2003 Z4 center brake light

C

ChazLuke

Member
 Atlanta, GA USA
I posted this in an existing thread and got no response so I'm starting a new topic.

I'm replacing mine for the third time. To me it seems the brake light being spring loaded in the mounting hole allows the brake light to move around and twist vertically when the trunk is closed. This could be what is putting stress on the plastic at its top if the light is momentarily not fitting flush all around. I have a couple of ideas that may apply.

What if we ran a bead of silicone on the inside of the lamp between the trunk and the brake light? If we keep the light seated properly with less twisting there would be less stress at a single point.

Also my trunk closes hard and you have to really watch what you are doing to close it softly. Is this normal? It has to do with how much weight there is on the rear of the trunk. There are dampers on the trunk lid. What is their purpose, to stop the trunk from opening too fast or from closing too fast? If they are supposed to stop it from closing too fast, my dampers may be wore out. In that case the brake light issue may be a result of faulty dampers. Anyone know a 2003 Z4 owner that doesn't have the issue and can tell us how his dampers work?
 
Got new ones myself. They should work like the bonnet. The idea is they hold the boot up, mine is also difficult for the boot to close, there should be sufficient pressure so that if the boot is half way it’ll just pop open. If less then it should just stay wherever you leave it. Mine doesn’t close of its own accord, I’ll push it all the way down and then give it a slight little push to just latch it back.

The lights are also weak. Have you got the newer springs? They’re not so strong so will put less stress on each screw point.
 
Swap the supplied nuts for nylock and don't do them up all the way. This will reduce some of the tension on the light fitting. The boot lid shouldn't twist when you close it, but the slamming action might be causing you an issue.

Mine is a cheap Chinese copy and it needed a little bit of heat just to bend it slightly to fit totally flush. It would not surprise me if the genuine ones would benefit from this as well. I used a heat gun mounted in a vice and just warmed the plastic until it would bend a little. I then just held onto it until it had cooled and the fitting stayed in shape.
 
My struts are the same. They hold the boot open no problem. If you let it go when you are lowering it will slam shut. Would be good if they have a soft close action.

My bonnet is the opposite. I have to give it a good sharp push when it’s fully lowered.
 
Not sure where I got mine! It was a while back! I think replace the struts then see how you get on with opening and closing... this should hopefully help the brake light last longer too! Try ebay? But if in doubt stealers? Being such a small item I can't expect it to set you back too much.
 
noiseboy72 said:
Mine is a cheap Chinese copy and it needed a little bit of heat just to bend it slightly to fit totally flush. It would not surprise me if the genuine ones would benefit from this as well. I used a heat gun mounted in a vice and just warmed the plastic until it would bend a little. I then just held onto it until it had cooled and the fitting stayed in shape.
Click to expand...

Just done mine today - Chinese unit and like yours the ends don't sit into the recess correctly. I can push them in but even with the nuts so tight they close all the gaps in the spring its not quite tight enough - I guess because the bolts arn't at the end.

Its got its test on Thursday so not doing anything before then (while its working!) but will try and adjust the fit over the weekend. What did you use to heat it up? I would use a hair drier or hot water with it in place on the car but not a hot air gun. What did you use?

The Chinese shell seems to be more robust than the gen BMW. Mine had the blown LEDs but the casing shattered as I pulled (almost crow-bared!) it out.
 
I used a heat gun held in a vice pointing upwards and then slowly worked the light over this. It's made of abs, so needs about 90C to get it soft enough to bend a little. I don't think you will be able to do this while fitted to the car, as you need to over-bend it and let it relax back to the desired radius.

Mine was superglued in by a previous owner, so was a nightmare to get out.
 
Put the new oem struts on and the trunk doesn't slam any more! It actually comes close to closing and then a gentle push and it latches. Now to replace the lamp and see if the strut change fixes the tail light breaking/leaking.
 
Replaced the lamp and it seems like I won't have an issue any more. I believe the trunk slamming was the issue. No more broken 3rd tail lights!
 
ChazLuke said:
Put the new oem struts on and the trunk doesn't slam any more! It actually comes close to closing and then a gentle push and it latches. Now to replace the lamp and see if the strut change fixes the tail light breaking/leaking.
Click to expand...
If you don’t mind me asking how much were the OEM struts and where did you get them :D
 
ChazLuke said:
Replaced the lamp and it seems like I won't have an issue any more. I believe the trunk slamming was the issue. No more broken 3rd tail lights!
Click to expand...

Great to hear! :D
 
The original problem was the springs. BMW replaced them under warranty way back when. The new lights should have updated springs.
 
You must log in or register to reply here.
Back
Top Bottom