23370773 Gear Housing Kit | Genuine Volvo Penta Part

🔧 Product Description

A genuine Volvo Penta complete lower gear housing assembly for selected 120S saildrives with a nominal 2.20:1 reduction ratio. The kit replaces the earlier complete lower-unit reference and is supplied as an assembled ratio-specific gear housing rather than as a loose gasket or bearing set.

⚙️ Key Features

• Complete genuine Volvo Penta lower-unit assembly
• Nominal 2.20:1 reduction ratio
• Designed for the 120S saildrive family
• Factory-set bearing and gear alignment
• Replaces earlier complete lower gear 3817150
• Engine type: Volvo Penta 120S saildrive lower gear housing
• Also supersedes Volvo part number 873107

📋 Kit Contents

• 1 x complete assembled lower gear housing / lower gear unit - Volvo Penta 23370773
• Ratio-specific vertical shaft, propeller shaft, bevel gears, bearings and internal seals are integral to complete assembly 23370773
• Internal components are supplied as part of the complete assembly and are not separately itemised under this kit

🔌 Function

The lower gear housing turns vertical input rotation through the bevel gear set and transmits it to the propeller shaft while supporting the shaft bearings and containing gear lubricant.

⚠️ Common Signs of Failure

• Housing is cracked or heavily corroded
• Gear oil contains metal or seawater
• Propeller shaft or bevel gears are damaged
• Lower unit produces abnormal gear or bearing noise
• Existing complete unit carries earlier reference 3817150

🛠️ Service Notes

• The drive has to come off for this, so plan for the drive oil to be drained and for the seals, gaskets and bellows disturbed by the job to be renewed
• Transfer or renew the internal parts exactly as the workshop manual for your drive directs, and set bearing preload and gear position using its measuring procedure rather than by feel — this is the part of the job that decides whether the drive lasts
• Check every mating face and seal seat is clean and undamaged, and use only the lubricants and sealants specified for that drive
• Pressure and vacuum test the assembled housing before the boat goes back in the water, then fill with the correct drive oil to the correct level
• Confirm the kit matches your drive model and serial number before starting, as housings and their gear sets are not interchangeable between drive types

🔄 Supersession & Cross Reference

OEM Supersession Chain

• 23370773 → Supersedes 3817150 → Supersedes 3583354 → Supersedes 3856833 → Supersedes 873090 → Supersedes 853555 → Supersedes 851646

OEM / Related Numbers

• 3817150 earlier number superseded by this part
• 3812349 earlier number superseded by this part
• 3583354 earlier number superseded by this part
• 3856864 earlier number superseded by this part
• 3856833 earlier number superseded by this part
• 873090 earlier number superseded by this part
• 853555 earlier number superseded by this part
• 851646 earlier number superseded by this part
• 120S upper gear and saildrive-leg components selected by serial number

📦 Condition

• Genuine Volvo Penta part
• Brand new
• Supplied in original or equivalent packaging