"Old" Galv Chassis - Best Protection / Coating / Coverings

[gruntus]

Hi All,

When I built my 90 on a new chassis circa 9 years ago I don't recall being aware of T-Washing and painting at the time much to my chagrine.

IIRC I was more concerned with someone seeing a nice shiny chassis and pinching my pride and joy and just needed it covered up!🙂

However, I gave it a lick of underseal at the time and thought that would suffice.

However, I noticed it isn't looking very well covered anymore and I've been under tonight and scraped off any loose stuff and wire brushed it and its really obvious it does need some protection.

So a couple of questions:

Q1:  Has anyone ever fitted a galv chassis before and never painted it?  Have they ever had any problems with the Galv wearing through and had the bare metal exposed? Just wondering what the worst case would be if hypothetically a galv chassis was left unprotected?

Q2: I want to give the chassis a good covering, what works well on "old" galv that will give it some good protection (I will need to put it on by hand obviously) and it will also stick like the proverbial to a blanket?

Would there be any issue with applying Hammerite Under Body Seal with added Waxoyl? Or is there a more recommended "tough" coating that can be used that will stay on well over time.

Any advice would be appreciated.

All the best

Grant

 

[western]

Think it would have to be well abused in a harsh environment for the galv to be worn off, a unpainted galv chassis on a daily use vehicle should be good for at least 20 or more years, 

Buzzweld do a straight to galv black finish IIRC. 

[oneandtwo]

I am on my thirteenth Land Rover with galvanised chassis (might be a record?!)

have had two early galvanised chassis that were fitted in the early 1990’s which rusted. One was an 88” which rusted on the fuel tank outrigger where mud and damp had been trapped between the tank and outrigger. All the galvanising had flaked off, I needled gunned it and painted it with galvafroid. The second was a 109 which similar had happened.

The insides of the chassis rails were fine.

 

[miketomcat]

I have a 110 galv chassis that has been in the sea far to often. The galv has flaked off in areas notably just before the back wheels. I clean the whole chassis up with a wire brush and a grinder for the flakey areas. I then coated with 2 coats of epoxy primer and a generic chassis paint. The chassis is around 15 years old I painted it last year. So we'll see how it does.

Mike

[cackshifter]

Old galvanised doesn't need T-wash. A while back I fitted a new galved rear crossmember to my 90, and before fitting I T-washed it and then it had 2 coats of epoxy primer & 2 coats of polyurethane top coat, both 2 pack. 8 years on, it had to have a new chassis but the crossmember was fine, the paint was still on it. I would fit something like the Gwyn Lewis kits to block mud getting sprayed on the front outriggers, and focus on the outside parts, eg round the radius arms bushings and the rear crossmember where you know it rusts normally before attempting to paint the whole thing. 

[reb78]

18 minutes ago, cackshifter said:

Old galvanised doesn't need T-wash. A while back I fitted a new galved rear crossmember to my 90, and before fitting I T-washed it and then it had 2 coats of epoxy primer & 2 coats of polyurethane top coat, both 2 pack. 8 years on, it had to have a new chassis but the crossmember was fine, the paint was still on it. I would fit something like the Gwyn Lewis kits to block mud getting sprayed on the front outriggers, and focus on the outside parts, eg round the radius arms bushings and the rear crossmember where you know it rusts normally before attempting to paint the whole thing. 

Have you got links to the paints you used?

[oneandtwo]

One of the 90’s I had on a galvanised chassis had rusted badly behind the bolt on rear shock absorber mounts, I’d forgotten about that one! Not one that I built, I always spray wax oil /grease behind them.

[cackshifter]

4 hours ago, reb78 said:

Have you got links to the paints you used?

The primer was Primer, and the topcoat was Topcoat. I also have used Jotamastic 87  very successfully. The biggest issue is mixing small amounts - I now use scales rather than trying to do it by volume, and normally just use an old jar, and spoons to measure the paint out. All have been applied by brush. I still have the crossmember. The topcoat can be applied to metal, I have used spare mixed paint to touch in unseen chipped bits.

[jeremy996]

My 110 has been back on the road 10 years now. The unpainted galvanised chassis is fine; the door frames not so much! The general paint quality was pants and if the painter wasn't already dead I would look to remedy that.

[cackshifter]

1 hour ago, oneandtwo said:

One of the 90’s I had on a galvanised chassis had rusted badly behind the bolt on rear shock absorber mounts, I’d forgotten about that one! Not one that I built, I always spray wax oil /grease behind them.

I presume if you have an ungalved bit (shock mount) you will accelerate zinc usage on nearby galved surfaces 

[jeremy996]

Just now, cackshifter said:

I presume if you have an ungalved bit (shock mount) you will accelerate zinc usage on nearby galved surfaces 

That what I have been told/read in the text books. Zinc is sacrificial, so it can run out.

[Bowie69]

2 minutes ago, jeremy996 said:

That what I have been told/read in the text books. Zinc is sacrificial, so it can run out.

Yup, but going to last 20 years at the least, in reality, especially if you treat the vulnerable areas as that, e.g. wax of some sort is normally enough behind bolted on components.

[oneandtwo]

1 hour ago, cackshifter said:

I presume if you have an ungalved bit (shock mount) you will accelerate zinc usage on nearby galved surfaces 

It rotted due to the amount of damp mud trapped in the small gap between the shock mount and the chassis.

[reb78]

17 hours ago, western said:

 

Buzzweld do a straight to galv black finish IIRC. 

The buzzweld stuff doesnt get good reviews - has anyone used it and is pleased with it?

[miketomcat]

2 hours ago, cackshifter said:

The primer was Primer, and the topcoat was Topcoat. I also have used Jotamastic 87  very successfully. 

Jotamastic 87 is the epoxy primer I used so that's encouraging. 

Mike

[gruntus]

Thanks for all the feedback so far gents. 👍

[cackshifter]

I always think marine paint is designed for seawater, small nibbly creatures,  and application on less than perfect surfaces, so it should feel at home. The downside is the mixing and it is generally in huge tins.

[gruntus]

6 hours ago, cackshifter said:

The primer was Primer, and the topcoat was Topcoat. I also have used Jotamastic 87  very successfully. The biggest issue is mixing small amounts - I now use scales rather than trying to do it by volume, and normally just use an old jar, and spoons to measure the paint out. All have been applied by brush. I still have the crossmember. The topcoat can be applied to metal, I have used spare mixed paint to touch in unseen chipped bits.

Thanks CackShifter, do you think Jotamastic could be applied with a small roller (radiator roller)?  I take it its quite "sticky" when applied?

Thanks again everyone! 👍

[reb78]

21 minutes ago, gruntus said:

Thanks CackShifter, do you think Jotamastic could be applied with a small roller (radiator roller)?  I take it its quite "sticky" when applied?

Thanks again everyone! 👍

Also - why is the primer airless spray only?

[SteveG]

Usually it’s down to the fact that the paint doesn’t atomize well. Typically if it can be applied with an airless sprayer it will go on with brush or roller ok.

[miketomcat]

9 hours ago, reb78 said:

Also - why is the primer airless spray only?

I applied jotamastic with a normal spay gun just used a large nozzle. There's no reason you can't use a brush or roller but you may need to use smaller mixes due to pot life. I went for spray to try and get it in all the nooks and crannies.

Mike

[cackshifter]

Hi, the paint (all 3 types)  is quite thick and Jotun give specs for film thickness. I have always just brushed it on fingers crossed of course, but I think it would roll fine, in fact have bought a small tray and some of the rollers to try, I have some new battery/tool boxes to do.  I wondered how good a finish was possible. As Mike suggests you have limited pot life, you have to move quite fast to get it on.  And you may have to brush it out to level it  after rolling it on. You could thin it, thinners are available, though they don't suggest you do that, but if it was really too thick that is possible. I think there are epoxy mastic primers available in smaller quantities, eg link but some of these kinds of paints are rather expensive. If you do decide to use this kind of paint I would recommend get some small scales and weigh rather than measure quantities, SML Paints do the scales  (less than £10) and publish charts of weights to mix rather than volume. 2 pack is a pain to use to be honest, but it seems to give a durable finish. 

 

[Bowie69]

I've successfully sprayed thick 2-pack epoxy 'anti-rust' paints, like Bilthamber:

https://bilthamber.com/product/epoxy-mastic/

Just got some extra thinners and thinned until it sprayed -as long as you aren't after showroom finish it will be fine (likely better than brush/roller anyway), just work fast, get a small spray gun and use small batches -as above it has short life and cleaning the gun straight after is very important....

As with Mike, I wanted all areas covered with no pinholes -something very difficult to do with roller/brush.

[cackshifter]

@Bowie69, was that airless spray? 

[Snagger]

On 9/16/2021 at 12:13 AM, gruntus said:

 

Q1:  Has anyone ever fitted a galv chassis before and never painted it?  Have they ever had any problems with the Galv wearing through and had the bare metal exposed? Just wondering what the worst case would be if hypothetically a galv chassis was left unprotected?

Q2: I want to give the chassis a good covering, what works well on "old" galv that will give it some good protection (I will need to put it on by hand obviously) and it will also stick like the proverbial to a blanket?

Would there be any issue with applying Hammerite Under Body Seal with added Waxoyl? Or is there a more recommended "tough" coating that can be used that will stay on well over time.

Zinc is sacrificial to steel, so eventually deteriorates, faster in harsh conditions.  Ships and maritime structures use replaceable blocks of zinc attached to the steel structures/hulls to similar effect as galvanising, but without the dipping process and easily swapped with new on overhauls.  There is nothing to prevent you bolting a few strips in areas that concern you.

I used exactly the Hammerite product you’re thinking of, and it has worked extremely well.  If you are getting any rust patches now, you’ll have to deal with them by removing as much rust as you can mechanically, chemically treating anything left, then using decent primer and paint to seal it.  The Underbody Shield is very good as coating over the primer and paint, but I wouldn’t want to guess at what it’s like on untreated steel or rust.  I have had no rust or deterioration on those spots I have had to modify with some welding on my galvanised chassis, having used red oxide or Zinc 182 primers and the Hammerite Underbody Sheild.