| Author |  Topic  | |
Dynorog
V4 Fanatic
United Kingdom
250 Posts |  Posted - 16 Oct 2019 : 20:04:35  
| Hi
I have water in one of my headlights and it looks like it is a little rusty.I noticed it after a very wet trip along the pennines to Saab fest in Bury.
The rubber seal at the rear of the bulb holder was intact so it could have entered via the lens surround.
I have another set of H4 lamps somewhere but where?
I have found a standard set and have taken them apart.It has probably been done before but this is how I've done it.
I thought I would see if I could refurbish/convert to H4 bulbs.
Soaked the lamp unit for 48hrs in a roasting tin.
Scraped of the "araldite" Soaked it again for 24hrs Scraped off more.
Used a mini cutting disk around the perimeter between glass and steel surround, soaked again for another 48 hrs and the back just lifted off.
Cleaned off rust staining with a little wheel cleaner.
Washed the semi stripped lamp. I think the bulb holder can be modded to take an H4.
Didn't clean the reflector properly but thought I'd try a splash of chrome enamel spray.
Only sprayed the bottom but better than it looked before but there is obviously s difference to original as you can see from the picture below by the differance in reflections.
Properly prepared, sprayed and polished a little. They may come out OK.
I will seal/fix the lens back in with Sikaflex 265
I'll post some more photos when complete.
Cheers
Dynorog |
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UK_Sub
V4 Guru
United Kingdom
2558 Posts | Posted - 17 Oct 2019 : 09:05:42
| I've heard of people taking these apart before, but I don't think I've seen photos - so this is great!
It would make a great technical article for the Saab Enthusiast magazine - if you're interested?
What did you soak the headlights in - it looks like milk in the photos!
And when you say you took a cutting disc to them - were you cutting through the sealant and if so, why the extra soaking?
Thanks,
Simon |  |
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stevebod
V4 Fanatic
United Kingdom
416 Posts | Posted - 17 Oct 2019 : 21:54:01
| | Nice work. Following with interest. | |
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Dynorog
V4 Fanatic
United Kingdom
250 Posts | Posted - 19 Oct 2019 : 11:22:39
| Thanks Simon and Steve.
Yes, I would be willing to write an article for the magazine if you think it would be of wider interest and IF the lamp turns out OK!
I missed out the most important bit in my post, was it semi skimmed or full fat?
Well believe it or not it was paint stripper.3 litres of it to cover the rim.
Other brands are available
The reason I used a mini disk was that the stripper only seemed to penetrate to a limited depth, so once I had had removed the fixative down to the level of the glass lip surface and the metal surround, exposing the joint, I raked out the joint, giving the stripper better opportunity to work.
Patience isn't one of my virtues but I didn't want to try and mechanically remove the fixative too much, so as to avoid stressing the metal and breaking the glass.
More later.
Cheers
Dynorog | |
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Derek
V4 Guru
United Kingdom
2191 Posts | Posted - 19 Oct 2019 : 12:08:20
| | Lots of sealant removers available and would be quicker and easier than stripper. I sprayed the outside of my reflectors with Smoothrite silver (if I remember correctly) that does tidy them a up a lot. My lamp units were otherwise good and I didn't take them apart. | |
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Dynorog
V4 Fanatic
United Kingdom
250 Posts | Posted - 19 Oct 2019 : 13:08:40
| Hi Derek
None of the official sealant removers I tried touched this stuff.
I tried panel wipe, meths, turps, adhesive remover,cellulose thinners,industrial acetone and Xylene (not nice, extremely carcinogenic that stuff).
Cheers
Dynorog | |
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Dirtbiker
V4 Guru
United Kingdom
1061 Posts | Posted - 19 Oct 2019 : 13:35:20
| Top work Rodger and very interesting.
Now get back to getting the two stroke on the road!
Cheers
Gareth | |
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UK_Sub
V4 Guru
United Kingdom
2558 Posts | Posted - 21 Oct 2019 : 10:40:19
| Thnaks for the extra info - keep taking photos, so we can use them for the article.
There must be a load of these headlights, unused because of rusty reflectors. I thought I had a good pair of headlights until I took a better look at them, they've been sitting on the garage floor ever since!
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billj
Starting Member
9 Posts | Posted - 10 Nov 2019 : 00:30:06
| Very interesting to see your approach. I haven't tried the right paintstripper, obviously. No chemical I tried made any impression on the adhesive. It isn't a sealant of any sort that the sealant removal products are intended to remove. It's a very hard, polymer-based material. I did look it up to find out what it was but I can't remember now. However, when I identified it, that gave me a clue as to how to tackle it.
For the headlamps we refurbish for customers I heat them in an oven to 100C. This softens the adhesive and then I rake it out with a hacksaw blade to get the majority of it out, then a Stanley knife blade to get as much of the rest out as possible, especially in the corners. I need to stop from time to time to reheat it. Eventually, when most is out and at least one corner is fairly clear, I heat it for a final time and put a hefty cardboard tube (it's what I had available) through the bulb-holder (I'm talking about the later type with the hole in the front) to contact the lens and then, with the lens facing upwards, press the reflector down towards the workbench and push firmly and repeatedly until the lens comes free (usually at one corner first).
I suppose heat also has the advantage of not damaging the paint as much as paint-stripper would, assuming it looked OK and didn't need repainting anyway.
Once the reflector is refurbished I refit the lens and run a bead of white polyurethane adhesive around it using an air-powered caulking gun to make a neat job.
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Edited by - billj on 10 Nov 2019 00:38:52 | |
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billj
Starting Member
9 Posts | Posted - 10 Nov 2019 : 00:54:18
| The finished article. I don't have photos of the process. I'll try to take some.
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Dynorog
V4 Fanatic
United Kingdom
250 Posts | Posted - 10 Nov 2019 : 11:54:38
| Thanks for the information Bill.
How do you refurbish the reflector?
I haven't done any more on the headlight yet or my cars for that matter, I've been banned by - I'm sure you can guess who, until I refurbish the ensuite.I wouldn't mind but she has only been waiting 11 years.
Cheers
Dynorog | |
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billj
Starting Member
9 Posts | Posted - 10 Nov 2019 : 16:16:37
| Hi, Dynorog. Once the lens is off we remove the bulb-holder, which is perhaps slightly easier on the later type shown in my photo than on your earlier type, especially since we have crafted some special tools for it. Then we strip the inside of the reflector. If the outside needs it we strip that too, bead-blast to get rid of any rust and then paint with a high-temperature primer. Then we send it off to our sub-contractor for vacuum metallisation, which is the process Hella used in the factory.
Meanwhile we bead-blast the bulb-holder and the retaining ring and apply a zinc coating.
When the now-shiny reflector returns, we refit the bulb-holder and the lens.
The primer we use on the outside needs to be high-temperature, not to withstand the heat of the bulb but rather to withstand the metallisation process as the lacquer applied under the metallisation is cured at a high temperature. | |
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Dynorog
V4 Fanatic
United Kingdom
250 Posts | Posted - 21 Dec 2019 : 17:09:46
| Thanks Bill
Wow "vacuum metallisation" that sounds expensive. I have some people who do that near where I live, so I've taken a step back and am now in the process of stripping off the whole unit inside and out. I'll prime the outside with HT stuff and then make some enquiries on one off prices for the vacuum metallisation, although usually anything with 'isation' in it is expensive .
Does anyone know if the lens pattern on an H4 is any different to the lens on the ordinary Hella units, they look the same to me.
Cheers
Dynorog | |
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| | Topic | |
Headlight strip down.
