For those of you running a JDM Rear Bumper how are you supporting the diffuser portion?
The USDM Rear Bumper has two tabs that you clip into the crash bar but the JDM Rear Bumper does not. I'm also running a Boosted Fabrication Crash Bar w/JDM License Plate Bracket.
Without any support the lower portion of the bumper seems to bow out. I'm contemplating fabbing up some sort of bar that I can attach to the tow hook area and then secure to the trunk.
Anybody else run into this issue? Or am I simply missing something and overthinking everything?

 

When I installed my JDM rear, I completely tig welded / fabricated my own crash beam out of aluminum. I engineered my way out of this problem that you describe with 2 little supports. You can see how I did it if you browse my threads- there is a link to my project in my for-sale thread (my car is for sale now)

 

Perfect! I figured there was no OE Solution. Probably going to order some pre-fabbed brackets off Amazon and then secure the bumper to the trunk.

 

I've been mulling over the same issue. The bottom diffuser/splitter section on my JDM rear is definitely "parachuting" out. Looking at the rear straight on, you can see it pushing out from the middle, like someone is pulling on it from the center. I'm assuming this is catching air and gradually getting worse over time. Mounting/fabbing something to the trunk underbelly and attaching it to the clips seems to be the only viable solution here.
​​​​​
I'm surprised that more people don't have this problem though. I see so many pictures of rear JDMs that look dead even at the bottom.

Please keep us posted!

 

Ordered some aluminum bars off Amazon and crudely bent one into shape to pull the center of the diffuser in more. There’s already a plastic bracket under the tow hook cover so that was the starting point. I mounted a rivnut to one end of the bar and secured it to the bumper. From there I just started bending until I had a shape that somewhat contoured the bottom of the trunk. I drilled another hole in the other end of the bar and used a paint marker to mark where I was going to drill into the trunk. Throw another rivnut into the bar and you can tighten everything down. I’ll probably trim the bar and paint it another day, but I’m otherwise happy with the results.

 

Hmmm I never noticed what my JDM rear is setup like but I have a usdm crash beam that's modified (extensions cut shorter) . I'll have to crawl under and take a look over the weekend.