C2 Headlight Motor Diagnosis, Test, and Repair Process

[Richard M.]

Re: C2 Headlight Motor Diagnosis, Test, and Repair Process

I too have had to mill down some thicker replacement gears to match originals. Overall, the speed differential on all the motors I've worked on translates probably to no more than a second difference, and that does not bother me. As you mentioned, there may likely be differences between the field windings that effect motor speed. I liked your idea of fabricating that replacement felt washer, very cleaver.

Dan I've found that different armatures affect speed as well. That was part of my experiment long ago. I have one marked "SLOW". Once I discovered that those are a factor too, I figured the combinations needed would outweigh the effort and told me to give up the attempt.

I can't recall but I think the armature is also used for GM power window motors. If so, they likely made tens(or hundreds) of thousands and likely didn't have a exact science when winding them. When I look at various armatures the winding wire ends are different where twisted together. All done by hand it appears.

Rich

[Richard M.]

Re: C2 Headlight Motor Diagnosis, Test, and Repair Process

Earlier today I took my spare Headlight motor assembly and did some tests and moving the infamous steel gear washer around in the gearcase. Here are 2 videos. They're long, around 5 minutes each.

I also took more measurements of my gear collection at different places and some calculations to show what the tolerances are inside the gearcase to accommodate the gears. I will be adding that information to the thread when I get time.

Videos...

This one has the steel gear washer in the "GM illustrated" location. It's a Dog.

This has the steel washer behind the conical washer, opposite of the "GM illustrated" location. It's a Cheetah.

If anyone here has direct experience about this oddity and has input I'd appreciate all feedback, any flavor............
........ Joe R. @ JRP ??? Brian T. @ CS_of_MW ??? Ernie @ Wilcox ??? Jay M. @ JM ??? Others ????

Thanks,
Rich

[Patrick B.]

Re: C2 Headlight Motor Diagnosis, Test, and Repair Process

I would bet that the total thickness of the washer pair is less when the flat washer is nested into the concave end of the concave washer. A thinner flat washer or a thinner gear would probably allow the washers to be placed in the factory sequence.

[Richard M.]

Re: C2 Headlight Motor Diagnosis, Test, and Repair Process

I would bet that the total thickness of the washer pair is less when the flat washer is nested into the concave end of the concave washer. A thinner flat washer or a thinner gear would probably allow the washers to be placed in the factory sequence.

Yes Patrick and that's the issue that I'm trying to resolve, but using factory parts though. With both flat and conical washers in the as illustrated factory positions there lies the problem. I went through the measurements and came up with a very tight tolerance for the pieces to fit...the factory pieces with no mods or shaving of gears. Next post will have the details of my research.

Rich

[Richard M.]

Re: C2 Headlight Motor Diagnosis, Test, and Repair Process

More data. I know this may be hard to follow but if you study it for a while it should make sense. It's basically adding up some pieces to see if they fit inside a box.

I re-measured all of the gears I have for the thickness of just the gear portion(Measurement B below). That plus the washers is the important number.
Axle(large OD end that has the slot for the bucket keyed shaft) to conical washer face(Measurement A) isn't a good reference for finding the tolerance because the axle end floats in the gearbox cover.

The range of B of my sample gears is 0.600" to 0.608". These are originals(#'s 1,3,4,5) and a repro(#2). Notice that one is the thickest of my samples and note the 4 circular dimples likely a sign of a repro.

References below. Measurement B is the critical one. That thickness plus the 3 washers is the total gear assembly inside the gearbox. I compare that measurement to the internal gearbox depth measurements I took(earlier diagrams) to decipher the actual tolerance of space allowed for the gear assembly.

Here are the gear thickness numbers.
HL_Motor_WasherTests001.jpgHL_Motor_WasherTests002.jpg

Here are the gearbox measurement diagrams again.
HL_Motor_WasherTests003.jpg


I corrected the 0.0344" depth typo from the earlier diagram. It's 0.344" as I expected
HL_Motor_WasherTests004.jpg


Here are my calculations to find the space allowed in the gearbox for the gear/washers assembly.


Space for gear and 3 washers = apx 1.148" (Cover depth to bronze bushing perimeter, average of the 4 sides)
+ recess(for gear plastic washer) = apx 0.030"
-----------------------------------------------------------
Depth allowance for gear thickness = 1.178" (+-)
- Thickness of the 3 washers combined = 0.215"
-----------------------------------------------------------
= 0.963"
- Gearcase Cover hole depth = 0.344"
-----------------------------------------------------------
Total gearbox depth allowance = 0.619"


Gear thickness of samples is 0.600" to 0.608". Subtract these from the above 0.619" depth allowance.


This leaves a tolerance of 0.011" to 0.019".

This is a very tight tolerance for a simple function. Now add grease between the steel washer and gear, and also between both surfaces of the plastic washer to the gear face and the cover recess. This will add additional thickness to the gear assembly, maybe a few thousandths? This exacerbates the problem.

Still head scratching,
Rich

[Richard M.]

Re: C2 Headlight Motor Diagnosis, Test, and Repair Process

Update...

I have two possible sources for getting some original engineering data on these motors. Eagerly anticipating some answers.

In the meantime, I have acquired the original internal gear from the 1963 motor used as the subject of this work. The motor gearcase was dated 11 62, so it is a very early unit. Here are some photos of the gear. It was replaced before I got the motor. The owner graciously sent it to me to help me with my analysis.

As you can see it is damaged and the teeth have been deformed from motor torque. This is very common with these soft cast gears being driven by a hardened worm gear inside the gearcase. When one motor waits for the other, this is the result over time. Often times one can just turn the gear 180* to get a new surface as the gear only rotates about that much for the bucket up/down limit.
Jerry_HL_Motor_0073.jpg

In this one, I think when that happened, someone opened the gearbox and turned this gear 180* to get fresh teeth. Eventually that side wore out too. One side is chewed off completely. I suspect someone leaned on the rollup/down switch waiting for the other motor to reach limit, a lot. I've not seen one this far gone before.
Jerry_HL_Motor_0074.jpg

Since this was likely the original gear manufactured in 1962 this adds to the samples I've taken measurements of while researching the "mystery washer" configuration. It's width is 0.608". This is right around the number I see on the repro gear I have. Other originals in my collection are less, albeit only by a few thousandths.
Jerry_HL_Motor_0072.jpgJerry_HL_Motor_0070.jpgJerry_HL_Motor_0071.jpg

to be continued.....
Rich
====

[Dan B.]

Re: C2 Headlight Motor Diagnosis, Test, and Repair Process

Great thread Rich, with the usual informative pictures.

I wanted to add my own recent experience (to augment) with a slower headlight motor (about 3 seconds) vs. the other side. Both motors had been previously rebuilt I was told and the task was to remove and analyze the slow motor.

After inspection the gear side looked good, but I discovered the motor side bearing had been worked on by Bubba. There was no retaining spring present at all, and the bearing had been placed back in the cavity imbedded in silicon to hold it. The motor actually spun pretty good but by fixing the bearing in place it could not self align and thus produced DRAG. So I removed the spot welded retainer and installed a new bearing, spring retainer and top plate. I elected to spot weld everything (not that there is anything wrong with the JB weld and Rich's write up) just because I wanted to. The upshot of the new bearing being able to float and self align resulted in the slower motor now being a fraction of a second faster than the other one now. I can live with that and called it a day. Dan
Credit to LICS who supplied all the parts the very next day !

Here are some photos of my process:

[Richard M.]

Re: C2 Headlight Motor Diagnosis, Test, and Repair Process

Great rework Dan. Nice welds too.

Rich

[Gerald C.]

Re: C2 Headlight Motor Diagnosis, Test, and Repair Process

I took the H/L motors out of my 63 to "freshen" them up by polishing and painting. I reassembled them and one works and the other doesn't. Thay both worked when I took them out! The gears spins freely with little resistance. When I put power to the motor, nothing happens! Not sure where to go from here.

Thoughts?

[Richard G.]

Re: C2 Headlight Motor Diagnosis, Test, and Repair Process

Tap the housing with the wooden handle of a hammer. Sometimes that will seat the brushes. I suspect one of the brushes is not seated.
If a light tap doesn't fix it you will have to take the motor apart again. Watch to confirm both brushes are seating.
Cheers.

[Gerald C.]

Re: C2 Headlight Motor Diagnosis, Test, and Repair Process

I'll give it a shot and pay special attention to the brush orientation.

Thanks

[Richard M.]

Re: C2 Headlight Motor Diagnosis, Test, and Repair Process

Jerry, Is that the one that went to the beach in Puerto Rico last year?

When you apply power and turn the manual wheel, what happens?

Rich

[Gerald C.]

Re: C2 Headlight Motor Diagnosis, Test, and Repair Process

Okay. I checked the positioning of the brushes and they look good to me. I put power to the motor and nothing except a slight click. I tried moving the wheel with the power attached and the wheel moves but no electrical movement in the motor. I've attached a few of similar pictures of the set-up. Is there something I'm missing???

Thanks

HL Motor-1.jpgHL Motor-2.jpgHL Motor-3.jpg

[Gerald C.]

Re: C2 Headlight Motor Diagnosis, Test, and Repair Process

Rich,
It's passport got voided!

I put power to the unit and spun the wheel....nada!!

[Leif A.]

Re: C2 Headlight Motor Diagnosis, Test, and Repair Process

Rich,
It's passport got voided!

I put power to the unit and spun the wheel....nada!!

Is the unit grounded, as well??