Suspension Changes and Headlight Aiming Problems

[JAJ]

When I installed my KW ClubSport suspension, I was very careful to make sure my headlight aim sensors remained undamaged and were reconnected every time I had it apart. At the rear, you have to drop the rear lower control arm to adjust the ride height, so it was apart four or five times by the time I was happy with it.

I have to admit that I've always been baffled by the posts about "my headlights are out of alignment after a suspension change". The whole point of the aim sensors is to keep the headlights at exactly the right angle, regardless of the front or rear ride heights. The system uses two sensors, a computer and a servomotor in each headlight to make sure that if either end is unusually high or low, the headlight aim is correct. It just didn't make sense to me how, if the sensors were undamaged, it could go wrong.

That was before MY headlight aim went wrong after I installed my Clubsport suspension. I did it all perfectly, and yet there the headlights were, fixed in one position, refusing to adjust. Luckily, the ride height was so close to normal that it was ok, at least for a few days.

When I had the next chance to dig into it, I jacked the car up and messed with the sensors a bit. Now, when I had an aim problem on my E39 M5, I learned a lot about the sensor system. For instance, it's fast. You can unscrew the sensor rod, move the arm with your fingers and the headlights will respond immediately, moving up and down as you move the arm. So, I put the car on the lift, pulled the left front wheel, unscrewed the sensor rod and started moving the front sensor arm. No dice. Headlights were staring straight ahead, not moving. I figured that whatever was wrong must be wrong somewhere else.

Here's how the front sensor is supposed to look when it's connected properly to the rod assembly:



As you can see, the rod is actually bent from the factory and there's only one way to put it together (that's important).

Well, if the front sensor wasn't producing any adjustment, how about the rear one? I pulled the left rear wheel off and took a look (the sensor is immediately inboard of the spring). Sure enough, the rods and ball joints were connected but something didn't look right.

After I studied it for a while, I realized that it was possible to put it together two ways - the wrong way and the right way, and mine was wrong!

Here's a picture of the the right way to put it together:



In the wrong way, you position the sensor arm (at the top, plastic with cross ribs) hanging straight down, so the H-shaped arm that links it to the bracket at the bottom reaches sideways instead of up and down. In that "wrong" position, there's no stress on the sensor (it doesn't get broken) but it doesn't work either. Hence the system locks the headlights in one place and waits for someone to repair it.

When I undid the sensor arm and moved it up (to where you see it in the picture) the headlights started to move as I moved it. System function was fully restored, and there was no need to adjust the manual headlight adjusters.

So, if you're one of the guys who've had to do a manual headlight adjustment after a spring or suspension install, check the rods and arms on the rear headlight sensor. If they don't look like the picture, get it checked out by a qualified mechanic.

[By the way, if you look at the photos on an iPad, they're the wrong way up. On my PC and Mac browsers, Chrome, IE, Safari and Firefox, they work fine. On the iPad Safari browser, they revert to the original camera orientation, which was determined by getting the lens aimed at the sensors for the pictures. The front picture was taken upside down and the rear was taken sideways. If they look strange, switch browsers.]

[aus]

Where the hell is the rear one? Obviously somewhere close to the spring, but is it in front of the spring or behind it?
Thanks for the pics.

[sparkyg]

Great catch JAJ, always a positive contribution.

[rzm3]

Originally Posted by aus

Where the hell is the rear one? Obviously somewhere close to the spring, but is it in frong of the spring or behind it?

It's to the inside of the spring.

[AMPowerJ]

Awesome catch. I think mine is incorrect now that I look at it. So since I manually adjusted my headlights if I put the sensor back in the correct position I guess my headlights will self-adjust back to an incorrect position and I would need to adjust them again I suppose.

[AMPowerJ]

I fixed my rear adjuster ... I had to raise the headlights a number of turns back to what I suppose is close to the original factory position. I remember lowering the headlights quite a bit when I first installed my springs so this makes perfect sense. I also opened the trunk and pushed down on the rear to see if the headlights adjusted and they seemed to. Thanks for the great info.

I believe many of us are driving around with our self-adjusting headlights crippled based on re-installation error. Nice to have this functioning again as it was intended.

[aus]

Originally Posted by rldzhao

It's to the inside of the spring.

Thanks, and thank OP for the info.

[elm3]

This is awesome, I fixed mine the way JaJ did his and it will self adjust now. Where before, it was too high and I was blinding people. I was always wondering why is it that the head lights were not adjusting to the position of the suspension. I'm glad that I did not manually adjust the head lights...

[aus]

This should really be a sticky since it's almost always done wrong.

[808MGuy]

I just fixed mine this weekend too and now its back to normal. Good find by the OP. I'm glad I didn't attempt to manually adjust the headlights too.

[elp_jc]

I haven't touched my car, but will check that headlights adjust properly. Was wondering if the 'arms' pop out easily, or what's the trick to remove them?

And for those who already adjusted their headlights, you should do this fix and readjust your headlights since you have no headlight leveling now. Good catch OP . The only question left is what the hell is the front arm for . This is the first car I own that has two adjusting arms; there's always just one at the rear. And when you moved it, it didn't respond; Did you try after fixing the rear arm??? Wonder if it responds now . Later.

[808MGuy]

Originally Posted by elp_jc

I haven't touched my car, but will check that headlights adjust properly. Was wondering if the 'arms' pop out easily, or what's the trick to remove them?

And for those who already adjusted their headlights, you should do this fix and readjust your headlights since you have no headlight leveling now. Good catch OP . The only question left is what the hell is the front arm for . This is the first car I own that has two adjusting arms; there's always just one at the rear. And when you moved it, it didn't respond; Did you try after fixing the rear arm??? Wonder if it responds now . Later.

My Audi had the same setup. One in the front and one in the back. To adjust it, I just loosened the 10mm bolt that holds the leveling arm bracket to the lower camber arm. Once that is removed, you can move the arm freely. Then just adjust it so that the assembly is as shown in the OPs picture and then reinstall the bolt. Took me about 30 min to jack the car up, remove the wheel, make the adjustments and then put the car back. That included taking the front wheel off too so I could check the sensor connection there. As the OP said, the front can only be done one way so it would be hard to screw it up without breaking it.

[elp_jc]

Originally Posted by 808MGuy

My Audi had the same setup.

Must be a German car thing then.

Thanks for the tips, but if arm was put wrong, it had to be removed first, so I was curious how easy it pops out. And remember if you loosen the nut, you'd have to mark the original position, or adjustment would be off. That's why maybe installers just pop the arms out, then put them back on, apparently backwards. Take care.

[808MGuy]

Originally Posted by elp_jc

Must be a German car thing then.

Thanks for the tips, but if arm was put wrong, it had to be removed first, so I was curious how easy it pops out. And remember if you loosen the nut, you'd have to mark the original position, or adjustment would be off. That's why maybe installers just pop the arms out, then put them back on, apparently backwards. Take care.

Never heard of anyone just popping the arms off. Even the suspension DIY on this forum shows the 10mm bolt being removed and then reinstalled.

[JAJ]

Originally Posted by elp_jc

Must be a German car thing then.

Thanks for the tips, but if arm was put wrong, it had to be removed first, so I was curious how easy it pops out. And remember if you loosen the nut, you'd have to mark the original position, or adjustment would be off. That's why maybe installers just pop the arms out, then put them back on, apparently backwards. Take care.

The swing-arm doesn't actually come off the sensor - it's permanently attached. The arms are attached by a rod (two rods at the rear) that end in a small ball joint attached to the suspension member. There's a small screw (10mm hex nut) that comes off to disconnect the rods from the suspension members. It doesn't "adjust" in any sense - it's either attached properly and it works, or it's wrong and it doesn't.

For everyone who said "thanks" - "You're welcome!"

[elp_jc]

Originally Posted by 808MGuy

Never heard of anyone just popping the arms off. Even the suspension DIY on this forum shows the 10mm bolt being removed and then reinstalled.

Makes sense, but how the heck can it be reinstalled backwards then ? The whole purpose of this thread was to alert owners that arm could be 'reversed'. And that can't happen without removing it, no???? Just trying to make sense of all the info here.

[808MGuy]

Originally Posted by elp_jc

Makes sense, but how the heck can it be reinstalled backwards then ? The whole purpose of this thread was to alert owners that arm could be 'reversed'. And that can't happen without removing it, no???? Just trying to make sense of all the info here.

If you actually look at it you'll see it. When the whole assembly is bolted to the camber arm, the sensor arm can be oriented in two different ways. One is the right way and one is the wrong way. I wouldn't really call it backwards. When installed correctly, the sensor arm should be near horizontal and the connecting rods to the bracket should be vertical. The whole assembly should look like a backwards 7. When installed incorrectly, the rods will be horizontal and the sensor arm vertical making the assembly look like an "L". Two different ways of getting from point A to point B.

[JAJ]

Originally Posted by elp_jc

Makes sense, but how the heck can it be reinstalled backwards then ? The whole purpose of this thread was to alert owners that arm could be 'reversed'. And that can't happen without removing it, no???? Just trying to make sense of all the info here.

Think about it in the context of your right leg, where your hip is the sensor: "right" is when you're sitting in a chair and your foot is on the floor. Your knee is bent in a comfortable way, and if your foot moves up and down, your hip joint pivots. Now imagine "wrong". Your your upper leg is pointed straight down, which doesn't bother your hip. To attain that position without moving your foot, your knee is bent backward 90 degrees and your calf is parallel to the floor. Now, even though your foot is the same distance from your hip as it was in the other position, your hip joint doesn't pivot if your foot moves up and down. Just like the sensor, the position doesn't damage your hip joint, but the position measuring process is disabled. As are you, unless (like your BMW) you have a very flexible ball-joint in your knee.

To respond to your "how does it get reversed?" question, the issue is that to drop the lower control arm for a suspension or spring change, you have to undo the ball joint that attaches the sensor connecting rod to the control arm you're about to drop (your "foot" in the example above). Otherwise you'll damage the sensor by ripping it's arm off. It's just a little 10mm nut to take off. When you reassemble it, the arm (your thigh) naturally hangs straight down (gravity wins!) and it's easy to pop the ball joint back into the hole and put on the nut.

That's why it's easy to re-assemble it so the sensor doesn't work.

[Bob MG]

You are a champion!!

I have KWV3 and my headlights were always blinding people even with low beam.

Checked it today and sure enough was in the incorrect possition

[montreal red]

thanks so much for posting this. i installed KWs a while back and my headlights were point way too high and blinding people whenever i am on two way streets. there tons of people who were flashing me because my headlights were blinding them. i finally checked my rear light sensor and it was indeed installed the wrong way. i corrected it and now my headlights are perfect!

thanks so much!

[wuzupfoo]

ahh.. im glad I ran into this thread, I just got my car lowered and was noticing street signs illuminated that typically werent before. I thought my lights were pointing up but this seals it.

Thanks OP for pointing this out!

[hhlou520]

After repositioning the arms and the rods of the sensors, the headlights, again, work as intended.

For additional reference, attached are a couple of pics (front & rear) with the RIGHT way to go.

Thanks again for the post - and for all those comments in the other posts pointing over to this post!