Shaft Alignment Help

[boatruptcy]

I've read and read but I have yet to see any photos, can someone clearly tell me how to check the shaft alignment on my 6bta mated to a zf 80v-1 in my 28te? It looks like I have a flange with 6 bolts. Do you unbolt all 6, and then try with a feeler gauge around 12,3,6 and 9 oclock and then adjust from there? It seems like the shaft will sag in the housing since it's a long run out to the stern tube. Is there a way to check now without unbolting the flange bolts? I'm not sure I have even have an alignment issue, just want to check because of a leaking shaft seal to rule it out. I can spin the shaft with one hand now, takes a little effort to get going then smooths out. Thanks in advance.

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[WillieC]

Same issue on my A25, which is why I added an additional support bearing at the top of the tube, downstream of the PSS seal. (not your issue.) While aligning, I stuck a shim under the shaft at the top of the tube to center the shaft in the tube, then took my measurements at the flange bolts, 4 in my case. Maybe not perfect practice, but how many of the ancient mariners in Sweden had a full machine shop at their disposal to align their shafts at the start of fishing season? Not being Swedist here, just practical.

[boatruptcy]

That actually is similar to the issue I had. I epoxied the stern tube to the bilge since I had an early model 28te. I still have a leak underway after compressing the pss seal again (it may need to be compressed even more), so wanted to rule out the alignment even though I don't feel any vibration and it was supposedly done recently by previous owner. Do you know if you can check it by just unbolting the flange bolts?

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[WillieC]

The proper alignment method would require removing the bolts, so the engine can be rotated and checked against the shaft flange at various angles, the whole idea being to average out differences. The issue, if I get your original post, was that the shaft drops when unbolted, making it impossible to take measurements. Then there is the whole, "If it ain't broken, don't fix it theory" given no obvious vibration and a supposed recent adjustment. But who did it, was it in the water, was it done after installing the (new?) PSS, etc.? All legitimate questions, but I like that it seems to be fine as is. I would weight that info. I am a big fan of DIY, but some of these jobs require specific tools, i.e. dial indicator that may not be in the bottom of your toolbox. And practice makes perfect. A good mechanic is worth his salt. The rest...? I would definitely be hanging over their shoulders to see how it's done 'the right way'. On the WillieC with normal shaft speed of 1000 rpm pushed by 36 horses...I am less concerned than The Big Boys with much more power might be.

The PSS bellows gets compressed from rest a specific distance based on shaft diameter. That information is easily obtained from R&D Engineering, I don't have those specs on hand. My 30 mm shaft takes 3/4" compression, IIRC. If new, there may be a bit of a break-in as the seal surfaces mate, but not long.

The WillieC had a horrible misalignment when we got it. We were brand new boaters so had no idea, but thought it odd that the shaft rose and fell with each rotation at the PSS almost a quarter inch just before entering the stern tube. That was a good first clue. Turns out we had bad engine mounts, bent shaft, and an eager seller. And we loved the boat. We learned.

[RobS]

Yes, remove the bolts, check that they are grade 8, clean and grease them for the reinstall. The coupler will only drop if you slide the shaft forward enough to disengage the pilot.

[boatruptcy]

Know the torque for reassembly?

[RobS]

Know the torque for reassembly?

In an application such as this, torque is 100% specific to the hardware you are using (size & grade) - see attached.

[boatruptcy]

You're a genius Rob, thank you!!!!