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Thread: No Lumbar, can be a easy fix!

  1. #31
    lefaudio is offline Cadillac Owners Member
    Automobile(s): 2007 SRX
    Join Date
    Feb 2013

    Re: No Lumbar, can be a easy fix!

    The 1/4" bolt does the same job as the broken off plastic head. it positions and prevents the screw from wandering out of the channel, which moves the motor out of its mount. The black plastic lumbar screw rotates on the 1/4 bolt, but there is enough slop to keep it from binding. The nut and washer on the bolt keeps the screw from traveling out of the motor. Good luck.

  2. #32
    swips88 is offline Cadillac Owners Member
    Automobile(s): 2008 SRX
    Join Date
    Nov 2012

    Re: No Lumbar, can be a easy fix!

    Thanks lefaudio for the images and your bolt fix method. i did a variation of this with our 2008 SRX. Had car in local auto shop and asked them to repair. Apparently they were not to familiar with the workings and just pushed motor back into its cradle. They even missed the fact that leadscrew that moves lumbar mechanism was broken! After getting car back from them a week later it stopped working again of course.

    After searching on this forum I found this thread and decided I should fix it myself since my wife is very uncomfortable without this feature.

    I removed seat back - see images - anchored by three automotive trim style push pins and two hooks at bottom of panel. Also two small nipples at sides where panel extends toward lower side of seat. Pull top part out carefully first then lift up to release from bottom hooks


    Rather than wrestling entire lumbar mechanism from its anchor points on seat frame I decided to try fixing in place. If removing it is much easier to remove inboard side by reaching in and pushing away seat foam to release clip and twist the plastic part off the metal seat frame. The outboard side is much more difficult to get your hand into to do likewise. This where I gave up trying to remove the assembly.

    You could still use lefaudio method and cut off the nipple that leadscrew idles on and drill the hole while in place however I have access to a metal lathe and decided to just make a small part to repair leadscrew where it is broken.

    I removed the broken plastic leadscrew. Turned a smooth square face on the end where it was broken. I used a piece of bronze to machine a new end that fits inside the center hole of plastic leadscrew. The actual ID of the leadscrew is 0.315" about 5/16". The end of leadscrew rotated in the nipple part of lumbar meachanism - this is part lefaudio cut off to replace with a 1/4" bolt. My bronze part did not require any cutting of this nipple since it just replaces the broken head of plastic leadscrew but engages the leadscrew through center hole of leadscew. The bronze part does not need to be anchored to plastic leadscrew since it does not serve any purpose other than an idler support for leadscrew. I made the part that protrudes into the hole of the plastic leadscrew a slight interferance fit so that it idles spins on the nipple instead of spinning on ID of leadscrew. Not that it matters any, like bolt method. The driven end of leadscrew was not broken and should not be broken on most of these repairs. The leadscrew actuates threaded section - nut - of black part in lumbar assembly to compress the white accordion section.


    It is about a 15 minute job on a metalworking lathe to make this part. So if you have ability to do this i recommend this as quickest method of repair. I neglected to anchor motor on bottom or shaft end as lefaudio mentions but it is recommended since I noticed when lumbar motor is fully disengaged motor noticeably pulls away from mounting cradle on bottom - shaft end.

    There is no mechanism to prevent over-torquing at end of stroke and I see this a failure of design combined with the weakness of the leadscrew - a very small cross section of plastic material when considering the 5/16" hole for idler pin. This is the weakest link which breaks when lumbar button is held down even a short time after motor has reached end of stroke.

    I recommend saving lumbar position as seat memory as mentioned by another poster here. I do not recommend saving lumbar in memory at a position all the way at either end of stroke. Also remember to only adjust your lumbar a small variation from saved position since actuating to end of stroke creates over-torque on a few components.

  3. #33
    Burstwurst is offline Cadillac Owners Member
    Automobile(s): 2008 SRX
    Join Date
    Mar 2017

    Re: No Lumbar, can be a easy fix!

    I had this issue with my driverís side lumbar support and was able to make a full repair. In my case, there were no broken parts, the issue was the small worm gear and bearing having slipped out of itís retaining clips on the gear housing. The worm gear only keys onto the motor shaft if it is fully onto the shaft. I could see that the bearing at the end of the worm gear was not retained by the two white plastic ears/clips intended to hold it fully onto the shaft. To make the repair, I did the following :

    - Remove the seat back
    - Cut the zip tie that holds the motor to itís frame.
    - Pull the motor out, disengaging the spline from the jack-screw that tensions the lumbar strap.
    - Remove the black insert that engages the jack-screw (activating the lumbar control before removing the gear housing will eject the insert)
    - Remove the white plastic gear housing from the motor (2 small screws)
    - With a small screwdriver, pushing against the worm gear, away from the motor, push out the worm gear and bearing.
    - Now, with the gear housing removed, push the worm gear onto the shaft fully. If fully engaged, it should go all the way, leaving no exposed shaft. In my case it was shy by about an eighth of an inch and therefore not engaging the spline. Rotate the gear relative to the shaft to align the spline, then tap the bearing to fully seat the worm gear onto the motor shaft. Now, remove the worm gear again. (This is just to knock the junk out of the spline interface to assure easier assembly in the next few steps.)
    - Replace the white gear housing.
    - Now the tricky part : Insert the worm gear into the gear housing. It is a trial and error operation aligning the worm gear onto the motor shaft. When it goes in far enough to allow the ears/clips to capture the bearing youíll know itís fully seated with the spline engaged.
    - Replace the black insert (gear mating with the worm gear)
    - Re-engage the black insertís spline with the jack-screw and snap the motor into place. I noted during disassembly that my motor was not fully seated at the bottom. This turned out to be important as when properly seated, the gear housing fits into the assembly in a way that backs up the ears/clips and prevents the ears/clips that retain the bearing from opening and allowing the bearing and worm gear from again coming out of place.
    - Finally, secure the motor with a new zip tie.
    - Close up the seat back and enjoy a much more comfortable and adjustable lumbar support in your seat!

    My lumbar is now working properly, but, I certainly plan to avoid taking it all the way to the stops at either extreme to prevent another failure.

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