Galvanising

[MJK 24]

Looking like I'm going to have to do a few jobs on the steering and suspension of my 27 year old Scirocco to renew its MOT this year.

Is there any reason why I can't shotblast and galvanise:

Front wishbones
Front struts
Anti roll bars front and rear
Rear axle

?

I'm aware that I'll have to tap threads etc. I've powdercoated items on other cars in the past but Galvanising will be more durable which is essential on a car that sees year round use.

Any thoughts?

Thanks in advance for any advice

[velocemitch]

Galvanising his a horrible industrial finish involving a lot of heat, I'd not go near it for large components like this. Spun Galvanising for small things like bolts is fine, but you can't spin an axle... well not in a galv bath anyway.

Try sandblasting and POR 15 paint system

[Rower]

I think the heat process in galvanising is likely to distort the parts which is not good, especialy these bits !

Rower

[Yertis]

I had a new chassis fifteen years ago for my TR6, supplied hot zinc sprayed. Then painted this with something called 'oil-rig paint', which I suspect is like POR 15, for blackness. I had all the wishbones and wotnot zinc-sprayed then epoxy-coated. I drive it year round and there is literally not one spot of rust anywhere.

But not the springs or anti-roll bars because they need to flex etc.

I'm going to do my Quattro next winter and I'll treat the subframes etc in exactly the same way.

[Humper]

Apart from whats already been said, you can't galvanise a closed section. IE, the struts would need to be galvanised inside and out, you'd need to drill holes in the wishbones etc, any sealed sections whatsoever and it can explode, spraying the guys working with some really not nice substances.
Good for a chassis, not good for what you're wanting, sorry.

[MJK 24]

Sounds like it's a no no! Thanks for the advice

[Spellbound]

Garnet blast and powder coat with the right materials, preferably by the same company. A service we will offer very soon

Peter

[a8hex]

Bilt Hamber do a coating called Electrox, which is a zinc based coating. Its supposed to give similar protect to hot zinc plating.
The tin weighs a ton.
Practical Classics did some tests a few years back and were really impressed.

[vvt]

As an alternative, I do remember being intreagued a few years ago as someone in Practical Classics had done a resto of their E types, IRS. They too wanted to prettify castings and hit on the idea of chrome plating the rough cast (I presume over a copper strike coating). The result, just like bright zinc but without the problem of dulling and tarnishing shortly afterwards.

I must try this on the next set of calipers I get redone.

Anyone else tried this approach? VVT

[a8hex]

vvt said:

As an alternative, I do remember being intreagued a few years ago as someone in Practical Classics had done a resto of their E types, IRS. They too wanted to prettify castings and hit on the idea of chrome plating the rough cast (I presume over a copper strike coating). The result, just like bright zinc but without the problem of dulling and tarnishing shortly afterwards.

I must try this on the next set of calipers I get redone.

Anyone else tried this approach? VVT

I'd expect that callipers and casting in the IRS would behave very differently. I'm not a metallurgist (I'll let my father handle that) so I have know idea what the temperatures involved in brake callipers will do to chrome plating. But I guess its the temperature that messes up the bright zinc (like my Zeus callipers on the front end of the XK). Brake components get damn hot. I'd expect that the callipers get hotter than the discs, since they'll have less air flow, but perhaps the pad gives them some insulation.

[vvt]

a8hex said:

I'd expect that callipers and casting in the IRS would behave very differently. I'm not a metallurgist (I'll let my father handle that) so I have know idea what the temperatures involved in brake callipers will do to chrome plating. But I guess its the temperature that messes up the bright zinc (like my Zeus callipers on the front end of the XK). Brake components get damn hot. I'd expect that the callipers get hotter than the discs, since they'll have less air flow, but perhaps the pad gives them some insulation.

Well for temperature effects on chrome plating you need look no further than a motor cycle exhaust pipe where it exits the head - temperatires in excess of 300 deg C and mild blueing.

I doubt very much if a caliper gets hotter than a disc - ever seen pics of the early Dunlop disc grakes in action - discs glow red hot, calipers a smouldering black - why - pad + disc = direct friction - REEEEEED whilst caliper = no direct friction and a higher surface area as well as bulk density to dissipate heat - BLAAAACK. Simples as the meercats say. Not a metallurgist but a junk trader that used to be a scientist.

[a8hex]

vvt said:

a8hex said:

I'd expect that callipers and casting in the IRS would behave very differently. I'm not a metallurgist (I'll let my father handle that) so I have know idea what the temperatures involved in brake callipers will do to chrome plating. But I guess its the temperature that messes up the bright zinc (like my Zeus callipers on the front end of the XK). Brake components get damn hot. I'd expect that the callipers get hotter than the discs, since they'll have less air flow, but perhaps the pad gives them some insulation.

Well for temperature effects on chrome plating you need look no further than a motor cycle exhaust pipe where it exits the head - temperatires in excess of 300 deg C and mild blueing.

I doubt very much if a caliper gets hotter than a disc - ever seen pics of the early Dunlop disc grakes in action - discs glow red hot, calipers a smouldering black - why - pad + disc = direct friction - REEEEEED whilst caliper = no direct friction and a higher surface area as well as bulk density to dissipate heat - BLAAAACK. Simples as the meercats say. Not a metallurgist but a junk trader that used to be a scientist.

Yes, I thought of the example of motorbike exhausts after I'd hit the send button.
You see lots of examples of photos of red hot discs, but I must admit to not paying too much attention to the callipers in the pictures. I was working on the basis of the disc having a lot more surface area and not being constantly heated all over, whereas the brake pad is constantly heated. I know they had huge problems with boiling the brake fluid even though it is under very high pressure. I guess the brake pad material provides quite a bit of heat insulation so there will be a significant difference between the temperature at the business end and that at the piston and mountings.
The disc is mostly spinning in free air which will help with cooling, whereas the calliper is stationary with respect to the car.

Also was a scientist once upon a time :-)