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2K views 12 replies 7 participants last post by  sraouf 
#1 ·
I'm thinking of underselling the car for the winter. Any tips? What's the best way of putting it on? Brush roller or spray? What's the best stuff to use?
Many thanks.


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#2 ·
The only way to do a proper job really is to remove the sill covers and wheel arch liners. This is where corrosion can hide because of the wet crud that gets trapped. Have a good prod with a screwdriver and scrape off any underseal that looks suspect. I spent a week under mine when I first got it. A dremel is good for getting in the knooks and crannies. Use a rust converter then waxoyl.
 
#4 ·
I have been spending a lot of time under my GTV project recently, dealing with rust etc. Here are some thoughts...

Spankdanny is speaking wisdom. Get behind the arch liners and sill trims and in all the nooks and crannies. Remove all the broken underseal, and treat the rust (kurust works well). There is plenty of debate as to the best way to protect the surface. Options are

1) just spray with Waxoyl (quick and cheap and should get you through the winter)
2) Paint with more underseal (rubbery-type or oily-type)
3) paint with zinc primer and chassis black paint (once old underseal is removed)

I'm going with option 3 for my restoration.
 
#5 · (Edited)
I agree with all of the above but would like to add to triprecorder's number 3.

I think the trick to not getting the rust back is getting a product that adheres to the suface really well, so in my experience I'd get some por-15 under coat on the metal surface (it's a bit of mix of urathine and something like superglue), so it asheres really well but is flexible and won't crack (definitely wear gloves when painting on). Then when it's hard give it a good rubber down to create a 'key' and apply some sort of rubberised underseal.

The problem I have found with these underseals is that if you do get a place where moisture does get in then it can seep unnoticed until you get a really big bubble up and by the time you see that it has spent ages attacking the metal underneath. This is where the pre-treatment of por-15 will save you. Just check for bubbles of underseal every year and if you find any then get that bit off and put some more on.

Waxoyl is really good for cavities, like inside the sills and behind wheel arch covers, on the underneath of the car it can make such a mess if your ever need to do any metal work again.

It's best to try and do this job once and well than quickly and having to do it again, because it can be quite a dirty and boring job with no visual or performance benefit. But done well it will give you piece of mind on the rust front and save you money in the long term.

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#6 ·
Treat light surface rust bilt hamber hydrate 80 and then paint over, finish with dynax ub. For arches i used deox gel to clear rust, then applied zinc primer and then painted and undersealed. For suspension components and wheels they have dynax clear. Which is a temporary seal and theb can be washed off for summer

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#8 ·
i did this exorcise last year after having a good look under the car and seeing flaked and dried factory original underseal, Also saw where some of it had lifted allowing rust to get a start,

I went for DINITROL RC800 rust converter, My garage got a wire brush to a drill head and then a dremil, they had never used the stuff before but i had done some research this Dinitrol stuff is loved by classic car restorers and the like it is sprayed on and chemically changes the rust from rust to not rust and as its doing its work it can be seen working because it goes blue ( or green ) then after 2 coats of that i had them apply a top coat of

HAMMERITE WAXOYL over the top of this................. was on a ramp 2 days and i must say was impressed with everything later

given the age of these cars anyone not having had a serious look under there car and removing the arch liners as well as the sill you really are tempting fate,Catch it early get it done and what ever it costs is a fraction of not doing it and then being caught for a huge welding bill 5 years later
 
#11 ·
the garage cleaned of the old stuff

Applied Dinotrol rc800 as the rust inhibitor and preventative

and then applied a protective coating of the Hammerite undereal over the top of all this as a protector
 
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