I've noticed that the headlights on my car don't sit quite as low in the parked (off) position as other S4's. the aft edges actually stick up above the fender surface about 3/8". when i turn them on they'll dip down (about to the point that they should be at to begin with) before coming up. they do "the dip" when turning off too. this is from the motor crank arm over-centering in the parked position and starting to drive back up on the other side (towards the radiator).
can i remove the nut and adjust the crank arm (counter-clockwise looking at the crank) to the lowest point, (it's splined like a wiper shaft) centered position?
if i do, it will over-center in the up (on) position. how will this effect the physical stops of the headlights themselves? i can already see some deflection of the cross-shaft when the lights come up. don't want to break anything.
if the motor shaft turns while adjusting the crank arm, do the stops change? or will it always stop in the same place?
can the headlight motor be run with the attach rod removed? are the stops internal to the motor like a wiper motor? or does the system look at the actual headlight position? i don't want to drive the crank arm thru the oil cooler lines on the radiator if i don't have to.
David R. Hendrickson
Yes, the arm can be adjusted on the motor. It should turn 180 degrees
down and back, there are up and down stops on the lights, so they can't come
too far up and the motor isn't holding them when they are down. The motor
position (on my 84)is adjustable with 3 small bolts, so you should be able
to adjust it to relieve the pressure and take out the deflection on the
cross arm. The stops are inside the motor, with the arm off the motor
should still only turn 180 degrees. I think on your year the wiring is
different, but the basic motor/linkage is the same.
It dos not sound like a motor adjustment. The arm on the spline of the motor is not in the correct position.
Put the lights in the off position
Disconnect the battery
Put a thin piece of plywood in front of the radiator
Loosen the nut on the motor that holds the shaft
Pry the shaft loose from the motor with a big screwdriver
Let the lights slip down to the correct lowered position
Re-tighten the nut on the motor
Double check to make sure both C clips are on the arm connecting the motor to the head light bar.
Remove the plywood
Reconnect the battery.
The tip off here is that the headlights are dipping to the correct position when they get turned on. The cut off of the reed switch in the motor is telling the motor to stop at the bottom of its swing, but the arm on the motor has not reached the bottom of the swing. So when the motor is first activated it first moves through the bottom of the swing and then pushes the headlights up. They are probably missing the top of the swing as well. I suspect that when the headlights are turned off they go up just a little before retracting. This would cause the headlights to point a little high and also be a little shaky, as they are not hitting their stops on the top.
If you use the three bolts to slide the motors orientation then it will bind with the stops on the way down and the headlights will not reach the full up position thus pointing even higher.
Good luck and be careful of that radiator
Adjusting H4 Headlights
From: Juha Vane Vane@compuserve.com
>1. The Hella spec calls for the upper horizontal cut-off of the beam to >be 100 mm (4") below the height (center of lamp to ground) of the >headlight. This is pretty low for a Porsche. Anyone using something >different?
I think what they mean; the 100mm is below the center height of lamp when car is backed up 10m.
An easy way to adjust the lights is following;
A. Park car on level surface lights on close to a wall.
B. Mark the corner of horizontal and upward slope of light beam on the wall. Car is as close as possible to wall.
C. Back car straight for about 5m (16,4ft)
D. The corner of projected light should be now about 5cm (2in)lower than the mark when car against the wall. Rule of thumb, 1cm per 1m should light point down.
>2. From the center of the each headlight projection, the upper cut-off >slopes up to the right at a 30 degree angle. For the motorcycle, there >is no confusion that this is centered. With the car, 10 m from a wall, >I could adjust it so I would see each headlight projection side-by-side >(as would be the case if two motorcycles were projecting against the >wall. Or, I could "toe in" the headlights so I would see the two >headlight images superimposed on one another, creating one brighter >image centered between the car's headlights. Does anyone have any >suggestions?
If You followed above instructions, You create an asymmetric beam of light, the beam is longer on your lane than on the oncoming lane. Remember that for to me unknown reasons US cars use symmetric headlight that give a blob of light in front and Euro use asymmetric that give a longer beam in front and a shorter one on oncoming lane. Do not toe in or out the light, the light slope up should stay in same vertical place when You back up the car, straight and level surface.
>Details, details. I guess I couldn't be happy with spending only $85 to >improve the lighting by 90%. Now, I'll spend 2 weeks obsessing about >the adjustment trying to get the last 10%. Does anyone else get accused >of being a compulsive-obsessive?...... I thought so.
Driving in a country with most roads are 2-lane it is quite important to have the lights adjusted correctly. Lot of cars have the nose full of lights and you go and blind them with your lights and they return with a couple hundred W. Surely You noticed that in US when driving in traffic, You have to adjust rear mirror as the lights from behind blind You, not so in Europe because of asymmetric lights.
If this sound confusing, send me a note and I try to clarify my wording.
Juha Vane Vane@compuserve.com
Wiring to the electrical headlight servo's. US models are not equipped with the euro style adjustment feature left of the driver seat.
the height adjust motor in the later 928's works like this:
The system works more or less like a normal servo motor:
a voltage is taken from the height adjust switch, basically splitting the voltage in 3 different levels, and feeds that to the height adjust actuator assembly. A motor in the headlight assembly works as the actuator. The motor moves an arm forward or backward, and an integrated potentiometer takes reading of the current position. A comparator in the electronics compares the setting with the actual position and adjusts by running the setting motor in either direction.
Sudden humming of the setting motor might be caused by contact issues on the potentiometer which cause the servo to get wrong feedback and adjusts accordingly. Some contact cleaner might help here although bad wear or oxidation will not be completely solved.