Type of Steel for Suspension Components

[metallurgyphil]

I'm restoring a series 1, FHC and although I'm still working on the body shell, all the running gear needs replating. I shall use zinc or zinc-nickel with a clear passivate and seal. My question is: What strength are the front wishbones so that I can determine whether they need to be embrittlement relieved after 'plating? The original material specification would be useful. Does the club have any links with LandRover Jaguar classic archives?

[J44EAG]

The problem with hot dip plating is firstly that prolonged heating above certain levels can seriously upset the former heat treatment of components. The second issue is that zinc plating tends to be sacrificial and will over a period of time tend to erode. Zinc acts as an anode which erodes when in contact with a more noble metal. The more noble metal acts as a cathode. Electrical currents flow from the cathode to the anode which is of a lesser nobility level and therefore erodes.

You might look at blast cleaning the components and then spraying with cold zinc pacification aerosol paint. Galvafroid is one such product but as just said, the zinc is an anode and will disappear in time.

Perhaps more productive would be to blast clean components, spray with two pack epoxy primer and then top coat with two pack polyurethane paint. That would be my preferred method of dealing with long term preservation of steel under-body components.

Mike K

[metallurgyphil]

Hi Mike.
This is the first time that I've asked a question through the web-site and really appreciate you taking the time to post a very thorough reply. I wasn't thinking of hot galvanising the parts which as you say would affect their properties but instead getting them zinc/zinc-nickel 'plated. This has the benefit of at least maintaining a sacrificial protection of the base metal as the original cadmium 'plating did which simply painting wouldn't. In fact once broken, paint will accelerate the corrosion of the base metal. During the electroplating process, hydrogen is absorbed by the parts which if not removed by baking, may cause parts to fail if they are under continual static load and are of a strength greater than 1000MPa (55tsi). The torsion bars I suspect, if electroplated would be a prime candidate for this. This is the reason why I wanted to know the strength of the material.
Yours,
Phil P.