Hitch

Good morning guys, A friend has been working on a 67 for a few weeks that has needed various items corrected but not a full restoration. One of the items on this car that needed work was the headlights, buckets and motors. This is not highly unusual for our cars but felt that some of the things learned would be helpful to all.

The buckets were removed and it was discovered that the pivots and ***** would need to be replaced. After cleaning up the original motors and replacing the gears it was determined that the motors were marginal and that the new replacement motors would be purchased and installed.

Here is some information provided by said friend that I beleive will be helpful to anyone looking at purchasing headlight motors/assembly from the normal parts houses. I hope by posting this it will save others some frustration and time.

After several years of trying to operate the headlight motors on a 67 Corvette with siezed pivot *****, the original headlight motors needed replacing due to both mechanical and electrical problems.

Reproduction headlight motors were procured from two Corvette parts houses. These reproduction motors have a number of problems which are listed below. The right side motor has less problems than the left side motors. We had to obtain two different left side motors from two different sources.

Operating Noise.
When we tested the motors on the bench prior to installing them, the first left side motor sounded like it had rocks inside the motor and we went no further with this motor, but returned it as defective.

Left side pivot shaft alignment.
When we attempted to install the second left side motor on the pivot shaft we found the hole in the L-bracket and the slot for the main drive gear were misaligned and the motor could not be installed on the pivot shaft with the plastic bushing installed in the L-bracket. After swapping the reproduction L-bracket for the original bracket and changing the drive gear for a new drive gear, the problem is in the upper gear case housing casting. The location of the hole in the housing is misaligned just enough to prevent the proper alignment of the pivot shaft and drive gear slot.

We did correct this by slightly grinding the hole in the L-bracket to permit proper alignment with the bushing installed. Not the ideal solution, but since both left side motors had the same problem, it appears all the left motors are this way.

Drive gear washers.
Original motors have a nylon washer on one side of the main drive gear, a flat steel washer and conical thrust washer on the other side of the gear. The convex side of the conical washer is oriented toward the drive gear and bears on the flat steel washer to prevent the hardened thrust washer from destroying the pot metal drive gear.

When we disassembled the gear case of the new reproduction motors we found there was no steel washer and the convex side of the thrust washer was reversed from the factory orientation. We attempted to install the washers correctly using a flat steel washer from the original motors and found the motor to be locked up tight.

By chance, the inner diameter of the flat steel washer is the same as a distributor shaft shim and we installed a 0.010 inch shim on the drive gear and oriented the thrust washer correctly. The hardened distributor shim gives the conical thrust washer a bearing surface to protect the drive gear. We tested the motor on the bench using a 10 amp battery charger and it ran fine in both directions pulling 6 amps by the battery charger gauge.

Motor binding in full up or down positions.
After getting the motor reassembled we installed the modified motor on the car and it seemded to operate except that in the full up or full down position, the gear train bound up and the motor would not move to the point it tripped the circuit breaker. Without relieving some of the pressure on the gear train with the handwheel, the motor was locked up tight.

Clearly this was a gear train problem so our initial thought was to just swap the new reproduction gear box for the original gear box. The reproduction motor armature is slightly longer than the original motor armature and after installing the original gear box, the motor would not turn at all.

On examining the reproduction gear train, particularly the intermediate shaft worm gear and main drive gear we noted the reproduction worm gear crown was very sharp as compared to the original intermediate shaft worm gear which has a flat crown and that the main drive gear teeth were narrower and finer than the original gear teeth. We believe the sharpness of the intermediate shaft worm gear is causing the binding we experienced. Additionally, the end play of the intermediate shaft in the "top hat" end bushings seem excessive.

To correct this condition, we installed the original motor intermediate shaft and a new drive gear in the reproduction motor gear case and this solved the binding at full up or down. As a side note to this, the new drive gears available made to original GM specs will not work in the reproduction motors due to the differences in the reproduction worm gear cut on the intermediate shaft.

We have advised the supplier of the motors and they are going to pass this along to their source. In the interim, reproduction headlight motors should be considered off limits unless you make changes similar to the ones we had to make to get the motors to operate properly.

In addition to the problems with the motors themselves, the reproduction torque restraint straps that attach to the motor and to the bushing on the nose header bar will not fit correctly with the reproduction motors without some bending to fit. The reproduction torque restraint strpas are made of heaverier gauge metal than the original torque straps which makes connecting the torque restraint strap and electrical ground wire to the motor difficult with the limit of a 3/8ths inch long bolt into the motor housing to prevent damage to the motor field windings.

joec

thanks for the great write up.. what really pains me is that these things are being sold. What ever happened to testing stuff before you sell it??? I wonder if anyone else is having an issue with them. It seems you went to great lengths to make these work...

I think some type of sticky thread should be written with supposed repro parts that are junk or just don't work.. It would help us all in the long run..

/joe

67L36Driver

While I have no experience with the repo headlite motor/reducers, I can share some tricks to help those refurbishing their originals:

By subing a wave lock washer for the "conical thrust washer" (Bellville spring) and a thinner flat steel washer you can reduce the gear train drag 500% (that is from 25 inch-pounds to 5 inch-pounds).

By stacking small nylon washers (about 3/16" dia. x 1/16" thick, measure for yourself) between the 'top hat' bushings and the housing you can reduce endplay and resultant gear binding.

I obtained the above bits from Ace Hardware.

Red63SW

I just installed repop motors in my car last week. I had this same problem on the left side. Mine were close enough that I was able to use a dremel tool with a sanding drum to open up the bushing I.D. enough to get it to slide in smoothly. Hopefully, the bushing holds up over time.


I did not have this problem. Mine went together just fine with no modifications.

The other problems you listed have been in the back of my mind causing me to lose sleep. I plan on getting the electrical system completed so I can make sure the motors are working properly before I install the radiator, grille, and bumpers. Thanks for sharing this. I hope I don't need it, but it wouldn't surprise me if I see some of the same problems on mine.

JohnZ

The bottom line is, don't buy the reproduction headlight motors - rebuild yours, or have yours rebuilt by someone who does it every day (like Steve Hack).

Hitch

Agreed..

Hitch

"I would at the least check and fix the spring washer and steel washer issue in the headlight gear boxes and as suggested either shim up or replace the intermediate shaft with an original type shaft to prevent gear binding and to permit use of a standard drive gear. If you compare the repop drive gear to an original or current supplied gear, the differences are obvious and the current drive gear will not work with the repop worm shaft gear.

We used the term conical thrust washer to be more descriptive of what a person actually sees since many are not familiar with the Belleville term for this type spring. Some type of spring washer is needed since the drive gear teeth are cut at an angle to mate with the worm shaft gear and thus some axial thrust in both directions is applied to the drive gear as it rotates in either direction.

As noted, distributor shaft shims are the correct size and come in various thicknesses (0.005, 0.010 and 0.030) We used the 0.010 shim to minimize load on the gear train.

As a side note, some end play is also required in the armature shaft and there is an adjustment for this in the gear case housing (screw and lock nut). Mis-adjustment of the armature shaft end play is a contributor to the motor running slower in one direction than the other direction, as well as slop in the intermediate shaft as noted in the previous post. I have not seen a spec on correct armature shaft end play but about 0.010 inch seems to work best for us.

As currently installed in reverse in the repop motors, the spring washer is bearing on the drive gear teeth and this certainly can't last long."

Dave

Hitch

It's always curious to me that information like this gets no comments or very little views but a thread about a rusted bolt will go four pages and get a couple thousand views. Dave

62Jeff

I applaud the effort you spent to document all of your data and findings. However it was so comprehensive and complete I didn't have anything to contribute to it other than "good job".

So, good job

Jeff

Hitch

Jeff I appreciate that, but you know I don't post for acceptance.. I just find it interesting that we all have some of these problems but the HOW BIG OF RIMS can I fit on my car threads pop up all the time and get a lot of exposure. I just worry sometimes that the forum information could be better put to use. Dave

6T5RUSH

Dave,

Thanks for the detailed writeup on these repo motors. I've been living with a s-l-o-w-w driver's side up/down motor since I bought the '5 in '81. Ya' think it's time to correct it??? Do feel the route to go (after seeing this post) is to rebuild mine.

Thanks again for this insight!

Regards,

Jim

red67

I purchased a pair of new headlight motors from Paragon about a month ago for my 64. The instalation was as easy as the originals, and they work perfect. They are faster than my 67, which has rebuilt original motors. They even open and close almost exactly at the same rate. I was very happy with them.

62Jeff

Ehhh, you just needed a more sensationalized thread title. Something like "OMG - Repro headlight motors almost cost me my life!!!"

Could be worse, at least the Zaino threads thankfully stay in the other side of the forum

LT1driver

good info, thanks. note to self to stay away from repops motors if I need them.

Ron Miller

I've come to believe over the course of years that it's best to stay away from reproduction anything rather than a good restoration of the original, if at all possible. Just my observations . . .