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Post by brummieboy on Oct 10, 2021 8:55:30 GMT
I think also that the 'off the shelf' engine mounts offered at any chandlers never help with any adjustment. My boat was fitted from new with what I subsequently found out were R & D mounts. After 12 years or so one of them failed, so I sought out replacements. As I have Aquadrive, I was advised to use soft mounts, After persevering for a couple of years with the rubber cotton reels I'd been sold, I did a bit more research and found what was originally fitted. R&D wanted to know the engine, gearbox, type of coupling and boat length, and then specified 2different mounts for front and rear. Aquadrive makes it easy, but the difference in vibration is incredible. They probably cost 3 times the 'cotton reels' but well worth it.
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Post by Deleted on Oct 10, 2021 9:10:48 GMT
As Tony B says, its sounds like it could be a frustrating process. I am torn between having a go, and just giving the job to someone else. Access isn't particularly good, and my knees aren't getting any younger. If you give the job to someone else, how will you determine whether they are going to be better at the job than you would be? Time is a big factor when getting a job done professionally. One advantage of DIY maintenance is that time is much less of an issue, so more time can be spent getting it right. I am a great advocate of 'having a go', and I am sure with enough time and colorful words hurled at the engine I could get it done, though this is far from certain. However, some jobs, perhaps its just easier to admit are not worth the effort in terms of time and frustration. I don't know what it would cost in terms of time and money to get someone in, and they probably wouldn't do the job any better than I could, but they may save my knees and sanity in the process. I assume there is a noticeable difference between aligning it correctly or not, so unless they have a way of measuring it that I am not aware, the results should be similar. I guess anything can be done if you spend enough time researching it, have enough time to execute it, and the tools to do it. I suppose with this job, its a question of how often a shaft will need aligning. Its probably not a regular occurrence, but having the skills to do it could prove useful in the future assuming my body is still obliging.
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Post by Deleted on Oct 10, 2021 9:20:32 GMT
Thanks Tony. One last question. I have made the massive assumption that it is in fact the shaft misaligned, somewhat confirmed by the measurement made on the coupling, though the coupling may have been distorted. However to help diagnose the problem, I noticed that whilst I ran the engine in both forward and reverse gear,the vibration is definitely noticeable in forward gear, but increasing the revs reduces it to almost zero. There is barely any vibration when in reverse gear. So, could it be that the shaft itself is bent, or bent and misaligned. Again, I know its a hard question to answer without actually seeing it. Thanks If you just disconnect at the gearbox flange, it will be pretty obvious straight away if there is significant misalignment. You can always reconnect again without doing any adjustment if you think it’s too difficult. But you will know whether or not there is an alignment issue vs a mounting or drive plate problem. Ok. This sounds like a solution to stop me procrastinating and get on with something. I will add it to the list of jobs.
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Post by tonyb on Oct 10, 2021 10:16:19 GMT
If you just disconnect at the gearbox flange, it will be pretty obvious straight away if there is significant misalignment. You can always reconnect again without doing any adjustment if you think it’s too difficult. But you will know whether or not there is an alignment issue vs a mounting or drive plate problem. Ok. This sounds like a solution to stop me procrastinating and get on with something. I will add it to the list of jobs.
It will only be really obvious for radial misalignment, as the shaft will jump as you pull it back. Angular is far more subtle and needs feeler gauges and as the gearbox makers specify the maximum angular misalignment as either 0.5 or 0.25mm the angular misalignment may look OK to the eye. Even when you have the same gap all around the coupling joint, you need to turn the flexible half through 180 degrees in case the flexible has taken a set. Don't get too hung up on those values, as long as you get it closer than it was.
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Post by Telemachus on Oct 10, 2021 10:36:12 GMT
Ok. This sounds like a solution to stop me procrastinating and get on with something. I will add it to the list of jobs.
It will only be really obvious for radial misalignment, as the shaft will jump as you pull it back. Angular is far more subtle and needs feeler gauges and as the gearbox makers specify the maximum angular misalignment as either 0.5 or 0.25mm the angular misalignment may look OK to the eye. Even when you have the same gap all around the coupling joint, you need to turn the flexible half through 180 degrees in case the flexible has taken a set. Don't get too hung up on those values, as long as you get it closer than it was.
Rather than using feeler gauges, I found you could eyeball it with a mirror and a torch. The eye is pretty good at seeing a tiny gap that light is shining through, you can use the mirror to look at the lower part of the flange whilst trying to shine the torch through any gap. Anyway, with flexible mounts it’s not an exact science. Perfect alignment in neutral probably won’t be quite right with the engine producing torque and squishing the mounts.
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Post by Deleted on Oct 10, 2021 11:07:23 GMT
DIY job, or best left to those versed in the intricacies and finer details of thinking in three dimensions whilst wielding a set of enchanted feeler gauges? Answers on a postcard please. Always done it myself since being told by an expert that he could not get it any better than me.
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Post by Deleted on Oct 10, 2021 13:58:13 GMT
It will only be really obvious for radial misalignment, as the shaft will jump as you pull it back. Angular is far more subtle and needs feeler gauges and as the gearbox makers specify the maximum angular misalignment as either 0.5 or 0.25mm the angular misalignment may look OK to the eye. Even when you have the same gap all around the coupling joint, you need to turn the flexible half through 180 degrees in case the flexible has taken a set. Don't get too hung up on those values, as long as you get it closer than it was.
Rather than using feeler gauges, I found you could eyeball it with a mirror and a torch. The eye is pretty good at seeing a tiny gap that light is shining through, you can use the mirror to look at the lower part of the flange whilst trying to shine the torch through any gap. Anyway, with flexible mounts it’s not an exact science. Perfect alignment in neutral probably won’t be quite right with the engine producing torque and squishing the mounts. Half tidy machinist should by able to clock a 4 jaw lathe chuck to within .004” (0.1mm for anyone born after 1972 🤪) without the use of a DTI. R+D flexible couplings make shaft alignment a doodle - the red tit with a feeler gauge comes in to its own.... 👌👍
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Post by Deleted on Feb 20, 2022 11:02:03 GMT
Many many months later....... I marked up the positions with a centre punch as described. I disconnected the half coupling from the R&D type flexible coupling. There didn't appear to be any significant drop in the prop shaft, though the distance between half coupling and stern tube is minimal. Loosening the stern gland and sliding the half coupling back and then forward again allowed realignment with the R&D coupling with no discernible force required on my part. At this point I reconnected the couplings together. Armed with feeler gauges and a spanner, I loosened the top nuts holding the engine to the flexible mounts. Using the feeler gauges inserted on the red nut on the flexible coupling, I rotated the shaft. There is definitely more of a gap on one side than the other ( I shall call it 9 o'clock, looking aft). Slightly apprehensive, I tried adjusting the height of the engine, by raising, first the back two adjusters, and then the front. This seemed to have little effect on the gap. I was kind of expecting the gap to be at either the 6 o'clock or 12 o'clock position. At this point, I gave up and returned the engine to its original position using the marks. So, my questions are: 1. What adjustment,if any, is required to reduce the gap at the 9 o'clock position. 2. Is it possible the flexible coupling is the cause of the gap, due to distortion or the shaft itself is bent? Many thanks postimg.cc/CB48hZBJETA, Damn, still can't insert images. It could be the engine is to high, and needs dropping a bit. I always adjust the mounts near the bulkhead, then adjust the front ones as a start point. It's a fiddly job and takes time to get it as close as possible. I use feeler guages and a set square. Mine has to be pretty spot on as i have a vetus shaft seal, which should never have a flex coupling.
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Post by Deleted on Feb 20, 2022 12:25:59 GMT
Rusty's image if it helps people.
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Post by brummieboy on Feb 20, 2022 16:48:30 GMT
If you have a gap at the '9 0'clock position, and it stays in the same place as you turn the shaft, then this must indicate that the engine and shaft have a sideways misalignment. As the shaft will be rigid in the stern tube, this may need some adjustment of the mountings on the bearers. This could be achieved by widening the mounting holes and side packing once in the right position. Not a quick job.
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Post by Telemachus on Feb 20, 2022 21:25:31 GMT
If you have a gap at the '9 0'clock position, and it stays in the same place as you turn the shaft, then this must indicate that the engine and shaft have a sideways misalignment. As the shaft will be rigid in the stern tube, this may need some adjustment of the mountings on the bearers. This could be achieved by widening the mounting holes and side packing once in the right position. Not a quick job. The engine mounts on our Beta 43 have the vertical adjustment by means of the studded rod/nuts, but also lateral movement by means of slots on the holes attaching the base of the mounts to the bearers. So probably you need to slacken these latter ones off and move the engine sideways a bit. You can see the slots in this pic: Obviously you will need to move the front of the engine sideways more than the rear, so the flange ends up in the same place but at a slightly different angle.
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Post by Telemachus on Feb 21, 2022 10:32:34 GMT
Thanks guys. I don't think the engine mounts have a lateral adjustment, but will have a closer look. Not sure I know how to determine if the gap remains the same on full rotation, as I only have the R&D coupling bolt as a reference point. I think the point is that the gap could either be caused by lateral engine misalignment, or by a bent shaft either of the prop shaft or the gearbox. With a engine misalignment, the gap always stays in the same place regardless of the rotational position. With a bent shaft, the gap rotates as the shaft rotates. You could perhaps lightly bolt the coupling together using one bolt at a position where there is no gap, then rotate the whole thing 120degrees and see if the gap is still in the same place, or if it has moved 120degrees. And again for the other 120degrees. Look for and measure the gap between the gearbox flange and the white bit near the base of the studs. Edit: I said 120degrees because I thought there were 3 studs, but in fact it looks like there are 4, so substitute 90degrees for 120 degrees!
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