- Nov 26, 2006
- 7,628
- Boat Info
- 2008 44 Sedan Bridge
- Engines
- Cummins QSC-500's
Straight Drives
I am not an expert. I learned almost everything I know on this forum. I took my knowledge and aligned my port engine this afternoon after work. Here are my steps. Perhaps it'll provide one-stop shopping for someone. This is a DIY job - Especially at $100/hour. My method may not be perfect, but with others' inputs, you should be able to use it to save almost a cool grand, about $1500 Obama money (pre tax).
Note: Now that pictures are added, realize that the text was written for the port engine but the pictures are from the starboard.
What are we looking at? The engine and transmission are bolted together firmly. On the front of the transmission is the coupler (flat disc) that mates with the shaft coupler (flat disc) which is attached to the front end of the shaft. The prop shaft travels through the hollow shaft of the transmission so the two discs can be mated forward of the assembly. They have to be completely flush and aligned before they are mated and bolted together. The shaft is supported aft by the Cutlass bearing which is a hard rubber bushing which is mounted firmly (under bottom of boat). The forward end is supported by the transmission/engine assembly. It passes through the exact center of the shaft seal (ideally) inbetween the two where the shaft passes through the hull.
What are we going to do? We are going to separate the two halves of the coupler and observe/measure to determine whether or not we need to move the engine/transmission assembly around to align it with the shaft in its permanent location.
1) Mark coupler halves - one is painted black, one is bare metal -- I used a scribe to make a line from one piece to the other (forward/aft). These are on the very front of the transmission and are bolted together using 4 bolts.
2) Remove 4 bolts, washers and nuts.
3) Rotate the forward section, which is attached to the prop shaft. As you rotate, apply forward pressure to separate out the two halves of the coupler. Once you have separated them about 1/4", the forward section will fall free from a lip around the aft section which is attached to the transmission. Observe the two flat coupler sections (2 saucer-sized plates that were bolted together). From directly above, see if they are in line with each other.
Lift the shaft (forward section) and apply moderate pressure upward and note displacement vertically from the center of the aft piece. Allow it to fall down and note displacement from the center. Raise and lower a couple of times to determine whether or not the center point of the shaft (fwd piece) aligns with the center point of the transmission (aft piece) vertically. The shaft is supported in a rubber Cutlass bearing toward the aft end, just in front of the prop. It is sealed, but not supported as is passes through the hull by the shaft seal.
Ideally, the center point is achieved when it can be displaced equally up and down. Gravity is pulling down on the front several feet of the shaft, so when you disconnect them, it falls down - lift it and determine the center point as described above. Compare it to the transmission center point to see if you need to raise/lower the transmission/engine assy.
4) When observing the pair from above, if the center lines are not in line with each other, do the following: Loosen the 2 bolts/nuts just inboard of each forward engine mount. The bolts are parallel to the centerline of the boat with the nuts attached to the front.
Not Centered:
Assembly of clamps that hold the front of the engine (entire engine, actually) in place - stops from moving left/right:
Once they are loose, insert a pry bar (old screwdriver) in the slot on the top of the clamp which is securing the transmission to the stringers. The goal is to free the mounting rod from the clamp so you can move the front of the engine left and right.
Edit: The rear mounts are actually on feet that can move around. Use a pry bar, your foot, or a really large neighbor to slide the front of the engine/transmission assembly side ways to align the centers of the two couplers when viewed from above.
I used a feeler gauge to compare the overlap on the left to the right (remember that the aft coupler has a lip which goes around the shaft coupler). Once they are in line, tighten the 4 bolts on the inboard side of the forward mounts (2 per side). Check the center alignment again. Lift the shaft to line them up (as if you could view them from the side). Ensure that they are still centered when viewed from above.
Centered:
5) If you need too much pressure upward to fit them back together, you'll need to lower the front of the engine or all 4 mounts. If you have to push the shaft down to align them, you'll need to raise the front of the engine or all 4 mounts. You won't know until you get close to the right height and alignment exactly how much each will have to be moved. Each adjustment affects the others. Follow the next steps to get the vertical alignment correct if required (mine wasn't required).
6) Fit the halves together with your initial scribe lines lined up. Before you clamp them together by hand, fit a feeler gauge in between the two halves. I like the 8/1000's size. When it is held between the two halves firmly, but still moveable, slide it around the perimeter and determine where the two couplers fit their tightest. There may be imperfections around bolt holes - ignore those measurements. Slide them couplers apart and work the feeler into the gap at the tightest point - firm, but don't crush it. Slide it out and move it around the perimeter to the opposite side (should be the widest gap). Measure the gap with the feeler gauge to determine which one fits with the same pressure as the original piece. The difference is how far out of true your alignment is. Mine was about 11/1000's. The tight area was the bottom, inboard point (7:30 on the clock if viewed from the front).
Determine where you need to lift/lower the engine/tranny assy to make the plates line up and meet with a constant gap around the perimeter. For mine, I needed to lower the front, starboard (inboard) mount and raise the aft port (outboard) one. From bottom to top, each mount point has: Mount base with bolt sticking up. Lower , height adjusting nut. Lock Washer (with tabs). Engine bracket. Top Nut which secures the engine mount down to the lower nut. (There may be a washer or two in there.) To adjust a mount height, loosen the top nut. Straighten the tabs on the lock washer which are keeping the lower nut from turning.
Rotate the lower nut up or down to lift that section of the engine up or down. In order to raise one corner, lower the opposite (diagonally) corner. You can't just move one mount - move two. The engine doesn't twist. If they are diagonal, move them opposite. If they are side by side, you can move them the same way (raise the back of the engine as an example).
If the two plates are perfecly aligned, but they are touching at the top with a wide gap at the bottom, you'll need to lower the back two mounts the same amount as each other. Realize that as you do that, you'll displace the transmission coupler (back plate) upward. They may become aligned as two flat plates face to face, but the aft one will be displaced up too high. Now, lower all four mounts the same amount to make the couplers align in all dimensions (up/down, left/right, tilt up/tilt down, tilt left/tilt right).
If your boat was ever in alignment and hasn't been damaged, you shouldn't have to do too much. Mine needed about 1/16" slip of the front of the engine to starboard, and the back outboard mount needed to come up about 1 1/2 turns and the front inboard mount needed to come down about 1 1/2 turns.
7) Now, you think all is lined up, or getting close. As you proceed, rotate the forward coupler (shaft side) with the feeler gauge in place. If the shaft is true, there should be no change in the gap around the circumference. If there is, get the shaft fixed/replaced. All good? Begin to tighten engine mounts and continue to check alignment. Periodically, separate out the two halves enough to allow the shaft coupler to fall free. Check for alignment. Once all is well with all mounts and securing nuts tightened, bend tabs back to secure lower nuts. Rotate shaft to align your scribes. Replace four bolts, washers and nuts through the coupler assembly. Tighten slowly rotating 180 degrees, then 90, then 180, then 90. Stand back and smile hugely. You've saved hundreds in labor and thousands in potential damage. Also, you know it's done right.
For a quick check, remove four bolts, separate halves - note alignment. Push halves back together and insert feeler around circumference to check for deviations. Replace 4 bolts.
Experts - correct my terminology. Correct my procedures. I'll give credit and correct this post so people can use it as a checklist for aligning their own V-Drives. Do it soon so I can fix any errors on my boat - we're heading out again Friday!
Note: Now that pictures are added, realize that the text was written for the port engine but the pictures are from the starboard.
What are we looking at? The engine and transmission are bolted together firmly. On the front of the transmission is the coupler (flat disc) that mates with the shaft coupler (flat disc) which is attached to the front end of the shaft. The prop shaft travels through the hollow shaft of the transmission so the two discs can be mated forward of the assembly. They have to be completely flush and aligned before they are mated and bolted together. The shaft is supported aft by the Cutlass bearing which is a hard rubber bushing which is mounted firmly (under bottom of boat). The forward end is supported by the transmission/engine assembly. It passes through the exact center of the shaft seal (ideally) inbetween the two where the shaft passes through the hull.
What are we going to do? We are going to separate the two halves of the coupler and observe/measure to determine whether or not we need to move the engine/transmission assembly around to align it with the shaft in its permanent location.
1) Mark coupler halves - one is painted black, one is bare metal -- I used a scribe to make a line from one piece to the other (forward/aft). These are on the very front of the transmission and are bolted together using 4 bolts.
2) Remove 4 bolts, washers and nuts.
3) Rotate the forward section, which is attached to the prop shaft. As you rotate, apply forward pressure to separate out the two halves of the coupler. Once you have separated them about 1/4", the forward section will fall free from a lip around the aft section which is attached to the transmission. Observe the two flat coupler sections (2 saucer-sized plates that were bolted together). From directly above, see if they are in line with each other.
Lift the shaft (forward section) and apply moderate pressure upward and note displacement vertically from the center of the aft piece. Allow it to fall down and note displacement from the center. Raise and lower a couple of times to determine whether or not the center point of the shaft (fwd piece) aligns with the center point of the transmission (aft piece) vertically. The shaft is supported in a rubber Cutlass bearing toward the aft end, just in front of the prop. It is sealed, but not supported as is passes through the hull by the shaft seal.
Ideally, the center point is achieved when it can be displaced equally up and down. Gravity is pulling down on the front several feet of the shaft, so when you disconnect them, it falls down - lift it and determine the center point as described above. Compare it to the transmission center point to see if you need to raise/lower the transmission/engine assy.
4) When observing the pair from above, if the center lines are not in line with each other, do the following: Loosen the 2 bolts/nuts just inboard of each forward engine mount. The bolts are parallel to the centerline of the boat with the nuts attached to the front.
Not Centered:
Assembly of clamps that hold the front of the engine (entire engine, actually) in place - stops from moving left/right:
Once they are loose, insert a pry bar (old screwdriver) in the slot on the top of the clamp which is securing the transmission to the stringers. The goal is to free the mounting rod from the clamp so you can move the front of the engine left and right.
Edit: The rear mounts are actually on feet that can move around. Use a pry bar, your foot, or a really large neighbor to slide the front of the engine/transmission assembly side ways to align the centers of the two couplers when viewed from above.
I used a feeler gauge to compare the overlap on the left to the right (remember that the aft coupler has a lip which goes around the shaft coupler). Once they are in line, tighten the 4 bolts on the inboard side of the forward mounts (2 per side). Check the center alignment again. Lift the shaft to line them up (as if you could view them from the side). Ensure that they are still centered when viewed from above.
Centered:
5) If you need too much pressure upward to fit them back together, you'll need to lower the front of the engine or all 4 mounts. If you have to push the shaft down to align them, you'll need to raise the front of the engine or all 4 mounts. You won't know until you get close to the right height and alignment exactly how much each will have to be moved. Each adjustment affects the others. Follow the next steps to get the vertical alignment correct if required (mine wasn't required).
6) Fit the halves together with your initial scribe lines lined up. Before you clamp them together by hand, fit a feeler gauge in between the two halves. I like the 8/1000's size. When it is held between the two halves firmly, but still moveable, slide it around the perimeter and determine where the two couplers fit their tightest. There may be imperfections around bolt holes - ignore those measurements. Slide them couplers apart and work the feeler into the gap at the tightest point - firm, but don't crush it. Slide it out and move it around the perimeter to the opposite side (should be the widest gap). Measure the gap with the feeler gauge to determine which one fits with the same pressure as the original piece. The difference is how far out of true your alignment is. Mine was about 11/1000's. The tight area was the bottom, inboard point (7:30 on the clock if viewed from the front).
Determine where you need to lift/lower the engine/tranny assy to make the plates line up and meet with a constant gap around the perimeter. For mine, I needed to lower the front, starboard (inboard) mount and raise the aft port (outboard) one. From bottom to top, each mount point has: Mount base with bolt sticking up. Lower , height adjusting nut. Lock Washer (with tabs). Engine bracket. Top Nut which secures the engine mount down to the lower nut. (There may be a washer or two in there.) To adjust a mount height, loosen the top nut. Straighten the tabs on the lock washer which are keeping the lower nut from turning.
Rotate the lower nut up or down to lift that section of the engine up or down. In order to raise one corner, lower the opposite (diagonally) corner. You can't just move one mount - move two. The engine doesn't twist. If they are diagonal, move them opposite. If they are side by side, you can move them the same way (raise the back of the engine as an example).
If the two plates are perfecly aligned, but they are touching at the top with a wide gap at the bottom, you'll need to lower the back two mounts the same amount as each other. Realize that as you do that, you'll displace the transmission coupler (back plate) upward. They may become aligned as two flat plates face to face, but the aft one will be displaced up too high. Now, lower all four mounts the same amount to make the couplers align in all dimensions (up/down, left/right, tilt up/tilt down, tilt left/tilt right).
If your boat was ever in alignment and hasn't been damaged, you shouldn't have to do too much. Mine needed about 1/16" slip of the front of the engine to starboard, and the back outboard mount needed to come up about 1 1/2 turns and the front inboard mount needed to come down about 1 1/2 turns.
7) Now, you think all is lined up, or getting close. As you proceed, rotate the forward coupler (shaft side) with the feeler gauge in place. If the shaft is true, there should be no change in the gap around the circumference. If there is, get the shaft fixed/replaced. All good? Begin to tighten engine mounts and continue to check alignment. Periodically, separate out the two halves enough to allow the shaft coupler to fall free. Check for alignment. Once all is well with all mounts and securing nuts tightened, bend tabs back to secure lower nuts. Rotate shaft to align your scribes. Replace four bolts, washers and nuts through the coupler assembly. Tighten slowly rotating 180 degrees, then 90, then 180, then 90. Stand back and smile hugely. You've saved hundreds in labor and thousands in potential damage. Also, you know it's done right.
For a quick check, remove four bolts, separate halves - note alignment. Push halves back together and insert feeler around circumference to check for deviations. Replace 4 bolts.
Experts - correct my terminology. Correct my procedures. I'll give credit and correct this post so people can use it as a checklist for aligning their own V-Drives. Do it soon so I can fix any errors on my boat - we're heading out again Friday!
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