ukchris Posted April 15, 2018 Share Posted April 15, 2018 I have the fenders/wings off so it’s time to think about the rivnuts. On the back left one was spinning loose but was accessible so easy to remove, another was spinning but not accessible so I had to cut it off. This leaves me needing to replace at least these two the holes are two big so I assume I need an alternate approach, especially the inaccessible one, I assume that at a push I can put a bit/washer on the other one. So, questions... 1. Where’s the easiest place to get replacement bits? I couldn’t see any at Home Depot etc. 2. What is the best approach for tackling the oversized hole issue when I cannot get to the back of the hole? I’ve read about replacing with plastic, it seems the guidance is theyllnshear ifntheres impact, what are the pros and cons and where would I get plastic ones? I don’t expect to spend much of any time on the track, in that case is it appropriate to considernplastic? Chris. Link to comment Share on other sites More sharing options...
yellowss7 Posted April 15, 2018 Share Posted April 15, 2018 McMaster Carr has the nylon bolts and I believe some riv nut options. The nylon bolts definitely save your skin and rivnuts if you do hit a cone when Autoxing. Ask me how I know. :svengo: Tom Link to comment Share on other sites More sharing options...
xcarguy Posted April 15, 2018 Share Posted April 15, 2018 Chris, Ditto on the nylon bolts. Aloong with the nylon bolts, I use insulating rivet nuts to secure both my rear wings (fenders) and the front wing (actual aero wing on front for downforce) to the car. Last month while running at VIR, a cone sacrificed itself when it deliberately jumped in front of my car. The front wing was pretty much destroyed by the cone, but the nylon bolts sheared, thus preventing the wing mounting assembly from incurring any real damage. In 2015, I had an accident at TeXas World Speedway where I went airborne for a bit. During the impact with the ground, several the nylon bolts on both rear wings sheared. This save a lot of fab work and replacement of parts when I rebuilt the car. A cone was also sacrificed during this adventure. :jester: Useing a 1/4” nylon bolt, along with the appropriate sized insulating rivet nut, will require your drilling a 1/2” hole for mounting. However, it works great. Links us for both: https://www.mcmaster.com/#standard-rivet-nuts/=1cf92he https://www.mcmaster.com/#nylon-bolts/=1cf98nz also, I’d go this route, you may have shorten a bolt here and there to keep it from bottoming out on a fraMe rail, etc. A rZor knife works well here. Link to comment Share on other sites More sharing options...
yellowss7 Posted April 15, 2018 Share Posted April 15, 2018 The M5x25 nylon bolts are the right size for the existing rivnuts installed by Caterham. Link to comment Share on other sites More sharing options...
ukchris Posted April 15, 2018 Author Share Posted April 15, 2018 My thinking is that I’m reluctant to replace all of the rivnuts, does it make sense to get M5x25 nylon bolts to use on the existing rivnuts but 1/4” and re-drill the ones that are missing? Link to comment Share on other sites More sharing options...
yellowss7 Posted April 15, 2018 Share Posted April 15, 2018 My thinking is that I’m reluctant to replace all of the rivnuts, does it make sense to get M5x25 nylon bolts to use on the existing rivnuts but 1/4” and re-drill the ones that are missing? :iagree::iagree::iagree: Link to comment Share on other sites More sharing options...
ukchris Posted April 15, 2018 Author Share Posted April 15, 2018 For the M5 Nylon bolts I thought when I took them out they were under an inch in length, I was thinking 20mm but you said 25? I suppose with nylon they’re easy to shorten... so 25mm or 20mm? Nylon washers or reuse the existing ones? Link to comment Share on other sites More sharing options...
xcarguy Posted April 15, 2018 Share Posted April 15, 2018 My thinking is that I’m reluctant to replace all of the rivnuts, does it make sense to get M5x25 nylon bolts to use on the existing rivnuts but 1/4” and re-drill the ones that are missing? I would use the existing rivnut if usable. The insulating rivet nuts slide in the hole once drilled and can be easily replace if needed. But, if you can use your existing hardware, don’t reinvent the wheel. Link to comment Share on other sites More sharing options...
ukchris Posted April 15, 2018 Author Share Posted April 15, 2018 Can you help me understand what you mean by an “insulating” rivnut? They don’t seem to be listed that way. Link to comment Share on other sites More sharing options...
ukchris Posted April 15, 2018 Author Share Posted April 15, 2018 Doh! Found them! Link to comment Share on other sites More sharing options...
xcarguy Posted April 15, 2018 Share Posted April 15, 2018 A bit more info on installing insulating rivet nuts. And they are known by many different names. https://www.mcmaster.com/#93495a321/=1cfdsfa https://www.youtube.com/watch?v=H18KTamGLLg&app=desktop Link to comment Share on other sites More sharing options...
ukchris Posted April 15, 2018 Author Share Posted April 15, 2018 Here’s what I have so far... 99602A430 Nylon Hex Head Screws, M5 x 0.8 mm Thread, 20 mm Long 99091A153 Black Nylon Hex Head Screws, 6-32 Thread Size, 1" Long 93495A110 Rubber-Insulated Brass Rivet Nut, 6-32 Thread, 3/8" - 33/64" Material Thick Range Now, rivets... I’ve got a rivet gun (came with the car) but have never used rivets, seems it makes sense to maybe order some rivets while I’m at it, is there a fairly generic size I should get? Any other useful spares while I’m at it? Link to comment Share on other sites More sharing options...
ukchris Posted April 15, 2018 Author Share Posted April 15, 2018 You beat me to it with details, my list is now as follows... Nylon Hex Head Screws, M5 x 0.8 mm Thread, 20 mm Long Black Nylon Hex Head Screws, 1/4"-20 Thread Size, 1" Long, 3/8" Wide Head Rubber-Insulated Brass Rivet Nut, 1/4"-20 Thread, 1/32" - 3/16" Material Thick Range Link to comment Share on other sites More sharing options...
ukchris Posted April 21, 2018 Author Share Posted April 21, 2018 You beat me to it with details, my list is now as follows... Nylon Hex Head Screws, M5 x 0.8 mm Thread, 20 mm Long Black Nylon Hex Head Screws, 1/4"-20 Thread Size, 1" Long, 3/8" Wide Head Rubber-Insulated Brass Rivet Nut, 1/4"-20 Thread, 1/32" - 3/16" Material Thick Range Okay, so the bits and bobs are here. The outer “flange” on the rubber insulated rivnuts looks huge/thick, does that compress when installed? Looks almost 1/8” think or so. Better figure out what to do with them.... so I drill a 1/4” hole, pop it in but then what? Does the bolt sqush it up or am I foolishly not realizing there’s a tool I need?!! Link to comment Share on other sites More sharing options...
xcarguy Posted April 21, 2018 Share Posted April 21, 2018 Chris, The nut will compress on the back side when bolted in place (see photo). As for the thickness of the flange, you can always reduce the thickness with an xacto knife. Part number 93495A310 provides a thinner flange, however, it is for thinner material (see photo). Link to comment Share on other sites More sharing options...
ukchris Posted April 21, 2018 Author Share Posted April 21, 2018 Did you trim yours down? If not did it leave the fender sitting away from the body? As I’ll be mixing the original rivnuts and these I’m concerned about making a kink in the fiberglass. Link to comment Share on other sites More sharing options...
xcarguy Posted April 21, 2018 Share Posted April 21, 2018 I dint trim mine. Used the rubber nuts all the way around (uniform). I also used fender welting in between the Fender and the body panel. Link to comment Share on other sites More sharing options...
ukchris Posted April 21, 2018 Author Share Posted April 21, 2018 Okay thanks, I’ll give it a shot this afternoon and see how things go. I guess if the fits not right I can just drill out the other rivnuts and replace with rubber. Link to comment Share on other sites More sharing options...
xcarguy Posted April 21, 2018 Share Posted April 21, 2018 Using all rubber nuts at this point will most likely be the easier route. Link to comment Share on other sites More sharing options...
wemtd Posted April 21, 2018 Share Posted April 21, 2018 Chris:My birkin fenders are secured into a threaded steel round. there are two offset rivest securing this to the inside of the aluminum skin. If you're interested i can PM you a picture. p. Link to comment Share on other sites More sharing options...
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