popping (literally) headlights (Page 1/1)
1985 Fiero GT DEC 29, 12:07 AM
i have a 1985 Fiero, gen 1 headlights, when i lower the headlights, the motor runs for a split second, then there is a pop/clunk (that i can occasionally feel inside the cabin), then the headlight goes down like it is supposed to. It is not caused by the headlight system getting hung up on anything, it seems to be just the geometry of the lowering mechanism and the amount of free play in the gear assembly, as the motor can run for a split second either direction without actually moving the headlight, and because of the geometry, the mechanism somewhat locks in position when in the up position, so the motor will run until it has reached the end of free play, then once the mechanism actually starts to move, it is accelerated rapidly by the weight of the headlights and doors. because at this point the headlight is in free fall it then rapidly moves down until it has "caught up" with the motor, which causes the clunk. in short free play in the system seems to cause a disconcerting clunk/pop when i lower my headlights. I have had this a while, and noticed 2 other Fieros occasionally have it, not as bad as mine, but present, how common is this, is there a "fix" or is it just a fiero feature.
theogre DEC 29, 01:07 AM
Likely the motors are iffy & runs until gears & output shaft finally moves. Likely will fail totally soon.

Gen1 motors spin maybe a fraction of 1 rev just to climb up/down the gear to activate the limit switches but you likely won't see it happen.
If "rubber" bumpers are bad then might see it happen because more distance for motor to reverse loading the rest of it. Bumper bad then rest of gears soon will fail.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

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olejoedad DEC 29, 06:31 AM
What Ogre posted is true.

Additionally, does this happen with the front hood open?

If it doesn't, try readjusting the bracket that holds the headlight assembly to the space frame.
1985 Fiero GT DEC 29, 08:22 AM
It doesn't make the sound, as the weight of the headlight doors contribute to that, but they do lurch when the hood is open, I will try to get a video of it today

[This message has been edited by 1985 Fiero GT (edited 12-29-2023).]

1985 Fiero GT DEC 29, 08:50 AM
Ok, got the videos

Mechanism view:https://youtu.be/qcn7frvOwTw

Hood closed:https://youtu.be/KUBBwOYdmiE

So what exactly would be "broken" here, and why would it cause that consistent free play, while not having any slip, or grinding noise, etc. at all, and what would be the procedure to fix it.
Thanks.

[This message has been edited by 1985 Fiero GT (edited 12-29-2023).]

theogre DEC 29, 12:19 PM
Large Gear(s) &/or bumpers are bad to get that much slack on the output shaft.

If nothing is wrong but bad bumpers, can replace the bumpers "easy & cheap."
But when other things break/broke... Fix/"rebuilding" can cost a lot of time & money.

Is why many switch to Gen2 & get new Gen2 Motors too.
Even if new Gen2 motor break the pins/dowels for any reason can fix w/ Dorman part w/ minor sanding of them. That way Motors still have the "weak" pins when doors are jammed again.
1985 Fiero GT DEC 29, 01:11 PM
Oh ok, I was looking at some pictures on Rodney's site, and now I understand, originally I thought the bumpers acted like a kind of clutch, braking and fully disengaging the motor, now I see they are more of a shock absorber, and I likely don't have them anymore haha, thank you for the quick resolution, $8 per headlight from the Fiero store is not bad!
buddycraigg DEC 30, 07:23 PM
yep
green bumpers are gone.
the motors could last for years like that.
1985 Fiero GT DEC 30, 07:45 PM
Yeah, they likely have, both have already had the brushes fall off, I fixed that with Rodney's kit, so electrically they are mint, now I'll be fixing them mechanically too haha