Headlight levelling System

[sabrje]

I realize that the 'hydraulic' headlight levelling system on E30Ôš's is probably one of the weakest points of the car (apart form maybe the headlight cleaning system ), but if youÔš've got it its better functional than not . What I want to know is whether anybody has tried to revive it.

IÔš'd have thought that either the fluid leaks out or the moving bits get jammed. I was thinking of cleaning the tubes etc out with some sort of solvent, but then what fluid goes back in? Oil, antifreeze, brake fluid or some other specialist fluid??

I stand to be corrected or if anyone has any handy hints IÔš'm sure lots of people would be glad to hear them!!

Cheers
Richard

[cros]

Tried that. Wouldn't bother again.

Had a total of 4 car's bits. Between them I had 2 good cylinders and controllers. I used 50/50 anti freeze mix as the new fluid and cut the hoses off the slave and master ends.

The nylon hoses loose their elasticity over time and become brittle. The barbs on the slave cylinders aren't mounted in enough plastic and crack the housing meaning all the fluid escapes. The bleed ports are a one-time plug and can't be removed without cracking the port.

Slave: To get the correct pressure into the system you have to compress the spring in the slave piston (nuts & washers on the headlight control rod), then inflate he fluid bag inside with a syringe.

Master: Set the dial to the lowest setting, then inflate he fluid bag inside with a syringe.

The above was done submerged in a bucket of fluid to prevent air bubbles.

I flushed the hoses on the build car through with fresh fluid. Then I got a gas torch and heated the hose ends slightly. They then slid easily over the barbs on the cylinders. While they were still elastic I compressed them into the barb grooves to get a good seal. Then for good measure I covered the lot in self-vulcanising tape.

Immediate result: perfect functionality restored. Both beams moved in unison over the entire allowable range.

Next mornings result: the fluid pressure had escaped overnight and the system was once again dead.

Overall a complete waste of a few hours. I got an underdash kick panel without the adjuster cutout and manually set the beam height once with the slave cylinders screw adjustment.

Forget about the hydraulic adjusters or mabye look into the E34 electric ones. It's hardly a critical function anyway.

Just don't bother!

[sabrje]

So basically it wouldn't be worth my time.... I'll just have to blind other people when I've got heavy loads in the back

I'm just wondering if the fluid had been a bit more viscous it might not of leaked out. So is the standard fluid definitely water/antifreeze?

[cros]

No idea what the standard stuff was. It looked like water to me.

Antifreeze mix was just my idea of something suitable. Gave the hoses a nice orange colour too!

[Demlotcrew]

I converted mines to electric ussing the E34 motors.

Andrew

[ian332isport]

I converted mines to electric ussing the E34 motors.

Andrew

Andrew,

I did mine using Mk4 Cavalier motors, but they need to be modded slightly.

Where the E34 motors a direct fit ?

If so, it would be nice to get those GM parts removed

Ian.

[cros]

e30.de has a writeup on fitting the E34 ones.

demlot, did you make up a rig to mount a variable resisitor in place of the master cylinder for that "factory look"?

[ian332isport]

e30.de has a writeup on fitting the E34 ones.

demlot, did you make up a rig to mount a variable resisitor in place of the master cylinder for that "factory look"?

When I did mine, I totally gutted the original factory adjuster and fitted a variable resistor inside it. It looks totally original, but was a lot of work.

Ian.

[Demlotcrew]

e30.de has a writeup on fitting the E34 ones.

demlot, did you make up a rig to mount a variable resisitor in place of the master cylinder for that "factory look"?

No i used a Z3 switch which fits right next to the Hazzard/rear demister switch.

Ian i had to shorten the shaft a little, also one of the raised bits needs to sanded down a little to fit, you cant see both of the mods.

Andrew

[sabrje]

Can't do German - can anyone give me a pointer to the correct page on e30.de and a translation website???

Cheers

[cros]

When I did mine, I totally gutted the original factory adjuster and fitted a variable resistor inside it. It looks totally original, but was a lot of work.

Can you give me any pointers on doing this?

Must I crack the hydraulic master open?

A single wire through the bulkhead, and tap power from the dip beam?

[ian332isport]

When I did mine, I totally gutted the original factory adjuster and fitted a variable resistor inside it. It looks totally original, but was a lot of work.

Can you give me any pointers on doing this?

Must I crack the hydraulic master open?

A single wire through the bulkhead, and tap power from the dip beam?

Unless you're a bit handy with electronics, I would mount the E34 switch somewhere.

When I modded the original E30 adjuster, I removed the back, and took all the guts out. I then had to make a mounting plate for a rotary potentiometer to mount on. I also had to fit a small trimmer pot to fine tune the output voltage range. This was needed to set the main pot to give the correct height on the lights.

Once this is all done, you need to run three wires from the contoller down to the lights where you can pick up the power and GND, and also hook up the motors.

Ian.

[Davenotouring]

Awesome knowledge/skills. Wish I could do all that!

[A1BMW325iSport]

if you want the original e30 system the dealers can order you one for about 36quid ;)

Matt.

[cros]

OK - a little how to:

The old hydraulic body opens easily. Take off the arrow pointer on the front and undo the screw. The knob and screw piston come out the front (watch out for the bearing on the spring). Use a hacksaw to cut a slit in each side of the base and take it off with a screwdriver.

You could reuse the plastic backing if you don't crack it and can find a pot with a long enough shaft. Mine cracked so I had to make do:



It didn't turn out as cleanly as I'd hoped, but it'll look 'factory' from the outside!

I carved a second bearing notch so that both rotataional extremes are locked.

The E34 controller gives ~12v in the unloaded (0) and ~7-8v in the loaded (2) position. The top 4.7k pot is the main cab adjustment, the bottom pot is a one-time adjustment to lazily set the lower limit (~7v). All the values are approx and ratioed. The 330ohm resistor is a current limiter (for safety?) like the E34 controller.



Motor colours:
Grey/Black = 12v
Brown = gnd
Black = adjust

Should get around to fitting it soon...

[Demlotcrew]

Nice one mate!

Im now looking for a Kick pannel that doesnt have this cut out.

Andrew

[Brianmoooore]

Cros - How did you arrive at those resistor values? I measured the controller I removed from a 91 E34 and get a constant 950 ohms between 1 and 3, varying between 394 to 1338 ohms between 1 and 2, and 1340 to 394 ohms between 2 and 3.
This equates to a 950 ohm pot across the 12V supply, with a 394 ohm resistor connected to the slider.
The series resistor is similar to your value, but the resistors across the supply differ by a factor of about fifeteen.

[cros]

Sure, I got much the same from the E34 controller...

The 12v to gnd resistors are just a voltage divider. Given a high impedence load, the only thing that matters is the ratio (within reason).

I was just using the parts I had lying around, but you'll probably find that 1k to 20k pots are easiest to get a hold of.

In the end I used 4.7k and a 20k pots. Made a loom and put the lot on the car today - at the moment the 20k pot is trimmed too give adjustment from Vbat to ~6v, which gives a rediculous range of adjustment (down to a 2m reach of light!). On the beam setter this corresponds to a 40mm drop from on the target. I reckon it should be trimmed to 8 or 9 volts as BMW intended ;)

You have to shave one of the lobes on the motors, replace the rubber washer with something like fabric (thin compressable shim) and saw about 10mm off the adjuster rod (at the screw and not the ball joint end!). To mount the RHS motor in the same way as the LHS, you'll also have to temorarily remove the motor mount from the lamp mount (two pegged expansion clips)

It's all fresh in my mind at the mo. Any questions, just ask...

[Brianmoooore]

If yours works OK, then your divider must be able to supply enough current to work the motors. Haven't actually powered the motors yet to see what sort of current they take. Was trying to make sure there wasn't a low current and high current version of the motors around.
Thanks for the fitting tips. I haven't tried to fit them to a headlamp unit yet - just noted that it has been done, and that the business ends of the hydraulic and electric units LOOK sinmilar.

[cros]

The two motors drew less than 1mA adjust on my setup (I think!). It's enough to cause a small V drop on my high R setup; when one motor is unplugged the other adjusts fractionally.

I imagine the adjuster input goes into an op-amp inside the motor, with the other input coming from a voltage divider pot on the screw track.

If you need more convincing, open the E34 controller (watch for the spring loaded '0' bearing). The wiper arms are tiny!

[cros]

Eating my own post, it looks like 4.7k is technically too big.

Rather than being a voltage divider, the majority of the drop comes from the I2R drop across the 4.7k pot.

Not really an issue though as the required effect is there. Just that the adjustment is:
12v to (7.5v to 0v trim)
instead of:
12v to (12v to 0v trim)

You decide if this is an issue for you.

[Brianmoooore]

Just been trying the motors out on the bench, using the original E34 adjuster and my bench power supply.
At 12V I'm getting a static current of about 30mA, and a total current when the motors are adjusting of about 230mA. i.e. about 100mA per motor.
The system seems to work happily down to about 7V, although a lot slower.

[cros]

30mA - 230mA power supply current, but < 1mA sink into the adjustment pin, right?
When you say slow, does the noise of the motor change or is there different gearing?

[Brianmoooore]

Didn't measure the black wire current. The 30mA - 230mA readings came from the bench power supply's built in meters.
Can't be a lot of current on the black wire, since there's a 400 ohm series resistance.
At 7 volts the motors run slower and have less torque.