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Motor Mounts and Shaft Alignment

bdolnik

Member
"<[img]"http://www.marineengin

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I paid a mechanic to replace this motor mount which was in pretty sad shape. I finally got to run the boat last night and I "think" there is a slight vibration now. I want to check the alignment, and the crusader manual shows the following procedure.

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My question is, since the shaft is already bolted on does this procedure still apply? Will I be able to still measure a gap and adjust for it? Or is there something else I need to do to make sure everything is in alignment?"
 
"Gotta remove the bolts and re

"Gotta remove the bolts and reseat the coupler before measuring.

did you pay the mech for the whole job or just to R&R the mount, w/o alignment?"
 
"The whole thing was a fiasco,

"The whole thing was a fiasco, he said he "checked it", which is probably not true... I'm just glad to be finished with him and move on. I'll check it myself. One of the bolt heads was broken off which I pointed out to him on the initial visit, but when he came back two weeks later to do the work he didn't have the correct tools because he didn't know the bolt head was broke off! He ended up having to cut it off with a torch."
 
"Understand.

You may want t


"Understand.

You may want to do a search, using the button at the top. There have been a few threads over the past year on alignments; you find find a few 'tips' reviewing them."
 
"[i]There have been a few thre

"There have been a few threads over the past year on alignments.

Funny how that little bit of insight helped, I had searched previously on 'motor mounts' and not come up with much, searching on 'alignment' is a whole different story
happy.gif


Thanks makomark!"
 
I just put the motor back in M

I just put the motor back in Miss Nancy and that was with all new motor mounts and having to trim down the engine beds because the new mounts were taller then the old. All that said a friend of mine came over and taught me how to do the alignment. It was not as hard as I thought it would be but took a little time. You will need to make sure the shaft is lined up side to side and then the up and down. We did side to side first and then the raising and lowering of the mounts as needed. Sounds complicated but its not to bad. Just have patence and when its done then have cold beer availible to celibrate.
 
"Thanks Paul, I found the foll

"Thanks Paul, I found the following through a search on here, is it the procedure you used?

Shaft alignment:
1) remove all four coupler bolts
2) using a pair of vice grips and a thin,flat washer as a spacer, squeeze the couplers together.
3) adjust engine position until the 3 remaining hole locations have all the same spacing, using feeler gauges.
4) target +/- .002 as your goal."
 
bryan -

you want to make su


bryan -

you want to make sure the shaft is centered in its log before you start moving the engine around. Sounds simple but can require innovative thinking. Having the shaft sitting on the 'bottom of the log' and being perfectly aligned with the coupler on the gear will require a major fix in short order.
 
Well I was feeling pretty good

Well I was feeling pretty good about attempting to do this myself but now you have me worried Mark. I'm going to take a closer look tonight and may take some pictures to post if I have any questions.
 
didn't mean to scare you.

didn't mean to scare you. just wanted to make sure you had some info I didn't see earlier in the thread (centering). Also wanted to convey I think it is rather critical.

I shouldn't worry you anymore than reconnecting a gasoline line...
 
"Mark,

What's the proce


"Mark,

What's the procedure for centering the shaft in the log? Seems to me if the cutlass bearings in the struts and the shaft log are all in line and straight then you should be okay. Or is that what you are referring to. Can you provide the steps or a link to another thread? Thanks."
 
"Thanks for that question Greg

"Thanks for that question Greg, I'd like to know this also. My shaft is covered by the PSS dripless where it goes into the log so can't even see it.

Here is what I think I'm going to do, SOMEONE please tell me if this 'might' be ok. It seems logical to try but maybe not since I'm new at this.

Attached is a photo of the two rear mounts, the new one and the existing one. It's pretty clear the new was left at it's top most adjustment, where the existing one is adjusted much further down. I checked the front mounts on this motor and front/rear on the starboard motor and they are all very similar in their adjustments. So I'm thinking since everything was aligned and running smooth before the replacement, rather than unbolting the coupling and doing a complete realignment, I might be able to just turn the adjustment on the new mount so it matches the other side. Any thoughts?

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"Bryan,

I don't think t


"Bryan,

I don't think that would be a prudent way to go. Looking at the photos you have provided, the rubber donut on the new mount appears to be lower in position than the old possibly indicating why the difference in its top most position. Additionally, it does'nt seem to take that much adjustment to make some moderate changes at the shaft.

My problem with the shafts was that the alignment was good but placement with the log was so poorly off center it rubbed away at the material creating a leak thru the shaft log.

Blindly twisting the mounts may be more of a problem than even an educated guess ... unlike a carb mixture screw where you can just seat it, then back it out "X" amount and you will be within the starting ballpark, so to speak."
 
"Concur with Al - messing with

"Concur with Al - messing with mount adjustments w/o checking isn't a prudent action.

Most setups with Gas engines I've dealt with are all single bearing (in the strut) setups. Assuming the strut was installed properly aligned to the log (& it isn't bent), you need to set the shaft in the center of the log and then move the engine to get the couplers aligned. Its a reasonably low risk assumption if the drive train has been performing ok in the past.) Either haul it or hire a diver if there's any doubt.

The quickest way to find "center" for the shaft is to move the coupler up & down, then left & right, center being half way for both. The trick is making the measurements and then 'fixing' the shaft to get a reference for the engine to get aligned to. My shafts are 1.5" OD and the ID on the log is 2". That a whole lot of flex room when its properly aligned. If you don't center the shaft, you can easily wind up in the same spot Al was - and those leaks are no fun.

What I've done in the past is to use the gear's coupler as the reference "datum", find center, then block up the shaft in its centered position. If this is done securely, then go to engine alignment.

That new mount looks like it's lag is way overtightened... My manual says 50#*ft of torque is sufficient.

I've also found assuming symmetry exists on a boat is another "dumb idea". With the variables involved with hand work and fiberglas, its a rarity to see.

Finally, when doing the engine alignment with new mounts, if you move the engine (vertically) any significant amount, its best to add a shim (or remove existing ones) to get those mounts in their midpoints of adjustment. Over time, the mounts do wear and they will need to be adjusted."
 
"Ok, I'm glad I asked [img

"Ok, I'm glad I asked


I think I understand it a little better now, and maybe that old post I found were it said to use a washer is not the best method. Seems like what you guys are suggesting is more along these lines:

Shaft alignment:
1) remove all four coupler bolts
2) determine center by move coupler up & down, then left & right, center being half way for both
3) block shaft securely in this position with coupler close to but not in contact with engine
4) adjust engine position until 4 sides of coupler have the same spacing from engine, using feeler gauges.
5) target +/- .002 as your goal.

Does that sound right?"
 
"One tweak and one clarificati

"One tweak and one clarification:

TWEAK:
target +/- 0.00" as your goal; use 0.003" as a threshold - owners manual may say 0.004".

Clarify:
the other posting you foun, I think, with the washer, is ok..I think it just has the 'center the shaft' part understood."
 
"Well here she is... I'm g

"Well here she is... I'm going to spray some PB Blaster on tonight and let it sit before attempting to loosen the bolts.

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"Man, I have nightmares about

"Man, I have nightmares about bolts like that...
uhoh.gif
AND... After seeing your motor mount all rusted up. I picked up a few cans of corrosion spray grease and JUST got back from unloading a can on the boat in several spots INCLUDING the new starter I put on 2 weeks ago. I have too many knuckle scars from those things"
 
"I don't know if you can t

"I don't know if you can tell from the picture, but are those some kind of special bolts. It's kind of tight in there and hard to see, but I noticed it last night when I was down there putting the PB Blaster on... they don't look like regular hex heads, I hope it's not that they are stripped."
 
If they are like the bolts in

If they are like the bolts in my Walter V-drives they are only special when you go to buy them.
 
"Bryan,
If it was me I would


"Bryan,
If it was me I would replace those bolts with regular ones, grade 8 fine thread."
 
"Coarse thread! No advantage t

"Coarse thread! No advantage to fine threads if the bolt is tightened properly, but fine threeads like to rust and end up like what you see in the photo.

Jeff (Old Merc outboard guy--and they used fine threads everywhere, blast 'em!)"
 
Discovered a great way to get

Discovered a great way to get those zillion bolts out without twisting even one off (if you're interested).

Jeff
 
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