Got to the bit of understanding my car where I am taking things off and refitting. However not getting younger and reaching around for nuts as they fall off is getting tedious. So, to forward plan, I think I’ll fit RivNuts into the fibreglass. I have only ever used them on metal so was just check there use in fibre glass, especially as it seems so thin. Last example is the wiper motor. The nuts inside the foot well - nearly put out my shoulder !
Before committing, has anyone got any concerns or history with them? Should they be avoided for any particular reason? Or are there any other equivalents that I should consider so that the reverse side of the fibreglass does not need accessing? I’ll use stainless wherever possible.
I have used aluminium Rivnuts in various locations on my +2 with mixed success. Generally I coat the rivnut with mixed fibreglass resin when fitting it. I also have used a small washer on the back side when access is available and the fibreglass is thin.
The success of rivnuts on fibreglass ,I have found. tends to be dependant of the thickness of the fibreglass in that particular location. If the fibreglass is thin then they don’t work well at all. They work well where the fibrglass is thicker. i.e the main structure of the body.
Just to add though, I definitely wouldn’t use them anywhere that was structurally dependant!
Thanks Alan for the feedback - I am tiptoeing forward carefully. I am mentally trying to think what the pro and cons are and what the failure modes might be, or whether I was overthinking it. I am conscious these cars are old and the fibreglass is so thin.
Pre-coating with an epoxy to spread the load is a good idea.
I would probably only use them on the usual spots - engine side of wheel arches, such as the wiper motor bracket, the boot area that is below the tank, for my fuel pump etc. bolting things down in the boot, although I will probably fit an aluminium plate behind as well.
Yes, aluminium might be better as it will spread out better on the back. Or brass? I’ll call up a supplier for advice.
Standard rivet nuts are great for sheet metal. There are better options for fibreglass such as chloroprene well nuts, adhesive bonded nuts and composite-specific rivet nuts such as the above or this SKU from McMaster
I have used rivnuts on my +2 bulkhead to connect non standard brackets for washer bottles and coil packs, but I have also used Wellnuts which perhaps are a bit kinder to thin fibreglass
My series 1 Elise is held together by Wellnuts as standard and I have used them on my motor home to replace exterior door catches with great success. For holding things like washer bottles etc they would be ideal and much better than rivnuts.
I used Rawlnuts/Wellnuts on a few areas on my S4. Things like fusebox to bulkhead, repeater lamps to the wings, relays to the inner wings, harness P-clips, etc. I even found some that had the same thread as that used on the front Lotus badge.
Thanks, everyone, for your suggestions. I’ll put Rivnuts aside for the moment and look at the other suggestions. My initial question was prompted by my suspicion that Rivnuts might just be a bit too brutal for us on the fibreglass, and thanks for the steer based on all your experiences.
Bear on mind that the rivnuts/rawlnuts and similar require quite a big hole relative to the fastener : an m5 needs a10mm hole; also these types of fixings are generally threaded: for fully threaded bolts (machine screws) . I have had good success with the smallest size normal rawlpugs requiring a 4-5mm hole, so long as they have at least a small surface “head”, for simple attachments eg the P clips on the bulkhesd harnass, engine bay fuseboxes, air intake grilles and transmission tunnel panels etc..the hole reqd is much smaller and will take simple screws sizes 4 to 8..Worth considering for the lighter tasks..Tony
I know this will probably go over like a lead ballon, floater in the punch bowl, but here is how I have dealt with RivNut situation in my Lotus bodies. I make my own. You will have to bare with me, because all the photos of their construction were lost in a hard drive failure and non-recoverable.
I used a round of aluminum stock of the appropriat diameter, say 1", and turned it down in my lathe to what could be best described as a “T"nut. Threaded on the inside in 1/4-20. The 'Stem” was reduced to 3/8" and threaded to 3/8 course., length as needed. A larger round of aluminum was parted off, similat to a Fender washer, Diameter as needed with a 3/8" hole. A section of the round used for the “T” nut was knurled to a finger gripping length, bored and drilled to 3/8 course. On the Plus2, I used them on the bolt that holds the hood prop to the body, and also where I mounted a 10 fuse block on the left side firewall. Also where I mounted my electronic lost spark ignition coils and controller on the right side footwell.
I have reached the point in life where the light at the end of the tunnel is getting dimmer with each step forward, and will be thinning the heard. As a start, Is there anybody in the SoCal area interested in a Dunlop Alignment gauge, Dial indicator bump steer gauge assembly, and a camber gauge? Due to size, pickup is about the only choice. PM me for contact info and location.
Could not find what you meant on carbuilder ( unless you meant these - Nut Plates – Car Builder Solutions) - or is this the sort of thing you meant - Master-Plate bonding studs for composites. My engine bay is a bit like Swiss cheese with all the modifications to it over the years So long term I hope to sort it out and may end up putting a new matt of fibreglass over the bad portions and then painting over. Or I may not bother , I’ll see.
Go into car builder and use drop down menu - one of them is ?,?, fixings. Go to that folder and I think the first item shown are glue/ glass in fixings. I believe the are used in the aircraft industry.
