1957 5047991 Slow Park Wiper Motor

[Richard M.]

Part# 5047991 is specified for later 1957 Corvettes. It is defined as "Slow Park".

Can anyone describe this technical functionality of this motor, Slow Park versus Fast Park(5047984)? Is this slow park function noticeably different enough to be seen visually, e.g. in a PV?

From the 1962 P&A catalog....

62PA30S_1361.jpg

Also for reference from Wilcox Corvette....

http://repairs.willcoxcorvette.com/1956-1982-corvette-wiper-motor-numbers/

1956-1982 Corvette Wiper Motor Numbers

1956e	5047799	early
1956	5047924	Front cover has no plastic actuator switch; it has a flat metal slide. Access to the back side upper left cover attaching screw is thru a hole in the mounting arm.
1957e	5047984	s/n 1400 984 was fast park. 991 is a slow park design.
1957	5047991	slow park des. Dec 1957and later Dec. of 1957 and later cars only
1958	5044266	came with a new internal style switch design.. Better
1959	5044266	came with a new internal style switch design.. Better
1960	5044266	came with a new internal style switch design.. Better
1961	5044266	came with a new internal style switch design.. Better
1962e	5044266	s/n 2000 came with a new internal style switch design.. Better
1962	5044479	changes to this motor were: a plastic coated internal wiring and phillips screws on the actuator stand.

[David B.]

Re: 1957 5047991 Slow Park Wiper Motor

Rich, Chevrolet Service News Vol. 28 December 1956 Number 12 devotes it's entire 4 pages to the 5047991 Slow Park wiper operation. The service news states 5047991 is identical externally with the electric wiper used on first production 1957 pass cars. If you have a copy of vol 28 #12 it should answer all your questions. 5047984 Fast Park is 1st Series, 5047991 is 2nd series.

[Richard M.]

Re: 1957 5047991 Slow Park Wiper Motor

Thanks David, I've just asked for a copy of that from a friend.

Earlier I also discovered a website that helps outline the differences for the Passenger car motors. It states...

"As the name implies, a new style drive gear is incorporated in the wiper which returns the wiper blades to the lower edge of the windshield glass very slowly when the wiper is turned off."

It also mentions that the earlier Fast Park motors had a retaining ring on the gear axle which can be seen externally. Item "B" below. If it has the retaining ring, it's Fast Park, if not, it's Slow Park.



The 1957 pass car 2nd style motor is a 5047988. A photo below. No axle retaining ring.


Here is a 5047991 Corvette Motor. No axle retaining ring.
I suspect the only visual difference(other than the plate part#) between this and the Pass car motor(above) is the ground wire riveted to the Pass car motor, versus no ground wire on the Corvette motor, as it's a separate longer wire that attaches to the mount arm, then to the valve cover inner rear bolt.
s-l1600.jpg

Thanks for the help,
Rich

[Gary C.]

Re: 1957 5047991 Slow Park Wiper Motor

Rich,

Basically, a slow park wiper slowly returns the wiper blades to the bottom edge of the windshield (park) when the wipers are turned off.

Gary
....

[Richard M.]

Re: 1957 5047991 Slow Park Wiper Motor

Rich,

Basically, a slow park wiper slowly returns the wiper blades to the bottom edge of the windshield (park) when the wipers are turned off.

Gary
....

Gary, Thanks, Yes that's what I've discovered too, but trying to determine what's on a friends car.

Also looking for a photo of the early 5047984 motor gearbox/switch assy and if it has a external axle retainer ring.

Rich

[Rod K.]

Re: 1957 5047991 Slow Park Wiper Motor

Rich, don't have a photo but my 984 motor from mid-Nov build S/N 008XX does have the snap ring.

[Brian T.]

Re: 1957 5047991 Slow Park Wiper Motor

The 988 passenger car motor can use either quick park, or slow park switches. Not typical with Delco motors. Do not know why they did not have a different part number, but they do not. I have seen many of each.

[Richard M.]

Re: 1957 5047991 Slow Park Wiper Motor

Rich, don't have a photo but my 984 motor from mid-Nov build S/N 008XX does have the snap ring.

Thanks Rod, My research tells me then that it is a Fast Park unit if it has the retainer.

====

The 988 passenger car motor can use either quick park, or slow park switches. Not typical with Delco motors. Do not know why they did not have a different part number, but they do not. I have seen many of each.

Thanks Brian, The Service News states that some were built with both switches, and on the Slow Park design to simply not use switch terminal 5(note in Fig 2 Vol28-12).

I'm certain you've seen many of these over time and if you happen to come across a photo of a 984 gearbox/switch at some point it would be helpful.

====

Attached both Service New Docs below (Thanks to Gary Chesnut), and the lead to the docs from David earlier. Great info.

Rich

[Bob W.]

Re: 1957 5047991 Slow Park Wiper Motor

So can a 988 passenger car motor be used on a c1

[Richard M.]

Re: 1957 5047991 Slow Park Wiper Motor

So can a 988 passenger car motor be used on a c1

Bob, Brian may know for sure, but my suspicion is that it can be used but would require the ground wire be modified by removing it from the riveted point on the arm(left wire below) and a separate longer ground used in it's place, attached to the mount screw. Possibly the power wire(right wire below) would have to be extended on the 1958-1962 as well due to Ballast Resistor placement is on Pass side versus Driver side on 1956-1957.


Also, as long as the position of the drive mechanism is the same when in "Park" to properly mate with Corvette dash mounted transmission.

Early 57 Pass 981 car left, later 988 right. 988 Arm angle changed to allow easier access to distributor cap.

[Bob W.]

Re: 1957 5047991 Slow Park Wiper Motor

Rich, Thank you for your reply.


Bob