Developed a way to rebuild windshield wiper motor a 1971 FJ40! (1 Viewer)

[TrailRunner40]

Thread Update

This is a great fix outlined by Keith and thought I would add a few pics of the process.

I thought my motor was toast as I could not get it to budge or make a sound. Multimeter showed it was getting juice so I assumed it was burned and started looking for another motor. After seeing the prices associated with 40 year old windshield wiper motors, I thought I would give it a shot to see if it still had life in it. I was more than happy with the outcome.

As listed by Keith and per Coolerman, jump the wires from your plug to the battery. Positive first and then your high then low wires (Test high and low separately). I got the motor whirring when I hit hit the high switch but nothing with the low (first pic). Decided I could live with high only if necessary.

Take the screws out and pull out the wiper shaft and what you see in pic 2 is the junk that needs cleaning. 40 year old grease and dirt was thick. Lots of paper towels help.

Pic three shows the motor out and mine had dust/dirt/grit all around the contact points. I took some 220 grit sandpaper and LIGHTLY brushed the contacts and the coil.

I repacked the gears with bearing grease and started putting her back together and then discovered the original problem: The windshield wiper shaft (with attached gear) on the passenger side was seized! The gear would not turn at all. I sprayed PB on her and let it sit a while but it took a pair of channel locks and a plumbers wrench to get any movement. If you have elf finger, there is a tiny little clip that can be removed and then you can pull the shaft but I could not get that sucker off to save my life. I sprayed with PB, waited, slightly worked the gear and repeated (for a day). FINALLY, the PB fully penetrated the shaft and she loosened up like a skank on prom night.

Put it back together and I now have functioning wipers and saved a bunch of cash. Cleaning the contacts brought the low speed back to life and it's now working great.

 

[mcwinery]

Thanks for the post. this was helpful

 

[FJ40CRUISER78]

are you still rebuilding the fj40 wiper motors? If so, i am very interested in having mine done.

 

[BigSurFJ40]

Ive run into an issue during my rebuild, was going smooth until I tried to put things back together.....
I broke a contact point off in the motor housing (see picture below), WTF....any chance this can be
soldered/welded back together? Please advise...

 

[spotcruiser]

By contact you mean a brush, correct? Those can be replaced with tool brushes. It's not a big deal and it looks like you need new brushes all around, anyway. I posted the part number for a suitable brush years ago and you should be able to find that with a search. I've noticed that a local hardware store has tool brushes in their hardware section and you just need to find brushes that are similar.

 

[BigSurFJ40]

Awesome thanks,

Ya 12 pack of those brushes is expensive, hopefully I can find some at the hardware store!

Thanks!

 

[spotcruiser]

I was able to buy the brushes individually from the Graphite Store years ago, but sometime after that they started the minimum order. I noticed tool brushes in the hardware section of a local "Do It Best" hardware store recently and I think Ace probably has them also. You need to find brushes that are appropriately-sized so that they can be sanded down a little to fit the brush boxes on the wiper motor and sanded shorter if need be (most likely). You'll need to clean up that brush plate with some contact cleaner or similar so that you can solder the new pigtails in properly. Then you just remove an old brush, cut the contact plate off of a new tool brush pigtail and sand the new brush to fit the brush box properly (make sure it slides smoothly but isn't too loose and wobbly), and solder the new brush pigtail to the brush plate connection. You, of course, reuse the old spring that is already in the brush box. The brushes are not very expensive, so if you screw one up just buy another. Easy-peasy.

 

[BigSurFJ40]

Another question,

How do you get the motor back on without breaking the brushes? The springs have to be depressed but I just don't see how to do it!

Thanks

 

[spotcruiser]

Pull the rotor out of the housing and insert it into the gear up to the brushes (you have to rotate it slightly to get the rotor worm to mesh with the gear as you insert it). Then you can pull or push the brushes back carefully until you can slide the commutator down between the brushes. It helps to have a second pair of hands when trying to do it this way, but I've done it by myself.

Perhaps a better way is to remove the clips holding the brushes and springs in the brush boxes. I've done it both ways without too much effort. If you look at your photo above, you can see the white nylon clips at the back of each brush box. You can carefully pop those off (pry gently up from the plate on each side of the clip and it'll pop off) to relieve the spring tension and let the brushes slide back in the box leaving room to set the rotor down into place. Then you can push the brushes and brush springs back into the boxes and reseat the clips. Don't lose the brush springs when you pop off the clips or break the nylon clips. Those 40+ year old nylon clips are probably brittle and I don't know where you'd get replacements except from another wiper motor, so do it carefully.

Another question,
How do you get the motor back on without breaking the brushes? The springs have to be depressed but I just don't see how to do it!
Thanks

 

[handcannon]

Something I saw a few years ago might help you get everything back together with the brushes still in the correct location. Go to post #24 and look at the first pic. The brush holder has a long slot in the top for the power wire to connect to the brush and exit the holder and allow it to connect to the contact on the plate. See if the brush can be pushed into the holder until the face of the brush is past the end of the slot. If so, use a toothpick to hold the brush back, and away from contact with the armature while re-assembling the motor.

I once had an alternator I was changing brushes on and it was worse than this wiper motor for access to the brushes while re-assembling the alternator (couldn't see the brushes once you started inserting the commutator shaft into the alternator case). It had holes in the exterior alternator case, and holes in the brush holder. A small dowel, the size of a toothpick, was inserted through these holes, holding the brush back, while re-assembling the alternator. Worked slick, and I have tried using this method ever since.

Don

 

[BigSurFJ40]

Thank you so much for the help, got the motor back together, went to ACE and they had brushes that I was able to sand down. Clips came right off with no issue! High and low works beautifully!

I really appreciate this forum of guys!

 

[spotcruiser]

Yup, it's nice having wipers.

 

[thebigredrocker]

Do I drive the wiper arm shaft out to remove the round gear?

Do I dare unthread the (linear)rectangular gear to remove and inspect the cable?

Will bearing grease suffice?

I don't see where @Coolerman covered secondary gear remival.

 

[Coolerman]

My apologies for not finishing that page! HEre is a brief run down of what should be there:
Count the number of exposed threads on the shaft the linear gear threads onto, loosen the lock nut, then un-thread the linear gear to get it off. When you re-assemble it thread it on until the same number of threads is showing then tighten the lock nut. That will get it back where it was. I'm sure there is a proper spec for that but I have no idea what it would be.

The shafts are held in place with a wire clip. The gear DOES NOT come off the shaft! It is peened on there!
Once you remove that clip (be warned it will try to fly when released, never to be seen again! There are no replacements!) the gear and shaft will slide out of the threaded section if you are lucky. They tend to seize. Make sure to clean these inside and out and apply a light film of grease before reassembly.

 

[thebigredrocker]

It is seized.

**EDIT**
To break it free I tapped on the crescent with a hammer. I was able to work the rod/cable back and forth 1/2". I kept trying to feed oil into the sheath as I worked it. Eventually the force of my hammer blows probably increased. Therefore, the (cable holder ferrule?) popped off the cable sheath. Here's a pic:

I'd love buy a new rubber cushion if anyone has one they'd sell.

 

[65swb45]

Mark, the small nut is a jam nut. You have to loosen it first.

 

[thebigredrocker]

Here's how I'd free the rod/cable next time:

Hold the secondary linear gear and rotate the outer cable sheath clockwise as shown below. The clockwise turning will compress the spiral cable sheath in hopes of not expanding it.

You may need to keep watch on the cable end that is not in the picture. Ensure that only the sheath is rotating clockwise. You might need to twist the rod end not pictured counter clock to keep it out of bind.

Once it broke free I fed oil with the cable vertical and worked the rod/cable up/down and continuously mopped up rusty gunk that flowed out.

It is my best guess that the seizure was caused mostly by the rod section of the secondary linear gear. Below is a picture of the cable ferulle end that came off the primary gear side. Note the rough inner bore.

 

[thebigredrocker]

Wiper motor is back together. Whew!

Could not get slow to work. Upon my 3rd visit to Coolermans "wiper science" page, I read his observation that LB from the main harness bullet actually needs to go to LW on the motor and LW harness to LB motor. VIOLA! Followed his generous advice and I now have slow & fast speeds

to @Coolerman

Here's how I was testing my rebuilt wiper assembly. Not using the windshield frame harness is what initially caused me to scratch my head why I had fast wipe but no slow.

 

[ginmtb]

Wiper motor is back together. Whew!

Could not get slow to work. Upon my 3rd visit to Coolermans "wiper science" page, I read his observation that LB from the main harness bullet actually needs to go to LW on the motor and LW harness to LB motor. VIOLA! Followed his generous advice and I now have slow & fast speeds

to @Coolerman

Here's how I was testing my rebuilt wiper assembly. Not using the windshield frame harness is what initially caused me to scratch my head why I had fast wipe but no slow.

View attachment 1487254 View attachment 1487255

Same thing happened when I rebuilt mine - couldn't get the low/high to work. Found Coolerman's instructions too and solved the problem! Too bad the wipers still aren't very good at wiping water off the windshield. But they do work!

 

[thebigredrocker]

A 75-76 “small” wiper motor.

I replaced this old grease with standard bearing grease. NLGI #2

Anyone know of a more appropriate grease? Note the park assembly is in with the grease.