Engine Alignment in 1974 MTDC with Ford Lehman 120

Hi All
Im having a new driveshaft and tides seal put in my 34' MTDC 1974. The mechanic says the mating surfaces between the driveshaft and the transmission are out of tolerance - he is looking for 4/1000" and getting 100/1000". The adjustment is in the fore engine mounts, on the starboard side the mount is centered, on the port side it's all the way to the end of its travel to move the front of the engine to port, needs to go another 1/4" or so. Any ideas how to handle this? Anyone dealt with similar situation? I was getting a fair bit of vibration running it before. Stringers feel solid, despite the one clearly being out of alignment...

Thanks
Brian

Do you know which plane is displaying the 100/1000" difference? I cannot be certain from your description, but it sounds as if the misalignment is in the horizontal plane rather than the vertical. Of course, the vertical is always simpler to correct because that's the way engine mounts are designed, but there there are ways to correct the horizontal plane. If all you need is a tenth of an inch correction to port, remove the foot of the mount with no travel left and grind out the mounting hole a tenth of an inch. It would not be detrimental to the strength of the mount. You just need a come along to temporarily take the weight off that foot. I once horsed one of my boat's engines around using a couple of stand jacks, but a come along seems like a better idea in this case.

Hi, thanks
Yes it's a horizontal correction, although he is saying that the 10th of inch I need at the tranny corresponds to about 1/4" at the front of the engine. If I drill out the foot plate (piece that bolts to the stringer and receives the foot) I'll get somewhat close to the edge - I'm not sure how much torque are on these? I could also potentially drill out the right angle piece that bolts onto the engine? Or, perhaps tap the bolt out of the stringer, dowel it with epoxy, and redrill a new hole where it needs to be? The new hole in the stringer would be about 1/2"-3/4" from the old one. Another option might be - the foot plates at the rear don't have any travel at all in them, perhaps I could channel these out to give a bit of travel at the back?

What Rich suggested will get it done.
I am curious to know why grinding became necessary. I mean at some point that engine was put in place centered both H & V leaving room for fine tune adjustments with room to go in any direction. Or so I would have thought. To be at the end of adjustment now?
Is the coupler on the shaft square to shaft? Is the shaft straight?

Another idea to move the forward end of the engine could be a combination of adding some shims/washers between the engine mount on the stbd side of the engine and the engine as well as grinding out some of the port mount's foot. I doubt the footers do any more than just give a secure point on the beds for the mounts to rest upon and get little side-to-side push; after all they are slotted to begin with.

Yeah, I agree, it's definitely a question. All the structural materials in the bilge appear solid, but the alignment appears to have somehow shifted over time. He thinks the structural integrity of the boat is compromised, but I don't have any other indications of this, although I'm not an expert. It's only at the end of travel on one side with no play in the stringer bolts, and still centered on the other side - almost as though it were improperly installed at the get go although this seems unlikely.. Its a brand new driveshaft, so I have to assume the coupler is square. Relying on what the mechanic tells me here, but I'm going to have to get him a bit more travel in order to get that alignment..

You may have to actually move the mount if it is out that much. Is there room on the bracket that the motor mount is sitting on?

brianaderer said:

Yeah, I agree, it's definitely a question. All the structural materials in the bilge appear solid, but the alignment appears to have somehow shifted over time. He thinks the structural integrity of the boat is compromised, but I don't have any other indications of this, although I'm not an expert. It's only at the end of travel on one side with no play in the stringer bolts, and still centered on the other side - almost as though it were improperly installed at the get go although this seems unlikely.. Its a brand new driveshaft, so I have to assume the coupler is square. Relying on what the mechanic tells me here, but I'm going to have to get him a bit more travel in order to get that alignment..

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Well you do have to move the engine to get it aligned with the shaft. So you will have to do whatever in necessary to do so. Hopefully the boat is in the water and has sat for several days before you tried the alignment. The boat may relax and move when it was launched and off the blocking. If the boat is still on the hard then I would stop trying to align it until after it has been in the water for a few days. Then see what it is doing. I do a simple alignment before it is launched but then wait a few days and do the real alignment.

"You may have to actually move the mount if it is out that much. Is there room on the bracket that the motor mount is sitting on?"

-You mean the plate that the foot rests on? yes, although grinding out that much channel would start to get a bit close to the edge but there is room, I just don't know how close I can go. Based on what he is telling me I need an extra 1/4" on that side of the engine, I have .46" right now between the end of the channel and the edge of the metal bracket so taking out 1/4 would leave me about .2" clearance - feels a little tight to me?

Comodave said:

Well you do have to move the engine to get it aligned with the shaft. So you will have to do whatever in necessary to do so. Hopefully the boat is in the water and has sat for several days before you tried the alignment. The boat may relax and move when it was launched and off the blocking. If the boat is still on the hard then I would stop trying to align it until after it has been in the water for a few days. Then see what it is doing. I do a simple alignment before it is launched but then wait a few days and do the real alignment.

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Ok great thanks I will run this by him. It's on the hard right now and has sat all winter like this

brianaderer said:

"You may have to actually move the mount if it is out that much. Is there room on the bracket that the motor mount is sitting on?"

-You mean the plate that the foot rests on? yes, although grinding out that much channel would start to get a bit close to the edge but there is room, I just don't know how close I can go. Based on what he is telling me I need an extra 1/4" on that side of the engine, I have .46" right now between the end of the channel and the edge of the metal bracket so taking out 1/4 would leave me about .2" clearance - feels a little tight to me?

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Easy to weld a bit more metal to the end before you grind. Would probably cost me 20 bucks at my local friendly welder.

rgano said:

Easy to weld a bit more metal to the end before you grind. Would probably cost me 20 bucks at my local friendly welder.

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Thanks, I was thinking the same thing. It sounds like it's a good idea to splash it and give it a few days to see what we really need, and then do some mounting plate work if necessary

brianaderer said:

Ok great thanks I will run this by him. It's on the hard right now and has sat all winter like this

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The boat could be blocked so that it is racked a bit. Once it is in the water the hull will relax and go back to it’s normal shape unless it was really blocked badly and the hull was damaged, but this is fairly uncommon. Just idle it to a slip after you launch and let it sit for a while and then do the alignment. If the alignment is that far out I wouldn’t run it very fast that way. I would hope your mechanic knows about this or maybe you need to look for a new mechanic. My yard usually blocks the boats pretty well and you can get the alignment fairly close but you should always do the final alignment in the water.

brianaderer said:

...... I was getting a fair bit of vibration running it before. Stringers feel solid, despite the one clearly being out of alignment...

Thanks
Brian

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Brian, what Dave is saying makes sense but then I re read and see you were getting this vibration before it was out of the water.

May want to confirm shaft is straight, end of shaft coupler is square before it goes back in the water.

I thought they put in a new shaft. But it could have been way out of alignment before it was hauled. So maybe the engine mounts were not installed in the right place. Could have been like that forever. Hard to say without seeing it before they did the work.

Comodave said:

The boat could be blocked so that it is racked a bit. Once it is in the water the hull will relax and go back to it’s normal shape unless it was really blocked badly and the hull was damaged, but this is fairly uncommon. Just idle it to a slip after you launch and let it sit for a while and then do the alignment. If the alignment is that far out I wouldn’t run it very fast that way. I would hope your mechanic knows about this or maybe you need to look for a new mechanic. My yard usually blocks the boats pretty well and you can get the alignment fairly close but you should always do the final alignment in the water.

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I don't think the blocking is the culprit, not this time anyhow, but it definitely makes sense that it would change shape a bit. Seems as though it's sort of migrated a bit over time, how that happened is a question. Definitely planning on putting it back in the water and then doing the final alignment there, and have a couple of suggested plans to shape out those motor mounts if need be - thanks! We are also going to do the cutlass bearing, just in case that has something to do with it. It's high time for that anyhow

Yes, new shaft on second read found that too.

Wait, you are going to do the cutlass bearing, so is the new shaft in there before that was done.

Comodave said:

I thought they put in a new shaft. But it could have been way out of alignment before it was hauled. So maybe the engine mounts were not installed in the right place. Could have been like that forever. Hard to say without seeing it before they did the work.

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Yes, was definitely getting quite a bit of vibration before the haul. This is my first boat this size so don't have a basis for comparison, but it felt like a lot. It almost seems like it was originally installed in the wrong place, because there is no play in the stringer bolts and the stringers themselves are solid and don't show evidence of having moved, at least not that I can see. I'm pretty sure it has been running out of alignment for a while, the shaft had an uneven groove on it and there is play in the cutlass bearing, we are going to replace that here. The baseplate in question is run all the way to the end of its travel, and needs to go further to achieve proper alignment.

Soo-Valley said:

Yes, new shaft on second read found that too.

Wait, you are going to do the cutlass bearing, so is the new shaft in there before that was done.

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The shaft is sort of test fit in there right now, not mated to the transmission, so it can be pretty easily pulled again. Looks like the cutlass bearing just sits in the flange and that the whole tube is wet up to the driveshaft seal - does this sound right? There are actually a couple of slots in the flange right up against the keel, I can see the driveshaft through them so it looks like the bearing sort of floats out away from the boat stabilized by that flange. Thinking we are going to just cut it out with a sawzall and replace it so the whole thing is stable and true after going through all this.

There are probably some set screws in the cutless bearing that will need to come out first. Then you can cut it and peel it out. Or you can use some all-thread and press it out and press the new one in.

Comodave said:

There are probably some set screws in the cutless bearing that will need to come out first. Then you can cut it and peel it out. Or you can use some all-thread and press it out and press the new one in.

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Yes, two hex set screws. The yard here signed on to cutting it out and installing a new one without removing the flange. There are a couple of ports in the sides of the flange right up against the keel - I can actually see the driveshaft through them. So it would appear that the whole tube that runs up into the boat is wet until the driveshaft seal?

The shaft will be wet right up to the packing on the stuffing box. Depending on your style of stuffing box depends on whether or not the box drips.

Comodave said:

The shaft will be wet right up to the packing on the stuffing box. Depending on your style of stuffing box depends on whether or not the box drips.

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The stuffing box was actually the reason I ended up here to begin with. Had the old style gland and packing, failed on the water and I managed to stem the water coming in and get it to a lift in time. I'm single handed though, so monitoring that adjustment is difficult without a helper, so I am upgrading to a Tides Marine dripless on this go with the new driveshaft. That was the original idea of pulling the driveshaft, then was advised that there was too much degradation on the transmission end to get a good mate, so we got a new one. Probably the engine out of alignment and the worn cutlass bearing had something to do with that..

brianaderer said:

The stuffing box was actually the reason I ended up here to begin with. Had the old style gland and packing, failed on the water and I managed to stem the water coming in and get it to a lift in time. I'm single handed though, so monitoring that adjustment is difficult without a helper, so I am upgrading to a Tides Marine dripless on this go with the new driveshaft. That was the original idea of pulling the driveshaft, then was advised that there was too much degradation on the transmission end to get a good mate, so we got a new one. Probably the engine out of alignment and the worn cutlass bearing had something to do with that..

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Probably. Good luck.

Comodave said:

If the boat is still on the hard then I would stop trying to align it until after it has been in the water for a few days. Then see what it is doing. I do a simple alignment before it is launched but then wait a few days and do the real alignment.

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I redid the shaft, cutlass, stuffing box etc.... on a Lehman 120 last season. Cant agree more to have it in the water. Your talking such small amounts that having hull flex could be the difference.

Additionally, i was very conscious of the alignment of the work I did DURING the installation of the new cutlass, stuffing box etc......

I don't want to seem like a negative person, but you could be trying to fix any misalignment of the new parts that were installed. (I mean, i was so damn anal about alignment checking at every step. I did one item at a time and rechecked the alignment for each item installation.).

It took longer than it should ( I did it out of fear, lol) since I was totally afraid of the alignment part. (Never did it before)

Once everything was done and aligned right (minor twerk to the rear mount port mount horizontally) I redid the motor mounts last. Easy peasy.

Again, not being negative. The question is, “how the hell is the alignment that far off?” Its not like its a new boat, or new motor etc....

Comodave said:

There are probably some set screws in the cutless bearing that will need to come out first. Then you can cut it and peel it out. Or you can use some all-thread and press it out and press the new one in.

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I had one set screw and it was pretty corroded and the screw hole was degraded. I had to drill out and retap. I could not get a bronze set screw, so i fashioned one out of a monel bolt and staked it.

Getting the hull resting in the water first

Comodave said:

Well you do have to move the engine to get it aligned with the shaft. So you will have to do whatever in necessary to do so. Hopefully the boat is in the water and has sat for several days before you tried the alignment. The boat may relax and move when it was launched and off the blocking. If the boat is still on the hard then I would stop trying to align it until after it has been in the water for a few days. Then see what it is doing. I do a simple alignment before it is launched but then wait a few days and do the real alignment.

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Absolutely you will not be able to accurately gauge the alignment until the boat has been afloat and settled out for a few days. Not possible with the hull up on the hard.