Does drilling holes in the front chassis members to rivet the side panels on weaken said chassis rails? I would think so.

what sort of spacings between rivets are people using??

cheers


Ed.

if your chassis is fully triangulated, then the weakening will be minimal and negliagable

cheers!

Just one of those "hang on a minute" questions!

Ed.

[Edited on 23/2/04 by ed_crouch]

i thought the same when i did my floorpan wityh about 500 rivets, lol - then realised that the overall strength of the chassis is increased due to more surface area strengthening

Agreed-especially if the panel is also bonded on too (with sikaflex or similar).

Basic answere to the question you asked is yes, any hole drilled into the side of a tubular section member will weaken that member when viewed in isolation. However as stated by others the action of attaching further bracing to the structure in the form of panelling will, (in most cases) actually increase the rigidity of the structure. You can reduce the weakening effect by using structural rivets, (basically pop rivets where the mandrel breaks flush with the head of the rivet when set and therefore adds to the shear strength of the rivet).
As for recommended rivet pitch, as a rule of thumb stressed skin construction in aircraft uses about 8 times the diameter of the rivet, (the size of hole you drill, not the head diameter) but in our case as the materials concerned are generally thicker and more rigid. I will be using pitches of between 8 and 12 times diameter depending on the thickness of the panelling material, (the thinner the panelling the smaller the pitch).
Finally, I fully agree with Stu's point,

Once you are really certain:
That you've got it all absolutely spot on
It won't have to come off again
You havn't forgotten anything

Use structural adhesive on the mating surfaces when you rivet up.

Mick

and if Mix's reply confused you silly, as a general guide, and my own experience, i used 4.8mm x 10mm rivets for the floorpan with a pitch (center of one hole for a rivet to the center of the next) of 25mm (1" and used sikaflex to adhere and seal the sheet steel to the floor as an extra support and to stop any unwanted draughts

I always use Cleco's until I'm ready to bond the panel.
Good prices from Harry @
postmaster@glosairparts.co.uk
Rescued attachment cleco.jpg

Don't they stick out too far to pass SVA?

Seriously though, I treated the aluminium on my car more as a decorative covering than a structural enhancement and only used rivets every 100mm, the floor was welded in as I didn't like the idea of ally held on with rivets underneath. The clecos are good, I use them to locate while drilling.

yours, Pete.

for added security I have staggered the rivets on my floor pan.
4.8mm structural rivets (cost a packet) @ 20mm spacing and a zig zag offset of 10mm. but I also used a sheet of 2mm ali for the floor panels, oh yes and PU adhesive for the lot. I used a decent jointing compound on each rivet prior to fitting to help prevent corrosion. feel quite confident in the result!

Protofj
What is the difference between normal pop rivets and structural rivets? And where can you get the structural ones from? What jointing compund did you use? ....Not Sikaflex by any chance?

Any help appreciated
Cheers
David

structural rivets, the shaft breaks off and is secured in the head and this gives strength to the rivet in terms of sideways sheer

Doesnt that happen to nearly all pop rivets? It seems to with the ones i have seen! Anyone know where to get the structural ones from. I found this place for all sorts of rivets, but they dont seem to have the structural ones or am i missing something?

http://www.rivetwise.co.uk/product/index.htm

Cheers
David

[Edited on 25/2/04 by flak monkey]

pop a "normal" blind rivet and then a "structural" one next to each other and you will see the differance

i've used about 500 normal 4.8x10mm rivets and a tube of sikaflex to get my 2mm steel floorsheet to make love to the chassis

You'll find a stuctural rivet's mandrel is held in place with a locking collar, where as the pop rivet's mandrell can be pushed out, or more likely fall out due to vibration.

I normally use a joining compound when using pop rivets (usually araldite) mainly to help stop the rivet from spinning when (god forbid) you have to drill them out.

A spinning pop rivet is one of the most annoying things to have.

Thats my two pence worth

chris

For jointing compound i used JC5A which is a military product for aircraft (dunno the civvy equivalent) - I 'acquired' a tin before i left the forces.....

The structural rivets were a right bitch to find. and damn expensive too.
I ended up getting mine from the states but had to have them delivered to an address in our US offices and them forwarded on..... cost me £44 per 600

I used Huck Magna-lok rivets both normal and countersunk.

You can get them over here from a company called Rivco

I believe they cost about £10 per 100 !!

They are infinately stronger than normal pop rivets but require a LOT of force to work them. You can do it with a normal set of pliers but you'll look like popeye by the end.

Be wary if you get a different type of structural rivet because a lot of them require special tooling or 'nose peices'

HTH

quick fix to a spinning rivet - get a steel punch and smak it with a mallet a couple of times - you either get lucky and it shoves it thru, or it stops it spinning

for 'normal' (read 'soft as shite' rivets i tend to just take the head clean off with a cold chisel and the just push the rest through......

there is that way aswell. lmao - soft ally easily deformes in a weak situation

As mentioned earlier I use high strength monel rivets. They are a little more expensive but well worth it.

Maybe a silly question....But, has anyone drilled and welded captive nuts instead of doing the rivets? My guess is that they would be stronger than rivets and resist vibration better. Also, easier to tighten. Plus, you could use round-head allen bolts...that would look trick.

Also you could easily remove a panel for replacement instead of having to drill out all the rivets.

Course you may go mad welding in all of them....

good idea? or Overkill?