Thoughts on sacrificial anodes for frame rails.

[Mark Maras]

Has anyone ever tried sacrificial anodes attached to the inside or outside of the frame rails to ward off rust? They could be made of zinc, magnesium or aluminum. In the shipyards they use zinc ingots cast with steel straps that weld onto the hull. They had to be replaced every few years due to the effects of salt water corrosion but on a car they should last a long time. Also, any thoughts about the use of cold galvanizing spray as a bare metal primer?

My 74 S30 project will be going up on stands soon so I can finish opening my holiday present, Then I'll find out whether I got gold or a lump of coal. I've tried many rust treatment products over the years with dissapointing results. This time, it's going to be phosphoric acid to convert the rust, if I can't remove it, and a topcoat, as yet not selected. If possible, I'm going to include an anode to prevent new rust from forming.

I'd like to hear anyone's thoughts about the idea or any products already out there that could be used as a sacrificial anode.

Mark in Portland

[Mikes Z car]

I read a scathing rejection of those on car sacrificial anodes once. Anodes on ships work because they can impose a current flow through the anode and the low resistance water. Getting electricity to flow through high resistance air is more difficult. I'd love to see additional opinions on sacrificial anodes on cars. I used to be the anti corrosion guy where I worked (among other nefarious duties) not that that makes me any kind of expert, it just makes me interested.

I remember reading the rust bullet website where they tested phosphoric acid conversion compared to other protections. Their testing, if assumed to be unbiased, showed other protections worked a lot better (rust bullet was one of the protections that worked better than phosphoric acid). There are dissenting opinions no doubt. The local Z mechanic used phosphoric acid on his Z car resto, I went with rust bullet for painting on surfaces and transtar amber spray for interior areas like rocker panels.

Mike in Boise

Edited January 20, 2014 by Mikes Z car

[ajmcforester]

FYI sacrificial metal can create rust spot because they focus the deterioration to a specific spot. In a ship the weld new plates the mount the rods or bars. Go look at a hot water heater it has a rod and the first place it will rust out is the connecting points. If you don't replace offten just like a hot water heater your asking for trouble. I know it was something they were selling year a go, but it just does not make sense to do. I would spend the money and time getting rid of the rust you have and sealing the metal.

[240260280z]

Sacrificial anodes are specific to where metals conducting electricity are immersed in water. Or where induced currents occur in a metal in water where the metal moves or the water flows. Since the Z is not driving around knee deep in puddles, a sacrificial anode will not function.

The metal needs to be coated for chemical corrosion protection.

The power returns for the lighting circuits could be improved by running parallel copper wire paths in the uni-body or using discrete return cables to bypass the uni-body completely

Edited January 21, 2014 by Blue

[Mark Maras]

I'm inclined to agree with all of you. Has anyone tried any of those rust preventers that run a trickle of current through the chassis either with or without sacrificial anodes? Some people swear by them, others swear at them. I'm assuming the supplied trickle of electricity is a substitute for the wet conditions that would normally drive the galvanic process. Testimonials, Anyone?

Mark in Portland

[ajmcforester]

I looked into several things since I started the restoration of my Z car. I do research at work and what I saw as evidence on how well this works on non-aquatic devices had questionable methods or used inferences that may or may not relate to improved rust protection in normal atmospheric conditions. Some of the studies made statements that fell within the statistical variance.

I'm such an anti rust guy that I even have looked at having the body zinc plated, primer powder-coated, electrostatic treated, and many other methods to reduce rust issues. Rust is something you got to work with by sealing and protecting the metal surfaces from contaminates and chemicals that can create oxidation. The cost of these questionable systems you can use a time test method of painting the metal then using a oil to keep water and other chemicals from entering chips and cracks in the paint. 1-2 cans on Gibbs oil will do the inside of doors, undercarriage, engine compartment and even a little left over to lube a couple stuck fasteners. Then use lock tight and anti-seize on the fasteners to keep water and chemicals from rusting threaded surfaces when ever you take a fastener out. This works very well for me, and I can tell when I missed one of the two treatments of oil each year on my daily driver, and the cost to keep up with anodes and cleaning rust off the contact points you might save money.

[Casey_z]

I work in the pipeline industry.

We install cathodic protection and it like that on ships depends on current going to ground and degrading the anode in the ground away from the pipe. You need to maintain 3ft. separation or the pipeline is subject to corrosion at that point. It is the same principle as on a ship using water as a ground. So if you could isolate the car and cadweld a anode to it and bury it it would work pretty good. You wouldn't get far.

I use an oil spray called Rust Check in all the susceptible spots. It is designed to creep into seams etc.

Edited January 22, 2014 by Casey_z

[ajmcforester]

I work in the pipeline industry.

We install cathodic protection and it like that on ships depends on current going to ground and degrading the anode in the ground away from the pipe. You need to maintain 3ft. separation or the pipeline is subject to corrosion at that point. It is the same principle as on a ship using water as a ground. So if you could isolate the car and cadweld a anode to it and bury it it would work pretty good. You wouldn't get far.

I use an oil spray called Rust Check in all the susceptible spots. It is designed to creep into seams etc.

I found one or two of these ground anodes when removing a tree, what fun to find a metal wirer coming up with a tree. Like you stated with the ground you need tranfer the electrons from point a to point b, how can you do that with just air

[240260280z]

Flow can induce current at a distance. I am guessing this is the pipeline separation rule of thunb mentioned above.

We get induced currents with submarine cables caused by the flow of tides/bottom currents over them. We also get esoteric parasitic currents from solar emissions every now and then...yes we watch "space weather".

[gnosez]

Since I sell frame rails for S30 Zs let me put forth a thought or two.

The OEM rails started rusting on the boat coming over here. Even so most lasted years and years before they needed to be replaced.

If those OEM rails had had some version of rust protection there would be more Zs in operational condition today.

The rails I sell are nearly three times thicker than the OEM ones.

If you didn't seam seal and rust proof them they would likely last for years before needing to be replaced.

With protection they are likely to last for a few decades (if you stop driving your Z when there is salt on the roads).

Anode sanode. These are cars not boats.

So clean up and or replace your rails, put on some protection and go drive your car.

How long will the rest of your Z last?

[Coastalman]

Gnosez, do you have a web site showing your rails? I would be interested in checking them out.

Charlie

[gnosez]

Bad Dog Parts, Datsun Z car parts and accessories

240z Frame Rails (FRONT) - $220.00 : Bad Dog Parts, Datsun Z car parts and accessories

240z Frame Rails (REAR) - $138.00 : Bad Dog Parts, Datsun Z car parts and accessories

We make them for 280Zs (coupe and 74-76 2+2s) as well $230.

All prices include shipping (lower 48 States).

Edited January 23, 2014 by gnosez