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MerCruiser Training Course

Sterndrives, Transom Assemblies

Technician's Guide

and Hydraulic Systems

11

Table of Contents Section 1A - Drive Unit General Information Section 2A - Alpha Drive Unit History Section 3 - Alpha Drive Unit Service

A - Alpha Drive Unit Components B - Alpha Gear Housing - Standard Rotation Unit Service C - Alpha Driveshaft Housing Service D - Alpha Gear Housing - Counter Rotation Unit Service E - Shift Cable Installation, Drive Unit Installation and Shift Setup

Section 4 - Alpha and Bravo Transom Assemblies Section 5 - Hydraulic Systems

A - Hydraulic Systems – Power Trim B - Hydraulic Systems – Power Steering

Section 6 - Corrosion Protection Section 7A - Bravo Drive Unit History Section 8 - Bravo Drive Unit Service

A - Bravo Drive Unit Components B - Bravo Driveshaft Housing Set Up - Earlier Models (Serial Number

0M198372 and Below) C - Bravo Driveshaft Housing Set Up - Later Models (Serial Number

0M198373 and Above) D - Bravo One Gear Housing Setup E - Bravo Three Gear Housing Setup F - Bravo Shift Cable Installation, Drive Unit Installation and Shift Setup

Section 9 - Service Literature

A - Alpha Reference Materials B - Transom Assembly and Hydraulic System Reference Materials C - Bravo Reference Materials

MC Alpha Drives Course Worksheets and Homework MC Transom Assemblies and Hydraulic Systems Course Worksheets MC Bravo Drives Course Worksheets and Homework

22

Drive Unit General Information

90-899907001 JULY 2006 Page 1A-1

Drive Unit Information

Section 1A - Drive Unit General InformationTable of ContentsMerCruiser Engine/Drive Model Year Reference Chart..................................................................................2Alpha U-joint Splined Yoke Identification..................7Bravo U-joint Splined Yoke Identification .................8Calculating Overall Drive Unit Ratios......................10Alpha Drive Unit Gear Tooth Counts and Related DriveRatios......................................................................10Bravo Drive Shaft Housing Gear Tooth Counts andRelated Drive Ratios (Model Year 2000 and Later)................................................................................11Sterndrive and Transmission Lube Capacity Chart................................................................................12

Gear Lube Monitors Used On Alpha and BravoModels.................................................................13

Sterndrive Unit 10-Hour Break-In Period (New or WithReplacement Gears)...............................................13Serial Number Locations.........................................13Gear Housing Pressure Test...................................14Drive Unit Rotation..................................................15Trim Tab Adjustment (to equalize steering pressure)................................................................................16MC-1 Propeller Shaft Parts Comparison.................17

Tapered Roller Bearing Diagnosis..........................17Good Bearing......................................................18Bent Cage-End....................................................18Bent Cage-Side...................................................18Galling.................................................................18Abrasive Step Wear.............................................19Etching.................................................................19Misalignment.......................................................19Indentations.........................................................19Fatigue Spalling...................................................20Brinelling..............................................................20Cage Wear..........................................................20Abrasive Roller Wear...........................................20Cracked Inner Race.............................................21Smears................................................................21Frettage...............................................................21Heat Discoloration...............................................21Stain Discoloration...............................................22

Mercury Marine Backlash Flags..............................23Bravo Shim Kit Listing.............................................24

Bravo One, Two and Three Series......................24

1 A

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Page 1A-2 90-899907001 JULY 2006

MerCruiser Engine/Drive Model Year Reference ChartUse only as a reference for determining drive model to be used with specific engine models.

Model Cu. In. Mfg. 1963 1964 1965 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976

39D 108 MCD I IA IA EZ IA EZ IA EZ

60D 139 Rov. IA EZ IA EZ IA EZ

60 67 Ren. 0" 60 0" 60 0" 60

80 89 Ren. 0" 80 0" 80 0" 80

90 95 Ren. 0" 90 0" 90 0" 90

100D 311 MCD II II II

110 153 GM I IA IA EZ IA EZ

120 153 GM IB IB EZ MC-I MC-I MC-I MC-I MC-I MC-I MC-I MC-I MC-I MC-I

140(6) 194 GM I IC IC EZ

140(4) 181 GM MC-I MC-I MC-I MC-I MC-I MC-I MC-I MC-I

150 230 GM IC IC EZ IC EZ

160 250 GM MC-I MC-I MC-I MC-I

165(6) 250 GM MC-I MC-I MC-I MC-I MC-I MC-I

470 224 MM MC-I

888 302 Ford MC-I MC-I MC-I MC-I MC-I

190(8) 283 GM II II II

200 292 GM II II

215H 302 Ford 215H 215H

215E 302 Ford 215E 215E

225 327 GM II II II II II

225S 302 Ford MC-I

225TR 302 Ford II-TR II-TR

233 351 Ford MC-I MC-I

250 327 GM III III III III

255TR 351 Ford II-TR II-TR

255TR 350 GM II-TR II-TR

255TRS 351 Ford II-TRS

270 350 GM III III III

310 409 GM II II II

315 409 GM II

325 427 GM III III III III III

390 482 GM III III

GM - General Motors MM - Mercury Marine MCD - Mercedes-Benz

Ren. - Renault Rov. - Rover

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90-899907001 JULY 2006 Page 1A-3

Model Cu. In. Mfg. 1977 1978 1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989

120 153 GM MC-I MC-I MC-I MC-I MC-I MC-I I-R I-R I-MR A

2.5L 153 GM A A A

140(4) 181 GM MC-I MC-I MC-I MC-I MC-I MC-I I-R I-R I-MR A

3.0L 181 GM A A A

530D-TA 183 VM B2

165(6) 250 GM MC-I MC-I MC-I MC-I MC-I

165(4) 224 MM A

3.7L 224 MM A A

170 224 MM I-MR A

175 262 GM A

4.3L 262 GM A A

470 224 MM MC-I MC-I MC-I MC-I MC-I MC-I I-R I-R

180 224 MM A

3.7LX 224 MM A A

636D-TA 219 VM B2

185 229 GM I-R I-R

185 262 GM I-MR A

190(4) 224 MM I-MR A

485 224 MM MC-I MC-I MC-I

488 224 MM I-R I-R

898 305 GM MC-I MC-I MC-I MC-I MC-I MC-I I-R I-R

200 305 GM I-MR A A

5.0L 305 GM A A

205 262 GM I-MR A A

4.3LX 262 GM A A

228TR 305 GM II-TR II-TR

228 305 GM MC-I MC-I MC-I MC-I I-R I-R

230 305 GM I-MR A A

5.0LX 305 GM A A

250 350 GM MC-I

260 350 GM MC-I MC-I MC-I MC-I I-R I-R I-MR A A

5.7L 350 GM A/II-TR A/B2

350MAG 350 GM A A A A

330TR 454 GM II-TR II-TR II-TR II-TR II-TR II-TR II-TR II-TR II-TR II-TR II-TR

330TRS 454 GM II-TRS II-TRS II-TRS II-TRS II-TRS II-TRS II-TRS II-TRS II-TRS II-TRS II-TRS

7.4L 454 GM B1/B2 B1/B2

370 454 GM II-TRS II-TRS II-TRS II-TRS II-TRS II-TRS II-TRS II-TRS II-TRS

454MAG 454 GM A A B1 B1

502MAG 502 GM B1

GM - General Motors A - Alpha One (R.H.) B1 - Bravo One

MM - Mercury Marine AC - Alpha One, Counter Rotation (L.H.) B2 - Bravo Two

VM - VM Motor Co. (Diesel) A2 - Alpha One, Generation Two (R.H.) B3 - Bravo Three

Nav - Navistar (Diesel) A2C - Alpha One, Generation Two, Counter Rotation (L.H.) BH - BlackHawk

MR - MerCruiser Redesigned R - Redesigned

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Page 1A-4 90-899907001 JULY 2006

Model Cu. In. Mfg. 1990 1991 1992 1993 1994

3.0L 181 GM A,AC A,AC A2,A2C A2,A2C A2,A2C

3.0LX 181 GM A,AC A,AC A2,A2C A2,A2C A2,A2C

D183-TA 183 VM B1,B2 B1,B2 B1,B2 B1,B2

D3.0L 183 VM B1,B2

4.3L 262 GM A,AC A,AC A2,A2C A2,A2C A2,A2C


D219-TA 219 VM B1,B2 B1,B2 B1,B2 B1,B2

D3.6L 219 VM B1,B2

5.0L 305 GM A,AC A,AC A2,A2C,B2 A2,A2C,B2 A2,A2C,B2


5.0 HB 305 GM

D254-TA 254 VM B1,B2 B1,B2 B1,B2 B1,B2

D4.2L 254 VM B1,B2

5.7L 350 GM A,AC,B2 A,AC,B2 A2,A2C,B2 A2,A2C,B1,B2 A2,A2C,B2,B3

5.7L EFI 350 GM B3

350 MAG 350 GM A,AC A,AC A2,A2C A2,A2C A2,A2C

350 MAG EFI/MP 350 GM

D7.3L 444 Nav. B3

7.4L 454 GM B1,B2 B1,B2 B1,B2 B1,B2 B1,B2

7.4L PT 454 GM B3 B3

454 MAG 454 GM B1 B1 B1 B1 B1

454 MAG EFI 454 GM B1


454 MAG MPI 454 GM

502 MAG 502 GM B1 B1 B1,B2 B1,B2

502 MAG EFI 502 GM B1 B1,BH


502 MAG MPI 502 GM






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Model Cu. In. Mfg. 1995 1996 1997 1998 1999

D2.8L 169 VM B1,B2,B3 B1,B2,B3 B1,B2,B3

3.0L 181 GM A2,A2C A2,A2C

3.0LX 181 GM A2,A2C A2,A2C A2,A2C

D3.0L 183 VM B1,B2 B1,B2

4.3L 262 GM A2,A2C A2,A2C A2,A2C,B2,B3 A2,A2C,B2,B3

4.3L EFI 262 GM A2,A2C,B2,B3 A2,A2C,B2,B3

4.3LX 262 GM A2,A2C A2,A2C,B3 A2,A2C,B2,B3

4.3LXH 262 GM A2,A2C,B2,B3

4.3LH 262 GM A2,A2C,B2,B3 A2,A2C,B2,B3

262 MAG EFI,Gen+ 262 GM A2,A2C,B2,B3

D3.6L 219 VM B1,B2 B1,B2 B1,B2,B3 B1,B2,B3 B1,B2,B3

5.0L 305 GM A2,A2C A2,A2C,B1,B2,B3 A2,A2C,B1,B2,B3

5.0L EFI 305 GM A2,A2C,B1,B2,B3 A2,A2C,B1,B2,B3

5.0LX 305 GM A2,A2C

5.0 HB 305 GM B2 B2 B2 B2 B2

D254-TA 254 VM B2

D4.2L 254 VM B1,B2 B1,B2 B1,B2,B3 B1,B2,B3 B1,B2,B3

5.7L 350 GM A2,A2C,B2 A2,A2C,B2,B3 A2,A2C,B1,B2,B3 A2,A2C,B1,B2,B3 A2,A2C,B1,B2,B3

5.7L EFI 350 GM A2,A2C,B1 A2,A2C,B1,B2,B3 A2,A2C,B1,B2,B3 A2,A2C,B1,B2,B3

5.7LX 350 GM A2,A2C,B2,B3 A2,A2C,B1,B2,B3

5.7LX EFI 350 GM A2,A2C,B1,B2,B3 A2,A2C,B1,B2,B3

5.7LX EFI Gen+ 350 GM B1,B2,B3

350 MAG 350 GM A2,A2C A2,A2C

350 MAG EFI/MP 350 GM B1 A2,A2C

350 MAG MPIGen+ 350 GM B1,B3,BH B1,B2,B3,BH A2,A2C,B1,B2,B3 A2,A2C,B1,B2,B3

D7.3L 444 Nav. B3 B3 B1,B2,B3 B1,B2,B3

7.4L 454 GM B1,B2 B1,B2,B3 B1,B2,B3

7.4LX EFI 454 GM B1,B2,B3

7.4L MPI 454 GM B1,B2,B3 B1,B2,B3 B1,B2,B3 B1,B2,B3

7.4L PT 454 GM B3

454 MAG 454 GM B1 B1 B1,B2,B3

454 MAG EFI/MP 454 GM B1

454 MAG MPI 454 GM B1, B3, BH B1,B2,B3,BH B1,B2,B3 B1,B2,B3

502 MAG EFI/MP 502 GM B1,BH

502 MAG MPI 502 GM B1,B2,B3,BH B1,B2,B3,BH B1,B2,B3 B1,B2,B3






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Page 1A-6 90-899907001 JULY 2006

Model Cu. In. Mfg. 2000 2001 2002 2003

D1.7L DTI (2002 -) 103 I A2,A2C A2,A2C

D2.8L D-Tronic (1997 -) 169 VM B1,B2,B3 B1,B2,B3 B1,B2,B3 B1X,B2X,B3X

D3.6L 219 VM B1,B2,B3

D4.2L 254 VM B1,B2,B3 B1,B2,B3 B1,B2,B3 B1X,B2X,B3X

D4.2LD (1999 -) 254 VM B1,B2,B3 B1,B2,B3 B1,B2,B3 B1X,B2X,B3X

D4.2L D-Tronic (1997 -) 254 VM B1,B2,B3 B1,B2,B3 B1,B2,B3 B1X,B2X,B3X

D7.3L D-Tronic (1997 -) 444 Nav. B1,B2,B3 B1,B2,B3 B1,B2,B3 B1X,B2X,B3X

D7.3L D-Tronic LD (1999 -) 444 Nav. B1,B2,B3 B1,B2,B3 B1,B2,B3 B1X,B2X,B3X

3.0L 181 GM A2,A2C A2,A2C A2,A2C A2,A2C

4.3L 262 GM A2,A2C,B2,B3 A2,A2C,B2,B3 A2,A2C,B2,B3 A2,A2C,B2,B3

4.3LH 262 GM A2,A2C,B2,B3 A2,A2C,B2,B3

4.3L EFI 262 GM A2,A2C,B2,B3 A2,A2C,B2,B3 A2,A2C,B2,B3

4.3L MPI 262 GM A2,A2C,B2,B3 A2,A2C,B2,B3

5.0L 305 GM A2,A2C,B1,B2,B3 A2,A2C,B1,B2,B3 A2,A2C,B2,B3 A2,A2C,B1,B2,B3

5.0L EFI 305 GM A2,A2C,B1,B2,B3 A2,A2C,B1,B2,B3 A2,A2C,B2,B3

5.0L MPI 305 GM A2,A2C,B2,B3 A2,A2C,B1,B2,B3

5.7L 350 GM A2,A2C,B1,B2,B3 A2,A2C,B1,B2,B3 A2,A2C,B2,B3 A2,A2C,B1,B2,B3

5.7L EFI 350 GM A2,A2C,B1,B2,B3 A2,A2C,B1,B2,B3 A2,A2C,B2,B3

350 MAG MPI 350 GM A2,A2C,B1,B2,B3 A2,A2C,B1,B2,B3 A2,A2C,B2,B3 A2,A2C,B1,B2,B3

350 MAG MPI Horizon 350 GM A2,A2C,B1,B2,B3 A2,A2C,B1,B2,B3 A2,A2C,B2,B3 B1,B2,B3

MX 6.2 MPI 377 GM A2,A2C,B1,B2,B3 B1,B2,B3 B1,B2,B3

MX 6.2 MPI Horizon 377 GM A2,A2C,B2,B3 B1,B2,B3

7.4L MPI 454 GM B1,B2,B3

454 MAG MPI 454 GM B1,B2,B3

454 MAG MPI Horizon 454 GM B1,B2,B3

496 MAG MPI 496 GM B1,B2,B3 B1,B2,B3 B1,B2,B3

496 MAG HO MPI 496 GM B1,B2,B3 B1,B2,B3 B1X,B2X,B3X, B1XZ,B1XR

502 MAG MPI 502 GM B1,B2,B3

CMD - Cummins MerCruiser Diesel MR - MerCruiser Redesigned B1X - Bravo One X

GM - General Motors A - Alpha One (R.H.) B1XZ - Bravo One XZ

MM - Mercury Marine AC - Alpha One, Counter Rotation (L.H.) B1XR - Bravo One XR

VM - VM Motor Co. (Diesel) A2 - Alpha One, Generation Two (R.H.) B2 - Bravo Two

Nav. - Navistar (Diesel) A2C - Alpha One, Generation Two, B2X - Bravo Two X

I - Isuzu (Diesel) Counter Rotation (L.H.) B3 - Bravo Three

R - Redesigned B1 - Bravo One B3X - Bravo Three X

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Model Cu. In. Mfg. 2004 2005 2006

D1.7L DTI (2002 -) 103 I CMD Product CMD Product CMD Product

D2.8L D-Tronic (1997 -) 169 VM CMD Product CMD Product CMD Product

D3.6L 219 VM CMD Product CMD Product CMD Product

D4.2L 254 VM CMD Product CMD Product CMD Product

D4.2LD (1999 -) 254 VM CMD Product CMD Product CMD Product

D4.2L D-Tronic (1997 -) 254 VM CMD Product CMD Product CMD Product

D7.3L D-Tronic (1997 -) 444 Nav. CMD Product CMD Product CMD Product

D7.3L D-Tronic LD (1999 -) 444 Nav. CMD Product CMD Product CMD Product

3.0L 181 GM A2,A2C A2,A2C A2,A2C

4.3L 262 GM A2,A2C,B2,B3 A2,A2C,B2,B3 A2,A2C,B2,B3

4.3LH 262 GM

4.3L EFI 262 GM

4.3L MPI 262 GM A2,A2C,B2,B3 A2,A2C,B2,B3 A2,A2C,B2,B3

5.0L 305 GM A2,A2C,B1,B2,B3 A2,A2C,B1,B2,B3 A2,A2C,B1,B2,B3

5.0L EFI 305 GM

5.0L MPI 305 GM A2,A2C,B1,B2,B3 A2,A2C,B1,B2,B3 A2,A2C,B1,B2,B3

5.7L 350 GM A2,A2C,B1,B2,B3 A2,A2C,B1,B2,B3 A2,A2C,B1,B2,B3

5.7L EFI 350 GM

350 MAG MPI 350 GM A2,A2C,B1,B2,B3 A2,A2C,B1,B2,B3 A2,A2C,B1,B2,B3

350 MAG MPI Horizon 350 GM B1,B2,B3 B1,B2,B3 B1,B2,B3

MX 6.2 MPI 377 GM B1,B2,B3 B1,B2,B3 B1,B2,B3

MX 6.2 MPI Horizon 377 GM B1,B2,B3 B1,B2,B3 B1,B2,B3

7.4L MPI 454 GM

454 MAG MPI 454 GM

454 MAG MPI Horizon 454 GM

496 MAG MPI 496 GM B1,B2,B3 B1,B2,B3 B1,B2,B3

496 MAG HO MPI 496 GM B1X,B2X,B3X, B1XR B1X,B2X,B3X, B1XR B1X,B2X,B3X, B1XR

502 MAG MPI 502 GM

CMD - Cummins MerCruiser Diesel MR - MerCruiser Redesigned B1X - Bravo One X

GM - General Motors A - Alpha One (R.H.) B1XZ - Bravo One XZ

MM - Mercury Marine AC - Alpha One, Counter Rotation (L.H.) B1XR - Bravo One XR

VM - VM Motor Co. (Diesel) A2 - Alpha One, Generation Two (R.H.) B2 - Bravo Two

Nav. - Navistar (Diesel) A2C - Alpha One, Generation Two, B2X - Bravo Two X

I - Isuzu (Diesel) Counter Rotation (L.H.) B3 - Bravo Three

R - Redesigned B1 - Bravo One B3X - Bravo Three X

Alpha U-joint Splined Yoke IdentificationAn identification letter is stamped on the U-joint splined yoke.This chart represents the letter stamps found on model year 2000 and newer drive units (new oruntampered with drive units). The letter stamp represents the drive unit overall gear ratio.Older (pre-model year 2000) drive units would have the U-joint yoke stamped with a letter thatrepresented the gear ratio in the driveshaft housing. Two drive units with different overall gearratios could have the same U-joint letter stamp. On these drives a technician would have to checkthe gear housing gear tooth count to determine the overall drive gear ratio.

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Page 1A-8 90-899907001 JULY 2006

Later (model year 2000 and newer) drive units have a stamped letter that represents the overalldrive gear ratio. Now two drive units could have different letter stamps, but the gear ratio in thedrive shaft housings could be the same.Service Note: When you order a service replacement complete driveshaft housing, the U-jointsplined yoke may have a different letter stamp than the one found on the unit that is being replaced.The letters used on service replacement units follow the pre-model year 2000 method ofidentification. As long as the correct replacement drive shaft housing assembly has been ordered,from the parts catalog, you should disregard the letter stamp.

Alpha One Standard Description U-joint I.D.

Alpha One - 1.32 Standard Rotation H

Alpha One - 1.50 Standard Rotation F

Alpha One - 1.65 Standard Rotation C

Alpha One - 1.84 Standard Rotation D

Alpha One - 1.98 Standard Rotation B

Alpha One Counter Description U-joint I.D.

Alpha One - 1.50 Counter Rotation F

Alpha One - 1.65 Counter Rotation C

Alpha One - 1.84 Counter Rotation D

Alpha One - 1.98 Counter Rotation B

Alpha One, Gen II Standard Description U-joint I.D.

Alpha One, Gen II - 1.47 (Earlier 1.50) Standard Rotation F

Alpha One, Gen II - 1.62 (Earlier 1.65) Standard Rotation C

Alpha One, Gen II - 1.81 (Earlier 1.84) Standard Rotation D

Alpha One, Gen II - 1.94 (Earlier 1.98) Standard Rotation B

Alpha One, Gen II - 2.00 Standard Rotation A

Alpha One, Gen II - 2.40 Standard Rotation K

Alpha One, Gen II Counter Description U-joint I.D.

Alpha One, Gen II - 1.47 (Earlier 1.50) Counter Rotation F

Alpha One, Gen II - 1.62 (Earlier 1.65) Counter Rotation C

Alpha One, Gen II - 1.81 (Earlier 1.84) Counter Rotation D

Alpha One, Gen II - 1.94 (Earlier 1.98) Counter Rotation B

Alpha One, Gen II - 2.00 Counter Rotation A

All tampered-with sterndrives: A sterndrive could have had the gear ratio changed for highaltitude use, or if the drive was used in a different boat, which would void the decal and the yokestamp information. The gear ratio would then have to be determined by counting the teeth on thesterndrive gears in the driveshaft housing and in the gear housing. These tooth counts would thenbe used in a calculation to determine the overall drive unit gear ratio.

Bravo U-joint Splined Yoke IdentificationAn identification letter is stamped on the U-joint splined yoke.This chart represents the letter stamps found on Model Year 2000 and newer drive units (new oruntampered with drive units). The letter stamp represents the drive unit overall gear ratio.Older (pre-Model Year 2000) drive units would have the U-joint yoke stamped with a letter thatrepresented the gear ratio in the driveshaft housing. Two drive units with different overall gearratios could have the same U-joint letter stamp. On these drives a technician would have to checkthe gear housing gear tooth count to determine the overall drive gear ratio.

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Later (Model Year 2000 and newer) drive units have a stamped letter that represents the overalldrive gear ratio. Now two drive units could have different letter stamps, but the gear ratio in thedrive shaft housings could be the same.Service Note: When you order a service replacement complete driveshaft housing, the U-jointsplined yoke may have a different letter stamp than the one found on the unit that is being replaced.The letters used on service replacement units follow the pre-model year 2000 method ofidentification. As long as the correct replacement drive shaft housing assembly has been ordered,from the parts catalog, you should disregard the letter stamp.NOTE: Diesel Sterndrives are listed as Bravo X series.

Driveshaft Housing—Gear Ratio and U-joint Marking

Sterndrive model Ratio U-joint shaft marking

Standard Bravo Three and Bravo Three X series 2.43:1 N

Standard Bravo Three and Bravo Three X series2.20:1 K

Standard Bravo Two and Bravo Two X series

Standard Bravo Three and Bravo Three X series2.00:1 B


Standard Bravo Three and Bravo Three X series1.81:1 G


Standard Bravo Three and Bravo Three X series

1.65:1 CStandard Bravo One and Bravo One X series



1.50:1 FStandard Bravo Two and Bravo Two X series

Standard Bravo One and Bravo One X series

Standard Bravo Three and Bravo Three X series1.36:1 H


Bravo One XR

1.50:1 R

1.35:1 L

1.26:1 M

Bravo Three XR 2.00:1 R

All tampered-with sterndrives: A sterndrive could have had the gear ratio changed for highaltitude use, or if the drive was used in a different boat, which would void the decal and the yokestamp information. The gear ratio would then have to be determined by counting the teeth on thesterndrive gears in the driveshaft housing and in the gear housing. These tooth counts would thenbe used in a calculation to determine the overall drive unit gear ratio.

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Page 1A-10 90-899907001 JULY 2006

Calculating Overall Drive Unit Ratios

a

b

e

20333

d

f

h i

g

c

a - Driveshaft housingb - Gear housingc - Input shaft (gear end of yoke shaft)d - Drive geare - Driven gear

f - Driveshaftg - Drive gearh - Driven geari - Propeller shaft

Example:Gear #1 - 22 Tooth Overall Ratio = RoGear #2 - 20 Tooth Ro = {Driven(2)/Drive(1)} x {Driven(4)/Drive(3)}Gear #3 - 13 Tooth Ro = {20/22} x {21/13}Gear #4 - 21 Tooth Ro = .909 x 1.615

Ro = 1.468 = 1.47Ro = 1.47 turns of input shaft to 1 turn of propshaft

Alpha Drive Unit Gear Tooth Counts and Related Drive RatiosThe gear housing tooth count, overall gear ratio and corresponding driveshaft housing gear toothcounts are displayed below. The same driveshaft housing gear tooth count can be found in anumber of drive units with different overall drive ratios. Overall drive ratios are changed by usingdifferent gear sets in the gear housing.

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Gear Housing Tooth Count Ratio DSH Drive Gear DSH Driven Gear

14-28 2.40:1 20 24

14-28 2.0:1 24 24

17-28 1.98:1 20 24

13-21 1.94:1 20 24

17-28 1.84:1 17 19

13-21 1.81:1 17 19

17-28 1.65:1 24 24

13-21 1.62:1 24 24

17-28 1.50:1 22 20

13-21 1.47:1 22 20

17-28 1.32:1 20 16

Bravo Drive Shaft Housing Gear Tooth Counts and Related DriveRatios (Model Year 2000 and Later)

The drive model, overall gear ratio and corresponding driveshaft housing gear tooth counts aredisplayed. The same driveshaft housing gear tooth count can be found in a number of drive unitswith different overall drive ratios. Overall drive ratios are changed by using different gear sets inthe gear housing.NOTE: Diesel Sterndrives are listed as Bravo X series.

Driveshaft Housing—Gear Ratio and Gear Tooth Count

Sterndrive model Ratio Pinion (drive) gear teeth Driven gear teeth

Standard Bravo Three and Bravo Three X series 2.43:1 23 30

Standard Bravo Three and Bravo Three X series2.20:1 23 30







1.65:127 32


Standard Bravo One and Bravo One X series 23 30


1.50:127 32


Standard Bravo Two and Bravo Two X series 27 29



Bravo One XR

1.50:1

16 191.35:1

1.26:1

Bravo Three XR 2.00:1 27 32

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Sterndrive and Transmission Lube Capacity ChartMODELS CAPACITY 1. MODELS CAPACITY 1.

PRODUCTION II (H.P. gear housing) 6.6 liter (7 qt.)

60 541 ml (18-1/4 fl. oz.) 215E-215H 3.8 liter (4 qt.)

80-90 651 ml (22 fl. oz.) IITR-TR 3.8 liter (4 qt.)

I 2. 237 ml (8 fl. oz.) IITRS-TRS 2.8 liter (3 qt.)

I 3. 532 ml (18 fl. oz.) HIGH PERFORMANCE MODELS

IA-IB-IC 2. 37 ml (8 fl. oz.) Alpha SS 946 ml (32 fl. oz.)

IA-IB-IC 3. 680 ml (23 fl. oz.) II SSM 4.25 liter (4-1/2 qt.)

I (120-260)-R-MR-Alpha One 946 ml (32 fl. oz.) III Clubfoot 5.32 liter (5.63 qt.)

Alpha One Generation Two (excludingmonitor) 1160 ml (39.2 fl. oz.) III SSM/III-A SSM 8.9 liter (9.38 qt.)

Alpha One Generation Two (includingmonitor B)4. 1892 ml (64 fl. oz.) IV SSM - V SSM (std.) 6.39 liter (6-3/4 qt.)

Alpha One Generation Two (includingmonitor A)4. 2247 ml (76 fl. oz.) IV SSM - V SSM (1 in. spacer) 7.10 liter (7-1/2 qt.)

Bravo One (excluding monitor) 1.9 liter (2 qt.) IV SSM - V SSM (2 in. spacer) 7.80 liter (8-1/4 qt.)

Bravo One (including monitor B)4. 2.65 liter (2.8 qt.) IV SSM - V SSM (3 in. spacer) 8.50 liter (9 qt.)

Bravo One (including monitor A)4. 3.36 liter (3.55 qt.) VI SSM (std.) 19 liter (20 qt.)

Bravo One LWP/DWP excluding monitor 1833 ml (62 fl. oz.) VII SSM (std.) 15.2 liter (16 qt.)

Bravo One LWP/DWP(including monitor B)4. 2188 ml (74 fl. oz.) BORG WARNER TRANSMISSIONS

Bravo One (Monit. B) - 2004 4. 5. 2.3 liter (77.5 oz./2.4 qt.) 1:1 1.9 liter (2 qt.)

Bravo Two (excluding monitor) 2.4 liter (2-1/2 qt.) 1.5:1 - 3.0:1 2.8 liter (3 qt.)

Bravo Two (including monitor B)4. 3.03 liter (3.2 qt.) V-Drive 4.25 liter (4-1/2 qts.)

Bravo Two (including monitor A)4. 3.73 liter (3.95 qt.) 5000 1.5:1 (8 deg. down angle) 2.4 liter (2-1/2 qt.)

Bravo Two (Monit. B) - 20044. 5. 3.8 liter (130 oz./4.1 qt.) HURTH TRANSMISSIONS

Bravo Three (excluding monitor) 1.9 liter (2 qt.) Hyd. Shift 4.0 liter (4-1/2 qt.)

Bravo Three (includ. monitor B)4. 2.9 liter (3 qt.) V-Drive 4.7 liter (5 qt.)

Bravo Three (Monit. B) - 2004 4. 5. 2.94 liter (99.5 oz./3.1 qt.) 630A (8 deg. down angle) 4.0 liter (4.2 qt.)

Blackhawk (excluding monitor) 1.66 liter (1-3/4 qt.) 800AM (8 deg. downangle) 4.1liter (4.4 qt.)

Blackhawk (including monitor B)4. 2.61liter (2.5 qt.) MERCURY MARINE TRANSMISSIONS

II 4 liter (5-3/4 qt.) All 1.9 liter (2 qt.)

1. Capacities given are approximate. Proper filling procedure is specified in the Service manuals and Operations and Maintenancemanuals.

2. Driveshaft housing.3. Gear housing.4. Following are types of gear lube monitors available for Alpha and Bravo models.5. Bravo with redesigned driveshaft housing.

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90-899907001 JULY 2006 Page 1A-13

Gear Lube Monitors Used On Alpha and Bravo Models

20316 20317

TYPE A – ROUND [473ml (16 fl. oz.)] TYPE B – SQUARE [355ml (12 fl. oz.)]

Sterndrive Unit 10-Hour Break-In Period (New or With ReplacementGears)

• Avoid full throttle starts.• Do not operate at any one constant speed for extended periods of time.• Do not exceed 75% of full throttle during the first 5 hours. During the next 5 hours, operate at

intermittent full throttle.• Drive unit should be shifted into forward gear a minimum of 10 times during break-in, with

run-in time at moderate RPM after each shift.

Serial Number Locationsa

20323Transom assembly decal

a - Transom assembly serial number location

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Page 1A-14 90-899907001 JULY 2006

a

b20324

Sterndrive unit - Port side decala - Sterndrive unit serial number locationb - Drive unit gear ratio location (or opposite side on Alpha S/N 0W500025 and above

and Bravo S/N 0M198373 and above)

Gear Housing Pressure Test1. Drain gear lube and install lower drain plug.2. Remove vent plug and install pressure test gauge. Tighten securely.

20326

3. Pressurize housing to specification and observe gauge for 5 minutes.

Gear housing

Pressure 48 - 69 kPa (7-10 psi)

NOTE: If test is being performed while drive unit is mounted on transom assembly, the cap on theoil monitor bottle is sealed, so it should hold pressure, if it is functioning correctly.

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90-899907001 JULY 2006 Page 1A-15

4. Rotate driveshaft, propshaft and move shift rod while housing is pressurized to check for leaks.

20328

5. Pressurize housing to specification and observe gauge for 10-15 minutes.

Gear housing

Pressure 103-110 kPa (15-16 psi)

6. Rotate driveshaft, propshaft and move shift rod while housing is pressurized to check for leaks.7. If pressure drop is noted, immerse housing in water (or use liquid soap and water mixture).8. Re-pressurize to specification and check for air bubbles.9. Replace leaking seals as necessary. Retest housing.NOTE: Vacuum tests are not recommended due to the design of the labrinth seal (it will not holdvacuum).10. Remove tester from housing, fill with lubricant and install vent/drain plugs.

Drive Unit RotationThere are two types of drive unit rotations, standard and counter. Following are shown when thedrive unit is viewed from the propeller end.

20329 20330

Standard-rotation (right-hand) Counter-rotation (left-hand)

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Trim Tab Adjustment (to equalize steering pressure)• If boat turns more easily to left than to right-turn back edge of trim tab to the left

22357

• If boat turns easily left or right you have balanced steering torque-set back edge of trimtab to center position

22358

• If boat turns more easily to right than to left-turn back edge of trim tab to the right

22359

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MC-1 Propeller Shaft Parts Comparison

a

b

22379

a

b

a - 1973 and older-gimbal housing casting, propshaft parts and shift cable adjustmentdimension

b - 1974 and newer-gimbal housing casting, propshaft parts and shift cable adjustmentdimension

Tapered Roller Bearing DiagnosisConsider the following factors when diagnosing bearing condition:• General conditon of all parts during disassembly and inspection.

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Page 1A-18 90-899907001 JULY 2006

• Classify the failure with the aid of the illustrations.• Determine the cause.• Make all repairs following recommended procedures.

Good Bearing

21046

Bent Cage-End• Cage damage due to improper handling or tool usage.• Replace bearing.

21047

Bent Cage-Side• Cage damage due to improper handling or tool usage.• Replace bearing.

17181a

a - Cage damage

Galling• Metal smears on roller ends due to overheat, lubricant failure or overload.

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90-899907001 JULY 2006 Page 1A-19

• Replace bearing - check seals and check for proper lubrication.

17539

Abrasive Step Wear• Pattern on roller ends caused by fine abrasives.• Clean all parts and housings, check seals and bearings and replace if leaking, rough or noisy.

21048

Etching• Bearing surfaces appear gray or grayish black in color with related etching away of material,

usually at roller spacing.• Replace bearing - check seals and check for proper lubrication.

17182

Misalignment• Outer race misalignment due to foreign object.• Clean related parts and replace bearing. Make sure races are properly seated.

17184

Indentations• Surface depressions on race and rollers caused by hard particles of foreign material.

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Page 1A-20 90-899907001 JULY 2006

• Clean all parts and housings, check seals and replace bearing if rough or noisy.

21049

Fatigue Spalling• Flaking of surface metal resulting from fatigue.• Replace bearing - clean all related parts.

17187

Brinelling• Surface indentations in raceway, caused by rollers, either under impact loading or vibration

while the bearing is not rotating.• Replace bearing if rough or noisy.

17543

Cage Wear• Wear around outside diameter of cage and roller pockets, caused by abrasive material and

inefficient lubrication.• Check seals and replace bearing.

17545

Abrasive Roller Wear• Pattern on races and rollers, caused by fine abrasives.

2222


90-899907001 JULY 2006 Page 1A-21

• Clean all parts and housings, check seals and bearings and replace if leaking, rough or noisy.

17550

Cracked Inner Race• Race cracked due to improper fit, cocking or poor bearing seats.• Replace bearing. Inspect installation area for defects.

17552

Smears• Smearing of metal due to slippage. Slippage can be caused by poor fits, lack of lubrication,

overheating, overloads or handling damage.• Replace bearing. Clean related parts and check for proper fit and lubrication.• Replace shaft if damaged.

17554

Frettage• Corrosion set up by small relative movement of parts with no lubrication.• Replace bearing. Clean related parts. Check seals and check for proper lubrication.

17556

Heat Discoloration• Heat discoloration can range from faint yellow to dark blue, resulting from overload or incorrect

lubricant.

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Page 1A-22 90-899907001 JULY 2006

• Excessive heat can cause softening of races or rollers.• To check for loss of temper on races or rollers a simple file test may be made. A file drawn

over a tempered part will grab and cut metal, whereas, a file drawn over a hard part will glidereadily with no metal cutting.

• Replace bearings if overheating damage is indicated. Check seals and other parts.

17188

Stain Discoloration• Discoloration can range from light brown to black, caused by incorrect lubricant or moisture.• Re-use bearings if stains can be removed by light polishing, or if no evidence of overheating

is observed.• Check seals and related parts for damage.

21050

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90-899907001 JULY 2006 Page 1A-23

Mercury Marine Backlash FlagsPart Number Stampings Measurement 1. Application

91– 78473

1 17 mm (0.660 in.)

Standard outboard flag. Also some MerCruisermodels

2 15 mm (0.585 in.)

3 13 mm (0.520 in.)

4 10 mm (0.390 in.)

91– 53459

I 19 mm (0.750 in.)Standard MerCruiser Flag. Also some outboardmodels.II 24 mm (0.935 in.)

III 29 mm (1.130 in.)

91– 19660 2.1 12 mm (0.455 in.)

100– 125 hp outboard (4–cylinder inline)2 16 mm (0.625 in.)

91– 19660– 1

1 12 mm (0.455 in.)Outboard (as above) Also some 40–60 hp 3–cylinder models.2 16 mm (0.625 in.)

3 12 mm (0.490 in.)

91– 84725M

40B 10 mm (0.410 in.)

Mariner Outboards (Japanese product)

85A 12 mm (0.480 in.)

55A 31 mm (1.215 in.)

60A 34 mm (1.330 in.)

30A 27 mm (1.070 in.)

91– 805481 15– 19/16– 27 35 mm (1.370 in.) Bravo 3 (inner shaft) 3.

91– 805482 15– 19/16– 27 22 mm (0.850 in.) Bravo 3 (outer shaft) 3.

91– 806192 15– 19/16– 27 30 mm (1.165 in.) Bravo 3 (spline lash) 3.

91-865116 16/19 Bravo "Shimmable" Driveshaft Housing 4.




1. Inside of hose clamp to stamped mark.2. Supersedes to the 91-19660-1 flag.3. Used on the BlackHawk drive.4. 2004 Bravo drives, serial number 0M198373 and above.

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Page 1A-24 90-899907001 JULY 2006

Bravo Shim Kit ListingBravo One, Two and Three SeriesDriveshaft HousingDriven gear(s) location 2.3 mm (0.091 in.) 23–87560091 (1999 and earlier)Driven gear(s) location 2.4 mm (0.094 in.) 23–87560094 (1999 and earlier)Driven gear(s) location 2.5 mm (0.097 in.) 23–87560097 (1999 and earlier)Driven gear(s) location 1.5 mm (0.061 in.) 23–861782061 (2000 and later)Driven gear(s) location 1.6 mm (0.064 in.) 23–861782064 (2000 and later)

Gear HousingPinion gear location 15–92914A1Driveshaft preload 15–86749A1Driven gear location (B1/3) 15–87157A1Driven gear location (B2) 15–55499A1Load ring (B1) 67440TLoad ring (B2) 23–66093TAft driven gear (B3) 15–805078A1Propshaft end play (B3) 15–805627A1

NOTE: U-joint pinion gear shims and driven gear thrust bearing races for 2004 (and later) Bravo"shimmable" driveshaft housings (S/N 0M198373 and above) are listed in the driveshaft housingsetup section.

2626

sterndrives, transom assemblies and hydraulic systems

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