What determines the speed of the mid-year headlight motors? My right one is almost 50% slower than the left one. I reconditioned both motors, no change, then I switched armatures, again no change.
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Re: Mid-year Headlight Motors
Intersting observation Mr. Schurr!
I too rebuilt both of my headlight motors. Both buckets rotate freely...and the left side runs about 50% slower than the right.
I just figured they were possessed & left it at that...
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Re: Mid-year Headlight Motors
Ken, I assume when you stated a 50% slower rate, you are testing it in the car. What are the relative speeds on the bench? I ask this question because the suggestions for what to look for will be different.
If it was a bench test, then I think the problem could be worn armature brushes or bushings. I assume your "reconditioning" of the motors included a complete cleaning and good greasing of the two gears and the gears do not bind.
If the units were installed in the car then it could be 1) What I stated above, 2) the bushings in the buckets causing a higher drag or 3) (my #1) a low voltage across the slower motor. This low voltage could be caused be a bad connection. I say "across" the slower motor because it could be the ground side and not just the 12 volt side. Is it the right side that is slower. I only ask that because it has more wire connections than the left side.
To answer your question about what determines the speed; Theoretically: the number of windings in the stator and armature, the load and the supply voltage.
Let us know what you find. GaryCComment
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Re: Mid-year Headlight Motors
Speed of headlight open/close is determined by torque of motor(s) and rotational inertia of each HL bucket. Mass of bucket is fixed, so delta in inertia flows primarly from bearing friction.Comment
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Re: Mid-year Headlight Motors
The worm (the rolled thread on the hard steel mainshaft) eventually bends and breaks the gear teeth on the soft die cast worm gear, which causes higher friction and slows the headlight rotation speed. Suggest you remove the headlight motors and disassemble them. If new worm gears are not available, one trick is to rotate the old ones 180 degrees. The worm gear traverses an angle of about 150 degrees in operation, so if you get the old worm gear reoriented properly only fresh thread will be loaded. Be sure to clean everything thoroughly and assemble the gearboxs with a white lithium grease. Wheel bearing grease is to "gummy" for this slow speed low load gearbox.
DukeComment
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typical friction factors
It sounds like you've already checked out the end pivots on the headlight pods, and you're certain the pods rotate freely when the motors are off the car.
Some causes of friction that I've found within the motor gearbox are:
1) hardened grease
2) worn teeth on the pot metal main gear
3) too much compression of the thrust washer on the main gear.
The last problem is the toughest to fix. To determine if this is causing your motor to run slow, loosen all four hex-head screws on the gear box. Only one turn is necessary. If your motor speeds up after loosening these screws, you need to reduce the thrust washer load.
The load on the slightly conical thrust washer is determined by the thickness of the steel flat washer on the opposite side of the main gear. Typically I find .035" thick flat washers, although half this thickness is plenty to take up the slop around the main gear. Rather than hunt down thinner washers to try, you can use a belt sander and a lot of patience to thin the original.
I normally use a mixture of gray moly lube and motorcycle chain spray lube for the gear box. This should be soupy enough to slightly drip.Comment
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Re: Mid-year Headlight Motors (dates)
Ken --- Don't believe any motor or gear changes '63 thru '67. There is a stamped month/year in the cast metal gearbox, which should tell if you if your pair is original.Comment
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Re: typical friction factors
Ken,
It appears that you have performed a correct rebuild and so I think that the problem points to either what Jerry Bramlett stated about friction or what I said about the voltage. I still think that you should ensure that you are getting proper voltage right at the connectors of both motors (and the ground is good). It is important that you measure the voltage when the motors are running because even with a bad connection, you can get a good reading. It has to be under a load. Compare the voltage between the two motors. If the speed difference is 50% and the problem is the voltage, you will see a big difference when measuring the voltages (e.g., it will not be 12 volts for one and 11.7 volts for the other. It should be a few volts difference.)
I have rebuilt my motors (I also have a '63) but, I have not reinstalled them on the car yet. At the bench, prior to disassembling, I connected 12 volts. One ran very slow and the other did not even run. After rebuild (I just cleaned eveything, repack the grease and adjusted the set screw) they both ran fast in both directions. I don't know the rpm either but, they were purring. You could tell that they were not straining (sp?).
Please let me know what you find. I am curious as to how mine may work.Comment
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