Current (Amp) draw comparing new versus old window lift motors

Discussion in '80-Series Tech' started by Kernal, Dec 13, 2011.

  1. Kernal

    Kernal

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    With my driver's side window regulator hanging free outside the door I noticed that the original window lift motor would bog down and stop when running in the down direction, which winds up the regulator spring. I wasn't sure if that was due to not installing the motor in the correct spot on the regulator, whether the regulator was binding (doesn't appear to be), whether the motor is designed to use the weight of the glass to help push against the regulator spring, or whether the motor itself wasn't putting out enough torque.

    Fast forward to today: I individually hooked up both the old motor and a new Dorman motor to the door harness and checked the DC current (Amp) draw of both while running using a DC clamp meter. Surprisingly I got a lower current draw for the used original Toyota window lift motor than the new Dorman. After a few runs in both directions the Dorman drew 2.35 Amps and the original Toyota motor first drew 1.54 Amps and a few minutes later it pulled 2.13 Amps. Best guess why the motor drew more current after it warmed up was maybe due to the armature bearing-bushing clearances tightening up?? The Toyota motor did get a bit warmer than the Dorman at the far end of the armature "tower", but this was after a dozen runs up and down. The new Dorman sounded a tad smoother and maybe ran a bit faster.

    Earlier I had sent an email to a Dorman tech rep who said a good motor will have a no-load draw of less than 5 Amps, so the used motor easily beat that assuming the same spec applies to the Toyota part?? Next I'll hook the Dorman motor up to the regulator to see how it does compared to the original motor.

    Edit: before the test I had completely disassembled the Toyota motor, cleaned and relubed the armature bushings, worm gears, pinion gear shaft, lightly sanded the commutator (1000 grit), and checked the brush lengths.

    Second photo shows the Dorman motor no-load running current, bottom photo is the original Toyota motor result.
    DSC07319.JPG DSC07324.JPG DSC07332.JPG
     
    Last edited: Dec 13, 2011
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  2. Brunt Force Trauma

    Brunt Force Trauma

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    I think this should be in the hardcore section. :lol:
     
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  3. Kernal

    Kernal

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    I'm not a DC motor or window regulator expert, but hoping that with the information above someone who is will chime in. When I took the original Toyota window lift motor apart I found that the grease used for the pinion shaft had turned into a very thick gum and had rolled up into little balls. It was so thick that it had to have caused significant drag on the motor IMO. On the other hand the green grease used for the worm gears was still smooth and lightly tacky.
    DSC05673.jpg
     
    Last edited: Dec 13, 2011
  4. Kernal

    Kernal

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    New window motors work better than old

    Got the new window lift motor connected to the regulator and it was able to fully wind the regulator up (that's moving in the glass down position) against the tension of the coil spring, and drew a max of 2.74 Amps. Moving in the glass up direction (with the help of the spring unwinding) it only drew 2.4 Amps. Comparing this to the original 16 year old Toyota window lift motor which was unable to fully wind up the regulator (no glass, out of vehicle) even after servicing the motor. The difference was easily apparent as the old motor struggled and stopped, the new motor just kept on moving. Before I took the old motor out of the door it had been sounding "growly" and once I had it out I could more easily hear the growl and see the motor struggle against the spring tension of the regulator. I think maybe the reason it was able to bring the window down against the spring tension of the regulator when installed was due to the weight of the glass helping it push down??

    What I've learned from my own experience and tests along with reading about every window thread is the obvious: old window motors don't work as well as they did when they were new. Best guess is due to a combination of weak magnets, worn cummutators, worn brushes, thick dry grease, loosening of tolerances, ---.

    IME my slow window was from a combination of a weak motor, dry regulator, dry rubber runs, and over time it all adds up. After the motor IME I would put the lack of fresh grease on the regulator moving parts. After I greased all the moving/friction points of this regulator while it was still in the door the window did go up quicker with the old motor.

    Some tips I learned: when removing and reinstalling the motor from the regulator place a bolt, screwdriver, or pin of some sort in the spring loaded plate to keep it from taking your fingers off. It is very difficult to reattach the motor to the regulator unless you pin the plate first. Also position the motor in the middle of the regulator as shown in the photo below when you put it back on. Not sure if it makes a difference while the regulator is out of the door but got that tip from both a Toyota collision tech and an auto glass installer.

    Top photo shows the Amp draw of the new motor while winding up the regulator (down direction). Bottom photo is new motor attached to original regulator. Note the tool (staged) to hold the regulator in place while attaching the motor.
    DSC07333.JPG DSC07343.JPG
     
    Last edited: Dec 14, 2011
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  5. Kernal

    Kernal

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    I found that the Dorman front left window lift motor came with the mounting hole inserts not threaded apparently because the same motor has a few different applications. I used a Craftsman 5mm 0.80 pitch tap and some cutting oil to tap the holes which went quickly as the inserts are aluminum. Also reused the original Toyota torx head screws, and after degreasing them I applied a low strength (Loctite Purple) thread locker on the threads before installing the motor to the regulator. I did have to remove one of the screws that hold the armature tower onto the housing as it prevented the tap from going all the way down the hole, then replaced that screw when done.
    DSC07255.JPG DSC07266.JPG DSC07285.JPG
     
    Last edited: Dec 14, 2011
  6. Ebag333

    Ebag333

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    Nice write up.
     
  7. Fosters

    Fosters

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    I found just running the Toyota screws through the dorman mount holes was enough to cut its own threads
     
  8. Kernal

    Kernal

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    Got the regulator back in the door, motor runs it up and down no problem (no glass yet). I accidentally found a new method to get auto-up for the driver's side window, you just have to hook up the wires from the motor to the harness backwards. Down is up and up is down, but then of course you lose auto down. I pulled the pins out of the connector and reversed them, back to normal operation.
     
    Last edited: Dec 15, 2011
  9. DARKNESS

    DARKNESS

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    In the process of doing my pass side and unpinned the regulator out of curiosity. To my surprise it didn't snap violently. There was very little force applied by the spring. I wonder if this is the issue? There are a couple tabs the spring can be used on, I wonder if its not on the right one? Mine wasn't set up like the one in Kernal's picture but its the Pass side so maybe its different. If I set it up to look like Kernal's the spring applies alot more force. Anyone got a pic of the pass side regulator set up?

    Came out of the door like this: Regulator 2.jpg

    I think maybe this is how it should go:

    Regulator 1.JPG
    The first one would barely scratch your finger if it got caught. The second would cut it pretty good.
     
    Last edited: May 15, 2015
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  10. rolliges

    rolliges

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    So, did tightening the spring make the window close faster?
     
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  11. DARKNESS

    DARKNESS

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  12. blkprj80

    blkprj80 SILVER Star

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    @DARKNESS I think the spring holding tab has a "hook" to help hold the spring. The way you hooked it, could it slip off?
    I saw your post about water in your linked writeup. Damn, that looked bad. Is that because the Dorman isn't well sealed? I'm worried...
     
  13. DARKNESS

    DARKNESS

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    Maybe but its been like 2 years and it seems fine.

    I think so, I just sealed the crap out of the new one. May have gotten a bad one.
     
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