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Prius Differential vs Transmission?

Discussion in 'Gen 4 Prius Technical Discussion' started by pnw_jk, Feb 22, 2022.

  1. pnw_jk

    pnw_jk New Member

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    I'm thinking of changing out of my Prius's transmission and differential fluids and have been watching some videos about this and got a bit confused.

    Does the Prius transmission and front differential use the same fluid reservoir? Also, is there a rear differential that I should be looking at to change the fluid of?
     
  2. Mendel Leisk

    Mendel Leisk Senior Member

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    There’s just one “transaxle”, here’s some info on fluid change (attached). You basically raise AND level the car, drain, then fill till it starts coming back out.
     

    Attached Files:

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  3. pnw_jk

    pnw_jk New Member

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    Perfect!! Thank you so much. Where do you get the PDF for these things?

    Also do you know what part number I would need for the drain plug gasket? off topic, but would it be the same gasket for the inverter and engine coolant drain plugs (if this car even uses drain plugs)?
     
  4. jerrymildred

    jerrymildred Senior Member

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    There is no rear differential in a front wheel drive car. As @Mendel Leisk pointed out, it's a simple drain and fill once you have the car up on jack stands and level.

    That's because the Prius "transmission" is not even remotely similar to a traditional automatic transmission except that it varies the ratio between engine speed and wheel speed. How it accomplished that function is pure genius. Here's a video that shows how it works.


    Here's one on changing the transaxle fluid on a Gen 3. Gen 4 is essentially the same.
     
  5. Mendel Leisk

    Mendel Leisk Senior Member

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    If you pick up the Toyota ATF WS and washers at dealership parts department, they can figure that out.
     
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  6. ColoradoBoo

    ColoradoBoo Senior Member

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    Yep, no rear differential unless you have an AWD model. Probably the hardest thing about the job is removing and replacing the under body covers....good grief!! (Come on, Toyota...use 10 mm bolts on EVERYTHING and stop with the 10-different types of plastic fasteners!!!) I have different colored electrical tape and will mark them when removing..makes reassembly a lot easier.
     
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  7. alanclarkeau

    alanclarkeau Senior Member

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    Hmmm - try a '70s VOLVO. Some bolts in Metric, some in imperial.
     
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  8. ChapmanF

    ChapmanF Senior Member

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    I had a 1984 Bronco II (German engine, Canadian body, Mazda transmission, Borg-Warner transfer case).

    Pretty much all the fasteners were metric. Just not the ones joining the tranny to the transfer case.
     
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  9. Elektroingenieur

    Elektroingenieur Senior Member

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    The PDF appears to have been created from an older version of the Repair Manual (more info) that was available by subscription to techinfo.toyota.com. (Today, of course, you’d get access to the latest version.)
    See my previous posting.
    There are drain cocks. The packing can be replaced (see catalog Figure 16-03, Radiator & Water Outlet, part name code 16400F, part number 16492-21050), but this isn’t required every time, as it might be for a plug.
    For step-by-step instructions, the Repair Manual is far more reliable than most of the videos I’ve seen, mainly for the reasons @ChapmanF discussed in this posting.
     
  10. pnw_jk

    pnw_jk New Member

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    The PDF says that I should drain and refill the transmission twice. Is that necessary?

    Mainly looking at this:
    (k) Repeat steps [#1] to [#10].
    (l) Repeat steps [#1] to [#3]​
     
  11. Jburner

    Jburner Member

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    My kids sidewalk chalk is my go to on that one.
     
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  12. Mendel Leisk

    Mendel Leisk Senior Member

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    Never noticed that; seems a terrific waste. I would just do one time.
     
  13. BiomedO1

    BiomedO1 Senior Member

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    Old style automatic transmissions with a torque converter, would require this - if you want to get to a 90% fluid change. Doesn't really apply to this CVT. Some old-timer engineer must've wrote those specs. LoL.
     
  14. Mendel Leisk

    Mendel Leisk Senior Member

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    3rd gen Repair Manual instruction says nothing about double drain-and-fill. Maybe the new rational is that since the fluid is "lifetime", a fluid replacement would only be needed if there was contamination, say someone accidentally added motor oil. Then a double, or even triple, drain-and-fill would be more warranted. Doubly so with a conventional automatic, where you only drain about half. The Prius transaxle you get upwards of 90% if I'm not mistaken.
     
  15. jerrymildred

    jerrymildred Senior Member

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    The double drain & fill would be appropriate if someone put in the wrong fluid and you wanted to get out as much as you could. In fact, I might do it three times in that case. Otherwise, once is fine.
     
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  16. 2004priusgal

    2004priusgal Junior Member

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    might u have link to that video?
     
  17. jerrymildred

    jerrymildred Senior Member

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    Just right click the video and select the appropriate option in the pop up menu.

    Screenshot 2023-01-19 at 7.29.13 AM.jpeg
     
  18. 2004priusgal

    2004priusgal Junior Member

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    got it, thanks! very interesting!