2nd Gen Headlight Pin Replacement (Page 1/6)
Fierology MAY 22, 08:05 PM
*Alternative headlight pin material?*

What is the material that the headlight gear pins are made of like? Mine have deteriorated and need replacement, but the pins Rodney and TFS sell look little different than slices of a rod of polyurethane-like plastic. Rodney's are made of delrin. Delrin is supposed to be a hard plastic, and it's properties sound similar to hard polyurethane. How much shock are they supposed to absorb? As easy as they are to replace, I wouldn't mind using any sort of semi-hard wood or plastic dowl as I know that will technically work, but I presume the pins are intended to absorb shock and thus protect the gears from stripping. Does anyone know just how hard they are? Can you depress them with a fingernail?

$12 dollars (that's including shipping) isn't a ton of money, but those parts do not look to be worth that much.

Thanks,
Michael
lateFormula MAY 23, 06:25 AM
The pins are not there to absorb shock, they act as a clutch between the gear and the shaft. They are very rigid and even though other materials might work, do you really want to have to rebuild the headlights a second time when you discover that the material you used does not provide the right traction between the gear and the output shaft?
theogre MAY 23, 11:15 AM

quote
Originally posted by lateFormula:
The pins are not there to absorb shock, they act as a clutch between the gear and the shaft. They are very rigid and even though other materials might work, do you really want to have to rebuild the headlights a second time when you discover that the material you used does not provide the right traction between the gear and the output shaft?


Sorry but the pins do absorb shock etc.
The pins are also a mechanical "fuse," called a Shear Pin, that breaks before other parts will fail. And You want the pins to fail when the module is dieing. You could find fried, even melted, motors from the dead module.

Shear pins/bolts/keys are a balancing act...
Too soft and pins will fail, likely often.
Too hard and more expensive parts will fail, like the gear or the output shaft with the aluminum hub. Especially when Module have problems.

Two common examples:
Some of you have "broken the key" on the flywheel on small gas engines, like when the lawnmower blade hits one too many rocks.
Many new snowblowers have plastic shear pins that breaks when the auger hits anything.

GM design the pins a bit soft that will fail in normal use over time...
Many using Delrin and other harder materials can cause problems too, like some here have striped Aluminum hub on the output shaft. (Use PFF search)

I got Delrin pins before I found out the pins are "shear" parts... maybe Delrin is too hard.

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Fierology JUN 01, 12:25 PM
BUMP

Thanks Ogre. Do you have any ideas? I imagine standard rubber rod would be too soft. Maybe a polyurethane material like is used in prothane suspension would work.

Anyone else?

-Michael
theogre JUN 01, 02:14 PM
Too soft is a pain but too hard is a bigger headache, even a nightmare.

To expand Example above: Replacing a shear key w/ a steel key (And many people do just that) in a lawnmower's flywheel then can cause the crankshaft to fail the next time you hit a big rock.

Some Rubber, Polyurethane, and others plastic/nylon could work. Problem is they have thousands/millions of formals.

To find a good one would help if we had old "pins" specs. No-one I know have that info.
To find a better one... You likely need a intact pins, and even a good motor and module etc, and shop to analyze the part and the load the part will see. That cost $...
lateFormula JUN 01, 02:41 PM
With all due respect Ogre, those pins act as a clutch. There is no mechanism by which those pins can "shear", unless they completely break down and turn to dust which is what they naturally do over time. Next time you need to rebuild one of these headlight motors, buy a set of Rodney's pins, and before you install them, grind 1mm off of their length. Reassemble the motor and you will find that the motor cannot lift the headlight assembly because the large gear cannot transmit it's rotational energy to the steel plate that is fastened to the output shaft. Those pins act as a clutch and will provide slippage if the motor is overloaded. The headlight drive assembly of large gear, delrin/nylon pins, and output shaft are controlled to have a specific spacing (preload) between the components by the shim washers that are used in the housing.

[This message has been edited by lateFormula (edited 06-01-2013).]

Fierology JUL 05, 07:12 PM
It looks like I'm in the perfect position, then. I have one good motor and one with broken pins. I also work at a shop with a quality metal-turning lathe. I'll do my own measurements of the good motor's pins and see if I want to try turning my own material. Thanks.

Some possibilities pre-analysis:
-polyurethane
-hdpe (high-density polyethylene)

-Michael
2002z28ssconv JUL 06, 01:17 AM
You guys really crack me up. You must have too much time on your hands... $20 and you can have all the bushings and gaskets to do both lights and not have to worry about them for years to come..
...Or spend 5 hours (or more) screwing around trying to make something work...

If for some reason you just don't want to buy them from the previously mentioned Fiero vendors, Ecklers sells them too.
But they're $2 each too. [long whistle]

http://www.ecklerscorvette....r-set-1988-1996.html

I'd rather spend the $20 and be done with the job in under an hour.
fierosound JUL 06, 01:10 PM

quote
Originally posted by 2002z28ssconv:

I'd rather spend the $20 and be done with the job in under an hour.



Agreed! The agony some people go through "reinventing the wheel" to save a couple of dollars amazes me too.
... and in the long run, it sometimes costs more in dollars or grief. We see it over on over on PFF in almost every category.

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Fierology JUL 07, 03:24 PM
You have a point, and I would agree with you to an extent. My issue is more with the replacement material. If I understand what delrin is like, it seems to be a harder, tougher material than the original. From the design of the gear, t looks like the original material was made to compensate for something blocking the motion of the motor so that it would not strip the gears. If delrin is in fact too hard for this function, then using that material could be bad for the motors should something get in the way of them opening up, maybe even something as innocuous as ice freezing the headlight doors shut. Contrary to my original claim, I now agree that the price Rodney and TFS are charging is not, in fact, horribly high. They're providing a good service. I'm asking this question concerning proper material before I put the parts in lest the Ogre's theory is correct and it strips the gears.

All the best,
-Michael

[This message has been edited by Fierology (edited 07-07-2013).]