Installation
Can the speedometer water pickup hose cause water intrusion into my lower unit?
No - the speedo pickup can't cause water intrusion into the gearcase. The barbed fitting simply screws into the gearcase housing and connects to a rubber tube that runs up to the gauge. Remove that barbed fitting from your old unit and keep it for reinstallation on the new one.
Do I have to remove the bearing carrier to replace the prop shaft seals?
It's much easier to pull the bearing carrier to replace them. We've heard of people doing it with the carrier still installed, but it isn't an approach we'd recommend. On MerCruiser applications the spanner wrench is the tool for removing the carrier.
How do I install the upper driveshaft into a new lower unit?
It's straightforward. Take the old clip off your old driveshaft, set the shaft into the new unit, turn it so the splines line up and it will drop down part way. Then strike the top with a rubber mallet until it clicks home. The test is simple: if you can still pull it out, hit it harder. There's no video needed - the new unit already has a fresh retaining clip waiting inside.
How do I know the driveshaft is properly seated in the new gearcase?
Lubricate the seals, insert the shaft, line the splines up by feel and then strike the top of the driveshaft once or twice with a dead blow or rubber hammer. You'll hear a loud click. The shaft will still feel sloppy until the water pump is assembled - that's normal. You know it's correct when you can no longer pull the driveshaft back out.
How do I remove the upper driveshaft from my old gearcase?
It's held in by a retaining clip that has to be broken to release it. Secure the old lower unit in a vice, grip the driveshaft in the middle with a pipe wrench or vice grips, and strike upward against it with a rubber mallet to break the fingers on the clip. Your new unit already has a new clip inside: oil the seals, line up the splines and give the top of the shaft a tap or two with a dead blow or rubber mallet and it will click in. You know it's seated when you can't pull the shaft back out.
I broke the plastic nipple that goes through the transom for the oil line - how do I replace it?
That's a very common problem and happens in the field constantly, because the plastic nipple gets brittle with age. The approach that works: when disassembling, cut the rubber line in two, then once the bellhousing is out of the way carefully cut the rest of the line away from both sides. Our own rule is that if a transom assembly is opened far enough for the bell to come off, the rubber line gets replaced as a matter of course.
I'm fitting a Yamaha lower unit and the gap won't close - what am I missing?
The gap doesn't close until the shift shaft splines line up along with the driveshaft and water pump, so a gap that won't shut usually means the shift shaft hasn't engaged. The splines don't start until about halfway up the tube at the end of the shift shaft on the outboard. Bring the lower up until it stops, then have someone very gently jiggle the shift handle at the helm - it'll make the connection and let you bolt it up. Forcing it closed in gear is what leaves people stuck in reverse.
Is the speedometer port on your Yamaha lower the same thread as the OEM?
Yes - the speedo hole is drilled to the same pipe thread as the OEM; there's no reason for us to change the pitch. If your old fitting won't thread in cleanly, we'd recommend fitting a new OEM plastic fitting for the speedo port rather than forcing the original.
My Yamaha lower shifts fine off the engine but won't shift once it's bolted up - why?
Almost always too much grease or debris packed into the shifter. Pull the unit back down and clean out the female shift coupler in the midsection. Then put only a little grease on the sides of the splines of the male shaft - nothing on top of the splines - and reinstall. That resolves the large majority of these.
My counter-rotation lower unit is binding and won't pull up tight - what's wrong?
This is almost always the shift shaft rather than the bolts. Take the unit back down and clean out the female portion of the shifter in the mid-section, then have someone gently wiggle the shifter at the helm as you bring the unit up - the splines are recessed in the female side, so it's hard to feel when you're actually lined up. If you're greasing the splines, put grease only on the sides, never on the top of the lower shift shaft. That resolves most of these on the Yamahas.
My drive won't seat fully against the bellhousing - what's stopping it?
Work through it in order rather than forcing it with the bolts. Check the drive is in forward gear and that the gimbal bearing is aligned with an alignment bar, then confirm the alignment again with the engine rotated 180 degrees. Make sure no alignment pin has stayed behind in the transom assembly. If it still won't come up, stop there rather than forcing it - call us at 813-925-7127 and we'll work through it with you.
My new Yamaha lower stops about half an inch short of seating - what's catching?
Three things to check, in order. First, make sure you don't have an alignment pin stuck in the midsection - if one stayed behind, the new unit can't come fully up. Second, have someone wiggle the shifter at the helm to confirm the shift shaft has engaged. Third, if it's in gear, turn the prop slightly to rotate the driveshaft and help the splines line up. Don't force it with the bolts.
My new lower unit won't slide all the way up - what's holding it?
On the Yamaha units, if the driveshaft is splining up correctly then it's either the water pump or the shift shaft holding it. The splines inside the Yamaha shift shaft don't begin until about halfway up, so it's easy to think you're engaged when you're not. Bring the unit up until it stops and have someone very lightly move the shifter at the helm to let the splines find each other. Also confirm the old and new gearcases both shift and turn the prop shaft in the same direction. On other brands the cause is usually different - call us at 813-925-7127.
My new lower won't go into forward gear after installation - what did I do wrong?
The most likely cause is that the shifter was past the forward detent when you installed the lower. Take the lower back off, find neutral on the unit, then install it with the boat's shifter in neutral. You may need someone to turn the engine over a tiny amount by hand to get the driveshaft splines to line up. We can send you the document that walks through finding neutral.
There's no yellow dot on my gimbal bearing - how do I orient it?
The dot exists to align a greaseable bearing with the grease port, so on a sealed bearing it doesn't matter and there's nothing to line up. What does matter is that the slots face toward the engine, and that it's driven in all the way. Beyond that there's nothing else to position.
What are the alignment dowels for, and do I have to use them?
Yes, use them - the bolts hold the unit up, but the dowel pins are what centre the gearcase. Ours are stainless steel. If a dowel has stayed stuck in your midsection, it's usually easier to remove the dowel from our lower unit instead: grip it with vice grips and twist while pulling up. They're not normally difficult to get out.
What gear is the unit in when it arrives out of the box?
It varies - the gear position can change during shipping, so don't assume. Spin the prop shaft and work out which gear it's in before you install it, and lock it into forward before fitting the shifter. On a standard right-hand rotation unit, forward is with the shift shaft turned fully clockwise: the prop shaft then locks turning counter-clockwise and ratchets clockwise.
What order does the prop hardware go on in?
Thrust washer first, then the propeller, then the splined washer, then the nut, then the nut cover, and finally the cotter pin. Getting the thrust washer and splined washer the wrong way round is the usual cause of a prop that won't seat properly.
What size socket do I need for the prop nut?
The prop nut is the same as the OE size - a 1-1/16" socket is what you need for tightening. Tell us which unit you have if you'd like us to confirm, and we stock the prop service kits if your hardware is due for replacement.
Where do the O-rings from the Bravo install kit go on the shaft?
The two small black O-rings are the same part and go together on the shaft. The larger brown O-ring goes at the end of the splines that go into the engine coupler. If you're unsure, lay them out by size before you start - the brown one is easy to identify.
Where do the O-rings go when installing an Alpha Gen II upper unit?
The water passage O-ring is obvious - it seats neatly in place. The driveshaft has three grooves: the two small O-rings go on the driveshaft where it passes through the gimbal bearing and have to stretch quite a bit to fit. The last one goes in the larger groove near the splines, though if your engine coupler isn't greaseable from the inside you don't need it. The big square-profile O-ring slides into the bellhousing.
Where is the gear lube drain plug on a newer Mercury lower unit?
On the newer units the plug below the prop shaft, on the bearing carrier, is the lowest drain - there's no separate drain hole in the bullet. Mercury moved to using only the bearing carrier drain on the newer units and we've emulated that, so if you can't find a bullet drain you haven't missed anything.
Why won't my trim tab bolt go in after assembling the drive?
Because it has to go in first. Put the trim tab bolt in loose in the lower unit before you install the upper unit on top - once the halves are together there's no access to start it. That's normal for the design rather than a fault.
Shift System
Can I convert a ratcheting gearcase to a non-ratcheting one?
There's nothing different in the gearcase housing between the two versions, but beyond that conversion you have to stay with the ratcheting gear set. Ratcheting and non-ratcheting gears and clutches can't be mixed - we only work with the non-ratcheting gears and clutches in our own sets, so tell us which you have before ordering gears.
Can the shift shaft travel be adjusted inside the lower unit?
No, there are no adjustments in the lower unit for shift shaft travel. Start by confirming the basics - does the shaft point forward at the 12 o'clock position when locked in forward gear (driveshaft clockwise, prop shaft counter-clockwise)? If that's wrong and everything external checks out, the unit would need to come back to us for inspection and repair.
Do you sell a 3-jaw reverse clutch lower unit?
No - any replacement lower unit, whether ours or an OE one, is now 6-jaw, because the 3-jaw design was known to be problematic and neither we nor Mercury still build them. Our unit is the updated 6-jaw, so to fit it to a 3-jaw motor you have to swap out the shift linkage in the mid-section, and that means lifting the powerhead. We sell the shift shaft kit that goes with it. Plan for that work before you order.
How do I know if my Mercury has a 3-jaw or 6-jaw reverse clutch?
Mercury switched from a 3-jaw to a 6-jaw shift system around the 1997 model year. Our SE205 is a 6-jaw lower - if your motor is the older 3-jaw type you'll also need the mid-section shift shaft kit (92-205-07K), and the powerhead has to come off to fit it. You can confirm by counting the reverse-clutch jaws, or look at the machined line just forward of the trim-tab bolt: straight across is 3-jaw, a 45-degree line is 6-jaw. Send us the engine serial number at 813-925-7127 and we'll verify it before you order.
How do I verify my lower unit shifts correctly before installing it?
On a standard right-hand rotation unit: with the shift shaft turned fully clockwise, the prop shaft should lock when turned counter-clockwise and ratchet clockwise - that's forward gear. Neutral is neutral. With the shift shaft turned fully counter-clockwise, the prop shaft locks clockwise and ratchets counter-clockwise - that's reverse. Lock the lower into forward gear before installing the shifter into the upper, and check that it points straight out when in forward. That's the correct state to mount it to the boat in.
Is there a specified shift rod travel measurement?
No, there's no specified measurement for shift rod movement - and no real reason for it to change, so if yours moves freely it should be fine. What does commonly go out of tolerance is the shift cables and shifter getting sloppy with age, which limits how far the shifter actually moves the rod. That's where we'd look first on a shifting complaint.
My boat won't go into gear properly after fitting a new lower - where do I start?
Work outward from the drive before assuming the unit. Original, worn shift cables are extremely common and are the single thing we see most - check the cables and control box are smooth and correctly adjusted, and that the handle being in neutral puts the drive in neutral. Also check the prop hub and the engine coupler, and drain the gear lube to inspect the magnet. Lower shift shafts do develop play between the brass bushings and the shift rod, and the seals that keep water out of the shift system are usually in poor condition by then - both worth doing.
What is the correct shift rod height on a Johnson/Evinrude gearcase?
It's specific to the engine model rather than universal - there's no single figure that covers the range, and the measurement only changes when the engine model changes. To take it: thread the shift rod into the gearcase, find neutral, then centre yourself in the middle of the play in neutral and measure from the mounting base of the gearcase to the eye of the shift rod, working it back and forth to confirm you're holding the centre. Tell us your engine model number at 813-925-7127 and we'll give you the figure that applies to it.
Why does the shift shaft have to change for a 6-jaw conversion?
Because the lever at the top of the shaft is a different length, which changes the overall throw of the clutch. Running a 6-jaw lower with the old 3-jaw throw doesn't engage the clutch correctly and can cause serious damage the moment you put it in gear under load. It's not an optional part of the conversion.