Reference Doc A · Universal (Sales + Techs)

Shaft, Coupler, Cutless Bearing & Seal Measurement

Measure once, order right. This is the field tool for the drivetrain side of a 4JH-CR repower — what to measure, how to judge condition to standard, and how we select GLIDE seals and bearings.

ID×OD×LCutless convention

GMS/GMSSBy length to coupler

SAE J755Shaft standard

Step 1

Measurement protocol — what to record

🛢️Stern tube

Bore / OD
Length

📏Shaft

Diameter (vernier — don't assume 25 mm = 1")
Overall length to the back of the coupler
This length selects GMS vs GMSS

🔩Coupler

Type
Bolt pattern (match new gearbox output)

Step 2

Shaft condition — to standard, by size

Item	Standard / guideline	Action
Shaft ends/keyway	SAE J755 (ANSI-recognized) — covers ¾"–8" (19–203 mm)	Confirm taper/keyway/hub tolerances
Straightness / diameter	Aqualoy / Aquamet (17/19/22/22HS) tolerance tables by diameter	Check runout/straightness; out-of-true → replace
Surface	GLIDE lip seal needs a smooth, unblemished shaft	Scored / pitted / electrolysis → replace
Cutless play	Plan a new bearing at ~1 mm play; ~2 mm practical max	Wear-down (poker/feeler); play equal all round

Sources: SAE J755 (SAE/ANSI); Aqualoy/Aquamet shafting tables.

Step 3

GLIDE cutless bearing

📐Size convention & rule

ID × OD × length — shaft dia (ID) × stern-tube/strut bore (OD) × length. GLIDE lengths follow the 4× shaft-diameter rule.

Shaft (ID)	OD	Length
1"	1¼"	4"
1⅜"	1⅞"	5½"
2"	2¾"	8"
2¼"	3"	9"
2¾"	3½"	11"

🔎Measure & judge

Record shaft dia, stern-tube/strut bore, and length/seat
Note retention: press-fit vs set-screw
Rock/lift shaft to feel play; ~1 mm = plan replace, ~2 mm max; equal all round
Keep water-lubrication flutes clear

GLIDE-100 material: low water-swell, dimensionally stable, self-lubricating, shaft-safe.

↗

Resource · Product data
GLIDE bearings & seal systems (manufacturer)

Step 4

GLIDE seal — GMS vs GMSS

💧Double-lip dripless seal

No mechanical/face parts; won't score the shaft even run dry; ~5-minute swap without flooding the bilge; kit ships with a spare seal. Must be fitted with the supplied install tool to keep the 4-year warranty.

Select by length to the couplerChoose GMS or GMSS from the measured shaft-log-to-back-of-coupler length; size by shaft diameter × stern-tube OD. Confirm model and length breakpoints against the GLIDE sizing chart.

A flexible coupling (R&D / Centaflex / Bullflex) keeps the shaft fixed while the engine moves on its mounts.

Step 5

Gearbox ratio

⚙️Read it, then select it

Record the existing ratio. We fit a new gearbox (re-use is a management-approved exception). Ratio pairs with prop pitch and hull type — selected for the new engine, not just copied. Flag prop pitch for a prop-shop check when power changes.

Field sheet

Drivetrain measurement sheet

Fill on the boat, then print and attach to the estimate request.