'91 500 SL ... power seat problems...
The electric motor that drives the seat's fore and aft movement connects via a flex rod to a "transmission" that is responsible for actually moving the seat. The transmission "failed" ... upon disassembly it was found that the flex rod connects to a spiral cut driveshaft via a hard plastic (nylon?) gear. The gear had cracked into two pieces and thus no power was being transmitted to the driveshaft; otherwise the transmission was flawless. The gear can easily be replaced.. if only it was available. M-B offers no repair parts for this transmission; cost for a new assembly is over $400.
Same situation for the seat's power head rest... the head rest motor drives a cable which in turn connects to a theaded rod assembly carrying the head rest. The metal threaded rod contains a plastic gear at the top.. and the gear has cracked and no repair parts are available from M-B.
Is there an alternate source for these gears?
I've contacted Odometer Gears Ltd (
www.odometergears.com) and he's willing to have a go at this. However, there remains the question of strength... the seat travel gear must be capable of bearing the weight of an adult... and if his standard issue gear is too weak/soft, he states an injection molded process would be required. The mold for such could cost >$5K and the lead time might approach 2 months.
Any suggestions?