Advice on sealing the underbody

[Ste]

Hi all,

New member here from Ireland. I own a 1993 SRi Cav saloon in RIOJA RED

The car is a bit of a project currently, doesn't need much work, has a healthy C20xe and has never been welded nor does it need any.

Has been away from salted roads since 1994 thankfully and stored in a shed the last 10 years.

However, age has still earned it a light dusting of surface rust in some of the usual places, rear arches, strut mounts, chassis legs etc.

Much of the car still has the factory underseal intact but once I treat the rust I plan on sealing it well as I want to drive this Cav rather than stick it back in a shed.

I'm looking for somewhat of a guide to protecting the underside and keeping it solid.

My plan is:

1) Wire brush rusted areas.
2) Use Bilt Hamber deoxy gel on the brushed areas.
3) Apply Bilt Hamber Hydrate 80 to convert these areas.
4) Prime the converted areas with a heavy Zinc primer.
5) Then paint the whole underside using POR15
6) Finally, seal all my hard work with Shutz underseal from an air gun.

So I'm possibly going OTT there but I want to do a job that I can be happy in the knowledge that the car is solid and sealed.

Can anybody see a step I'm missing or some problem that I may encounter?

I plan on doing that work once the rear axle, fuel tank and exhaust system are whipped out.

Any input welcome, thanks

[Ads]

I did my cav turbo a few years ago now, I stripped my back to bare metal. treated any rust spots with a rust killer, painted with a primer, then completely undersealed the floor pan and any cavities I could find, I have re undersealed the floor pan nearly every year since, I carnt remember the specific names of the products I used but you get the general idea, Ads

[btcctroy]

Just paint the floor with epoxy mastic. Use a stonechip rather than greasy Shultz

[Robsey]

On my project van, I treated the rust prone areas with Vactan.
It is used a lot in high risk areas.

It converts the rust patches and then seals the surface with a tough plastic skin.
Worked well on exposed metal on my van for well over two years.

Stonechip is a good product that can be quite resiliant to external attack - stones, weather etc...
shultz never dries 100% and can be quite messy.

[btcctroy]

Shultz can allow moisture in and not let it escape attacking the structure very severely. It's horrid stuff. Paint is your friend as problems that arise are more maintenance friendly

[Ste]

Cheers for the feed back everybody.

I'll definitely reconsider the Shultz and source a less manky option.

[Ste]

Ok, I've somewhat simplified my original plan

As mentioned, there is no rot on the underside (well...that I've seen so far!) and only surface rust in the usual places such as arches, chassis rails etc.

After reading a tonne, I think I'll go with the 3 step POR15 method (degrease, metal ready, POR15). It appears that when done in the way they specify, it should give a great result.

So, wire wheel the underside, degrease, prep with metal ready and then 1 or 2 coats of POR15. After that I'll spray the box sections with Dinitrol Cavity Wax and then seal all my work with stonechip as the POR stuff is UV reactive.

I've one question, what quantity of the POR15 paint is needed to cover the entire underside of a Cav? Want to do one heavy coat and then a lighter coat to finish. Or is this a one coat job seeing as I'll stonechip it all after?

Cheers! I'll throw up a project thread this week hopefully

[btcctroy]

Whats brought you to the decision to use por15.
por15 is good but has to be applied exactly as the directions state. doesnt like new clean steel that much and found it peels alot but is good on pitted steel.
its only single componant paint so eventually will break down.
Epoxy mastic was voted the best over a 3 yearly period by classic monthly .
http://www.auson.se/sites/default/files ... hly_uk.pdf
i only use epoxy mastic, metal ready is hopeless

[Lowrider Dave]

Interesting article Troy, thanks for sharing.

[btcctroy]

bilt hamber electrox on bare metal and epoxy mastic top coat for ultimate protection

[Ste]

To be honest, I've been jumping back and forth from POR to Bilt Hamber, trying to decide which route to take. One week I'll read something that would sway me one way or the other. What I do like about Bilt Hamber is that it seems like less of a shortcut, compared to just painting over rust.

I'm a bit of a perfectionist to be honest, so BH suits me that way I guess as I'd be meticulous about removing all bits of surface rust

That article you linked is quite reassuring.

Whats brought you to the decision to use por15.
por15 is good but has to be applied exactly as the directions state. doesnt like new clean steel that much and found it peels alot but is good on pitted steel.
its only single componant paint so eventually will break down.
Epoxy mastic was voted the best over a 3 yearly period by classic monthly .
http://www.auson.se/sites/default/files ... hly_uk.pdf
i only use epoxy mastic, metal ready is hopeless

[btcctroy]

Would be impossible to remove every bit of surface rust.
The situation is controlling it

[Ste]

Ah yeah, i mean metaphorically speaking! I want whatever works best basically.

[Telegram Sam]

As reported in separate posts I've put my faith for protecting my £££ investment in the professionals Rustbuster see www.rust.co.uk Ian Allen in Spalding rather than frig around with half measures myself. He ought to know what a Mk 3 looks like by now.

[btcctroy]

[quote="Telegram Sam"]As reported in separate posts I've put my faith for protecting my £££ investment in the professionals Rustbuster see http://www.rust.co.uk Ian Allen in Spalding rather than frig around with half measures myself. He ought to know what a Mk 3 looks like by now.[/quote]

I'm not doubting they did a great job! But certainly doing a job yourself is no 'half measures' if you have the time and skill to do so. I almost take that as an insult! Researching the best materials to use is a good starting point.
Tbh you put a lot of faith in someone else's work, he Is a business and shortcuts can be taken! Myself I have pride in doing the job right!

[Telegram Sam]

You will see that my comments were directed (only) at myself and anyone else who might be short on expertise experience and facilities. Rustbuster say that there are surveys that put them ahead of the competition but no doubt POR and Bilt say the same for themselves. For me it was important to get the full treatment protection from a company that's dedicated to fighting rust, but I'm not saying that this the only way. You pays your money ..