Lateral engine alignment

[Rick Stephens]

Good question. I forgot, what keeps the transom plate squared and aligned to the bearing and gimbal housing? I never paid attention when I did mine

6 studs and two bolts. The gimbal bearing is literally inside of the transom plate.

 

[Rick Stephens]

Slight update...
I had my wife push the engine to the starboard side while I tightened the rear mounts... After doing that, the alignment bar just about fell into the coupler... so obviously I was super excited... however, when I went to put the drive on... made it until about an inch to go and no dice... Whats more important, even spline marks or the tool going in super easy?
Seems like I could chase my tail for hours and hours trying to get even marks... seems like I can check it 5 times in a row when its close and it shows different each time depending on how you insert the tool, remove the tool, look at it, talk about its mother...

Any chance there is a collapsed rear mount? I've never had one, so I'm not sure how you would be certain. Seems to me if one of the rear mounts is down too deep you would not be able to tighten the bolts without twisting the motor.

 

[AShipShow]

Any chance there is a collapsed rear mount? I've never had one, so I'm not sure how you would be certain. Seems to me if one of the rear mounts is down too deep you would not be able to tighten the bolts without twisting the motor.

I guess it's always possible... I just cant get over how easily the alignment bar goes in now, and I got it so there's even splines the whole way around and I still cant get the drive to slide in... I've even given it the size 12 treatment with no luck... end up having to pop it back off with the trim rams...

 

[AShipShow]

I have a crazy idea lol...

Would it be a bad idea to try and put the drive on while the rear mounts are loose... Thinking maybe the lateral alignment still isn't perfect... if the drive goes on, then I can tighten the rear mounts..

The only thing I'm afraid of it maybe bending something if its not aligned well enough... I think if i go easy on the rear mounts though it shouldn't be enough to bend anything...

I'm grasping for straws at this point.

 

[Chris51280]

Dont' think this is iboats approved.
Once you start torquing down, you will put stress on the shaft and the coupling if it is not aligned

 

[AShipShow]

Also, here is the alignment tool going in...

 

[AShipShow]

Dont' think this is iboats approved.
Once you start torquing down, you will put stress on the shaft and the coupling if it is not aligned

I'm about to start doing a whole lot of things that aren't iboats approved if I don't get this drive on lol

 

[Chris51280]

You have it in forward gear and make sure the shift dog is in the correct position.

It is a bit tricky to get the last inch in

what she said.:lol:

 

[AShipShow]

Well, after trying a few more things....
-Removed O-rings from yoke to make sure that wasn't what was hanging up
-Inspected all the splines for any damage/deformation
-Messed with left/right biasing motor while tightening rear mounts more
-Got alignment bar at a balance somewhere between even spline marks and the easiest spot to install bar

After that I was out of ideas, so I took some 220 sand paper and went over the yoke right where the gimbal bearing goes cuz I noticed there was a little bit of what looked like galling and there was a very slightly raised spot, maybe .002-.003".

After that I wiped everything down, oiled the o-rings, and gave it one more try... As usual it stopped right where it had been stopping, but after a single calibrated "Merkick" it popped almost the whole way on... at that point I just used the nuts to get it the rest of the way... I'm not sure if I'm gonna ruin my coupler, but I don't know how I could have gotten it aligned any better...
I think I'm gonna run it as-is unless someone has any other suggestions

 

[Chris51280]

are there any burrs on the splines? maybe there is a nick in the coupler

 

[harringtondav]

There's a reason why Merc spec the 'parallelism' of the inner and outer surfaces of the transom. It matters, and is the main reason for apparent lateral misalignment... The quick diagram below shows the horizontal references for the couple, gimbal bearing and transom surfaces. I have exaggerated the taper, just for clarity. Any variation in how parallel the 2 surfaces are will have an affect on the lateral alignment.

Chris..........

Late response, but I concur with Chris. The gimbal plate is machined to align the gimbal bearing bore dead on (w/in manufacturing tolerances) to the center of the flywheel/crankshaft. Add the tolerances of the flywheel hsg and transom plate mounting surface locations plus engine coupler mounting, runout etc, and you have a pretty good tolerance stack up.

I mentioned earlier about the designed in clearance in the coupler/coupler yoke spline fit. This makes up for the worst case tolerance stack up above. The self centering gimbal bearing will relieve a little more misalignment, but not much.

The gimbal bearing bore center line has to be pointing near perfectly to the C/L of the engine coupler, up/down, right/left for things to mate up. My pal's 350 Mag Alpha II was getting more difficult to line up. We had the front mounts bottomed out. Turns out his transom was mush about 1/3 down the transom plate. The mated gimbal and transom plate's bore was pointing down lower than any mount tweaks could fix. Transom fixed. Alignment was fixed. Parallel and angular transom surfaces w/in Merc's specs are critical.