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2005 SLK350
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58 Posts
Discussion Starter · #1 ·
I tried everything on the original headlights, polished up the covers (needs doing monthly in summer if kept outside), fitted upgraded bulbs and still useless on dip to the point of being dangerous. I looked into original replacement units and saw the price, plus they still may not be that good. Replacement internal bits are not available. I looked at aftermarket and still very expensive, unknown results and not sure about the look.

Then I started thinking about adapting some form of universal dipped beam only headlight. A quick look at ebay revealed such things exist. Two sizes available. 90mm Hella as fitted to some TVRs and various other cars at £50 each and the ones I opted for, 50mm motorcycle units at £35 each. I purchased one to try out the beam. Plugged into a battery all looked good with a distinct cut off pattern.

Next question was how to fit. My initial idea was to dismantle my units and atempt to adapt the internals to take the new light. I may still do this at a later date. It could be done either by removing the existing dipped units and replacing, or it may be possible to fit them where the sidelights are (an alternative place for the sidelight bulbs would be needed. Getting adjustment could be an issue. I'd also like to have a choice of both alternatives to hand if I do this to see which fits best.

Instead I opted for a simpler way. I mounted them on brackets in the void between the grill and radiator behind the lower black grill (under the fin) as close to the outer edge as possible. the 50mm lens is just the right height for the grille height.
Automotive tire Font Watch Rim Automotive lighting
Font Circle Auto part Fashion accessory Rim

I used a simple L shaped bracket bolted to the upper crossmember. I cut a hole in the grille slats, the lights sit just behind the grille. Looking at the car from the front they are not that noticeable unless you crouch down as the fin overlaps them from above so fairly unobtrusive. I believe some models had a mesh grille instead of slats, that could be even better with no cutting.

Well I have so far fitted one and the results are impressive. An excellent spread of light with a distinct cut off. Even on the standard bulb supplied a huge improvement. With the second one fiitted I'm sure they will be up to modern car standards. I have left the originals wired in for legality (think there is a minimum distance from edge of car and it makes sense anyway). As I never use the equally useless foglights I have diverted the wiring from those so one pull of the lightswitch brings the new lights on together with the originals.

You could of course just stick them where the foglights are but too low to be legal unless used in fog and you'd be regarded as one of those idiots who use fog lights all the time and continually flashed.

This may be regarded as a bit of a 'bodge' job but for safety it's a simple, quick fairly unobtrusive solution. Mines a high mileage daily driver. You may not want to be doing this on a concours car of course.

One day I may get around to buying a spare light unit and experimenting (or maybe somebody else here might). Make sure you buy the correct left or right dip for your country. UK needs the left dip version. They also come as main beams so make sure it's a dip beam and make sure it's adjusted (by bending the bracket!) so the kink in the dip is straight ahead and the level below horizontal. I'm tempted to just disconnect them in case of any MOT tseting issues but I don't see any regulation against having more than two dipped headlights so long as the outer ones are near the edge of the car and all are adjusted correctly.

Dave
 

· *Registered
2005 SLK350
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58 Posts
Discussion Starter · #5 ·
The other thing to do is buy a 55..... :LOL: :cool:
Or you could source second hand parts from a 55, front bumper with washers and headlamp units etc from a scrap yard/breakers?
I've had a quick look and these items are available, you would be wise to gather all the relevant part numbers prior to looking. I could only see one headlamp with the ignitor. A bit of a conversation with a breakers yard may be fruitful?
Just a thought, good luck anyway.
Thanks but suspect my budget is a bit lower than yours Russ!
 

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2005 SLK350
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58 Posts
Discussion Starter · #9 ·
I just used a power drill and filed the ends off.with a metal file afterwards. There are probably better ways but all I had to hand.
That's very discreet most people would never even notice it is there. Did you take the grill out to fit it of have you just lowered a bracket down from the top?
Bracket down from the top, you can see it in the pics on top of crossmember. I'm going to reinstall iut with something a bit stronger. Haven't yet refitted the plastic shroud, it may need some adapting The grille looked quite tricky to remove without taking the bumper off so cut it in situ. You need a bracket thin enough to bend to adjust but thick enough not to vibrate. You could use washers to adjust by shimming it out I guess.
 

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2005 SLK350
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58 Posts
Discussion Starter · #10 ·
That is a very unique and interesting approach to improving the lighting, which is a universal problem with the factory halogens (and the bi-xenons are not much better). Thanks for posting this. How exactly did you cut your grill? I.E. what tools did you use?

I don't think it would be possible to fit these into the factory headlight assemblies, unless you want to forgo the existing main/high beams, which kinda defeats the purpose.
Coincidentally I had a chance to look in the back of the original headlight unit tonight as I had a bulb failure. My idea of fitting it where the sidelight is of course wouldn't work as the main beam is in same place so you are correct there. However it doesn't look impossible to replace the dipped units with these, there is certainly enough space, they are a similar shape but the mounting holes are in different places. It would mean dismantling and some fabrication would likely be needed. As my method does the job I don't think I could be bothered. If I was rebuilding a unit I would certainly want to give it a go. There's an opportunity there if somebody could produce and market an adaptor!
 

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2005 SLK350
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58 Posts
Discussion Starter · #12 ·
The 90mm units pictured are Hella. I didn't use those as too big for the grille apertures, also price higher. Could they be the same?

As for differences, I can only see through the bulb access hole. Four mounting screws but different spaces. Maybe the outer ring on originals could be left in place and new units mounted behind. I can take dimensions from my new ones if it helps.
 

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2005 SLK350
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Discussion Starter · #14 ·
Wood Auto part Magenta Metal Jewellery

The projectors have a lens, and the lens has curvature, how does the curvature compare between new and old? Roughly the same? One "flatter"? I know you can't measure this, I'm just looking for approximations that might explain the improvement and justify cutting an otherwise perfect set of headlights.
Gas Cylinder Auto part Magenta Metal
 

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2005 SLK350
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Discussion Starter · #16 ·
Hope the pics help. Can't really compare with originals as I can only see into the back of the unit. As my car is 17 years old I have no way of knowing how these would compare with new originals. Could be internal deterioration or that they were rubbish from new.
How about getting a second hand light unit off ebay or scrap yard?
It doesn't need to be in good condition, just good enough to play around with.
This one is £85 and will save you damaging your car and having to put it back together in this cold weather etc.
The breaker may have a cracked lens one that they can't sell?
This link has more pics of the back of the 90mm Hella units. Unfortunately no dimensions but looking in the back of my unit from under the wheelarch it looks pretty similar. If I was rebuilding I'd likely try one of these units. If you've got the uniits off you may be able to see better. It's of a similar era (Corsa C from 2000), wouldn't surprise me if they are the same unit.

 

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2005 SLK350
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Discussion Starter · #19 ·
Yes e marked on lens. Light not blocked as grille cut. All four would be on. Can't see why not legal for MOT? If set properly why would you blind anybody? Same as any other dipped beam. Level ground and measurement is all that is needed to align beams. It's a pretty simple process and I am very conscious of the need not to dazzle. Professional beam setters just make it quicker.
 

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2005 SLK350
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Discussion Starter · #21 ·
The ideal solution would be for somebody to try one of the eBay £50 new Hella units to see how good the beam is, then see if it fits in the original housing (guess the beam will be as good as a new Corsa C, Saxo, TVR etc that used these units).

Not sure how buying a nearly new original assembly can be a solution. The newest R171s are pretty old now, the lights weren't that good from new and how can you know it's nearly new? I've tried upgraded bulbs with minimal improvement, even with an LED. Detailing isn't going to work inside the units, Reflectors and lenses can't be polished inside the projectors. I've already polished the outsides to perfection, about all you can do in that direction (guess you could do the insides of the outer covers but would be marginal)

I don't have the money or time to invest further, I'm happy that I've dramatically improved the safety unobtrusively for a total outlay of £70 and a few hours work. Using them on the fog light switch means I mainly switch them in on the open road, not needed in poor weather or well lit roads when dipped beams are more to be seen than to see with and here the original lights are adequate.
 
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