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mgf
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Discussion Starter #1
I recently rebuilt my whining wiper motor and thought it'd be good to share. If you have ready access to cheap spares then replacement is the preferred option, but since I'm stubborn and like the satisfaction of fixing non-serviceable parts I thought I'd give it a go.

I started taking pictures late in the piece so the first part is going to be story telling..
 

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mgf
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Discussion Starter #2 (Edited)
Step 1 - Remove wiper from car.

I did not remove the wiper in the conventional fashion, which involves removal of the wiper-arms and wiper-assembly from the car. Instead I unbolted the wiper assembly lower mount and jammed an ~2 inch piece of wood between it and the body. This provided sufficient access for small ring spanners.



Remove the wiper arm linkage nut and star washer. You'll need a #13 metric ring spanner.
Remove the 3 #10 wiper mounting bolts.
Place bits in a suitable container / pocket without hole.
 

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This has the makings of a T-bar standard how to.

I found that reaching from the passenger side I could get to the nut holding the link without the wooden wedge.
 

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This has the makings of a T-bar standard how to.

I found that reaching from the passenger side I could get to the nut holding the link without the wooden wedge.
There is nothing wrong to create new one here, on the contrary, it is desireable.

@culyun please do continue with the rest of steps.
 

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mgf
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Discussion Starter #5
Step 2 - Motor Disassembly Overview

Apologies for the brief hiatus and general lack of pictures for this section.

Your goal is to dismantle the motor without breaking or losing parts. As it happens I was a bit rough at times, which meant that some of the parts were a little abused. But I'll point out the "be careful here" steps so you don't have to ("cough") repair parts along the way.

The fully disassembled motor is shown below along with the offending bearing.



To get to this point you need to:

  • Remove the black stator housing from the gearbox
  • Drill out the gearbox-housing rivets
  • Remove drive gear and rotor circlip
  • Tap out the rotor
  • Drill out the commutator board rivets
  • Tap out bearing
 

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Discussion Starter #6
Step 3 - Disassemble Stator Housing

Disassembly of the stator housing is fairly straight-forward, but is a little fiddlier to reassemble. Remove the two bolts holding the black stator housing to the gearbox housing and gently lever off the housing. Be careful with the rubber o-ring sealing the housing with the gearbox. The magnets will resist your attempts a little, but the housing should pop off relatively easily.

Clean off any gunk you find inside the housing. Mine had no gunk, but it's a commonly reported problem.

Store bolts and o-ring in the container previously purposed for the task (you guys are organised right ;-)
 

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Discussion Starter #7 (Edited)
Step 4 - Drill out gearbox housing rivets

Lightly clamp the metal gearbox housing in a vice so that the plastic cover is facing upwards. Use soft jaws, the housing is Aluminium.

Put on safety goggles.
Fit a 3 mm to 3.3 mm drill bit to a cordless drill. Don't go bigger than this - we plan to tap a 4mm thread later.
Put a drop of oil one of the rivets securing the plastic cover to the gearbox. Any oil will do.
Begin drilling -- slowly and firmly -- into the rivet.

How firmly? About 5kg. Put it this way if you see the drill bit bending back off. But drilling metal requires pressure, so don't puss about. You are wearing safety goggles right!!

How slowly. About 600rpm. There are proper numbers you can look up, but 10 times a second is an ok ball-park. You can control the speed with most cordless drills. Try to run the drill so you can see the bit turning. If it's a blur to your eye it's too fast.

Repeat for the remaining rivets.

I was a bit sloppy with the drilling and used a blunt bit to boot. This meant that I was a bit out with the holes. But it didn't matter too much in the end. If you have blunt bits you can give them a "rough as" sharpen on a bit of smooth cement, but they aren't too expensive so just buy a new bit!

Pry off the plastic housing. Dieter's site (google is your friend) talks about a gasket. Mine had none. The plastic housing was glued on with some kid of epoxy.
 

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Discussion Starter #8
Step 5 - Remove gear and circlip

Push out the plastic / nylon gear. There's a metal washer on the shaft. Don't loose it!

Remove the plastic grub screw controlling the rotor end-float.

Remove the rotor circlip. This is a little fiddly. To make things a little easier, start by putting the entire housing in a plastic bag so that you don't loose the circlip if it pings off. Use two jewellers screw drivers to flair open the circlip and when it begins to open lever it off with one of the screw drivers (wish I had a picture for this).

Put all the bits in the container..
 

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Discussion Starter #9 (Edited)
Step 6 - Tap out rotor

Setup a cheap folding workbench (or similar) like the one below. Wind the workbench in/out so that the rotor windings and commutator fit between the gap. The stator-facing part of the gearbox housing needs to be supported by the workbench.



Attach a plastic bag beneath the rotor. We are going to tap the rotor out and catch any bits that might fall out.

Using a nail-punch or suitable drift, tap the rotor shaft with a hammer. Wear safety goggles.

My rotor was fairly tightly mounted to the bearing so it required a moderate amount of force, but it came out without damage.

If you are clever, you might be able to pull back the brushes into their housings via their wires... Otherwise just try to catch the brush springs. I lost one, but found a suitable replacement...

 

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Discussion Starter #10
Step 7 - Drill out commutator board rivets

Lightly grip gearbox housing in vice. Mark a centre in each rivet for the 3mm / 3.3mm drill-bit using a punch (or nail).

Drill out rivets to around 12mm deep. Try not to drill all the way through the housing. It's not the end of the world if you do.

Scrape / file off the remaining rivet heads. Be patient, don't force the PCB off the rivets -- it will probably crack.

Tap an M4 thread in the holes, and clean up the surfaces with some light filing / sanding.
 

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Discussion Starter #11
Step 8 - Tap out bearing

Find / fabricate a small drift to fit into the aluminium bush from the gear-side of the housing. Squirt a small amount of penetrating oil around the bush and the cup that prevent the bearing falling out on the commutator side of the bearing.

Support the gearbox as before in the folding workbench. Tap the bush using the drift. Mine required a moderate amount of force and I damaged the bearing cup a little. But I was able to reuse it. So bash away... carefully.
 

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Discussion Starter #13 (Edited)
Step 8 - Fit new bearing

The wiper bearing (below) is dimensionally equivalent to the bearings used in skateboards and children's scooters.



Source a new bearing and reassemble with a dollop of grease into the gearbox housing. Tap the cup back into position using a socket.





You can see the extra drainage hole I drilled at the low point in the housing in the image.
 

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Discussion Starter #14
Step 9 - Fit commutator board and rotor

Take the commutator board and clean off any crud. I used a toothbrush and some CRC-226 electrical cleaner that I wiped off with tissues.

Refit the brushes into their retainers together with their springs. Tie back the flying leads as shown below. If the lead retainers are broken / too difficult to use just improvise..





Fit the plastic bearing stand-off thingey on the bearing and then screw the commutator board to the housing with 12mm M4 machine screws.



Gently clamp the housing in a vice and tap the rotor shaft through the bearing. It's a tight fit, but will tap on without damage.
 

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Discussion Starter #15
Step 10 - Refit stator housing

Refit the rubber o-ring and navigate the rotor into stator housing. The rotor will get caught on the stator magnets. Just be persistent. If you find (as I did) that the rotor does not want to push into the bush at the far end of the housing, fit the butt end of a wooden pencil into the bush and lever it so that the pencil is coaxial with the housing before trying to refit the rotor.

As it happened, my housing still required a wee tap to push the bush on to the rotor. But it seems to be fine.

Refit the stator housing bolts.
 

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Discussion Starter #16
Step 11 - Refit rotor circlip, gears, etc.

Don't loose the circlip! Put the wiper into a plastic bag and push the circlip into its groove on the rotor shaft.

Clean up the main plastic gear if necessary and regrease. By this stage I had found my silicon bicycle grease so I used that. I suspect the type of grease is not that crucial. Be sure to fit the washer over the wiper drive shaft.

Screw in the plastic end float.
 

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Discussion Starter #17
Step 12 - Refit plastic gearbox cover

If you have a gasket use it. I didn't so I simply smeared some windscreen sealant where there had been epoxy previously.

Then it was just a simple case of screwing on the plastic cover using 12mm M4 screws.

At this point I plugged the motor back into the harness and tested its operation. Much improved :nerd:
 

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Discussion Starter #18
Step 13 - Refit motor into car

This is essentially the reverse of step 1. Just be sure that the wiper linkage is pulled towards the bottom of its travel. If you don't the wiper will wipe down rather than up (wonder how he knew that).

The end.

Please jump in with extra comments / better ways of doing things..
 

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Great how-to!
Thanks!

I've all the thing to repair the wiper myself, but I was scared to attempt the fixing.

Now I feel more convident and will attempt indeed >:)

I think a couple of picture more in some of the steps could have helped, but I feel it's very good.
 

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how i do unscrew a nut of the shaft of the wiper motor?
it may be damage gear teeth it is made from plastic
 
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