Bell Housing / Crank Centerline
If the block has been align bored/honed, it is likely that the crank centerline
has been moved. Use a dial indicator attached to the flywheel to sweep the
inside of the bell housing bore while the crank is rotated (easier with the
spark plugs out). Maximum allowable offset is .007. We have a fixture available
for rent to correct this condition.
Drive Plate Run Out
Check for excessive run out on the drive plate. Use a dial indicator mounted to
the block or bell housing to sweep the splined hub while the crank is rotated.
Maximum run out is .005. You can use a brass drift to move the hub slightly. We
have seen some seriously defective drive plates. We can provide competition
quality plates for engines up to 1200 ft lbs.
Shifter Travel and installation
Check to see that the shift arm reaches the detents in forward, neutral and
reverse. Even though it is obvious, check to see that forward is forward (arm
towards front of boat.) We have seen a boat where new controls were
installed and the drives were switched, resulting in forward movement while the
trans was in reverse! Make sure the shift arm is not running in to the starter.
Vent
Stock vent is adequate for most applications, but the transmission case may be
tapped or spring cap removed for remote or extended vent if desired.
Cooler
Minimum cooler size is 2 x 8" bundle length (or equivalent), the Merc bell
housing cooler is more than enough for all applications. The fluid outlet is on
top of the transmission, and the return is on the bottom. If possible have the
fluid flow opposite the water flow through the cooler. Cooler lines must be a
minimum of # 8, #10 is better. Do not use any fitting smaller than 3/8 pipe. Do
not use a bushing and a 1/4 pipe fitting on the cooler outlet. Low pressure hose
(like Aeroquip or Parker push lock) is ok. Be sure to flush the cooler
thoroughly if you are re using it. We recommend a new cooler to play it safe.
DO NOT USE CHECK VALVE IN COOLER LINES!
Max Idle RPM
For longest life, we do not recommend shifting above 1300 RPM.
Drive & Tailstock
When installing a plug in style with a 3, 4 or 5 drive take a look at the guide
spring that goes on the aft end of the output shaft. Make sure that the edge of
the spring is not damaging the seal. You can grind or belt sand the end of the
spring if needed. When installing the drive, make sure that the shaft on the
drive is aimed at the female spline in the output shaft of the trans. It is very
easy to destroy the rear seal if this shaft is not lined up. If you are
installing the tailstock to the transmission yourself, make sure that the seal
does not get caught and/or roll over during installation.
Hooking up Gauges
There is a port on the top/rear of the transmission next to the cooler outlet
that may be used for a temperature or pressure gauge. Make sure that sender or
fitting you use does not obstruct the oil passage in the housing. Most
temperature senders will cause this kind of obstruction. An extension fitting
MUST BE USED to keep the sender from closing off the oil passage. As most
transmission problems are caused by low fluid pressure, we feel that a pressure
gauge is a better indication of potential problems.
Fluid & Fluid Level
USE Type F or FA, non synthetic fluid only,
and do not over fill!
Start the engine, shift in to forward and reverse a few times and recheck the
fluid level with the engine off. If using a Mercury bell housing cooler, or if
the cooler is mounted above the transmission, the fluid MUST be checked within
30 seconds of turning the engine off. This will prevent false readings as a
result of fluid draining out of the cooler.
Engine Alignment
The relationship between the transmission and out-drive is very important.
Misalignment can cause vibration that will quickly wear out the rear seal rings
and transmission housing.
The proper alignment tool should be used for all direct coupled
applications. A digital level should be used on driveline units to confirm that
the driveshaft flanges are exactly parallel.
