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Harsh downshift when warm/coming to complete stop

Discussion in '3rd Gen. Tacomas (2016-2023)' started by KansasTRDSport, Dec 31, 2023.

  1. Dec 31, 2023 at 11:48 AM
    #1
    KansasTRDSport

    KansasTRDSport [OP] New Member

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    TRD Sport
    I know, another transmission thread. I’ve scoured this forum and the internet but now want to ask what everyone thinks. After my 2019 TRD Sport 75k miles is warmed up (normal operating temp), I have a hard shift while coming to a stop, always 1st gear and on downshift, normal complete stop. It NEVER does this when cold (before normal operating temp) nor while slowing down and making a turn. Just a full stop. This is not (I believe) axel wrap nor the slip yoke. If I approach a stop and put it in neutral while coasting, it never has the harsh shift. The shifting (up and down) is smooth other than the final downshift into first gear. It doesn’t matter if I’m in shift mode or not, it still does it. Now, what have I done? This has been doing this with the factory fluid so I decide to change the fluid to see if that would correct it. I did it exactly as the manual stated (temp check mode included) and calculated I was a half quart low from the factory. The truck drives beautifully after change, except the harsh downshift to first gear is still there but not as bad though. I feel it did get better after the change and adding the extra half quart. No check engine light ever, no tune, no TCM reset. Any ideas?
     
  2. Dec 31, 2023 at 12:05 PM
    #2
    TacoMamba35

    TacoMamba35 Well-Known Member

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    My 2018 did this. The shift would be hard enough to make the driveline clunk.

    This symptom did not carry over in my 2021. I attributed it to the updated shift logic and/or updated ECM/PCM.
     
  3. Apr 17, 2024 at 5:05 AM
    #3
    KansasTRDSport

    KansasTRDSport [OP] New Member

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    So, I’ve solved my problem. Thanks for all those that replied and helped (sarcasm). For those that need help, here’s what fixed it. Read my OP. After all that, I still had a clunk at stop and stop only (my truck has 75k on it, clunk started at about 65k). I had read about greasing the slip joint but my clunk felt more forward (the slip yoke is more towards the rear). As a last resort, I removed the driveshaft at the slip yoke and greased the hell out of it and put it back together. It’s been 1k miles and it downshifts beautiful.
    Grease that slip joint. Simple as that for me.
     
    Chew likes this.
  4. Apr 17, 2024 at 11:24 AM
    #4
    M85

    M85 Well-Known Member

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    Do you have to do anything special to take apart the slip yoke, or does it just come apart when you remove the driveshaft? I am getting occasional clunks, but I haven't figured out a pattern of when it occurs yet. On my 4Runner, greasing the slip yoke (which has grease zerks) fixed a similar problem.

    Have you had the transmission software update TSB done? I just had it done on Monday, and it seems better on acceleration. I haven't gone on a long highway drive yet to see if gear hunting is reduced. No idea if it helps the downshifting issue you had, but TacoMamba35 suggests updated shift logic might help.
     
  5. Apr 17, 2024 at 12:25 PM
    #5
    KansasTRDSport

    KansasTRDSport [OP] New Member

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    To remove the driveshaft (assuming the 4Runner is like my 2019 Tacoma), jack the rear end up and BLOCK the front tires! Once you disconnect the driveshaft the vehicle could ROLL! Mark the driveshaft at the rear axle so it goes back on the same way! Remove the clamps holding the dust cover/accordion looking boot, remove the 4 bolts at the very end of the driveshaft where it attaches to the rear axle (those are torqued TIGHT!), slide the driveshaft towards the rear. I greased the splines (male end) and the female end with red and tacky grease and a lot of it. Reassemble. The splines (male end) only go in one way (one spline has a wider than the other gap). Slide it in, put rear of shaft on rear axle and line up just as before, put bolts in and torque to specs. This fixed my problem. By the way, the Tacoma does not have a zerk for the slip joint (and none on the u-joints either). It’s gonna take a lot of pumps to get in enough grease to what I’d say you need. There are no seals (a least on mine) so i don’t believe you’ll blow anything out. Try that before you remove it. Also, I did change the fluid in my transmission and was going to anyway. The problem was still there after the fluid change. There are several YouTube videos on the process, maybe watch a few of those first.

    The TSB? I don’t know. My truck has really never been in the shop. Maybe a few recalls, I trust they did what needed to be done. Does the 5 and 6 gear hunting bother me? Not really. I just put it in “S” and select the gear I want when it’s an issue. But, that was my next step if this didn’t work. How did I come to the conclusion that my issue was the slip joint/yoke was….when approaching a stop I shifted into neutral and coasted and I never had a problem with the clunk. My thought was when it was still spinning and under pressure it would release (rough) at final stop. I don’t know, Plus, I was having zero issues on anything. Just a clunk when coming to a completed to. Slowing down to turn but not coming to a stop, never any issues.
     
    Last edited: Apr 17, 2024
    Elvira2018 likes this.
  6. Apr 17, 2024 at 12:50 PM
    #6
    M85

    M85 Well-Known Member

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    Colorado
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    Thanks for the write up. To clarify I had (actually still have, but am in the process of selling) a 2007 4Runner. I just bought a 2019 Tacoma. The 4Runner had a clunk when I bought it, but grease fixed it. Now I need to work on the Tacoma's clunk.

    The front 4WD driveshaft on my Tacoma does have grease zerks, and from what I've read it sounds like they phased them out sometime in 2019. I greased them probably for the first time ever at 128k miles, and the old grease that came out was broken down, runny and black.
     

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