Help please with shift shaft bushing removal

[Moody Blue]

!970 merc 800.

Trying in vain to remove the shift shaft bushing. Have three lower units and was able to remove the bushings from two of the three with a homemade tool. Unfortunatley the driveshafts on those two units are corroded and pitted around the waterpump seals and I don't want to use them. The unit on which I can't remove the bushing has a driveshaft in great condition. Just my luck.

This bushing is really stuck tight. Have been soaking in penetrating fluid for a few hours. The notched edges in the bushing are beginning to round off.

Anyone with a trade secret to getting this thing out? Sure would appreciate some help on this one.

 

[emckelvy]

Re: Help please with shift shaft bushing removal

!970 merc 800. Anyone with a trade secret to getting this thing out?

Heat the sides of the gearcase in the area of the bushing. This'll expand the metal and make it easier to bust the bushing loose.

 

[Moody Blue]

Re: Help please with shift shaft bushing removal

Soaked the bushing in penetrating oil overnight. Made a chisel and squared up the shoulders of the notches in the bushing. Took the propane torch and heated the casing around the bushing threads and after a slight struggle it popped loose.

Thanks much. Now onto the next problem.

 

[jeff_smith_0423]

Re: Help please with shift shaft bushing removal

I was just about to ask a similar question. I bought a replacement shift shaft bushing for my l/u yesterday since it was covered in gear oil and gunk. I'm figuring that's the source of my water intrusion. Could you share with me how you got in there? Did you remove the shift shaft first? Does it just pull out ? I'm clueless as to where to start with this one.

 

[Moody Blue]

Re: Help please with shift shaft bushing removal

Jeff, you don't mention what motor you have but I can describe how my motor is set up. Had the same setup on a mid 90's motor as well so I think the same setup was used over many years and models.

Once the LU is removed, the shift shaft bushing (SSB) is readily replaced (usually). It is recessed inside the LU casing forward of the waterpump assy and is threaded into the LU casing. You should see a splined shaft about 3/8" diameter protruding out of the LU. This is the shift shaft. Situated on top of the SSB will be the plastic reverse lock cam spacer and reverse lock cam.

Take care not to rotate or change the position of the shift shaft OR shift linkage in the top end once they are separated. Makes putting it back together easier.

Pay attention to the orientation of the reverse lock cam before removing it. You will thank yourself later. It and the spacer just slide up off the shaft. Apply downward pressure on the shift shaft while pulling anything up over it. You DON'T want to pull the shift shaft out of its position.

With those two parts removed, the SSB is visible. To remove it you will need a special Merc tool or you can make your own. It is basically a steel tube with two tabs located 180 degrees apart. The tube slides over the shift shaft and the tabs fit into two notches on the top of the SSB. Use the tool to unscrew the SSB from its seat. Once it is fully unthreaded, just pull it up over the shift shaft. Remember, hold the shift shaft down while doing this.

The bushing is an assembly with two seals pressed inside and an o-ring installed at the top of the treaded portion. Just reverse the procedure for installation. Use a waterproof lube on the seals and shaft splines before sliding the SSB into place.

Good luck

 

[KCIDirect]

Re: Help please with shift shaft bushing removal

MoodyBlue, you mentioned about "Take care not to rotate or change the position of the shift shaft OR shift linkage in the top end once they are separated. Makes putting it back together easier." How can we be sure this is aligned properly when reinstalling the LU?
After replacing the LU in my Mariner 75hp 1985 outboard, and turning over the motor I see the prop is turning. I assume this is not correct, it should be in neutral and not turning. I have not started the motor and concerned that I have improperly inserted the "shift shaft" cable. Don't see any other posting, is there a way I can be sure this cable is properly aligned and inserted? What is the proper procedure for replacing the LU for proper connection/insertion of exhaust, drive shaft, water pump tube, shift shaft and pins? Thank You

 

[emckelvy]

Re: Help please with shift shaft bushing removal

If you shift the control box to Neutral and also the lower unit, it should go right up.

To make sure the lower unit is in Neutral, take a pair of vise grips or stout pliers; pad the jaws so they don't mar the shaft; then move the shift shaft CCW until you feel a positive detent. This should be Neutral which you can verify by spinning the prop shaft or driveshaft.

If you don't find Neutral, turn the shift shaft CW until you get a lot of rotational 'free play'. This should be Fwd gear. The prop shaft will stop when turned in one direction, 'ratchet' in the other. Now, from Fwd turn the shift shaft CCW until you shift into the detent, and this has got to be Neutral.

When you're inserting the lower unit, the 'guide tube' in the upper water pump body catches the copper water tube and guides it into place. As you're inserting more, you need to put the flat washers and nuts on the 'side studs' before the studs are too high to get the nuts on.

As you further insert the lower unit, the driveshaft splines begin to engage the crankshaft, and you'll need to rotate the flywheel just a bit CW to get the driveshaft engaged. The shift shaft should be coming up next, sometimes you have to wiggle the upper shift rod a bit with some long-nose pliers to get it to match up with the lower unit's shift shaft.

The exhaust tube pretty much takes care of itself. I find it'll go together easier if you spread some grease on the rubber gasket and also the end of the exhaust tube.

Now, if for some reason the shift shaft and shift rod don't want to engage, you may have to go one step further and disconnect the shift cable from the linkage inside the powerhead. Pull the throttle cable then undo the shift cable from its attachment to the shifter arm. Wiggle the shifter arm Fwd/Aft just a small amount and you'll find the shift rod drops right in.

The reason this happens is that typically, there's a bit of preload on the shifter cable and if it's too much, the preload pushes the shift rod past the point of perfect alignment with the lower unit shift shaft.

For this reason I'll typically install the lower unit with it in Fwd. However, for the average person who hasn't done a ton of these, it's usually easier to have the gearshift and lower unit in Neutral and dispel all doubt about what gear we're in!

Some are just so cranky that you can't get 'em back together no matter what gear you have it in, then you take the shift cable off and wiggle about.......others treat you nice and slide right up there the first time. If they were only all like that!

Well, HTH & that oughta get you back out in the water with the correct gears!.........ed

 

[Moody Blue]

Re: Help please with shift shaft bushing removal

Ed, thats a great explanation. I'm in the "won't mesh together easily" category. Got everything to align and fit EXCEPT the shift shaft. Tried numerous times so far using a helper to move the upper linkage back and forth. Ran out of daylight but will be back at it tomorrow.

KCI, I have noticed in my trials, that the prop shaft does turn in neutral when the driveshaft is rotated. If you put any load on the prop shaft it will stop moving. If you think the motor is in neutral, try spinning the prop by hand. It should spin freely in both directions. MAKE SURE THERE IS NO WAY THE MOTOR CAN START BY ACCIDENT BEFORE PUTTING YOUR HANDS ANYWHERE NEAR THE PROP.

 

[Moody Blue]

Re: Help please with shift shaft bushing removal

Well after some experimentation and cursing managed to get everything back together.

Tried reassembling with upper and lower units in neutral but this was very difficult because there was no play at all in the lower unit shift shaft. Could NOT get the splines aligned. Problem was worse for me because I am using a new control box and cables AND a different LU than was on the motor originally. Had no reference point for the neutral position.

Decided to put everything into FWD. The LU shift shaft then had lots of play in it and I was able quickly to rotate and align the shift shaft using needle nose pliers.

Thanks for everyones help.