Rivnut size and type
 

I'm planning to use Rivnuts for my trans tunnel, and to create a removable panel above the master cylinder. What size (diam, thread) and type (stainless, galvanized, aluminum, spin resistant) have people used with success?

Also, it seems like the top flange of the Rivnut would create a small gap between the panel and the surface it's mounted to, so the panel won't quite sit exactly flush as it would if it were riveted (make sense?). Is this a problem?

Lippy,

You could probably use 10-32 rivnuts or 1/4-20 if you want a little more strength.

If you use a thin gasket strip/stick on foam tape all around the mounting flanges, you will not have to worry about the thickness of the head of the Rivnut.

Use these and countersink by just touching the installation hole with a larger drill or countersink. 8-32 or 10-24 would be my preferred size, using a buttonhead allen screw.

Lippy - I use 10-24 rivnuts. The countersinking is a good idea - I didn't think of that. I may countersink the transmission cover holes on the underside instead. But I do plan to use a 1/8 inch weatherstip seal too.

I also used rivnuts to fasten the top transmission cover to the footboxes up under the dash.

If you haven't already, I would bookmark McMaster Carr for lots of small parts, tools, hose, weatherstrip, rivets, rivnuts, washers, grommets - about anything you can think of. And they ship quickly.

I have a friend who tried using 1/4 x 20 rivnut on his trannie tunnel and they were to large. He had to remove them.

10/24 with button head. Use Silicone to seal it. Remember it all covers with pad and carpet.

Dwight

Bob, will the rivnuts make the transmission tunnel stronger than the screws that it comes with? Trying to understand the benefits.

Kevin

I have used a bunch of these, fine and coarse. Stick with the coarse thread, you will be happier. easier to thread and for some reason when you pull them up the coarse thread seems to do a better job, probably quicker on the pull i would surmise. I would use 10 size which uses a 19/64 bit, 1/4 is getting pretty big but if you want i could send you one of each to purview and i don't know your panel size, etc. the button head screws are nice, but they really suck for stripping the allen head portion, not very much meat there. i switched all my button heads to stainless allen head for the adel clamps.

i use air guns on mine, and they will mash the flange portion pretty flat, right into the aluminum. the worst thing you can do is not pull them up tight the first time, but if you mess one up just drill it out like a rivet and do it again.

if you can find a local aircraft surplus parts store get their washers, they are the AN washers i believe and don't look like the farm stuff and they are zinc chromated, like the rivnuts.

here is where i get my stuff

https://www.lefthanderchassis.com/v2...dcategory=1145

the air guns have really gone up in price, but if you can swing one that would be my suggestion. i use around 80 psi on mine, pull the nut up then back it off and hit it again. you can lube the threads with silicone if they are not drawing up well and spray lube the inside of the gun every once in a while, just like anything else.

then when you are done you can go back and replace all the self tapping screws that were used.......

Thanks all. Very helpful info. Just what I was looking for.

I used rivnuts for several cockpit areas including the dash and custom center console. Mever noticed the two pieces looking like they were not flush, as long as you make sure you push them down flat. I don't recall the specific sizes I used, but they work excellent, and have held up great. If you over tighten, all you have to do is ream and replace with larger size. Highly recommended and solves all access issues.

Do you use the galvanized steel or the stainless rivnuts?

If you are going to use the 10-24 rivnuts, I would use these McMaster-Carr.

If the ends are going to be exposed you might want to use the closed end ones.

Kevin - the only real benefit I could think of is the elimination of pointy screw ends on the underside where you can hook some skin if under there fiddling with something. That and having a new tool for your tool chest to play with.

Terry, it just links to the general rivnut page. Which particular type do use?

Bob, I think I'm just going to use a bolt, nut, and washer to install if it works well, even if it takes longer.

That's what I thought...I believe when ERA builds turn-key cars, they use the same screws that my unfinished car came with. I love new tools and have considered rivnuts, but still trying to understand if there is a real improvement before going that route.

Thanks,

Kevin

the ones i linked to lefthander chassis are zinc-yellow chromated, they don't rust.

Threaded fasteners are more difficult to strip and can be installed/removed more often vs self taps. Threaded fasteners can be torqued higher, which isn't a factor in this application.

Lippy,

Depends on the material thickness. If you are going through at least 1/8" material and plan on using a 10-24 thread, I would use a steel rivnut with the ribbs on the side to keep it from spinning, P/N 95105A131. If the material thickness is thinner then I would use P/N 95105A127.

lippy,

Good advice as usual from Bob and fellow CC members.

I used PEM nuts and allen head / button head stainless button screws for my transmission tunnel, it turned out great.

Below is link to a web page with a chart, they come in #4, #6, #8 and #10. The chart has recommended sheet thickness and hole size needed.

PEM Self-Clinching Nuts, Type SP - Unified On S.W. Anderson

If you want a Bay Area over the counter source for PEM nuts and the button head screws, along with just about any other fastener you can imagine, try Olander in Sunnyvale they have a great selection.

THE OLANDER COMPANY INC.
144 Commercial Street
Sunnyvale, CA 94086-5298
Telephone :
800 538-1500 or 408 735-1850

Any reason not to use SS for the rivnut? May be harder to install but hard and corrosion proof.

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