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Oct 11, 2010 18:20:57 GMT
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When I got the mx5 roof, it had the HRW cable dangling off the glass. In an effort to stop the tabs being snapped off the window if the wire got snagged, I decided to take the cable off. In doing this, I snapped the tab off. There is still a good bit of metal on the window, I'll be able to solder it no problem, but will the heat break the window? It looks like it's already soldered on, but these rear windows are 1: Expensive and hard to get, and 2: Not covered by my insurance becuase the roof is not part of the car. This is the "before" picture:  During:  After:  |
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stealthstylz
Club Retro Rides Member
Posts: 14,865
Club RR Member Number: 174
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Oct 11, 2010 19:01:18 GMT
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Can you not hold the tab against the remaining metal then cover it with chemical metal? Though does chemical metal stick to glass?
Matt
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Oct 11, 2010 19:05:03 GMT
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they sell the repair kit for those at halfords don't they? or at least ive seen em somewhere... That said i don't think the heat would break the window... Might be worth getting the glass warm first tho with a small heater so you don't shock it.
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Oct 11, 2010 19:11:11 GMT
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There shouldn't be a problem - soldering irons give a very direct heat (electric ones, not gas) but if you're unsure, gently heat the glass with a hot airgun before you start soldering. Have the soldering iron ready to go so that the glass is still hot when you start soldering. Maybe have someone keeping the glass hot while you do it. Probably a bit OTT, but better than regretting not doing it.  |
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Oct 11, 2010 19:12:20 GMT
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I'd get the screen in a warm place and let it warm up - or at least work on a warm day so it's not really cold.
Tin the tab, and then solder it onto the screen. I'd use a powerful iron or soldering gun - an absolute minimum of 50w, preferable 100w or more - the glass will act as a big heatsink, sucking heat out of the joint. If you use a more powerful iron, you can get it soldered faster, meaning that the glass won't get as hot, reducing the risk of cracking.
I wouldn't try to dissipate the heat in the glass by using a wet cloth or anything, as this will increase the temprature gradient within the glass leading to higher stresses and more chance of cracking.
However, you can't guarantee that it won't crack - that risk is always there.
I hope you are successful.
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Oct 11, 2010 21:30:15 GMT
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have a look at where the tab came of the glass to see if the metal print is still on the glass, if it has come of you will need to clean above or below with some fine wire wool or fine scotch bright, BE VERY GENTLE at this point or you might take the metal print of the glass, you only want to make the metal print clean, but if the solder is still on the glass then it will be easy to solder back on, heat up the tab clean it and put fresh solder on it, get your iron hot and put the tab into a pair of long nose pliers, I use and have used a gas soldering iron for over 15 years and have never had a screen break on me, if you have someone else about to help they can hold the tab on the glass with the pliers and you can put the soldering iron on the back of the tab just untill the solder melt the bring the iron away while the other person holds the tab very still while it cools down, this has always worked for me so you should be ok good luck bud  |
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Last Edit: Oct 11, 2010 21:34:50 GMT by rusty998
MK2 Cortina Estate
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Oct 11, 2010 22:24:59 GMT
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dw1603
Part of things
Posts: 591
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Oct 11, 2010 23:56:46 GMT
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I have seen a rear screen shatter whilst trying to solder on a HRW tab, but it wasn't pre heated and it was an electric iron. Probably sloppy technique I expect. On the other hand, I have seen plenty repaired by gluing the tab back on then giving it a generous coating of conductive paint, such as the one recommended by Hardcore. Much less risky, I reckon. |
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Oct 12, 2010 11:04:13 GMT
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Conductive Glue. Used it all the time on computers. Look on ebay  |
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Oct 12, 2010 11:40:02 GMT
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How weird is that? my sis bought an MX5 the same colour and it came with a red hardtop the same colour as yours.
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Volvo back as my main squeeze, more boost and some interior goodies on the way.
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Oct 12, 2010 20:34:42 GMT
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Worked in windscreen assembly place and when new-
Rub down the area to solder with one of those blue hard pencil erasers to remove the insulating layer (should be done on yours already).
Tin the terminals of the tab (ours were pre-tinned)
Load some solder on the iron
Hold terminal in place with tweezers
Heat terminal with decent soldering iron, adding more solder where necessary.
No preheating etc ever happened, we never broke any from this. Lots from dropping though!
We did have special soldering heads that were forked to apply heat to both sides of the tab (most had two contact points) at the same time.
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Oct 12, 2010 21:55:54 GMT
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Talk about conflicting advice, lol. I've used the conductive glues and paints, but not been impressed.
I have a decent amount of tab still on the window, I think I'll try and solder it. I'll tin both ends, have a quick go with my iron (75w temp controlled) and if it doesn't immediately take I'll let it cool and try again.
Cheers chaps!
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Oct 12, 2010 22:01:11 GMT
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I put hot water on a screen and it cracked, I wouldn't use a hot air gun on it.
Use that silver conductive paint with a bit of glue.
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Oct 12, 2010 22:28:47 GMT
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I put hot water on a screen and it cracked, I wouldn't use a hot air gun on it. Chalk & cheese comparison. Hot water is a sudden shock to the glass. Hot air gun you can start from a distance and gradually get closer, allowing the glass to acclimatise to the temperature and gradually get warmer then hotter. It's not rocket science |
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Oct 12, 2010 23:37:02 GMT
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^Indeed - it's the rate of energy transfer into the glass, which causes hotspots.
I wouldn't mind betting that for hot water (~80 *C) onto cold glass (~10*C) over a large area the heat ransfer rate is in the kW, causing one side of the glass to suddenly heat up. OTOH, a soldering iron (or a gently used hot air gun) will be 100-ish W at most, so any heat change will be more gradual.
The thing that breaks glass isn't the temperature itself, but the temperature difference between different areas of glass, due to the glass expanding in the hot areas but not the cold.
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