Location: Campbelltown NSW
Posts: 1,864
Club: M.A.L.A.K.A.S.
Car: 2020 AMG GT C
need a sanity check here.
This is the 847th cruise actuator gear thread since 2008. I have counted. Stickied so the next time someone PMs me asking, I can link this.
That cream-coloured plastic gear inside the opened VDO cruise actuator. That is the part you mean. The actuator on these old Mercedes cruise systems is a sealed box containing a small DC motor, a solenoid, a position feedback potentiometer, and three internal gears. The thing that fails is one of the gears.
What you can see in there is the transmission gear (the big cream one on the left), the drive gear (the small white one top right), and the arm gear (the quarter-circle one bottom right that swings the throttle linkage). On W123 and W126 actuators the failure pattern is the same every time. The retaining or return springs let the gear plate stop meshing properly. Gears slip teeth. Cruise stops holding.
External unit is the VDO / Mercedes cruise control actuator at the throttle linkage. Common part number is Mercedes 002 545 86 32 (also seen as MB-0025458632). Fits R107 / C107, W123, W124, W126 depending on year and engine. Cross-check before you buy.
Three options to fix it.
(a) Print one in PETG. Files on Thingiverse and Printables, search "Mercedes cruise actuator gear". Free. Lasts 10 years if you use the right infill (30% gyroid). A bloke called Ralf in Hamburg has the best file. Search his name.
(b) Buy one from Mercedes-Benz Classic Centre Stuttgart for about $80. Quality OE plastic. Lasts forever. Slow shipping.
(c) Replace the entire cruise actuator with a known-good unit from a wreck. About $180 from a parts car at the right yard. Overkill if only the gear is dead but the rest of the actuator is also 40 years old so why not.
That is the answer. Stop asking. Search "cruise actuator gear" in the search bar above. 846 prior threads have the photos, the part numbers, and the print settings. The 847th thread you were about to post is in there too.
- V
