Saturday, February 05, 2005

Perspex *Rigid* Windows!

Ok so who is pissed off with side windows that bow out?? I bolted mine solid, fixed with bolts and no up and down mech - yet they still do it! Get to 80mph the windows bend and you get bad drafts...

I intend to go 130mph with new 1800 or 2000cc engine and don't want any drafts - maybe more? 140...175HP-200HP 600kilos? So I want a solution that rids the car of this annoying happening.

Using lightweight doors inspired me to use lightweight windows etc. Anyway a piece of perspex is gonna bow like anything without support unless its set at a lower angle than needed so it bends out when you close the doors so to create a pre-bending and loading that may stop the window bending out, as its already bent somewhat. Downside to that is you get doors that don't like to close without slamming and it strains everything and probably wont work anyway!

I made the things shown that go inside the doors to house vertical braces that go inside the window (as shown) the window screws to these braces, so to hold it 100% solid....you can set the angle at each end of the window by swivelling the top of the window in and out as its made to be able to pivot 10degrees either side of what should be fine. So you set the angle of thw window so it seals all round front and back as good as possible by adjusting the angle of the window on the braces, these offer some twist in the window, to get one or other corner in more than the other etc.

You can see I have only drilled the 1 hole which will be the hole that the brace rotates around when setting the angle of the window, I will wait and drill the hole once I have it all together before final assembly. I am working with a drill, jigsaw and file. Each piece is made by hand and needs final giggling I am sure to get it 100%...

I intend to set the windows up statically with someone on the outside just pushing hard enough to compress the seal at all points, I will then mark the last hole that fixes the angle of the brace, take it all apart drill it...then use Adheseal - I think its called that, its a stickaflex type glue, that sticks and grabs really hard, yet remains flexible, used in boat building.

I will bond the main braces to the inside of the doorshell and skin using this...the advantage of the twinskin door skins is that they can take over 60kilos before they flex to anygreat degree, so I can simply bond these on, do that to a normal plastic one I bet it will go out of shape over time, as the suction on the windows I recon equates to about a 4kilo tug at the top @ 90mph so will load the doorshell via the bracing.

I hope the windows will have the stiffness of the a normal road car window, as the braces will be rock solid and the door will not bend to any great degree...is the final solution? Its the best I can do at home with limited tools..

All the braces together weight 1200grams I can drill the final big holes now and get another 125grams back. Each of the window runners from original doors are 480grams, I saved weight there, I saved the weight of the glass window, the weight of the window mech, door catch mech, bump stop, glass holder....

Only things to add in weight wise to braces and door shell are a window catch, the perspex window, about 16 M4 nuts and bolts, two tiny hinges, few tuny angled brackets...

Note the alloy pole in the pictures? Thats a door handle, something to pull on to close the doors, my only comfort item...Also you can hang you sweaty socks on there between laps?

I will make an all alloy flick catch to operate the door mech without having to reach into the empty doorshell and find it...but thats not important atm!

I will be cutting the inner doorskin out of the doors completely, the roll cage has door bars these require me to cut the shell skin anyway as they go all the way out to the skin, once the skin is cut it goes all floppy and needs cutting out completely anyway, so thats a bit of weight saves...I am not concerned about the door going out of shape it just aint gonna happen, these are super doors! It'll look interesting I think and be the lightest and best solution I can make, hopefully it'll work I am already at a good 25Hrs of work into this....

Its a pain as the car is used daily, trying to get everything together, also having to do it at my folks place which is 40miles away is also a bind as theres no kit here yet.

I am also making pop out windows, within the main perspex side windows, these will use MGB GT Quarterlight catches, pop out 15cm, it will be reasonably sized, I think, the hinges will be bolted through the perspex at the front, on a plate that raises the hinge to the level of the pop-out window and seal when closed...,as required to get a seal and for it to work!

Hopefully 200mmx200mm will do and give decent venting without weakening the structure much, may play start small and see if the window goes floppy at all, shouldn't do as it'll bolted to the braces! I can always cut the hole bigger can't I? I have coolio ideas for how to make a huge pop out but retain strength, think a big line of vertical holes on inner window the hinge end...

You should be able to physically remove the whole window in a few minutes if needed.






1 comment:

James Carruthers said...

Those supports are a work of art!