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Replacing Your R, MR or Alpha One Gimbal Ring

Knowing your Gimbal
Before attempting to replace your Gimbal Ring you need to determine exactly which gimbal you have.
Older R-type units with the push-in hinge pins are not covered in this section.
If you need tips on replacing an older R-type Gimbal Ring just send us an email.

MR and Alpha One units have one of two styles of Gimbal Rings.
Early MR and Alpha One units had a splined upper Steering Shaft and hole.
This tended to fail so Mercruiser changed the Gimbal Rings and Steering Shafts to use a square pattern.

Before ordering parts you will need to determine if your gimbal ring has a splined hole or a square hole.
If you have a splined hole you will need to buy a Gimbal Ring Kit which updates to a square-hole-type Gimbal Ring.

There are a few special tools required to replace your Gimbal Ring.
We also suggest that you purchase a Shop Service Manual.

When replacing your Gimbal Ring you will also have to replace several other parts.
Items such as your Ujoint Bellows and Shift Cable will be ruined upon disassembly of the old Gimbal Ring.
Other common items are the Water Hose (either 3/4" or 5/8" ID), shift cable bellows, exhaust bellows, steering shaft seal, side thrust washers.
While the unit is disassembled you will have a chance to also replace your Trim Sender Switches if you so desire.

Why Replace Your Gimbal Ring?
There are few reasons as to why you might want to replace your Gimbal Ring.
The first is that it might be broken.
Never weld a gimbal ring. If it's cracked, replace it with a new one.

Another reason for replacing the Gimbal Ring is wear.
The hole at the top where the steering shaft passes through can wear out and cause play in the steering.
This is a very serious and dangerous condition. Never use a boat with play in the Gimbal Ring.
Damage, injury or death can result from steering failure.

Prevention. Updating your splined Gimbal Ring to a safer square-type Gimbal Ring is strongly suggested.
Older splined units can have a loss of steering if the splines fail.

Corrosion. Excess galvanic corrosion can weaken your gimbal ring.
Replace any and all galvanic corrosion damaged components.
Make sure you have a good drive bonding system, Mercathode and anodes to prevent galvanic corrosion.

94993A7 Gimbal Ring $607.33
Alpha One with square top steering shaft hole
88302A1 Gimbal Ring Kit $ 631.00
Replaces older splined-holed Gimbal Rings
Also order Bell Housing 42815A6 and Square/Splined Steering Shaft 88302A2
You will be able to use your old splined Steering Lever
Includes Hinge Pins.
42815A6 Bell Housing $592.50
Fits Alpha One.
Use this Bell Housing if upgrading to 88302A1 Gimbal Ring w/square hole.
88302A2 Splined Steering Shaft $206.58
Only use if upgrading with 88302A1 Gimbal Ring Kit and retaining the splined Steering Lever
98230A1 Shaft-Upper (Square-Square) $333.25
Upper steering shaft for Alpha One
22-88847A1 Access Hole Plug Kit $21.50
Used to remove and replace the gimbal ring with the gimbal installed on the boat
Kit includes a template, plastic threaded hole plugs and top steering shaft nut.
27-94996Q2 Gasket Set $8.50
For mounting the drive. Includes o-rings.
Fits Alpha One and Alpha Gen II
27-64818Q4 Gasket Set $8.50
For mounting the drive. Includes o-rings.
Fits older crowned-type drives such as Model 165, 888 and R drives.
92-96166Q1 Bellows Adheasive $ 10.00
Used to glue bellows and orings into place.
30-803097T1 Transom Seal Kit
(Fits R, MR and Alpha One w/exh bellows) $199.92

30-803098T1 Transom Seal Kit
(Fits R, MR and Alpha One w/tube) $212.75

91-78310 Hinge Pin Tool $21.00
Used for removing threaded hinge pins
Not used on older drives with pin-type hinge pins
91-45497A1 Bellows Expansion Tool $61.00
Used to install the exhaust bellows
Not required if you are installing an Exhaust Tube
60932A4 Ujoint Bellows w/clamps $77.00
Used if the Transom Seal Kit is not desired
Bellows and clamps only
27-94996Q2 Gasket Mounting Set $8.20
Used to mount an Alpha drive
Included in Transom Seal Kit
45518T1 Bushing and Lever Kit (Not required for Gen II) $54.58
This Kit has an improved shift shaft seal to prevent water from entering your shift cable.
Use installer tool 90-805057A2 to install this Bushing.
19543T2 Shift Cable Kit (changed to 865436A03) for Alpha 1 & Gen 2 $88.25
The cable is usually replaced when replacing the gimbal ring.
91-12037 Alpha Cable Installation and Removal Tool $32.00
This special socket is required to replace the shift cable.
90-805057A2 Bushing Installation Tool $22.00
Used to install Shift Shaft Bushing 45518T1
91-33491 Seal and Bushing Installer Tool $17.22
Used to install top steering bushing and seal in the gimbal housing.


Replacing your Gimbal Ring is a difficult job.
Review your Shop Manual before proceeding.
Remove all bonding cables from the gimbal.

Chances are very good you will ruin your old ujoint bellows and shift cable during the procedure.
Ujoint Bellows should be replaced every 5 years or sooner if neccessary.
To inspect your bellows externally turn the drive to one side and look in the folds.
There should be no evidence of dryness or cracking.
Inspect each fold on all sides to make sure there are no cracks or cuts.

A bad bellows will allow water to leak into the gimbal, the drive and the boat.
This can cause severe damage and possible submersion.

The best way to inspect the bellows is to remove the drive. Place the remote control shifter into forward gear before attempting to unbolt and remove the drive.
(Counter-rotation LH drives must be shifted into reverse gear before being removed).

IMPORTANT: Remove the battery negative cable as so the engine will not start or crank.
It the engine starts damage, injury or death can result from moving parts and/or propellars.

It is best to have a Service Manual to properly complete this repair.

Remove the two trim cylinders from the drive and let them hang out of the way.

Remove the six drive mounting bolts and try to pull the drive off.

WARNING: The drive is heavy. Use care to prevent injury. It is best to have two people as
the weight of the drive can injure you once it breaks loose.

If the drive does not pull off easily it might be stuck.
Lift the tail end of the drive a few inches and let it drop freely.
This "jarring" will usually break the drive free from the bellhousing.
The process might have to be repeated or exagerated a few times until the unit breaks free.

Once free, the drive should pull right off but remember to use care as it is heavy and you can damage your back.

Set the drive out of the way and inspect the gimbal and bellows.
Check for any cracks, water intrusion, wear, corrosion and/or free-play.
Plan your repair by making sure you list ALL the parts required for a complete repair.

Replacing the Ujoint Bellows will usually ruin your drive Shift Cable Assembly.
Plan on replacing the shift cable when performing this repair.

Some units have a stainless cable bonding wire attached to the bellhousing and fastening
to the gimbal ring. This important cable nust be removed to remove the bellhousing.

If you need to replace the shift cable, go to Replacing Your Alpha One Shift Cable and follow the removal instructions.

Turn the drive to one side and remove the two screws which hold the plastic Trim Sender
to the side of the Gimbal Ring. Pull the sender off and tie it up above the gimbal and out of the way.
Make a note as to which sender goes to which side. One is a TP Switch and the other is a TL Switch.

Insert your new Hinge Pin Tool into the hinge pin and unthread the pin (lefty-loosens).
It is common for the pin to be tight and the factory puts LocTight on the threads.
In some cases it helps if you first warm the pin with an propane torch.

Remove the pin and turn the drive all the way over to the other side.
Repeat the previous process using heat on the pin if needed.

Make sure you have tied both trim sender unit up and out of the way.

Now it's time to remove the clamps from the bellows and waterhose as so the bellhousing can be
pulled away from the gimbal ring.

Use a 1/4" drive rachett with a very long extension. On the end put a 5/16" swival socket.
Snake the socket in and on the forward ujoint bellows clamp screw and loosen the clamo.
Tilt the bellhoung up and loosen the rear exhaust bellow clamp.
Locate the rear clamp for the water hose and loosen it as well.
The water hose clamp is very difficult to get the socket on.
Sometimes we just cut and replace the water hose.

Now that the clamps are loose you should be able to break the ujoint bellows free.
In some cases we use a long large flatheaded screwdriver and we work the screwdriver
in between the bellows and the housing to break it's glued surfaces free from the gimbal.

Pull the exhaust bellow and water hose free from the bellhousing and the bellhousing should be completely free
unless you have decided to leave the shift cable attached.
If the cable is still attached, use extreme care not to bend, kink or twist the cable.

Notice the two brown plastic washers which were located on either side of the bellhousing.
You have to make sure these are in good shape and put back in place during assembly.

Use the long 5/16" socket and remove the other clamps as to remove the bellows, exhaust and water hose.
If you have also removed the shift cable it is a good idea to replace the shift cable bellows as well.

Clean up and inspect all components.
Inspect the areas where the bellows clamps to.
There must be good corrosion free surfaces to properly seal the new bellows into place.

Use 120 grit sandpaper to clean off any old glue around the perimeter of the housing where the bellows seats.
Wipe clean with acetone.

Remove the two clamp bolts from the top of the Gimbal ring.

Remove the cotter pin from the lower gimbal "tongue".
Gentle heat from a torchlamp can be used to aid in the removal of the cotter and lower steering pins.
Carefully tap out the lower swival pin using care not to crack off the tongues.

Cut out your paper templates that came with your Access Hole Plug Kit.
Position each template on each side of the Gimbal and punch a mark with a punch to
to mark where you will drill.

Use an 1-1/8" hole saw and cut the access holes into each side.
These holes will allow you access to remove the lever cross bolt and the top steering shaft nut.
Use two wrenchs, one in either hole, and unbolt and remove the lever cross bolt through the access holes.

Now the hard part... removing the top steering shaft nut.
Using a punch in one of the access holes tap the top steering nut as to unthread it from the shaft. You will only be able to hit the nut off so far before you loose a grip on the edge of the nut.
Turn the gimbal ring to the other side and access the nut through the opposite hole.
Tap off the nut as far as you can and repeat this procedure from side-to-side untill the nut id off the threads.
Let the steering shaft drop down and out and remove the gimbal ring.

Follw your manuals instructions to install and properly shim the new gimbal ring.
You must have the proper clearance/gimbal right height.

Now is a good time to make your final decision as to whether or not you want to replace your Trim Sender Switches.
It's pretty easy to complete at this point because the bellhousing is already removed for easy access.

To replace the switches, follow the wires up into the gimbal and you will see two screws holding a retainer plate in place.
The top screw is difficult to access. If you bend the head of a 7/16" box wrench over to one side about 20 degrees you can
access the bolt head much easier.
Mercruiser had made a wrench at one time but it is no longer sold.

Hop up into the boat and locate the two pairs of sender wires where they pass through the gimbal.
Cut or disconnect the old wires but take a note on how they were run through the engine compartment.

Outside the boat, once the two retainer bolts are removed you can yank the old wires out of the gimbal.

Pass the new wires through the hole and position the wire grommets as so you can install the retainer plate.
Route the switches as so the TP (Trim Position) switch is on the starboard side and the TL (Trim Limit) switch is on the port side.
Tie the new switches up above the gimbal as so they are way out of the way. Use care not to damage the wires.

Eventually you will have to attach the new wires up in the engine compartment.
The TL wires run over near the trim pump and plug into the blue and purple wires.
The TP wires will attach to a ground and a brown wire with a white stripe (gauge sender wire).

IMPORTANT: Your new water hose must be 13-3/4" long.
They often come from the factory too long.
If you install a water hose that is too long it will kink and cause overheating.
Measure and cut the new hose to a length of 13-3/4"

Use your Service Manual and look up the proper positioning on the bellows and water hose clamps.
Coat both mating surfaces of the metal and the bellow with Bellows Adheasive one at a time.
Do not let the adheasive dry for more than a minute or two.
It is best to install the item with the glue, wait a few minutes for the glue to dry and
then gently tighten the clamp.
The Ujoint Bellows will first be glued and clamped to the bellhousing. Make sure the UP or TOP is correct.
Make sure that the FORWARD on the bellows is towards the bow of the boat.

The Exhaust Bellow or Exhaust Tube will be glued and clamped to the gimbal housing (transom housing).
The screw for the clamp should be on top and facing towards the stb side.
There is a hole through the stb side of the gimbal shroud through which you can slip in a very long 1/4" extension.
Install a 5/16" swival socket onto the end of the extension and it will allow you to tighten up the exhaust clamp.

Make sure to use the correct hose for your application.
Older units used the smaller 5/8" ID water hose.
Newer units use the 3/4" ID water hose.
It must be cut to 13-3/4" long before installation.
The water hose will have to be forced onto the hose connector tube on the gimbal housing (transom housing).
The screw for the clamp should be on top.

The Shift Cable Bellows (if replaced) will be glued and clamped to the gimbal housing (transom housing).

Do not over-tighten the clamps or the rubber will slip off the mounting area.

The "secret" to making this job easier is getting the clamps in the proper position before tightening.
Take the time to review your manual for the exact clamp positioning.

If you have elected to remove and replace your shift cable you have a choice as to when you reinstall it.
You can "pre-install" the cable now, while the bellhousing is removed from the gimbal or you can wait to
install the cable until after the bellhousing is fastened to the gimbal ring.
Pre-installing the cable now makes it a little easier to feed the cable through the cable bellows and
in through the gimbal to the engine compartment.
The draw-back is that with the cable installed you have to take care not to bend, kink or twist the cable
while getting the bellhousing up and into position during installation.

Make sure to use the special deep Shift Cable Socket Tool when installing the shift cable into the bellhousing.
Coat the brass threads with Perfect Seal and do not thread the sheathing in all the way.
Do NOT install the core until after the gimbal is assembled.
Ideally there should be one or two threads left showing.

Squirt a little grease into the hole in the end of the shift cable bellows to lube the rubber.
Force the end of the cable through the shift cable bellows, through the gimbal and into the engine compatment.
IMPORTANT: While pushing the length of the cable into the bilge it has to be deflected off to the stb side of the engine.
Take care not to allow the end of the cable to get improperly routed into the flywheel housing/coupler area.
It is best to have an assistant up in the engine compartment to insure proper routing of the cable during installation.
They can use a long stick to push the entering cable towards the stb side just as it enters the gimbal.

Once the cable is properly routed you can push the bellhousing right up to the gimbal.
We prefer to do a "dry run".
With the bellows clamp in the proper position and NO GLUE on the forward end of the bellows...
push the bellows onto the gimbal by pushing the bellhousing in as far as you can.
This will actually be past the points at which the hinge pin holes line up.
This allows the ujoint bellows to "snap" into position on the gimbal.

During this dry-run you will be making sure that the shift cable is sliding in while you are making sure the
water hose is not getting in the way.
As you can see... there is a lot going on which is why a dry-run is good practice.
The next time you do this you will have glue on the front bellows mounting surfaces so you
be working against time.
Take a special note as to how far the bellows slide on.
There is actually a lip on the inside perimeter of the bellows whic must
properly seat in a groove around the gimbal collar.

Pull the bellhousing away from the gimbal and prepare the bellows for final installation.

Coat the inside of the bellow and the gimbal with a thin coat of bellows adheasive.
Position your clamp on the bellows (screw on top facing towards the stb side).
Like you did in the dry-run, push the bellhousing into place as far as it will go.
Make sure the bellows inner lip has seated in the gimbals groove.
DON'T MOVE!
Just hold it there for a few minutes to let the glue set up.
The longer you let the glue set the better.
With the glue well set you will be able to mess with the bellhousing and clamp
without worring about the bellows pulling off.

Once the glue is set, steer the gimbal as if the boat is making a left-hand turn and
this will allow you access to the forward ujoint bellows clamps screw.
Use a superlong 1/4" extension with a swival 5/16" socket on the end to snug up the clamp.
IMPORTANT: You MUST make sure the clamp is properly positioned on the bellows.
If the clamp is angles or not exactly in place it can ruin the bellows or pull it loose.

BE AWARE: If the bellows is not properly seated and/or installed you can sink your boat.

Once the clamp is firm you can straighten out the steering.
Use a flashlight to inspect the clamp all the way around, on top, underneath and both sides.
Feel around with your fingers where you can't see.
If it doesn't look or feel right chances are it isn't.
If you need to, remove and start over.

Clean up the threads of the hinge pins with a wire brush or wire wheel.

Back the bellhousing out enough to line up the hinge pin holes.
Turn the drive to one side just enough to install the hinge pin.
Make sure to position the brown plastic side washers between the bellhousing and the gimbal ring before installing the
hinge pins. They must be in perfect position of the hinge pin will bind against the washer.
Place a drop of loctight on the threads of the hinge pins and intall them.
You will have to turn the drive from one side to the other to complete the installation.
Torque to specification (see the manual).
Do not install the Trim Senders at this time. They are best installed after the drive is installed.

Center the drive and tilt up the bellhousing as to access the water hose.
Install the clamp in the correct position and force the hose onto the brass hose barb in the bellhousing.
The clamp screw will be facing down on the outboard port side.
Easier said than done! Yes. It's a tight fit and it's difficult to do.
Take you time and you will eventually get it on the barb.
The hose clamp must be in the exact correct position otherwise you won't be able
to get the socket on it to tighten it up.

If you had elected to install an Exhaust Tube instead of the Exhaust Bellow you
do not have any other work to do for the exhaust.
If you had elected to install the Exhaust Bellow, you will need to use the
Exhaust Bellows Expansion Tool.
You can NOT install new exhaust bellows without the Expansion Tool.
The tool needs to be inserted in through the exhaust passage to grab and expand the inside of the exhaust bellows.
For the tool to pass through the exhaust passage you will have to remove the shift shaft.
The shift shaft passes down through the exhaust passage and it's in the way of the tool.
Uncrew and remove the slotted set-screw in the shift lever.
Lift off the lever and drop the shift shaft out the bottom of the bellhousing.

Position the Exhaust Bellows Clamp onto the exhaust bellow.
With the shift shaft removed you will be able to insert the Expansion Tool and grab the exhaust bellows
in the first bellow "fold". Insert the handle clip onto the rear handle of the tool to keep it spread apart.
Hold the bellhousing down with one hand while pulling back on the handle of the tool to work and pull the
exhaust bellows into place and onto the bellhousing mounting cuff.
Slip the tools cross-pin through the tool to hold the bellows in place.
With the tool locked into place lift up the bellhousing and snug up the exhaust bellows clamp.
With the clamp firmly installed remove the tool.

With the shift shaft still removed you have a chance to upgrade your Shift Shaft Seal.
Most pre-Alphas and Alpha One's had a small shift shaft seal which is locted in the exhaust passage.
This seal was prone to failure and it would allow water to leak into the shift cable.
Mercruiser now makes a Shift Shaft Seal Bushing & Lever Kit which has an improved seal design.
Read more about installing this upgrade at Replacing Your Shift Shaft Seal.

Clean and grease the shift shaft. Install the shaft making sure to have the white plastic washer under the Shift Lever.

Steer the boat to the far left and access the small end of the Shift Cable Bellows.
The Shift Cable Kit or Shift Bellows Kit should have included a new crush-clamp for the small end of the bellows.
You can use this steel clamp if you like but we prefer to use a good hose-type stay-strap.
It has to be the type of strap with the internal radius as if for clamping a hose.
The nylon straps last longer, are easy to install and don't rust.

Complete your shift cable installation procedure by following the instructions at Replacing Your Alpha One Shift Cable.

Clean off all the old gasket material from the bell housing and drive.
The Gasket Kit includes new orings which must be properly installed.
Coat the outer perimeter of the large fat oring with Bellows Adheasive and
install it in the bell housing bore where the drivehshaft passes through.
It must be fully installed up against the rim in the hole.
Once in place, grease the inner oring with Universal Joint and Gimbal Bearing Grease.

Coat the water passage oring with Bellows Adheasive and glue into place on the bellhousing.

Replace the orings on the drivehshaft and grease.

Position the gasket onto the six studs and up against the bellhousing.
DO NOT apply any sealant or silicone adheasive to the gasket.

Use some Universal Joint and Gimbal Bearing Grease or use Mercruisers Coupler Spline Grease on the
splines of the drive yoke.
If neccessary, pump a couple of squirts of Universal Joint and Gimbal Bearing Grease into the cross-bearing
grease zirt fittings.
Do not install a drive if the ujoint cross bearings are bad.

Make sure your shift lever is in place so the roller is in the fork notch and
make sure your shifter is in forward gear.

Make sure your drive unit is in forward gear before installation.
This is done by looking down at the little shift "shoe" and turning it clockwise while turning the prop
in the left hand (counter-clockwise) direction. This will position the "shoe" straight forward and the prop will "lock" into forward gear.
CARE must be taken to make sure the drive stays in forward gear during its installation.
IF you bump the prop by accident it could bump the drive out of forward.
I have seen some techs strap the prop with a bungie chord pulling it in the counter-clockwise direction
as so it stays locked in forward gear.

It is best to have the height of the gimbal at the same height of the drive during installation.
This prevents you from having to lift the drive into place.

Position the drive into place while working the driveshaft through the gimbal bearing.
As you push the drive on you need to be aware of the position of the shift shaft.
If the shaft has come out of gear and cocked off to one side you will have to re-lock the drive back into forward gear.

You also have to take care to make sure the shift lever/roller stays in the fork slot.

The drive might have to be "nudged" up into place until it is fully seated.
Once in place quickly install one locknut to hold it there as so you can take a breather.

In some cases you will have to turn the prop in the REVERSE direction while pushing the drive into place.
This will help line up the driveshaft splines to the coupler splines.

If the drive just won't go on the last 1/2", it's usually because the shift shafts where not straight.
Forcing a drive on while the shift shafts are off will ruin $120 worth of shift shafts not to mention you will
never get the drive fully installed.

Once you have successfully installed the drive and fasted with one locknut, test the shift.
This is best done with two people, one in the boat and one to turn the prop by hand.
Shift into forward and have the prop-person turn the prop. It will rachett in the forward direction and lock in the reverse direction.
Shift into neutral and the prop should spin free in both directions.
Shift into reverse and the prop should rachett in the reverse direction and lock in the forward direction.
If you have trouble shifting you may have installed the drive wrong.

Install the rest of the locknuts and snug them up firmly.
Install the trim cyinders

Trim the drive to the FULL DOWN position as so you can install the Trim Limit and Trim Sender switches.
Turn the drive a little to one side as so you can position the switch onto the gimbal ring.
Before installing the switch look at the center rotor.
There is a notch on the center rotor which you must turn and line up with a hash-mark on the switch.
With these marks lined up the majority of your rough adjustments will be complete.
Position the switch onto the gimbal ring and into the hinge pin without allowing the center of the switch to rotate.
In general, the wires will be facing towards the bow of the boat.
Smear a little grease on the stainless screws and install the screws with the retainer clips and lockwashers.
Gently snug up the screws, turn the drive to the other side and repeat the process for the other switch.

Follow the switch final adjustment instructions in the Service Manual.

Place the boat into the water and check in the engine compartment to make sure there are no leaks.
Use care when starting the boat for the first time as it might start in gear if the drive was improperly installed.
Start and run the engine while checking for leaks and test the shift.
Perform any shift cable adjustments if required (see service manual).

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