Firstly hello!! My first post, and sorry for the amount of questions below...

Well, I've read lots of threads on this subject and am still confused.

I want to join my galvanised steel panels to my steel frame. I've managed to conclude that using Sikaflex between the chassis and panels is a good idea, but it's the rivet bit that's getting me confused.

I've read a bit on galvanic corrosion and I'm thinking I definitely want to avoid aluminium rivets and stick with steel.

But then there are lots of different types of rivet. People on here have mentioned that "structural" rivets have greater tensile strength. Seems reasonable, but when I'm looking for these on the internet, are they always named "structural". I've seen a few. But then I've seen some rivets described as closed-end which seem to be the same. Are these the same thing?

And then other people have mentioned that a large head for spreading the load is good. Again, seems sensible, but can you get "structural rivets with large heads"?

And then other people have mentioned dipping the rivets in sealer to be doubly sure of corrosion protection. Once again, seems like good advice. But to a newbie, "sealer" is too generic. Can someone give me an example of a trade-name that I can look out for? Or can I just use Sikaflex here again?
And it feels like I'd need to let the sealer dry to form a non-metallic layer, but then I've seen "wet" rivetting mentioned that presumably means rivetting whilst the sealer is wet?

Anyway, I think I may be suffering from too much information? Maybe I'm just suffering from first-build nerves!! Can anyone help please?

Cheers in advance.

i think i'm right in thinking old landrovers (series 1, 2, 3, and maybe even the newer Defenders) are steel chassis with aluminium body panels...

i woldn't worry too much about a few rivets to be honest. or counteract it with a big lump of zinc somewhere (i think that stops steel corroding, but don't know what it does to aluminium...)

Yes Landys still use steel bolts throught the aluminium body into the steel chassis & they do corrode the alloy body around the bolts, just look at the base of the body where it goes onto the rear crossmember on any over a few years old.
If you're using steel rivets to join steel panels to the steel frame then that deals with the disimilar metal corrosion issue, & surely any steel rivet would be well up to the job. I think the galv sheet would tear before the rivet sheared or snapped.
Just incase you dont know galv sheet isnt as good to paint, probably needs an etch primer. Somebody on here will know!
Keep asking questions though, I've yet to start my build & I see questions asked on here that never crossed my mind!
The above info is from my being an agric mechanic & fabricator.

Steel body panels?

It'll be even heavier than mine!

Probably lighter than mine though

Rich

As an alternative to rivets if you're going to use steel panels would plug welding be any good? There's obviously an issue with warping the frame due to the weld shrinking but it'd be strong, no holes in the tube to weaken it & the panel solidly fixed to the frame would stiffen things up. Mabye you wouldnt need so many diagonals?

Blind rivets 101!

A typical blind rivet comprises two parts, the rivet body and a mandrel. The blind rivet is first placed into an acurately drilled hole, and an installation tool is then used to grip the mandrel. Activating the tool pulls the mandrel, drawing it into the blind-end of the rivet body. This forms an upset head on the rivet body and securely clamps the application materials together. The mandrel then breaks, leaving part of it in the rivet body (more on this later).

The rivet body is available in a range of diameters, all imperial originally but now generally sold as metric (eg 3.2, 4.8 etc). They are also available in a number of lengths, to grip different thicknesses of material. Some blind rivet designs are able to clamp a wider range of material thicknesses and so this becomes less critical. The body can be manufactured from a variety of materials, this will effect the tensile strength (and shear less significantly) and the force required to pull the rivet. Finally, bodies are available with a number of finishes - a painted or anodised rivet should reduce the rate of galvanic corrosion. The mandrels are also available in a range of diameters, and the rivet tool will have a series of 'nose' pieces to accomodate these. If the mandrel is designed to break flush with the top of the surface of the body and to be positively retained in that position it will add a great deal of shear strength - this is a structural rivet. It will also be significantly more expensive! If the body is formed as a cup around the mandrel, rather than as a tube, it will seal the hole it is pulled in and help reduce corrosion of the chassis tubes. These are closed rivets.

Inserting the rivets 'wet' with sealer on them before pulling them up should ensure the holes are fully sealed, but is probably not necessary as the body will expand to fit the hole. A number of sealants can be used - standard silicone sealant from your local hardware store will do the job but you can also use more specialised adhesives (Wurth do a good one, as do Car Builder Solutions).

It will all be much less daunting when you get started!

Dom.

Why galvanised panels? Ally panels with sikaflex or simmilar between them and the steel are pretty corrosion resistant. One thing not mentioned about steel pop rivets. . . .They take a lot more effort to pull! If you are using a plier type hand riveter you will get hand and forearm muscles like Popeye! Closed end ally rivets are fine for panels, all ally rivets use a steel pin and I have not seen any corrosion problem with them.

LandRovers, Range Rovers and Discoveries all suffer from galvanic corrosion where water can stand for a time, door bottoms being the main problem followed by panel joints between ally and steel where water can gather and panels that are used as electrical grounds, common with bodged repairs to lighting.

Galvy steel has a rough surface and needs a specialist primer so will be horrible to get a nice finish on, cars that are built with"galvanised" body shells are not treated the same way as galvy sheet, they will be hot sprayed rather than dipped, this gives a smoother finish.

hope this helps1

caber

quote:

---

Originally posted by Clueless74
But then there are lots of different types of rivet. People on here have mentioned that "structural" rivets have greater tensile strength.

---

You could always use monel rivets to avoid corrosion problems. I've used them in the past for attaching aluminium panels to steel frames with no corrosion problems. Monel is what they used to make diving bottle valve gear from and it is suitable for salt water applications.

Just to add my 2p worth....

the larger head rivets are usefull for spreading the load on weak materials like GRP. for metal-metal I would stick with normal size dome or countersunks as you need.

Structural rivets are MUCH more expensive but will last longer and provide far more strength.

I have used a combination of monobolt type rivets (aviation type structural) throughout my build but expect to pay about £100 for a box of 500 !!!!

I coat ALL rivets with a JC5A jointing compound before inserting them, again as per aircraft building. this should minimize corrosion. JC5A is the military spec, I don't know what the civvy equivalent is or where you can get it - sorry...

finally - the most important thing for good riveting is the holes you drill! ensure they are not elongated by poor drilling or cheap/blunt drills. Ensure the hole is the correct size for the rivet - if you use 4.8mm rivets then use a 4.8mm drill - don't be tempted to use a 5mm because it's 'close enough'.. the result will always be that little bit weaker and will lead the rivet starting to fret sooner.

Thanks for all your advice guys.

I should probably say that I'm only using the galvanised steel panels for the floor. I'll go with aluminium for the side panels so shouldn't be too heavy. I still need to think about which rivets to use there!! Or might try rivnuts.

But anyway, it sounds like:
I don't need large-head rivets.
If I'm worried about galvanic corrosion I can go for anodised, painted or monel rivets.
Also I can also cover the rivet in Sikaflex before fixing. I assume the idea is that most will ooze out but after wiping it off, there will be a small amount left in any tiny gaps?
Steel rivets are harder to fix. I've got a lazy-tong riveter rather than hand pliers. This should be easier shouldn't it?

And despite another_dom's excellent post, I'm still a bit confused about structural vs closed-end rivets. Both features sound good but can you get both together?

Closed end vs structural rivets....

OK.
Generally a closed end rivet is a pop type rivet with little strength in shear. The end is litteraly closed off so that you do not have a 'hole' through the middle into your steel box section - think of it as an upside down top hat..

Structural rivets do not generally have a closed end however the mandrel is designed to break off inside the rivet body and permanently block it, so you get the same sealed effect. the presence of the peice of mandrel withing the rivet gives it far greater strength in shear.

there is some good info on rivet types here linky

just remeber - there is a world of difference between an Avdel Avex type rivet and the tucker pop type rivet you find in B&Q! (although they use a similair principle)

Personnally I chose Huck MagnaLok rivets for my floor pan linky

[Edited on 14/8/07 by DaveFJ]

Dave,

You work at Wattisham per chance? I'm 2IC 4 AAC Wksp.

Dom.

Small world!

PS: what you doing with all those MBCs now that they are no longer used.... I know a worthy cause

[Edited on 14/8/07 by DaveFJ]

Unfortunately the bulk of the Lynx expense went straight up to Dishforth. I panelled my kit before I started on the aviation side so no gucci rivets for me either. I did acquire some decent cable after the IPT declared it obsolete!

Dom.

Out of date POL?