🚗 Classic Fault — Mercedes-Benz W115 (1968–1976)
Gearbox synchromesh wear — 2nd and 3rd crunch
💰 Estimated Repair Cost
$200 – $600 USD
Parts and labour estimate
🔧 Tools Required
Gearbox overhaul tools
📋 Overview
The 4-speed manual gearbox synchromesh rings wear with age. Second and third gear are most affected. The crunch is worse when cold or when changing down at higher RPM.
🩺 Symptoms
- Crunching or grinding into 2nd gear
- worse when cold
- double-declutching eliminates crunch
🔍 Possible Causes
- Worn 2nd and 3rd synchromesh rings
- incorrect gear oil viscosity
- baulk ring wear
🛠️ Diagnosis Steps
Attempt smooth 2nd gear change when cold — crunch confirms synchro. Try double-declutch — if crunch disappears it is synchromesh rather than selector.
✅ Most Confirmed Fix
Gearbox overhaul replacing synchromesh rings. Ensure correct gear oil specification.
66% of users confirm this fix worked (11 reports)
🏷️ Parts Needed
Gearbox synchromesh ring set
🔗 Other Mercedes-Benz W115 Faults
Own a Mercedes-Benz W115?
Share your experience with this fault — or report a different issue. Your knowledge helps other classic car owners worldwide.