timf
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| posted on 26/6/03 at 10:51 AM |
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quote:
Originally posted by andyps
would the type of expanding foam used for sealing gaps around pipework in houses work to seal the ends of the tubes to stop the insides rusting?
i tried that with a set o roof bars i made , it dont work because the foam gives off gas as it expands and blows its self out of the tube
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ned
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| posted on 26/6/03 at 11:05 AM |
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get a blow torch and heat the chassis, gets rid of any moisture, then weld plates on all the ends. use nice little rubber washers/sealant round all
the rivets and it might be airtight enough not to let any moisture in? hence no rust!?!
is this the most stupid idea ever?
to summarise people are saying use zinc primer, lots of thin coats then dulux stuff for the top coat?
thanks,
Andrew.
beware, I've got yellow skin
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craig1410
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| posted on 26/6/03 at 11:55 AM |
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Watch out with poly urethance foam. I think I'm right in saying that it gives off very nasty fumes when heated. It certainly gives off nasty
fumes when you use it.
It might even be cyanide gas which would be very nasty indeed if you ever had to do some welding on a tube filled with foam...
I intend to seal the ends of my tubes but then drill a hole in the end for a waxoyl probe. Aftern waxoyling I'll then fill the hole with a
grommet with some silicon applied first. I'm only going to do this on some of the main long tubes such as J1/2, F1/2, C, A1/2, B1/2, O etc. And
any that have lots of rivet holes where moisture can get in. I don't think it's really necessary for tubes where you can get a good seal
with the welds but where it's easy to do then I don't see the point in NOT doing it.
Cheers,
Craig.
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Peteff
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| posted on 26/6/03 at 12:46 PM |
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Alfas used to use foam filled box sections in the 70's and it caused more rot than it cured. They were recalled to have it extracted as it was
making them rust at an alarming rate, even for Italian cars . I don't think the oxidisation inside the tubes will be a problem as far as
weakening the frame. Some people don't seem to be able to find enough to worry about.
yours, Pete.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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blueshift
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| posted on 26/6/03 at 02:17 PM |
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hey, I just want to get it right. Though I suppose cars have been built for years with pop riveted mild steel tube chassis and not rusted from the
inside? (someone tell me that's correct and I'll stop worrying)
but in the meantime.. what's this waxoyl thing?
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kingr
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| posted on 26/6/03 at 02:26 PM |
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It's a waxxy substance you put in hollow sections of chassis to try to stop it from rusting. Personally I'd just stop worrying about it,
if you seal the ends of tubes and use adhesive of some kind when you rivet panels on, I can't see that you're going to get severe rusting
any time soon.
Kingr
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blueshift
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| posted on 26/6/03 at 02:42 PM |
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That means squirting glue into the middle of every pop rivet, which would be a pain and fiddly to get a decent finish. might end up with glue
streaks.
I am a born worryer, I will sleep happier at night knowing my chassis is protected inside and out.
I wonder if I could get a bottle brush or some kind of thin paint roller on a stick and prod zinc primer down the tubes before using them.. hmm..
probably difficult to get a good coating.
perhaps copper plating in a bath, or something? not sure if you could weld through that.
I'm just thinking out loud really.
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andyps
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| posted on 26/6/03 at 03:21 PM |
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Has anybody had a chassis galvanised. Would be the ultimate way to stop rusting, just really difficult to weld if needed afterwards. There is also
often a problem of warping due to the heat required - I remember reading about someone who had a Fiat 500 shell galvanised and he had to include
masses of bracing to stop it twisting during the process.
Andy
An expert is someone who knows more and more about less and less
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GO
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| posted on 26/6/03 at 04:11 PM |
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I'm sure theres been a post about galvanising before. I'm not sure of the process involved, but if I remember the basics of the thread
correctly then you'd have to make the chassis from 20mm walled tube because the whole thing has to be cleaned via an acidic bath which actually
strips away a measurable amount of metal before it can be galvanised. I seem to remember somone mentioning that galvanising makes it weaker too??
Prob best you do a search for that thread cos I'm not renowned for stunning feats of memory powers (other than forgetting stuff!)
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Peteff
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| posted on 26/6/03 at 04:42 PM |
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That means squirting glue into the middle of every pop rivet
Pop rivets seal themselves when the stem pulls up and breaks. It leaves the ball inside so nothing will get in through there. When you make your panel
and fit it you use Tiger seal or something similar to prevent vibration and drumming, that alone would hold your panel on, trust me I've tried
to take them back off and it's not easy.
yours, Pete.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
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greggors84
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| posted on 26/6/03 at 06:33 PM |
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Can you get Zinc 183 or weathershield as a spray, i know this is unlikely but i dont want to brush it on as i dont want to leave brush marks and i
dont have a spray gun.
Some one said you can thin it down. How many coats do you need to do after you have thinned it.
EDIT: Just seen on the U-POL website u can get zinc 182 in a can
it looks good stuff.
Thanks
[Edited on 26/6/03 by greggors84]
Chris
The Magnificent 7!
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type 907
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| posted on 26/6/03 at 06:59 PM |
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Hi, you can get pop rivets with a closed end ("sealed rivets".
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blueshift
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| posted on 27/6/03 at 12:30 AM |
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closed end pop rivets eh.. interesting..
and in my experience with normal pop rivets, the ball doesn't seal, it rattles around inside its little distorted bit of tube, or sometimes
falls out (to go pinging around inside your chassis for evermore)
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Rorty
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| posted on 27/6/03 at 12:52 AM |
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Peteff:
quote:
Pop rivets seal themselves when the stem pulls up and breaks. It leaves the ball inside so nothing will get in through there.
Woha there boy!
Only the self sealing pop rivets will do what you describe, but then you are also left with the nasty sharp tip of the mandrel sticking up above the
surface of the rivet head. Would you believe aircraft builders would go around their panels, filing off the sharp tips of every single rivet!
There are "sealed" rivets available, which actually have a bucket end on the rivet, so nothing can get in or out past the mandrel. On
these rivets, the mandrel doesn't protrude after it's been set either.
In my experience, the sealed monel rivets are the best in this situation. Monel ones won't rust, and are stronger than plain aluminium rivets
too.
Cheers, Rorty.
"Faster than a speeding Pullet".
PLEASE DON'T U2U ME IF YOU WANT A QUICK RESPONSE. TRY EMAILING ME INSTEAD!
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DaveFJ
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| posted on 27/6/03 at 08:00 AM |
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Avdel rivets do indeed leave a small part of the mandrel protruding from the surface which , yes, we do often file down by hand but this is for a very
good reason....
the type of blind rivet you describe is FAR stronger than any monel 'pop' rivet. If you showed a 'pop' rivet to an aircraft
engineer he would laugh in your face!
Personally i am going for a compromise with my build (aircraft standards are not required on a car)
I will be using MBC (mono bolt concept) rivets. these are very similair to traditional avdel rivets however the mandrel breaks off flush with the
rivet head so no filing is needed. (a special tool head is needed though to work these rivets). MBC rivets are also available in both aluminium alloy
and steel for riveting different materials.
These rivets also provide a 'sealed system'.
(15 years as an Aircraft engineer!)
[Edited on 27/6/03 by protofj]
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blueshift
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| posted on 27/6/03 at 01:02 PM |
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as ever the situation gets more complicated. now I find there are a squillion different kinds of rivets. argh.
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Rorty
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| posted on 28/6/03 at 02:01 AM |
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protofj:
quote:
the type of blind rivet you (blueshift) describe is FAR stronger than any monel 'pop' rivet. If you showed a 'pop' rivet to an
aircraft engineer he would laugh in your face!
I accept every thing you say, but as I said:
quote:
...the sealed monel rivets are the best in this situation.
Cheers, Rorty.
"Faster than a speeding Pullet".
PLEASE DON'T U2U ME IF YOU WANT A QUICK RESPONSE. TRY EMAILING ME INSTEAD!
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kiwirex
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| posted on 2/7/03 at 08:29 AM |
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"Fish oil"?? (if there is such a thing)
When I was reading earlier in the thread about preventing rust from the inside the words "fish oil" popped into my head, and a thought of
pouring a little fish oil into your tubes and shaking it around to coat the inside.
Where this thought came from I've got no idea, but I've a vague feeling I've read it somewhere as a tip for just this, that
it's supposed to work okay, but that it stinks to high heaven when you're using it (I guess it goes away once you've sealed your
tubes or it's dried or something).
Now this might be the result of too much pizza before bed, or it might actually be something that I've read somewhere.
I'm not even sure what is meant by "fish oil"
Anyway, just thought I'd throw that idea in the mix.
- Greg H
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