Rivnuts - Weakening Chassis

[nickharding]

Noticed everyone uses millions of rivets to hold on all of the panelling. I can get hold of an unlimited amount of rivnuts. Not sure if you know what they are but you countersink them and work the same as a rivet but are a nut. Super strong too. Once applied they will be flush with your tube. Then same as normal stick the ali sheeting over the top then bolt through it into the rivnut. Only concern is weakening the chassis? I plan to use 1 rivnut every 8 inches (8 inches apart) but to apply this rivnut, i will have to drill a 6mm hole for each one. Should i be concerned about weakening the chassis? don't suppose its any different to having a 2 - 3mm hole 2 inches apart?

It just means that access to all of the underneath and inside can be gained by just removing the bolts and then the panel. Instead of having to drill the rivets out and have them rattling about inside the chassis each time.

P.s I plan to put in extra bracing around the place for added strength.

[robo]

I am partial to a rivnut. But I cant see any reason for not using the normal rivet on the underfloor. Once bonded and riveted that floor would never come off in one piece, I also cant think of a reason to ever remove it once installed anyway.


Bob

[wylliezx9r]

I riveted all the aluminum panels. But all my body work is held on with riv nuts. It's suprising how many times that the bodywork (particularly the scuttle) needs to be removed to gain access to stuff.

[MikeB]

The rivnuts I use protrude by about 1mm from the rail they are inserted in. Are there ones that sit absolutely flush?

[robo]

Countersunk rivnuts .http://image.made-in-china.com/2f0j0...ut-Metric-.jpg

If I did want a removable underfloor it would be a lot easier with those self tapping self drilling bolts.http://www.google.co.uk/imgres?q=sel...7&tx=106&ty=95 and the hole would be no bigger than the normal rivet.



I picked up one of these swivel headed rivnut tools off ebay. Dead on for getting in tight spots. http://www.rivetnuttool.net/images/w...ivetsrivet.jpg

Bob.

[flyerncle]

Rivnuts come in all different configerations and you possibly need thin sheet one's MikeB.

The question of weakenig the chassis is a good one,normally if something splits or cracks the fix/cure is to drill a small hole at the end of it,so I would think that unless you can drill a square hole you should have no problems and with square tube you have three other sides to support it.

[HandyAndy]

Originally Posted by robo

I am partial to a rivnut. But I cant see any reason for not using the normal rivet on the underfloor. Once bonded and riveted that floor would never come off in one piece, I also cant think of a reason to ever remove it once installed anyway.


Bob

I agree with Bob on this.

My floor is bonded & rivetted to the chassis with 182 rivets ( had biceps like popeye after that lot )

& like wylliezx9r I have done the same with the body panels.
( my rear wings are bolted to my rear tub so that the whole back end can be taken off in 1 piece ).

IMHO...1 rivnut every 8 inches apart is too much, its surprising how few rivnuts you,ll need to hold everything in place,
Theres, only 28 rivnuts in my whole car, & not all are secured into the chassis steel.

just my opinion of course .

cheers
andy

[nickharding]

Well I thought of using rivnuts underneath as then access to the prop can be gained easily. Now I think about it I can just rivet the bottom panel underneath same as everyone else, and just rivnut the inside tunnel panels and the back panel behind the seats. That might work out better.

[HandyAndy]

Originally Posted by nickharding

Well I thought of using rivnuts underneath as then access to the prop can be gained easily. Now I think about it I can just rivet the bottom panel underneath same as everyone else, and just rivnut the inside tunnel panels and the back panel behind the seats. That might work out better.

What you can do is not "panel in" the underside where the tranny tunnel is, that makes the prop easy to get at from below,

or

fully panel in the whole bottom/underside & make the top of the tranny tunnel interior panel removeable ( this is how mine is ) as I thought getting into the prop would be easier from above rather than from below.

Also worth noting.....The IVA tester "may" want to see inside the tranny tunnel come test time.

cheers
andy

[MarkB]

You only need a few rivnuts to hold things on, but the floor wants to be riveted and bonded as this adds to the stiffness of the chassis. Panel all away across the bottom as you don't need to get to the prop underneath. There are better alternatives to rivnuts but they cost a lot more, check Merlin Motorsport for range of natty fixings. I have some somewhere that came from Jordan GP when my brother worked there and they are made from titanium, superb wee things and it's what they used to hold the nosecone on. The daft blue thing I built used them along with as many NAS bolts and K Nuts as I could(came courtesy of Jordan GP.....)