My car is going to be quite classic in appearance. However, its getting a full cage. 60s roll hoops often appear to have a chrome/nickel finish. I know chrome is a no-no structurally but what about nickel plating?

Steel is usually nickel plated first and then chrome plated on top, that's why its often referred to as 'Nickel Chrome'.

So whatever makes Chrome a 'nono' would probably also apply to nickel ... but why is chrome a nono anyway?

Yes Tim, do tell, I'm intrigued to know as well.

If i remember right people say don't use chrome on wishbones because you cant see if the tube gets a crack in it

A quick Google led me to:
http://www.corrosion-doctors.org/Forms-HIC/embrittlement.htm

Make the cage in stainless, and polish it ???

You'll be dead of natural causes first.
And how can H2 be injected by nickle plating?
If you are really worried attach another sacrificial cathode from a chandlers and let that produce the H2 remotely.
Forget natural causes, I would bet you'll win the lottery and get hit by a rogue satillite before you roll your car and get killed from an over hardened roll cage failure due to hydrogen injection.
Silver hammerite is an option though!

I've decided that the point is moot (or 'moo'* if you're a fan of Joey on friends.)

It won't look classic, it'll just look tarty. Its back to powdercoat for me.




*A 'moo' point is something that a cow would say, and therefore unimportant.

[Edited on 22/10/10 by TimC]

I've not used nickel plating for roll hoop, but have used it extensively on wishbones and subframes.

Hydrogen embrittlement should not normally be a concern as this is generally only a problem on steels with UTS exceeding 1000MPa (the reason why it is unusal to see fasteners grade 10.9 and above electroplated).

The bigger concern is ensuring that all (corrosive) process chemicals can be adequately drained from the structure, this can be resolved by positioning holes in the material capping the end of the tube or externally to prevent closed cavities.

I have found that with thin nickel coating crack testing is not effected, on the early S2 wishbones that were prone to fatigue after a couple of seasons, crack testing was successfully used and as the nickel is cathodic to the steel rust bleed is often present at the sight of cracks, obviously this is not an ideal situation for items that are rarely inspected / in a corrosive environment as failure will be accelerated.

Ian

quote:

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Originally posted by Ian-B
I've not used nickel plating for roll hoop, but have used it extensively on wishbones and subframes.

Hydrogen embrittlement should not normally be a concern as this is generally only a problem on steels with UTS exceeding 1000MPa (the reason why it is unusal to see fasteners grade 10.9 and above electroplated).

The bigger concern is ensuring that all (corrosive) process chemicals can be adequately drained from the structure, this can be resolved by positioning holes in the material capping the end of the tube or externally to prevent closed cavities.

I have found that with thin nickel coating crack testing is not effected, on the early S2 wishbones that were prone to fatigue after a couple of seasons, crack testing was successfully used and as the nickel is cathodic to the steel rust bleed is often present at the sight of cracks, obviously this is not an ideal situation for items that are rarely inspected / in a corrosive environment as failure will be accelerated.

Ian

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Why not chrome powder coating?

http://homepage.ntlworld.com/carlfothergill/new/EMcolour%20chart%202010.pdf

Powder coat is the way mate, I have seen some done properly and it looks 99.9% real chrome, a much better finish than nickel.

I wouldn't worry about chrome on a roll bar. The embrittlement is negligible and the biggest problem with chrome is on parts that inherently flex, like chassis and wishbones. The problem is that steel will flex nicely but chrome won't, leading to cracks in the finish usually at welds. This in turn leads to a stress point where the chrome has failed and the possibility of further cracking or a sudden failure of the component at that point.

Your roll cage is not likely to be flexing enough to suffer from this! IMO

[Edited on 24/10/10 by Strontium Dog]