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Re: About to take delivery

Posted: Thu Dec 28, 2017 11:26 am
by Dieselman
xmexclusive wrote: I examined 7 dip beam reflectors and none showed any sign of heat damage to the silvering or evidence of oxidation.
Six were from Mk 2 lamps and one Mk 1 lamp.
Settled dust was a factor from long service.
Similarly dust was the only factor on the main beam reflectors.
I remain certain that reflector heat damage is not an issue with XM headlamp reflectors.
I have a selection of series 1 lamp units and have definitely experienced heat damage to a number of the reflectors. The heat damage is evident by the silvering becoming cloudy and brittle.
Series 1 lamp units also suffer severe reflector oxidysation if not in use, or dry storage.

Maybe series 2 units don't suffer this.

I think a good solution would be to use reflectors from another modern model of car. I think Laguna mk1 and Mk2 units would fit into XM lamp units well and possibly Volvo V40. These would alleviate the need for any lens as the reflectors are genuine complex parabolas, focussing the light without any further requirement.

Re: About to take delivery

Posted: Thu Dec 28, 2017 12:18 pm
by xmexclusive
Hi Dean

The XM units were designed by Valeo to Citroen specification.
They were the first use of complex surface reflectors for headlights.
The dip beam design achieved the retention of all output to within then French regulations limiting pattern.
It was claimed to light this area better than any previous design.
That means no scatter and does not claim full and even coverage, just the best that had been achieved at that time.
Valeo and Citroen state that:-
"The output and efficiency of headlamps is determined by the manufacturing quality, shape and above all, the size of their reflectors".
They accept that round reflectors are the best option and easiest to manufacture.
However in response to the demands of stylists and aerodynamicists car body shapes took precedent.
Their spec revolved mainly around the already fixed body shape and therefore available lamp slot.
The glass rake angle was a major design constraint as optically a 20% slope absorbs 12% of light output.
They also note:-
"Today, when most headlamps are of varying shapes, one rarely sees the old round type.
However these different shaped lights have inferior performance to round parabolic ones".

Valeo will have designed the Rover lights to UK dip spec and specified size and shape.
With previous experience from the XM design I am not surprised they achieved better with a later design.
The body shape spec may well have been less demanding and Valeo a bit more vocal to get that better result.

There are a number of possible options for upgrade.
Most that have been tried so far do not meet either output or compliance requirements.
For UK approval the complete modified unit and bulbs must be approved by test in the vehicle it is to be used in.
I find this a very difficult hurdle in the way.
My personal solution is based on new and refurbished Mk 2 standard units.

John

Re: About to take delivery

Posted: Thu Dec 28, 2017 2:17 pm
by White Exec
Room for one of these inside the dip-beam enclosure?
http://www.myhellalights.com/index.php/ ... -headlamp/
The unit is H4 ECE, so will be capable of proper dip pattern (main beam too).
Hella halogen units are outstanding in quality, I remember.
Anyone's guess what the additional XM front glass will do.

Re: About to take delivery

Posted: Thu Dec 28, 2017 2:40 pm
by russ92xmsed
Dieselman wrote:
I think a good solution would be to use reflectors from another modern model of car. I think Laguna mk1 and Mk2 units would fit into XM lamp units well and possibly Volvo V40. These would alleviate the need for any lens as the reflectors are genuine complex parabolas, focussing the light without any further requirement.

Interesting thought. What about Vauxhall Calibra. They were very narrow headlights. Or Peugeot 406 or even 306.

I'd be very interested to see Rays conversion.

Re: About to take delivery

Posted: Thu Dec 28, 2017 4:15 pm
by Dieselman
I think for OEM replacement lights from Hella, these would be better than sealed beam lights. http://www.myhellalights.com/index.php/ ... dule-gen2/" onclick="window.open(this.href);return false;

The downside to all projector type lamps is the light passes through a thcick glass lens, which will always reduce output, hence I think a modern reflector lamp is a better idea, as all teh light is reflected forwards.

Re: About to take delivery

Posted: Thu Dec 28, 2017 5:11 pm
by White Exec
The Hella units I suggested above are not sealed beam units, but metal reflector/glass front/H4 units designed to replace sealed beam with much more efficient halogen. I used the round versions numerous times to replace OE 7" and 5.75" sealed beam on Rover P6, Dolomite, 1300 and Mini. Output and coverage was first class on both beams.

Re: About to take delivery

Posted: Thu Dec 28, 2017 5:40 pm
by djg
Those 90 mm modules are really nice, there are even versions without the high beam. I never disassembled our headlamps (having the benefit of Mk2 and LHD, I never really needed to do so) but those of you who did, is something like this feasible? Do these come to replace the usual units from behind, fitting-wise?

Re: About to take delivery

Posted: Thu Dec 28, 2017 6:31 pm
by xmexclusive
The XM dip reflector is a separate part, it screws in with 4 screws.
Mounting holes are 150mm lateral by 65mm vertical.
That Hella unit only specifies the lateral fixing holes at 143mm.
I estimated the vertical fixing holes at 72mm apart vertically.
The opening for the XM dip front reflector is 150 lateral by 70mm vertical.
The Hella unit will be a very tight fit vertically in the XM outer case probably preventing beam adjustment.

John