Experiencing a frustrating jerky acceleration in your Mercedes, particularly after switching to a manual transmission? You’re not alone. Owners of classic Mercedes models who have opted for a manual swap, or even those with original manual transmissions, sometimes encounter a perplexing issue: a noticeable chugging or surging sensation, especially in lower gears and during light throttle inputs. This behavior can detract from the smooth and refined driving experience Mercedes vehicles are known for. Let’s delve into a real-world scenario and explore potential causes and solutions for this issue in Mercedes Manual Transmission Cars.
One owner of a 1985 Mercedes 190D 2.2, who retrofitted a manual transmission from a 1987 190D 2.5, reported precisely this problem. They described it as a back-and-forth motion, most pronounced in 2nd and 3rd gear, and exacerbated when engine power is minimal – such as when approaching intersections, cresting hills, or even when using cruise control. Careful and deliberate throttle control could minimize the effect, but the underlying issue remained.
To investigate, this owner meticulously checked for drivetrain backlash. By jacking up a rear wheel and measuring movement at the tire circumference, they quantified the backlash across all gears. The results indicated increasing backlash as gear ratios increased, from 1 inch in 1st gear to a significant 3.5 inches in 5th gear. Reverse gear showed the least backlash at 0.75 inches. Initially suspecting the clutch or front of the transmission, a closer inspection followed. Dropping the transmission revealed considerable play in the clutch disk itself – approximately 3/4 inch at the circumference. A new clutch disk was installed, but unfortunately, the jerky acceleration persisted with almost identical backlash measurements.
This detailed troubleshooting process eliminated the clutch disk as the primary culprit and suggested that the backlash might be inherent elsewhere in the system. The owner, an engineer by profession, theorized that the issue could stem from a feedback loop within the car’s control system. This loop encompasses the driver’s foot, accelerator linkage, injection pump, engine, clutch, transmission, drivetrain, wheels, and the driver’s perception of speed – all influencing each other. While the transmission, clutch, and drivetrain were investigated, the root cause remained elusive.
Comparison with other manual transmission vehicles, including a 1987 Caravan 5-speed and a 1983 Mercedes 240D 4-speed, revealed similar backlash measurements. However, these other vehicles did not exhibit the same jerky acceleration issue. This observation further complicated the diagnosis, suggesting that backlash alone might not be the sole determinant of this behavior in mercedes manual transmission cars.
If you are experiencing similar symptoms in your Mercedes manual transmission car, especially after a transmission swap or in older models, understanding this detailed case study can be a valuable starting point. Contributing your experiences and insights could help identify common threads and potential solutions within the Mercedes-Benz community. Have you encountered and resolved this issue? Your knowledge could be crucial in helping others enjoy the smooth and responsive driving experience that a well-sorted Mercedes manual transmission car should offer.
