This month's TechCheck will explain, and show what is correct for your 1955/1956/1957 passenger car. There will not be a lot of narrative because the photos will do most of the "explaining."
Table #1
Model Year Application | Motor # |
1955 ----------------------- | 5047787 |
1956 - 1st Style ----------- | 5047906 (Time change from 1st style to 2nd style unknown.) |
1956 - 2nd Style ----------- | 5047905 |
1957 - 1st Style ----------- | 5047981 (Used until Dec. 1,1956) |
1957 - 2nd Style ----------- | 5047988* (Used starting Dec. 1,1956) |
1955 - 57 Replacement---- | 5044280* (Replacement only) |

Several items to notice about the "787":
6. This motor happened to be built December 16,1954.
- Square cover (Held in place with slotted, round-head screws)
- Part # stamped in area pointed out with arrow A.
- Retaining ring pointed out with arrow B (Any of these wiper motors with the retaining ring will not have the "slow park" feature.)
- Riveted, black ground wire with straight bayonet end. (All of the original passenger wiper motors had this type of ground.)
- Most had the "offset" nylon switch, but some had the "straight" nylon switch found on the 1956 wiper motors.
7. No gusset in area pointed out with arrow C.

Several items to notice about the "906":
- Square cover (Held in place with slotted, round-head screws)
- Part # stamped in area pointed out with arrow A (Screw many times covers the 6 of the part #.)
- Retaining ring present - no "slow park" feature
- Will also have the riveted, black ground wire with straight bayonet end.
- "Straight" nylon switch
- No cast aluminum gusset in area pointed out by arrow B

1956 2nd Style Wiper Motor #5047905 (See Photo #3.)
Several items to notice about the "905":
- Switch cover has one rounded corner (Held in place with slotted, round-head screws.)
- Part # stamped in area pointed out with arrow A
- Retaining ring present - no "slow park"
- Also has riveted, black ground wire with straight bayonet end.
- "Straight" nylon switch
- Notice cast aluminum gusset pointed out by arrow B

Several items to notice about the "280":
- This is a correct motor for any Original Class 1955/ 1956/1957 - it was, and is just a replacement for the original 1955 & 1956 motors.
- Switch cover has one rounded corner.
- Part # stamped in same area as "905".
- No retaining ring, thus this motor does have the "slow park" feature. (See Arrow A.)
- Has riveted, black ground wire with straight bayonet end
Used the "straight" nylon switch like the "905."
- Has cast aluminum gusset like the "905."
- Notice 1962 production date on the "280" that we photographed. (See Photo #5.)

1957 1st Style Wiper Motor #5047981 (See Photo #6.)
Several items to notice about the "981":
- Switch cover has one rounded corner like the "905" and "280."
- Part # stamped in same area as "905" and "280."
- Has retaining clip - no "slow park" feature.
- Uses a straight nylon switch with metal cable retainer with slotted screw and nut. (See Photo #6A.) (Different switch than used in the "905", "906" & "280.")

6. Has cast aluminum gusset like the "905" and "280."
7. Used for 1957 passenger cars through November 1956.

Several items to notice about the "988":
1.Switch cover has one rounded corner like the "981"
2.Part # stamped in same location as "981"
3.Unlike the "981" the "988" does not have the retaining clip, thus it does have the "slow park" feature.
4.Uses the same nylon switch as "981"
5.Same black ground wire as the rest.
6.Has cast aluminum gusset as the "905," "280" & "981."
7.Used on 1957 passenger cars starting in December 1956.

The 1955 and 1956 wiper motors (#5047787, #5047906 & #5047905) used slotted, round-head screws to secure the end case. The 1957 wiper motors (#5047981 & #5047988) use hex-head bolts to secure the end case.

All of the original electric wiper motors used a small fiber (cardboard-type) cover over the drive mechanism block to take up the slack in the wiper drive drum mechanism. This kept the wiper motor quieter when in operation.

The 1957 (2nd Style) "988" has a mounting bracket that will NOT tilt the wiper motor quite as much as the other original electric wiper motors ("787," "906," "905" & "981"). With this new bracket, the distributor cap could be removed more easily. Notice the greater angle on the left wiper motor, the "988" is on the right.

All original electric wiper motors had brown power lead wires. The 1955 & 1956 wiper motor leads had straight fork connectors with a black plastic insulator, while the 1957 wiper motor leads used a 90-degree fork.

Most of the time the hardware that adjusts the end play of the motor armature are as pictured, but not always.
Bob Kemmler Date 2/7/2014
Where can I order the screws for the end case and what size are they