calteg

iTrader: (18)

So I got bored and ordered this little fella from carbonmiata. Props to them for shipping it quickly, during a pandemic, from China. The recommended installation is 3M double sided tape. As much as I love the idea of $80 worth of carbon fiber falling off my car at speed, I'd welcome a more permanent way of attaching it to the bumper

technicalninja

rivnuts might work .

But when it comes to double sided permanent tape I use 3M VHB (very high bond) tape.
3m sells it in huge rolls that are very expensive but you can commonly find some one selling small amounts on e-bay
3M VHB Double Sided Adhesive Tape 4941 White Industrial Grade 3/4 Inch x 10FT 888519025208 | eBay

When I purchased this stuff the red backed "automotive" grade was not available and I got the white backed "industrial" version.
I don't know which one is better...
The white stuff I got can be removed just after install but if you wait a day it cannot. They use this stuff to mount aerodynamic instruments to aircraft wings and they stay on. This is the stuff that is used to mount cameras to skydiver helmets.
Stupid sticky....

curly

iTrader: (25)

I wouldn't use Rivnuts. They require a large hole drilled in your bumper, and still wouldn't hold well, especially if they got significantly hot. If anything I'd use 1/8" rivets with backing washers, or a small 4 or 5mm SS button head with large fender washers and nylon lock nuts.

DNMakinson

iTrader: (3)

Like TN said, VHB is good. It comes in a transfer adhesive only, or with various foam substrates, of various thicknesses. For this use case, if you use one of the foam core types, I would suggest looking for fairly thin (1/32") that is UV stable. This really should work.

DNM

rleete

iTrader: (21)

I worked for a company (Morrison-Knudsen) building subway cars for many years. We build the "new" Caltrans cars (back in the early 1990's) using a stainless steel framework and FRP panels, held on with what was a fairly new adhesive, the 3M VHB tape. If a panel was installed incorrectly, the workers had only a few hours at most to remove it. Otherwise, it would destroy the panel and possible the frame.

Real 3M VHB is going to hold up better than the rest of the car will.

technicalninja

Curly is right here as he usually is...

But, I've had thin composite things crack when I used a pop rivet and a backing washer. That would **** me off if I paid $80 for a nice carbon fiber part which I immediately cracked.
I was trying to decrease this tendency with the rivnuts but Curly is still right, rivnuts have the issues he brought up.

But I have another trick up my sleeve...
Modern GM vehicles (within the last 10 years) have moved to a single use plastic pop rivet to hold inner wheel liners in.
They are stupid expensive from the dealer and there's a bunch of them holding the liners in.

Harbor freight has a cheapo set up that works fine.
Hand Riveter with 40 Industrial Strength Poly Rivets (harborfreight.com)
That kit has enough rivets to do a couple of late model liners and is cheaper that 1 set of rivets for a single vehicle.
They don't take much force to install and the back sides splay out big time, no need for a backing washer...
The only issue with these might be heat tolerance which may be an issue with the VHB tape as well. I've not tried it in a high heat installation.

Which leaves you with button headed hardware with locking nuts installed softly which WILL work fine.

Calteg, I'd be happy to send you 6" of the VHB stuff I have. PM me if you'd like me too. No charge...

calteg

iTrader: (18)

I just might take you up on that, I'm just down I-35. I'll PM you my address. Carbon miata included some sort of 3M tape...the entire package is written in Chinese with the exception of the word "Strength"...not sure I'm willing to put my full faith in that product just yet. Thanks again!

technicalninja

Incomimg!

calteg

iTrader: (18)

When you're running pig rich, but you're too lazy to actually tune your car, just add carbon fibre! Thanks technicalninja! We'll see if it sticks long term

calteg

iTrader: (18)

It did not stick long term. Prepped the bumper, used the VHB tape, clamped it together for 24 hours, it started peeling away about an hour after I took that photo. Looks like the tape didn't want to adhere to the back of the carbon fibre. I'll probably end up using Curly's suggestion

calteg

iTrader: (18)

Ended up using Curly's idea of 1/8" rivets + backing washers, we'll see if it sticks long term