Carbon Fiber Doors Finally Finished (Almost)

[bigjae46]

Just finished the left and right door. I'm happy to say they open and close, fit reasonably well, and are quite sturdy! Definitely race car grade. I used a spread tow fabric for the outer layer which is very difficult to work with on anything not totally flat. The weave got messed up on the left side, learned some lessons, and then the right side came out a lot better!

I've never been a fan of the typical carbon fiber look but for some reason I love the look of this spread tow! Spread tow has much better mechanical properties but also has a lower resin content than regular carbon fiber. Per SQ YD it costs about the same as regular 1x1 or 2x2 twill but...it takes about 2-4 layers to achieve the same thickness. A panel made of spread tow will be approximately 20% to 40% stiffer and about 10% lighter than an equally thick regular carbon panel.

But I'm poor so it's got one layer on top because I like the look. haha




First gotta make the molds. Polyester resin is not fun in the TX heat. I cut off the hinge studs so no I have 2 useless doors.





Layup the fabric and consumables and bag the part.





And then do a vacuum drop test...this is the 2nd most painful part. Lots of pressing down on tape, listening and searching for leaks. Once its leak free then start the infusion!


Epoxy ain't cheap so its best to minimize waste. Take the time to calculate how much epoxy is needed.

[bigjae46]

Then let it bake in the TX sun and pull it from the mold in 24 hours - which is the worst part. Pulling peel ply off sucks!




Trim, bond, and get it ready to install!





I learned a trick, snug the hinges to the door so it takes some effort to move the hinges but it stays in plate. Then install the door on the hinges, make the adjustment and carefully lift the door off. Torque the hinge nuts and it should be spot on.

No good pics but I have a universal mini-latch from Speedway. Left door...had to drill some extra holes. Again, learnings here and the right door went on easily. Close the door, put the latch on the striker and then trace the striker onto the door. The door handles have been more of a challenge. I got them to work but it take a little yank. Definitely not BMW smooth!

The left door is 14lbs, right door is 11lbs - with everything attached. The OE door with everything was 35 lbs.

This is the disappointing part. I was calculating to be at an optimized 2570lbs. I have the 2nd oil cooler and brake ducts in so I should be around 2585. Just scaled the car and its 2598lbs - no fuel no driver. Not sure where the car gained 13lbs...need to figure that out.

[Slideways]

bigjae46 have you seen this video on making carbon doors for an E36? Thought it was pretty impressive given their fairly limited experience in making carbon parts.

[bigjae46]

bigjae46 have you seen this video on making carbon doors for an E36? Thought it was pretty impressive given their fairly limited experience in making carbon parts.

Saw that. Coupe doors aren't too bad since there is no window frame. Learned the painful lesson of adding reinforcement to molds. Especially for the outer skin, the mold tends to curl as the part is heat cycled.