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Windshield Wiper Rebuild Project

Category: Electrics

Contributed by Dick Bishop

Summary: This project covers the repair of the American Bosch windshield wiper motors that are common to most Nauticats built in the 80s and 90s.
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Last year I built a simple puller to remover the arms from the windshield wiper shafts. Now I have pulled the motors and rebuilt or serviced the drives. I did a survey of the available replacements in case I got into trouble. I was not able to find motors from American Bosch, but three other companies manufacture exact copies plus improvements. Vetus, AFI and Ongaro all have excellent replacements for the physical dimensions plus two speed, and self park. The prices run from $99. to $189 so shop carefully. The trick all three seem to use is to change the splined knob on the end to a larger size so that you have to use their new arms. I talked to Frank Ongaro (owner of Ongaro Marine) in NJ, USA, and he offered to sell direct to us if we could not find a convenient distributor. Defender handles his motors at the best price I found anywhere. However, I have three wipers on Triumph and did not want to lay out so much for three new systems so I decided to try rebuilding.

The Problem:

All three shafts were frozen from salt exposure and lack of use. After removing the motors from the bulkhead and removing the connecting link inside, I found that all motors ran fine. The problem seems to be rust forming on the inner steel shaft. The circuit breakers would trip on my panel which protected the windings in the motors. Frank Ongara told me his motors use stainless shafts and this cannot happen on Ongara wipers. His wipers were adapted from American Bosch motors by his parent company in Sweden about 10 years ago.

The Solution:

Step by step: I first removed the arms, disconnected the two wires and unscrewed the cover nuts on the shaft outside the cabin; removed the one mounting screw then pulled the motor and shaft out of the boat. I places a small piece of rubber hose over the outside end of the shaft to protect the metal splined parts and had Eileen tap as I pulled from the inside. I then took the back cover off the gear housing to expose the cam, worm and connecting rod. See photo # 1. Remove the U shaped brass clip holding the connecting rod to the short arm on the end of the drive shaft. This allows the connecting rod to come off. You will probably need pliers to work it a little. Be careful to not drop the white pivot cap on the shaft center of the large cam wheel. With the connecting arm removed, reconnect the two electrical wires and test the motor. If it runs as I expect it will, you are in luck.


The Real Work:

The next steps I did at home where I could make a bigger mess than on the boat. After trying several things, I found a combination that worked to free the non movable shafts. My technique was to drill a 3/32-inch hole through the brass outer shaft to gain access to the inner steel shaft. The little red extensions used on spray can of penetrating oil, WD-40, etc., are about 3/32-inch. Try to locate the hole on top about mid way of the shaft so that it is covered by cabin material when reinserted. Through this 3/32-inch hole I injected Rust Blaster penetrating oil. Then I heated the tip of the shaft (steel part) with a propane torch. Then inject more oil. As the shaft cools it draws the oil in to the tight places. The expansion breaks the tight rusted bond. Repeat this several times. Heating the brass outer shaft was not as effective as heating the inner shaft tip. I wrapped the splined ends with rags and used pliers to try turning the shaft. Once it starts turning, keep using the penetrating oil and heat.


Side Note:

The outer brass shafts are pressed into the housing and may be removed if necessary. I removed one by taking the lock nut off the outside of the shaft and tapping it out. I would not remove the shaft unless necessary for some other reason. Leaving it in place gives you good leverage to turn the shaft by gripping the motor. I had hoped to find a manufacturer that would sell me the shafts only, but no luck so far. Once the shafts are free I worked them and kept adding oil. Two were free enough to turn by finger tips, but one required pliers to grip. I reassembled the hard one and ran it on the work bench. It ran without any problem. Note: All of my wipers used the 85 degree position on the cam.

Lubricating; Paint and Test:

Before reassembling everything, I wanted to inject grease into the shafts to help prevent moisture from entering the shaft. To do this I built a simple greaser out of a 3/4" pipe strap, an automotive zirc fitting, and a piece of 5/8" ID plastic hose. After putting several strokes of grease from my grease gun into the hole, I lubed all the other moving parts with grease as I put the drive back together. I touched up all the rusty metal and peeling black paint with Rustoleum. Finally, I bench-tested all three units before returning them to Triumph.

I am pleased with the outcome, and found it much easier than I thought originally. I certainly would do it again. I may have a problem getting the spline knob to hold on the old arms, but there is a set screw on the arm cap which I can drill and tap if necessary. The last thing I plan to do is to stop the motors at the end of a stroke before returning to the boat so I know which position to mount the arms.