Front engine mount wont go low enough to align gimbal bearing

[Chevyls6]

Calling all alignment experts. What can i do to get the front engine mount to go lower when im all out of threads? If i stick a spare driveshaft into the splines it touches at the bottom of the gimbal bearing inner race.

Are there shim kits available for the rear mounts? I replaced them both when i had this thing apart.

140hp 1974 engine mc1 drive

 

[Scott06]

Did u center the gimbal bearing by inserting alignment tool and smacking it up, down left and right?

Would be concern that you may have a bad transom

 

[Rick Stephens]

1974 boat..... a rotten transom allows the gimbal housing and transom plate to sag. This puts the rear mounts low. I would suspect that or collapsed bushings.

 

[kenny nunez]

If the transom is not rotted then what may have happened is the hull has settled just due to the age. The easy fix is to remove the front mount and have a welding shop cut and re weld 1” out of it. Also a very good chance that the rear mounts should be replaced.

 

[Fun Times]

You’ve already changed the rear motor mounts? What brand/part number did you use?
They changed designs so the following may be a guide for you to help out, https://static.perfprotech.com/files/images/mcmServiceBulletin.PDF

 

[achris]

If you've had the engine out, did you put the spacers back in when you re-mounted the engine?

A bit more history would help.

Chris.....

 

[dubs283]

Are there shim kits available for the rear mounts? .......

140hp 1974 engine mc1 drive

No, there are replacement parts available but your issue supercedes this step

1974...as mentioned your boat most likely has suffered transom/stringer rot. Remove the engine/transom assy and study up/post in the restoration forum

 

[Chevyls6]

A little more background info may be needed to clarify the situation. I already had the engine and transom assembly out and the transom itself had a little rot but nothing that seemed terminal. It's an exposed piece of plywood being an aluminum boat. the rear bushings are new

I had to make a new front mount and it may have ended up a little taller than the old one. I was mostly looking to find out if there are select a shim type parts for these to change the mount geometry before i go hacking my new support up.

 

[Chevyls6]

If the transom is not rotted then what may have happened is the hull has settled just due to the age. The easy fix is to remove the front mount and have a welding shop cut and re weld 1” out of it. Also a very good chance that the rear mounts should be replaced.

I did think about slicing 1" out of the front mount just to get me on the water this season. I have an AC/DC tig welder so i can do it myself.

 

[Chevyls6]

You’ve already changed the rear motor mounts? What brand/part number did you use?
They changed designs so the following may be a guide for you to help out, https://static.perfprotech.com/files/images/mcmServiceBulletin.PDF

One of them was sierra the other was a new old stock mercury. They looked like the old ones just less collapsed in the rubber part.

 

[Chevyls6]

If you've had the engine out, did you put the spacers back in when you re-mounted the engine?

A bit more history would help.

Chris.....

Yes spacers and lock washer spring things are in place

 

[Chevyls6]

Did u center the gimbal bearing by inserting alignment tool and smacking it up, down left and right?

Would be concern that you may have a bad transom

Yes i tried rotating the bearing in its housing.

 

[dubs283]

AC/DC

 

[achris]

I did think about slicing 1" out of the front mount just to get me on the water this season. I have an AC/DC tig welder so i can do it myself.

Have you welded aluminium before? If not, this is not the piece to start practicing on!

If the engine WAS in alignment, and now it's not, then I'd be concerned as to why. Chopping a section out of the front mount is not the answer. It might look like it is, but trust us, it's not. Find out why a problem now exists, and fix that problem, don't try to 'band-aid' it. That never ends well. (I'd bet money on chopping the front mount won't get you into alignment)

Chris.......

 

[kenny nunez]

I had to keep a cut down mount in stock because the Galaxy boats usually had the front too high which was caused by the “X” dimension too low.
And also Mercruiser did make a “short” front mount at one time.
As Chevyls6 stated in #8 that he had replaced the front mount and it may be too high.

 

[Chevyls6]

Have you welded aluminium before? If not, this is not the piece to start practicing on!

If the engine WAS in alignment, and now it's not, then I'd be concerned as to why. Chopping a section out of the front mount is not the answer. It might look like it is, but trust us, it's not. Find out why a problem now exists, and fix that problem, don't try to 'band-aid' it. That never ends well. (I'd bet money on chopping the front mount won't get you into alignment)

Chris.......

Yeah ive welded aluminum castings before. It's my least favorite material to work with because of how nasty the impurities are. My tig welder picked yesterday to have a problem with the ac function but it was good enough to do the job.

 

[Chevyls6]

I chiseled 1/4 inch out of the wood mount i made and chopped the front mount 1" or so.

I can now get the alignment bar into the coupler with threads to spare in either direction on the front mount.

Is it strictly necessary to have perfect spline contact on both sides of the tool? I believe theres some wear in the aluminum spline in my coupler because i cant seem to get both sides to touch equally. It does contact all the splines just not along their entire length.

If i insert my spare driveshaft it seems the center of its movement corresponds with the center of the bearing race.

 

[1960 Starflite]

Turn engine 180°, grease marks on alignment bar should rotate 180 also if its the coupler. I don't believe you have a problem.