Windshield Wiper Linkage Repair
The basic design of the windshield wiper operating assembly used in M-bodies has been used by Chrysler in different variations since the mid-1970s and probably earlier.
The wiper assembly is located under a plastic screen in a cowl cavity under the hood and just in front of the windshield. The assembly consists of a stamped steel bar called the "drive link", which is attached to a "drive crank". The drive crank is attached to the wiper motor with a 7/16" nut. The drive link is also attached to a second crank which is attached to the driver's side (or left) wiper pivot. The driver's side crank is attached to another longer stamped steel bar called the "connecting link" that runs to a third crank attached to the passenger's side (or right) wiper pivot.
As the wiper motor turns, the drive crank rotation causes the drive link to move back and forth. This back and forth movement is transferred to the driver's side (or left) crank, causing the driver's side wiper to move back and forth. The back and forth movement of the driver's side crank is also transferred to the passenger side (or right) crank by the connecting link, causing the passenger's side wiper to move back and forth.
Plastic bushings are used at the pivot points of the assembly to allow free movement. There is a bushing at each of the following pivot points:
- Drive link (the short bar) - where it attaches to the drive crank on the wiper motor
- Drive link (the short bar) - where it attaches to the driver's side (or left) wiper crank
- Connecting Link (the long bar) - where it attaches to the driver's side (or left) wiper crank
- Connecting Link (the long bar) - where it attaches to the passenger's side (or right) wiper crank
The bushings can dry out and crack over time, causing erratic wiper operation or complete failure. If the plastic bushings are bad, Dorman Products
manufactures replacements under the Dorman or Motormite brand. The part number is 49440, and they are called "Wiper Linkage Bushing-Chrysler". AutoZone, NAPA and most parts chains have "help" sections displays with them in stock. Mopar parts dealers may also have them under Mopar part# 3799089.Bushing Replacement Procedure
It is much easier to remove the entire wiper assembly for service. Once the assembly is removed, you can replace all four of the Wiper bushings on a work bench. Below, originally posted by members Rick T, Mjk5thave and Sedge is the procedure for replacing the bushings:
- Disconnect the battery ground cable
- Remove the wipers from the wiper posts
- Gently remove the black plastic screen over the cowl cavity by prying at the attachment points with a flat plastic scraper or a screwdriver.
- Unscrew the ring nut from each of the wiper posts. These nuts are on the outside of the car, and hold the wiper posts up against the cowling. When unscrewed, the wiper posts will drop out of sight into the black hole of the cowling space. Don't worry. Place the nuts and the "D"-shaped washers in a safe spot.
- Disconnect the nylon bushing on the wiper motor to the main arm going to the left side wiper. Use a big flat screwdriver. Just destroy it.
- The entire assembly will slide to the left....three metal arms, two posts, and the bushings...and then remove the entire thing from inside the cowling. You may have to slide it back and forth a bit to get it out.
- Replace the bushings on the arms one at a time..use some lithium grease when you press the metal ball joint into the nylon bushing... these arms are confusing if disassembled into pieces, so just do one bushing at a time. I used an old socket and a vice grip as a way to press the bushing into place..when they "click" it's good. You can also use lithium White grease in a spray can to help with the installation and it works like a charm.
- Make sure the wiper posts turn freely on their bearings. Mine were so stiff, I think the resistance wore the nylon bushings out. I used penetrating oil to loosen them up, then some 30 wt. This is probably not as good as regreasing them, but I could not get the posts apart to regrease, and the grease inside was plainly worn out. Of they rotate freely, but not spin... you are good to go.
- Press the last nylon bushing into place.. the one that connects to the wiper motor... on the arm. Now the whole assembly is ready to slide back in, and only one connection to be made... the one to the wiper motor. This is where a long-nose vice grip comes into play. Try about 23 times, and on the 24th time, it will go together...I think this is what takes them an hour at the shop. It's hard to see, but, very do-able and it will save you big bucks!! And, when those wipers begin smoothly travelling, it will be worth it!
- Install the wiper posts back through the holes in the cowl.
- Install the "D"-shaped washers and the nuts on the wiper posts - torque to 200 in/lbs
- NOTE:Rick T's method for removing the drive link is to leave the drive crank on the wiper motor and pry the old bushing apart. This requires reaching through the hole in the cowl to press the last bushing back into the drive crank on the wiper motor. The Factory Service Manual method, outlined by Mjk5thave, is to use a 7/16" wrench to remove the drive crank from the wiper motor, press all four bushings in on a bench, reinstall the assembly and connect it to the drive crank.
- Replacement wiper linkage bushing (Courtesy of Dorman Products )
- Wiper linkage diagram for a 1977 LeBaron (Courtesy of Chrysler Corporation)
- Wiper assembly removed from car with new bushings installed (Courtesy of Sedge)
- Compiled Farley's posts by members Rick T, Mjk5thave and Sedge
- Compiled Moparts posts by members Stumpy and Walter
- Factory Service Manual