The manual transmission in your 2020 Impreza should shift smoothly through all gears. Grinding when shifting indicates something isn't synchronizing properly—either the clutch isn't fully disengaging or the synchronizers are worn.
How Manual Shifting Works
When you press the clutch, it disconnects engine from transmission. Synchronizers then match the speed of the gear you're selecting to the input shaft. When everything works, shifts are smooth. Grinding means speeds aren't matching.
Grinding Patterns and Causes
Grinding into specific gears:
- Usually synchronizer wear for those gears
- 2nd and 3rd are most common wear points
Grinding into all gears:
- Clutch not fully disengaging
- Low transmission fluid
- Hydraulic clutch issue
Grinding only when cold:
- Fluid viscosity issue
- Synchro wear more apparent cold
Common Causes
- Worn synchronizers - Can't match gear speeds smoothly
- Clutch not disengaging - Hydraulic issue or wear
- Low/wrong gear oil - Inadequate lubrication
- Shift linkage wear - Prevents complete engagement
- Clutch hydraulic air - Incomplete clutch release
Diagnostic Steps
- Check if clutch fully disengages (try shifting with engine off)
- Check clutch hydraulic fluid level
- Verify correct transmission fluid type and level
- Note which specific gears grind
- Does double-clutching help? (suggests synchro wear)
Double-Clutch Test
If you clutch-neutral-clutch-gear and grinding improves, synchros are worn. The extra neutral step lets input shaft slow naturally.
Repair Costs
- Clutch hydraulic bleed: $75-$150
- Gear oil service: $75-$150
- Slave cylinder: $200-$400
- Clutch replacement: $800-$1,500
- Synchronizer rebuild: $1,500-$3,000