come and live down here. ( Bloody Grand kids!!)
Cheers Nick.

[BadBong]

Ok guys, reviving an old thread that I've started ages ago here as I've finally got off my rear-end to make this happen.

I've whipped up this design last night and I'd thought I'll share this with you all while I'm on my lunch break.

I would appreciate any constructive feedback and also ideas on how to improve it

This design is based on the MX5Plus twin hoop roll bar. Photos of it can be found here: http://www.mx5plus.com.au/part_display.php?part=60&cat=8

Please find attached the draft design of the windblocker I have in mind without the dimensions.

110706.MX5.Wind blocker design.V5.jpg

The material I'm planning to use is Lexan, which is commonly used as a light weight windshield in performance vehicles and bullet resistant windows. It will be UV tinted for practicality and longevity reasons. At this point in time I'm liaising with a U.S. based supplier who specialise in making windblockers but let's hope I don't get a heart attack when I see the bill...

The idea of this windblocker is to have a large piece of Lexan that spans the whole distance between the outer rims of the 2 hoops to give the best wind protection. At the same time, the mechanism should be invisible from behind. To ensure that I can still access the roof while I'm inside the cabin, I've designed a hinged mechanism that allows the part of the lexan between the 2 hoops to work like a vertical door or like the boot door of a range rover. This 'door' will need to open forward towards the front of the car.

Here's some explanation on my diagram:

Black = Outline of the rollbar. Note that there is a significant gap between the bottom of the rollbar and the carpet behind the seats;
Blue = Outline of the main piece of the wind blocker;
Orange = Outline of the holes required to run the velcro tape through;
Green = Where the velcro tape will be when the windblocker is installed onto the rollbar;
Red = Indicates where the 2 pieces of lexan will come in contact as part of the door mechanism. Rubber tubes will need to be used to minimise gaps and possible noise from contact between the 2 pieces especially at high speeds;
Purple = Hinges, ideally ones that only opens up to 90 degrees forward towards the front of the car. Given its location, it is highly visible and it should be black in colour. Furthermore, I don't know how big the hinges should be for it to be strong and long lasting but at the same time not so big that you can see clearly from the back of the car;

and finally...

Brown = I feel that this is going to be the trickiest part. This is the 'switch' mechanism that the whole design is based on. There will be 2 of these switches altogether, one on each side and its purpose is to lock and stablise the main piece with the door piece of lexan together when you want the windblocker to be up. An L-shaped switch looks like a good starting point and it should be screwed onto the main piece of lexan. There should be foam/rubber lining on the inside of this switch so that it's a snug fit onto the door lexan piece whenever it's in 'lock' mode. Whenever I want to put the roof back up, I'll unlock/rotate both switches, open the door forward, pull the roof up and then lock the door back up with the switches again;

An example of what I'm talking about is here but again, I envisage it in a L-shape:

http://www.isaaclord.co.uk/image/GlassDoorHinges.jpg

This design didn't work in my other MX5 as it had aftermarket MS seats with wide shoulders, which would have been an obstruction for the door to open enough for the driver to access the roof handle. However, I believe that with NB8B seats and definitely NB8A or NA seats that this design would work like a treat.

What do you think guys? and is this achieveable?

For those guys with a NB8B and the twin hoop install, I would love to get your feedback on the feasibility of this design before footing the bill from half way around the world...

[Old Dude]

Hi Bad bong,
I still think that you might find that the door will hit on the NB8B seats, where the shoulder support is, I just checked mine and I think it will foul.
After shoulder surgery myself I no longer lift my top whilst sitting down either, (just like nick viner) and as of late it seems to be getting colder or I'm getting older and are feeling the cold more with the top down (which is all the time), so are also looking to maybe increase the width of my blocker to cut down on intruding cold air
I would like to try and use the bolts in the bar(behind the seats) some way and mount it to them, but would be interested in any ideas also.

Cheers
Dale

[Mr Morlock]

I am not sure why you would use a US supplier- I certainly would not consider it- their hourly rates with overheads etc will be much the same as Au. If you are getting something made it is always an advantage to deal with someone local where you can talk or visit. Sourcing lexan sheets etc is simple here - see Nick Viner's comments- and a constructor can quote based on a fully dimensioned drawing. Ultimately you are only attaching a pc piece between 2 bars. Small volume or one offs are essentially about time and materials . Engineering shops making jjgs and fixtures can do these things if they want to. PS just cut a piece of cardboard and attach for a trial or cut some craft wood with a jig saw before finalising shape etc. The proto can be fixed with cable ties.

[BadBong]

Thanks OD.

If I'm willing to shrink the width of 'door', how much distance do you think the red lines (outer edge of the door) should to come together by to prevent it from hitting the NB8B seats?...

Unfortunately, that would mean that the rubber surrounding the side of the 'door' will be visible from the back but within reason, I think it's more important to retain access to the roof.

Hm... Morlock - good point there. I might have to have a shot with carboard pieces this weekend (however, my roll bar is not mounted on the car yet hence that's why I need your help to see whether the door would work). Unfortunately, it's slightly more complicated than attaching a small piece between the 2 bars cause I think that any obstruction with the bigger piece would come into play when designing the door piece.

[Old Dude]

OK just did some tests, and you would need to come in about 25mm each side from the bar to clear the sides of the seat, but that will also vary depending on how much your seat lays back.
I also agree with Mr M, there are plenty of places in Aus that will cut what ever you want at a reasonable price, ...good idea about some cardboard cut outs thats how I checked mine
Cheers
Dale

[BadBong]

Hm... sounds like it's time to raid the supermarkets for some large pieces of cardboard then ;)

OD, since you're keen on getting a more protective windblocker, you might want to wait till I get this design sorted and you can just use the design? (for 1 piece if you're not keen on the door).

Any other feedback are always welcomed!

[Lokiel]

Mazda had a lot of design engineers working on their OEM version; their solution was to make a foldable windblocker that folded backwards, NOT forwards, due to the fact it would hit the seats, and the foldable section was about 1/3 the way down the windbocker, it didn't fold at the parcel shelf.

Trying to prevent rattling of your hinged lexan windblocker will be a big hurdle.

[Apu]

Vic, I posted pics of my blocker in my "Journey to Apu" thread in Garage Chat. Bizi and I had the top down on the way back from Wakefield and we hit...110kmh...and it did the job fine. The only problem was a gust on my right hand as that corner beside the B pillar is open.

I bought a piece of tinted acrylic from Allplastics in Chatswood for $40 and cut it with a jigsaw. It's big enough to keep it nice and quiet in the cabin but small enough that you can even install/remove it with the soft-top up.

However, if you want a full sized windblocker, I actually have one with a bronze tint. I'll be putting that up for sale soon . That came out of the US and has a bag/sack as well.