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Discussion Starter #63
I've always loved the look of the BNR34 V Spec II rear diffuser, unfortunately they're expensive second hand and even carbon fibre copies are £1k. So i decided to attempt to make my own using inspiration from it. I'm by no means a fabricator so please be easy on me lol

The first decision was material, I wanted the brackets to be strong, the main diffuser strong enough to be sturdy but doesn't weigh a tonne. I decided to use 2mm thick angle iron for the side and rear brackets and 1.5mm steel box section for the front bracket.



Looking at mounting points and there is a part of the chassis that sits lower than the bumper, this should be ideal



The diffuser and fins were going to be made out of 0.9mm sheet steel. I did think Aluminium as its easy to work with but its too soft IMO. I started off with a card board template, unfortunately the exhaust sits too low at an angle for the whole diffuser 'body' to be a single piece. I tried cutting a hole to try and clear it but it left minimal material at the bottom and it would eventually snap.

So i went with a 2 piece design instead





I started off with the passenger side as it was smaller and easier to mount. A slot was cut for the exhaust hanger with enough room for any movement. The rear is braced with a piece of 2mm flat bar which uses a bolt in the wheel arch to the right side of the shock absorber.



The box section bolts through the boot floor, this helped angle the diffuser down rather than having it flat. This was the first prototype for the box section, later on I made it longer so it covered the width.



You may remember me making a rear tow hook awhile back. I decided to incorporate it into the design by cutting a slot, again enough roof to not catch it when fitting/removing.



I seeked help from some friends as I don't have the skills/equipment to weld or fold sheet metal perfectly.



With the fins folded I could mock the ends up. These would be bolted on and use the same mounting points as the diffuser itself





The rear bracket was made and mocked up at the same time. I also marked the holes for the centre fins ready for drilling. At this point I decided to give the front of the diffuser a minor bend upwards rather than leaving it straight.



With everything fitted for one final time,checking clearances and everything was solid and not rattling/vibrating it was time to drop it off for powder coating. Originally I thought about having it done in black, but with the lower black trim just above it, I feared it may get lost and wouldnt be seen. Only other option was silver, the powder coater only had a satin silver so I bit the bullet and went with that.

I ordered stainless nuts, bolts, washers and rivets for the final fit













I've made flat under bumper splitters, canards and other little bits and pieces in the past but this was certainly my biggest challenge. I think its turned out very well :)
 

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Terry
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Well that is an art I would like to master,metal fabrication that is.

That does look very good although I would have gone black but that would be my only change but it is easy to be critical from a keyboard. It is a job well done and thank you for uploading the pictures.

The car does look sweet.


Sent from my iPhone using Tapatalk
 

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Discussion Starter #65
The silver is really thin, depending on how it survives the elements it may possibly get changed to black
 
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