Fog/Driving Light Wiring
03-07-2007, 07:20 PM
#1
Drifting
Thread Starter
Fog/Driving Light Wiring
Today has been one of those frustrating 928 days, involving replacement of the RHS fog/driving light in an 88 S4.
The existing lens has a small crack in it. I found a new lens unit on eBay but ran into problems removing the old one. The 4 bolts holding the lens unit to the rear of the headlight unit were rusted in. Someone had obviously tried to remove them in the past as a couple were badly chewed up. I succeeded in chewing all of them up!
So I drilled off the heads and the lens unit came away fine, but it proved impossible to remove the remains of the shafts from the threaded holes. Tried filing flats onto them and gripping/turning but the shaft is just too narrow to get a proper grip. Tried cutting a slot into top with a Dremel but the metal just deformed when I inserted screwdriver and tried to unscrew. In the end I could get them out but only by drilling them out so ruining the threads.
No problem I thought. Just buy the plastic rear of the headlight unit. But then looking at the parts diagram I see you can only buy either the lens insert (which I had) or the complete unit including the rear and the insert.
OK so I'll just have to buy a whole unit.
So at last my question. On the diagram there is a kind of appendage coming from rear of the unit, and I see the same appendage on photo of the part on 928 Intl (they call it Right Fog/Driving Light 87-95) though the part no. is different from my parts catalogue, perhaps because of US/UK differences.
My original part had no such appendage. There's just a hole at the back of the light, and the wires come through a grommet with connections for the parking, fog and driving lights and grounds.
So what is this appendage? Some kind of multi-connector which mates with wiring loom? My parts diagram is the 91 one but is supposed to be Ok for 88 cars. I don't want to buy a headlight and find it doesn't install into the '88 car, nor find that you can't get a replacement for the original light and exisitng wiring.
Some of you may be tempted to suggest helicoils, but the existing threads are bonded into plastic, so I can't see how you can tap the plastic for an insert? Maybe I'm misunderstanding how to use helicoils.
Anyway thanks in advance for any advice/moral support.
Adrian
The existing lens has a small crack in it. I found a new lens unit on eBay but ran into problems removing the old one. The 4 bolts holding the lens unit to the rear of the headlight unit were rusted in. Someone had obviously tried to remove them in the past as a couple were badly chewed up. I succeeded in chewing all of them up!
So I drilled off the heads and the lens unit came away fine, but it proved impossible to remove the remains of the shafts from the threaded holes. Tried filing flats onto them and gripping/turning but the shaft is just too narrow to get a proper grip. Tried cutting a slot into top with a Dremel but the metal just deformed when I inserted screwdriver and tried to unscrew. In the end I could get them out but only by drilling them out so ruining the threads.
No problem I thought. Just buy the plastic rear of the headlight unit. But then looking at the parts diagram I see you can only buy either the lens insert (which I had) or the complete unit including the rear and the insert.
OK so I'll just have to buy a whole unit.
So at last my question. On the diagram there is a kind of appendage coming from rear of the unit, and I see the same appendage on photo of the part on 928 Intl (they call it Right Fog/Driving Light 87-95) though the part no. is different from my parts catalogue, perhaps because of US/UK differences.
My original part had no such appendage. There's just a hole at the back of the light, and the wires come through a grommet with connections for the parking, fog and driving lights and grounds.
So what is this appendage? Some kind of multi-connector which mates with wiring loom? My parts diagram is the 91 one but is supposed to be Ok for 88 cars. I don't want to buy a headlight and find it doesn't install into the '88 car, nor find that you can't get a replacement for the original light and exisitng wiring.
Some of you may be tempted to suggest helicoils, but the existing threads are bonded into plastic, so I can't see how you can tap the plastic for an insert? Maybe I'm misunderstanding how to use helicoils.
Anyway thanks in advance for any advice/moral support.
Adrian
Last edited by StratfordShark; 09-11-2014 at 12:30 PM.
03-07-2007, 08:02 PM
#2
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Its just the loom connector and comes with the individual high temp insulated wires that go to the H3 lamps though the grommet. You will have to get into the front fenders to disconnect the existing connector (remove wheel, front splash shields & wheel liners).
Unfortunatly those threads can get wet and corrode too easily - lube new ones well before reassembly. I'd suggest you look at drilling and J-B welding epoxying in some threaded spacers - well worth a try if the only other option is to replace the whole shell - otherwise maybe a junk yard like 20th street will have one where the lenses have already been taken...?
Alan
Unfortunatly those threads can get wet and corrode too easily - lube new ones well before reassembly. I'd suggest you look at drilling and J-B welding epoxying in some threaded spacers - well worth a try if the only other option is to replace the whole shell - otherwise maybe a junk yard like 20th street will have one where the lenses have already been taken...?
Alan
03-07-2007, 08:04 PM
#3
Burning Brakes
Can you just use through screws with nuts on the back side to hold the lens in place? I know it means that you have to remove the light but it sounds like you did already and you would have to do this to replace the light anyway.
03-07-2007, 08:07 PM
#4
Shameful Thread Killer
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Whatever you find in the junk yard will be as bad or worse than your hash-up now. I know, I checked. When you get it sorted out, are you going to offer your lens? Hint - I need one now.
03-07-2007, 08:23 PM
#5
Drifting
Thread Starter
Originally Posted by Alan
Its just the loom connector and comes with the individual high temp insulated wires that go to the H3 lamps though the grommet. You will have to get into the front fenders to disconnect the existing connector (remove wheel, front splash shields & wheel liners).
Unfortunatly those threads can get wet and corrode too easily - lube new ones well before reassembly. I'd suggest you look at drilling and J-B welding epoxying in some threaded spacers - well worth a try if the only other option is to replace the whole shell - otherwise maybe a junk yard like 20th street will have one where the lenses have already been taken...?
Alan
Unfortunatly those threads can get wet and corrode too easily - lube new ones well before reassembly. I'd suggest you look at drilling and J-B welding epoxying in some threaded spacers - well worth a try if the only other option is to replace the whole shell - otherwise maybe a junk yard like 20th street will have one where the lenses have already been taken...?
Alan
If the headlight comes with the same loom connector then I could just disconnect the one it comes this from the new headlight unit re-connect the existing one without having to remove wheel liners etc? The existing one just had spade terminals to push onto the grounds and bulb +ve connectors.
I will look into the threaded spacer option you suggest. Will certainly use anti-seize on the new one!
Regards,
Adrian
03-07-2007, 08:26 PM
#6
Drifting
Thread Starter
Originally Posted by WICruiser
Can you just use through screws with nuts on the back side to hold the lens in place? I know it means that you have to remove the light but it sounds like you did already and you would have to do this to replace the light anyway.
Maybe I could just screw the lens into the rear section and not use any nuts?
Thanks for the idea,
Adrian
03-07-2007, 08:57 PM
#7
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Adrian,
On mine the wiring comes through a molded on grommet - not an open type - it may be hard to get the grommet into the housing without access to the back -- but may still be possible - if your existing wiring is good should be possible...
Alan
On mine the wiring comes through a molded on grommet - not an open type - it may be hard to get the grommet into the housing without access to the back -- but may still be possible - if your existing wiring is good should be possible...
Alan
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03-07-2007, 09:00 PM
#8
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I had same problem with mine, I just taped the hole out in the plastic and used IIRC a 10-32 screw, has held up well so far- just don't over tighten or you will strip out the plastic.
Mike
Mike
03-08-2007, 03:52 AM
#9
Drifting
Thread Starter
Originally Posted by Alan
Adrian,
On mine the wiring comes through a molded on grommet - not an open type - it may be hard to get the grommet into the housing without access to the back -- but may still be possible - if your existing wiring is good should be possible...
Alan
On mine the wiring comes through a molded on grommet - not an open type - it may be hard to get the grommet into the housing without access to the back -- but may still be possible - if your existing wiring is good should be possible...
Alan
Thanks Alan
03-08-2007, 03:55 AM
#10
Drifting
Thread Starter
Originally Posted by michael j wright
I had same problem with mine, I just taped the hole out in the plastic and used IIRC a 10-32 screw, has held up well so far- just don't over tighten or you will strip out the plastic.
Mike
Mike
Mike what do you mean by "taped the hole out"?
Today I'm going to get lots of assorted screws, slip nuts and threaded spacers to experiment. Will cost a fraction of new unit (about $400 here) and wil be good experience anyway for similar probs in future.
Adrian
03-08-2007, 05:31 PM
#11
Drifting
Thread Starter
Managed to bolt in the headlight lens without buying a new one.
I took the suggestion to try threaded spacers. Picked some up today (hexagonal nylon, 6mm diameter, 3mm thread). After drilling out the existing threads in the rear section the spacers were a nice tight fit in the holes - had to persuade them in with a hammer. Got them in 3 of the 4 holes, but the 4th one was too damaged from the drilling to take a spacer.
The correct bolts to go in the spacer are much narrower than the original ones, but the heads are just big enough to hold the lens insert in. I was able to squeeze the grommet moulded to the wiring through the hole in the rear section, then bolt the rear section into the fender.
Now my only problem is that the new light is lovely and clear/bright, but the old one looks dull and the condensation inside is very obvious!
Thanks for all the advice in this thread which encouraged me to try a solution before buying a new light.
Adrian
I took the suggestion to try threaded spacers. Picked some up today (hexagonal nylon, 6mm diameter, 3mm thread). After drilling out the existing threads in the rear section the spacers were a nice tight fit in the holes - had to persuade them in with a hammer. Got them in 3 of the 4 holes, but the 4th one was too damaged from the drilling to take a spacer.
The correct bolts to go in the spacer are much narrower than the original ones, but the heads are just big enough to hold the lens insert in. I was able to squeeze the grommet moulded to the wiring through the hole in the rear section, then bolt the rear section into the fender.
Now my only problem is that the new light is lovely and clear/bright, but the old one looks dull and the condensation inside is very obvious!
Thanks for all the advice in this thread which encouraged me to try a solution before buying a new light.
Adrian