Date registered: Jan 2018
Vehicle: 1988 560 SEC
Location: Hutto Texas, USA
Mentioned: 6 Post(s)
Quoted: 73 Post(s)
Last weekend I got around to installing a set of gears in my driver side extender. Below are some before and after pictures. There are two gears, the smaller fully exposed gear is the drive motor gear and the other is the extender arm push/pull gear. I wanted to replace both even though the motor gear looked good. Once I got everything apart, I could not get the new motor gear to go on the motor shaft. I know the splines were lined up correctly as it would slip almost half way down but stopped. If I pushed on it I could feel the plastic of the gear expanding so I did not force it as I did not want to break it. Since the original motor gear was in excellent shape, I re-installed it. Getting the large C-clip back on the gear requires you to remove the back cover of the motor and push up on the large gear in the motor's gear box so the shaft exposes the slot for the C-clip. There is no way around this since the shaft sinks in to the motor's case if you push down on it. My apologies for the lack of pictures. If I do the passenger side I will certainly take more.
Two mistakes I made were, I did not measure the distance of the spring before I loosened it so I could ensure it was re-tightened to the same length when re-assembled. I also did not take any measurements regarding the micro-switch. During re-assembly I simply "eye-balled" it which I am sure is not the way it was done at the factory. There was no evidence of any type of grease on the gears do I did not place any on them. Was this a mistake? Only time will tell.
The verdict, my extender works again... sorta. There are two micro-switches, one that is easily seen and one on the back of the arm assembly. These need some fine tuning and performing "trial and error" work is cumbersome as I feel you need the tension of the seat belt being pulled out to ensure it is working properly. Mine sometimes can't make up its mind where it wants to be. It works 100% of the time about 1 out of every 4 operations. This is probably a combination of the relay box and micro-switches. My personal conclusion, if I take it apart again I may just un-plug the relay box so the motor does not run and the extender stays in the panel. The reasoning for this is, if they get stuck in the extended position you either need to cycle the accessories setting on the key and work the seat belt to get it back in. If you are unsuccessful, the extended arm is a liability as you risk running in to it and breaking it while exiting or re-entering the vehicle.
Take my personal experience and thoughts for what you will. I am a big proponent for having all equipment working as it should, especially items that are unique to a particular vehicle. However, its a lot to go through for something that in my opinion, adds little value to the driving experience.