|Mercruiser Sterndrive Information|
Rebuilding your Alpha One Lower Gearhousing Assembly.
Most "Do-It-Yourselfer" customers would not attempt to rebuild an Alpha lower. The special tools required to do this job right are expensive.
Extreme accuracy is required to build a drive that will last. The gears are spaced apart with the use of shims behind the bearing races. Precise measurements must be taken to insure exact clearances and one small error can destroy a new gearset.
We suggest that you purchase a Service Manual before attempting such a repair. Even our most experienced Merc techs still refer to the manual when building a drive.
There are a lot of internal parts in an Alpha lower. Roller bearings, shims, seals, washers, gears and shafts must all be kept in neat order as so you can keep track of the procedures that you are doing.
Use a good size work bench with large trays to place your parts in. It's good to have a "dirty parts" tray and a "clean parts" tray.
The work space needs to have a large vise, a stand to place the drive in, a hydraulic press and a parts washer.
It must be well lit and we recommend a good compressor with an air gun and air tools.
Make sure your shop area is CLEAN. Have all debris removed from the benches and floors.
Have an oil pan to catch an dripping oil of greasy parts. Keep a good supply of lint-free towels near by.
The Right Tools
You can not build the drive without the right tools.
Below is a list of tools required to build an Alpha One lower.
Backlash Indicator Rod 91-53459
Bearing Carrier Retainer Wrench 91-61069T
Bearing Preload Tool 91-14311A04
Belleville Washer 12-54048
Dial Indicator 91-58222A1
Dial Indicator Holding Tool 91-89897
Drive Shaft Nut Wrench 91-56775T
Drive Shaft Tapered Bearing Driver 91-87119 Included with 91-31229A7
Driver Cup 91-34379T
Driver Cup 91-36577T
Drive Shaft Bearing Retainer Tool 91-43506T
Needle Bearing Driver 91-33491
Oil Seal Driver 91-31108
Oil Seal Driver 91-44110
Pinion Gear Shimming Tool 91-56048T
Pinion Nut Adaptor 91-61067A3
Puller Bolt 91-85716
Puller Jaws (order 2) 91-46086A1
Shift Shaft Bushing Tool 91-31107T
Slide Hammer Puller 91-34569A1
Torque Wrench - Lb. In. 91-66274
Universal Bearing Removal and Installation Tool 91-31229A7
Bearing Adaptor 91-15755T
Bearing Driver 91-52393T Included with 91-31229A7
Bearing Driver 91-32336 Included with 91-31229A7
Bearing Driver Rod 91-37323
Bearing Installation Tool 91-38628T
Driver Head 91-36569T
Driver Head 91-37311 Included with 91-31229A7
Driver Head 91-37312 Included with 91-31229A7
Pilot Washer 91-36571T
Pilot Washer 91-37324T
Pilot Washer 91-37350T
Puller Head 91-36379 Included with 91-31229A7
Puller Rod 91-37229 Included with 91-31229A7
Puller Rod Head 91-32325T
Roller Bearing Removal and Installation Tool 91-37292
Puller Rod 91-52394 Included with 91-31229A7
Universal Puller Plate 91-37241
Guide Plate 91-816243
Bearing Cup Installation Tool 91-18605A2
Shift Shaft Tool 75104A7
We also recommend the Heavy Duty Carrier Puller (see below)
This tool is the best way to pull the carrier.
Trying to build an Alpha lower without even one of the above tools is almost impossible.
We also recommend a Pressure Tester to pressure test the drive after it is assembled. Pressure checking the drive is a very important part of the assembly procedure. Time and time again we find leaks in newly assembled drives.
As mentioned above, you will need some sort of drive stand. We use a drive stand made by Bob Kerr Tools. A complete Bob Kerr drive stand can cost well over $500.00. The stand is nice because you can rotate the drive into different positions. Otherwise, we have seen customers cut a "vee notch" in a work bench to slide the drive into. Whatever you use, it has to hold the drive FIRM and be strong.
You will be torqueing the rear cover nut to 250 ft lbs. so it needs to be right.
You will also need a good set of standard sockets, wrenches and screwdrivers, dead blow hammer and a long .025" feeler gauge.
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