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I'm modifying my doors to cut some weight out. My aim is to keep them looking like a stock door, but with no speaker or handles so I'll clad them in vinyl and keep the top padded strip.



I have already done the following:
removed the side intrusion bar (I have a full cage)
removed the rear slider for the window - it works fine off the central and 'A' window slide
drilled holes in and trimmed of spare tabs of the central slide for the window
cut out nearly the entire interior skin of the door, except for areas I need to keep.

I'm going to:
replace the 'A' window with polycarb
lighten the structural twin skin frame along the top of the door

I think with these changes I'll have removed a good 30% of the weight from each door. The main weight left is the glass itself.

Has anyone tried to replace the window glass with polycarb? Maybe try and heat it over the top of the old window so that it bends to the form. The only issue I see is the flexibility of the polycarb vs the wind and the window scratching if I raise and lower it.

Do you need to raise/lower the 'window'? Permanently mount the polycarbonate window in the 'up' position and install a NACA duct.

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Poly windows won't take a shape. You have to brace them. This can be done many different ways, most of them ugly... because race car.

Or a little sliding window to get your burgers shoved through.

No need for burgers, but it's handy to be able to chat to officials / competitors whilst queuing up for a run.

I ended up putting the glass window back in, but at some point I might try bending some 4mm acrylic over the glass window and see if it's rigid enough to work. The other option is to mount the window up without the electric winder which is probably the lightest option, but I've drilled holes in my nice CF center console for electric windows! I did put 3mm acrylic in the 'A' window which is a bit lighter than the glass.

I'll report back if I try the acrylic window.

Bit off topic but last night whilst I was working on the doors, I also made some panels to fill in the gap left from removing the popup headlights. These panels will bolt to the bonnet but be removable so that I can reinstall my headlights if I do a night event. I've never really done any sheetmetal work previously but they came up really nice just by taking it slow and getting the tools setup right. The only tools I used was a hammer, tin-snips, 2 lengths of steel angle and a bench vice.

I DIY'd polycarbonate windows for my Integra, along with a DIY slider. The benefit is that I have a full frame to fix the window to, but the centre portion of the window is flat (or concave).





Plastics 4 Performance in the UK make a brace for frameless doors. Have a look at their site - it's pretty neat.

How did / will you:

madjak wrote:- lighten the structural twin skin frame along the top of the door
- removed the side intrusion bar

Particularly interested in how you remove the side intrusion bars...can you go into some detail please?

My car is a Eunos import so it didn't have intrusion bars from factory but I think the process is similar to stock bars. Mine were added when the car came to Australia. To remove the door bars I drilled out the spot welds at each end. You can see the three holes in my photo. Then I used a cut off disk to cut the bar in half to remove from the door... it's best to place an approx 3mm or so thick plate between the bar and the door skin so that you don't nick the skin.

In the end I didn't lighten the twin skin section on the top rail. To do this I would have made two thin cuts at either end with a cut off disc, lightened the rail by either trimming the rail with a cut off disc, or by drilling holes then weld it back in. There is a bit of weight in this rail because the second skin is fairly thick. I'll do this if I go for a fixed window.

Dug through my archives assuming I would have a photo relevant to the topic.... I was right.

Basically everything that I could try cut out, I cut out. The windows are 3mm lexan with an aluminium tube frame and a few self tappers. It's reasonably easy to make lexan windows because you usually have a glass template to copy from. The door latch protrudes from the rest of the door unfortunately... I welded a gusset to it to keep it sturdy. The 'door trim' is a simple flat sheet.
The door is floppy as hell without the door trim installed. It really adds a lot of stability to the door.

I drilled out the end of the door with a 20mm bit for extra weight savings. I've actually had another hack at it since the photo was take with even larger 32mm stepper drill bit.

Ooh...that is pretty extreme Brendan! I don't quite want to cut out so much as the door will flex too much but I do like the idea of drilling holes in the door ends to lighten it more.

I'll have to see if I can see the spot welds on the Integra. If not, I'll just do what Brendan did with his door ends...just drill and hopefully find the spot weld to release the intrusion bar.

These doors would be the lightest way to go. It may be possible to put the sliding rails and mechanism in. But that woul add weight. From memory they weighed about 2.0 kg before the hardware and window went in.
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