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HC Rear lights

PostPosted: Thu May 03, 2018 12:47 am
by vauxhallbitz
Just noticed that one of my rear light clusters has pitting on the chrome where it curves around the rear wing.
I have seen this before on some cars but these lights were NOS only fitted last year and have been regularly polished and never been out in salty roads.
Is this a common problem and, if so, how can they be protected?

Re: HC Rear lights

PostPosted: Thu May 03, 2018 7:28 am
by lord13
I believe they are made of 'Mazak', which is apparently called 'Zamak' everywhere else but the uk called it by a different name because they couldn't use the 'high-purity refluxer zinc' it needed (wikipedia is my friend), and it pretty much disintegrates over time , which is why all badges, light surrounds, and door handles have those little 'worm holes' in them, there's not much you can do, it's a characteristic of the alloy that occurs from exposure to moisture, oxygen, life etc, i guess :/

Re: HC Rear lights

PostPosted: Thu May 03, 2018 9:36 am
by vauxhallbitz
Thanks for that, I knew they were Mazak but I did expect to get more than a couple of years without pitting, very disappointed.

Re: HC Rear lights

PostPosted: Thu May 03, 2018 10:15 am
by droopsnoot
When you say "polished", what do you use?

The reason I ask is that when I had door handles chromed for my Firenza, I asked the plater what I should use to keep them shiny, whether I should use Solvol Autosol chrome cleaner. He was horrified, and said that's a very fine abrasive more used for cleaning up dirty chrome, and if I use it on new chrome it'll gradually thin out the surface. So only use a wax on new chrome, not anything abrasive.

Re: HC Rear lights

PostPosted: Thu May 03, 2018 5:15 pm
by 1972nail
From memory and looking at the myriad of old tail lights I have I think the Lucas ones are more afflicted with pitting than the Magnatex ones. I would guess that yours will have Lucas ones as it is a late '75 car. Unfortunately a Lucas to Magnatex conversion is not a straight swap, the connectors on the main loom are different. The Magnatex ones will have some pitting but suffer more from thin chrome plating which goes like a spider's web after a year or too.

I remember that when my brother bought a brand new E coupe, Monaco White as it happens, the tail lights did start pitting very early on in it's life. When we resprayed it Garnet Starfire at about 3 to 4 years old we replaced both tail lights for new ones....they didn't last long either. I think that they are still in the hoard I have in the roof space.

Re: HC Rear lights

PostPosted: Fri May 04, 2018 12:45 am
by vauxhallbitz
Thanks for the information guys, I did use a cleaner similar to Sovol Autosol but will stop using it now.
It's strange how they seem to go in the same place.

Re: HC Rear lights

PostPosted: Fri May 04, 2018 9:24 am
by 1972nail
I have a pair of new surrounds for my Magnatex lamps but have resisted fitting them for the very reason you've noticed. They all seem to go in the same places. So my reckoning is that if I have a good pair on the car that are not too bad then that's as far as they go and they will be OK for quite a long time. My new ones will get fitted when the state of the old ones really offend me.

I've noticed that the chrome is very thin on the rear edges which butt against the lenses and that's where the pitting seems to start.

Re: HC Rear lights

PostPosted: Fri May 04, 2018 10:19 am
by droopsnoot
Now I knew there was a reason other than cosmetic that the HPF had black painted light surrounds :) . When I replaced the seals around mine earlier in the year I took a minute (and only that, as you can tell when you look closely) to whip the surrounds off and give them another coat of paint.