SL-C - tub to body screws
- Thread starter OJ86
- Start date
Neil
Supporter
After frustrating experiences with trying to epoxy nuts to the backside of panels (and Nutserts or Riv-Nuts that spin in their holes), I have become a firm believer in using aircraft-style "nut plates" instead. They are available in two types, a "fixed" and a "floating" style. The floating nut plate allows the threaded portion to move around a little to line up with its mating screw fastener.
Here is what I have been using in my build when I need threads in the fiberglass parts:
Neil:
I had no idea those existed, the floating ones are awesome, would have saved me tons of re-dos, I had to redo most of them due to using the wrong screw (fine vs coarse thread) and popping them off. Thanks for the tip, too bad came almost at the end of my build .
Hector
Kurt
Elegant solution as well, I did not know about those rivet nuts either, thanks , hope this is super helpful to other builders early in their process. the only downside to the rivets is that they are specific to certain thicknesses, and the fiberglass parts we have vary so much in thickness. even within a few inches length.
Hector
Neil
Supporter
A nutplate is not subject to turning in its hole and "grip length" is not a factor. The length of the screw is not important as long as it engages the threads fully.
Scott
Lifetime Supporter
It depends on how the car was built. IMO, you don't want screws visible in the door jamb. The tub is attached to the chassis and if trimmed properly, the body and tub do a good job of indexing into each other without the need for visible screws in the door jamb. If you're not having squeaks or movement in that area you probably don't need screws there. In any event, if you did you'd probably want to remove the body to install nut plates on the back side as discussed above.
I've used the floating nut plates described by Neil. They are very useful and have distorted threads which prevent the screws from backing out. They are designed to be used use solid rivets which can be installed completely flush on thin metal panels. Pegasus sells the rivets as well as the rivet squeezer which works great. To create durable nut plates for the body I riveted the floating nut plates to pieces of aluminum which were then boded to the body. This approach helps distribute any loads on the fiberglass. As can been in the top right assembly, the rivets are flush with the bottom of the aluminum.
>...I've used the floating nut plates...
Do these come in Aluminum? (Any concern of dissimilar metals Steel/Aluminum oxidation?)
Found stainless: https://www.pegasusautoracing.com/productselection.asp?Product=MS21060
Do these come in Aluminum? (Any concern of dissimilar metals Steel/Aluminum oxidation?)
Found stainless: https://www.pegasusautoracing.com/productselection.asp?Product=MS21060
Scott
Lifetime Supporter
Aluminum wouldn't be strong enough. The steel is coated and the solid rivets are brass. If installed properly will not move in any way shape or form against the aluminum (the floating part is captured within the steel body). I don't see any issue with steel/aluminum corrosion in our application, but if you're worried about it you can go with stainless.
Neil
Supporter
I often mount nut plates using 1/8" AVEX countersunk blind rivets. I drill out a #29 hole to accommodate these rivets. If you don't want to drill the holes oversize. a 3/32" countersunk "Pop" rivet works just fine. https://rivetsinstock.com/rivets/blind-rivets/nail-type-basic-blind-rivets.html
Joel K
Supporter
I used the Pegasus Floating Nut plates to mount the oil sump and intercooler tanks. I like the Pegasus because they come metric sizes and have the distorted threads.
I used Domed Head Sealing Blind Rivets. They are pop rivets that seal the hole up. The aluminum ones have 100lbs sheer strength and the stainless are 900lbs. Plenty strong for an M6 size screw.
I used the aluminum because they are easier to drill out than stainless.
Here is a link…
www.mcmaster.com
I used Domed Head Sealing Blind Rivets. They are pop rivets that seal the hole up. The aluminum ones have 100lbs sheer strength and the stainless are 900lbs. Plenty strong for an M6 size screw.
I used the aluminum because they are easier to drill out than stainless.
Here is a link…
McMaster-Carr
McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.
On my SLC I used a 1 1/2 inch flat bar 1/8 thick with 5/16 floating nut plates attached that is slipped in from the rear wheel well area on top of the body lower lip which was sitting on top of the chassis tub. I then bolted each side with 4 stainless steel 5/16 bolts through a thin stainless flat which was underneath the fiberglass side skirts. The floating nut plates really help with minor misalignment issues when doing it this way.
Neil
Supporter
Nutserts or Riv-nuts?
oops, yea Riv-nuts -- I always call them the wrong thing
