Is Bilt Hamber Dynax-S50 good for this?

[ex-Chinese Dave]

Is Bilt Hamber Dynax-S50 all that's needed to protect the jacking points when they have been straightened? There is obviously some rust on them at the moment so when repaired they need protecting. I was thinking about using this S50 and then spraying some Hammerite underbody seal over the top just to tidy it up. The S50 will also be used on the inner arches when I get the panels off.

Thoughts?

 

[ex-Chinese Dave]

Or is it better to just use DINITROL 4941 on its own?

 

[Mr Underhill]

You can use DINITROL 4941 and Bilt Hamber Dynax S50 together, but they’re for different purposes. To do the job right:

• Pop the skirt off and scrape off all rust and loose paint with a wire brush. Get to the bare metal
• Degrease it well.
• Hit it with Hydrate-80 to kill the rust, let it dry (24 hrs).
• Slap on zinc primer.
• Use an over-paintable stone chip coating like DINITROL 447 or Bilt Hamber Dynax UB - they dry fast and take paint well.
• Spray on factory-matched paint - see Rapid Paints online

Finish with Dynax S50 in seams and cavities. Job done.

4941’s for underbody but it’s the sort of stuff you’d use to touch up areas where the underseal has broken and isn’t ideal for painting over.

The jack up points are layers of metal pressed together, so a magnet for trapping moisture. Dinitrol 447 or UB FTW. Prep’s key - don’t trap rust.

 

[ex-Chinese Dave]

I ordered the Dinitrol 4941 last night as an underseal and to replace any original underseal that's missing. I've got a pot of Kurust that should be enough for the jacking points and those areas once i've straightened them and cleaned them up.
I've just ordered the Dynax S50 to do box sections and inside the rear quarters, and also the Dinitrol 447 to do exposed areas along the sills which will then have a coat of 4941 over them. The outside of the sills look fine. I'm more worried about the rear quarters (although I had a look a while back and they looked ok) and also the filler cap area which I'm sure will need some work from the back doing. The bumpers will be off so I can have a look at those hidden areas, too.

 

[Clio_fool]

I remove my carbon cannister and there was quite a lot of rust behind it so check there too if it's still fitted when you whip the bumper off. It was worse than the inner arch here.

 

[Mr Underhill]

Very common for them to rust behind the canister. Same process as before. Wire brush down to metal and build back up with degreaser, hydrate-80, primer, 447/UB, then a lick of paint. Picture of mine when I did under the arches and it’s still holding out nearly 4 years on.

 

[ex-Chinese Dave]

Looks new, that.

 

[Godsense]

You can use DINITROL 4941 and Bilt Hamber Dynax S50 together, but they’re for different purposes. To do the job right:

• Pop the skirt off and scrape off all rust and loose paint with a wire brush. Get to the bare metal
• Degrease it well.
• Hit it with Hydrate-80 to kill the rust, let it dry (24 hrs).
• Slap on zinc primer.
• Use an over-paintable stone chip coating like DINITROL 447 or Bilt Hamber Dynax UB - they dry fast and take paint well.
• Spray on factory-matched paint - see Rapid Paints online

Finish with Dynax S50 in seams and cavities. Job done.

4941’s for underbody but it’s the sort of stuff you’d use to touch up areas where the underseal has broken and isn’t ideal for painting over.

The jack up points are layers of metal pressed together, so a magnet for trapping moisture. Dinitrol 447 or UB FTW. Prep’s key - don’t trap rust.

Recently did my sills from your advice on another thread, its very difficult to fully rust free the layers of pressed metal.

Zinc Primer should only go on bare metal really, BH state the same.

Dynax UB will take paint, or am I reading that wrong?

 

[Mr Underhill]

Zinc Primer should only go on bare metal really, BH state the same.

Are you confusing a zinc primer with BH Electrox? BH Electrox, requires direct contact with bare steel for its zinc to work effectively, but Hydrate-80 creates a barrier that prevents this. A generic zinc primer applied over Hydrate-80 bonds well and provides additional protection. I’ve used BH Electrox with BH Epoxy-Mastic several times. In that scenario, I’d have the steel shot blasted first to ensure it’s clean, then apply BH Electrox, Epoxy-Mastic, and paint.

Dynax UB will take paint, or am I reading that wrong?

Dynax Seam is better for overpainting, but since I’m dealing specifically with sills, I’ll spray Dynax-UB inside the cavities and, once it’s touch-dry, paint over it. This is purely for aesthetics, as I’m covering the car sill with skirts anyway.

I’ve found it works for me. But feel free to try your own methods and let us know the results.

For larger areas, where getting in between cavities/seams isn’t that crucial, Dynax-seam is the better choice in the BH range as it takes paint much better.