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Vibration

luhrs_40

luhrs_40

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I have a 89 luhrs 40 with 454s

I have a 89 luhrs 40 with 454s crusaders..i am getting a vibration between 2700 to 3300 RPMs Thats where i can feel the vibration more than any other rpm It seams to be louder on port side but not sure..had a look at engines while runing didnt see anything unusual...checked mounts and shafts behind trans all seam ok..cant check under boat is on water...any ideas or suggestions? Thanx in advance
 
"..."..checked mounts and

"..."..checked mounts and shafts behind trans all seam ok.."

And how did you determine this, visually? You need to do an alignment check on the shaft coupler, and that requires tools, feeler gages, time, patience and effort. Then again, you might have a bent propshaft. Let's hope not.

Jeff

PS: ALL inboards vibrate due to the shock waves coming off the prop blades pounding the hull as the blade swings past. No way out of it. One of the advantages of outdrives."
 
Jeff is there away to check th

Jeff is there away to check the shaft aligment while the boat is on the water and running?
 
"Shaft alignment:
1) remo

"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.

I have a 6 page procedure, but basically, do the above."
 
Thanx Dave thats a good winte

Thanx Dave thats a good winter project when boat is on hard....Meantime i will keep looking to see where the vibration is coming from...its noticeable but not really that bad
 
shaft alignment on the hard is

shaft alignment on the hard is not the same as in the water due to the flexability of the boat.
 
"I have learned it takes two t

"I have learned it takes two to four days AFTER the boat is in the water to get its "floating" shape back and it may reflect in your shaft alignment by as much as 3/16" at the shaft log. On our boat this is WAY TOO much.... actually caused the shaft to rub against the shaft log and wear it away.

I was so shocked to see that we could have had one of those BOAT US sinking moments as the only thing keeping water out was the tube on the stuffing box...We did replace both shaft logs and re-aligned everything. One note: the greatest thing we did to eliminate all vibration was propscan. What our problem will be next is that there are areas of our bay that are so shallow and shoaling changes so rapidly, we will likely bang the props and knock them out of balance again somewhere"
 
We dont have a proscan place i

We dont have a proscan place in ontario.. so i may have to wait for winter take props off and take them or send them to a proscan to get them check out..
 
"Yeah, do the shaft alignment

"Yeah, do the shaft alignment in water. On the hard, do the cutlass bearing test for free play. By hand, yank on the shaft in several radial directions. Sometimes, even the rubber insert gets loose and moves with shaft rotation."
 
I will check the cutlass beari

I will check the cutlass bearing also...does the bearing suppose to have any play?
 
"Pete,

Propscan is great bu

"Pete,

Propscan is great but expensive. If you boat in an area where your prop could likely hit something, then if you do hit something, even a very minor strike, your Propscan work goes out the window. If you are trying to correct a vibration due to an out of balance prop then a good prop reconditioning will take care of this. Plus if you eliminate the vibration you can always go and get the propscan done at a later date."
 
"Even a new cutlass does have

"Even a new cutlass does have some play. You can force maybe 1/4" out of a large shaft (>2"), but for us, maybe 1/8 or 3/16" is the upper limit of wear. I find that to insert a shaft on a new bearing, the paint must be removed. Also, look at the wear pattern at the forward exit end of the rubber. It should be even."
 
"You MUST check the coupling a

"You MUST check the coupling alignment with the boat sitting in the water, and only after a week or so.

Jeff"
 
Our cutlass bearings had to be

Our cutlass bearings had to be pressed out on a 50 ton press. Took off the struts and brought them to the shop. Turned out to be good though since we then replaced the plywood backing plates as well. The new bearing are smooth and easy top turn but have no free play. You can see however that the boat flexes about 1/4" on the shaft length during some maneuvers when we hauled it for prop change
 
"I removed mine by sawing thro

"I removed mine by sawing through the shell of the cutlas bearing with a Sawz All, then splitting what was left and removing it. Not hard at all.

Jeff"
 
i will check a few more things

i will check a few more things next time on the water if i dont see anything i will wait till the boat is on the hard to check props and cutlass bearings
 
"Start with the simple "th

"Start with the simple "there might be growth on the prop throwing it out of balance". Why can't you check under the boat while it is in the water? A wetsuit, mask, and scraper could work wonders. If you don't want to do it, I'm sure you could fine someone to hire."
 
""Growth" on a prop is

""Growth" on a prop isn't what causes vibration--bent blades are.

Example: Had a (questionable) shop repitch an 11 pitch aluminum prop for me. Told them to make it a 13 pitch. They made it useless junk! Cavitated and vibrated like mad. Took it back, raised hell, and they "fixed" it. Now it's smooth, but it's still an 11 pitch! So I'm back where I started from, but 30 bucks poorer.

Jeff"
 
One blade covered in barnicale

One blade covered in barnicales with two relatively clean will cause vibration.
 
"i have a couple questions her

"i have a couple questions here on shafts and props. the boat is an 85 silverton with 270 crusaders.been out of the water for 4 years.i've gone through everything just about,starters,hoses,
belts,carbs,filters,lines,tuneups,fuel pumps,raw water pumps,batteries,cables,risers,elbows,heat exchangers,you name it.i noticed the short hoses after the stuffing boxes. should i change them,they look ok. and should i change the shaft packing and should i soak that with water to expand it prior to putting the boat in the water? is it hard to pull the shafts? i'm new to boating but an experienced wrench.the boat ran fine up till it was dry docked due to family health reasons."
 
"Given the info you provided,

"Given the info you provided, I'd say change those stuffing box hoses, now, while she's out...not recommended to do while floating.

Do the packing in the boxes at the same time.
You don't have to soak any of the modern materials though you will have to seat them.

You don't have to pull the shaft to switch the hose....usually only the coupler at the front end."
 
how do you go about doing the

how do you go about doing the packing? whats inside the hose? do you have to slide the shaft out at all to change the hose or is there enough room to get it around the forward end. what do you mean seat the packing? thanks
 
"to replace the stuffing hose:

"to replace the stuffing hose:
1. remove the coupler from the shaft. This is typically not easy. Requires best case a puller or homemade press, worse case a thin bladed angle grinder and 2 hours...
2. remove the hose clamps, the packing box and then the hose.
Yes, you can do all this in the water, understand that water will come in, get rags and bilge pump ready. Its not too bad if the shaft is still in place.
3. Use a marine exhaust rated, thick wall, no wire hose for this.
What's inside the hose? just water and the shaft. It provides water/lube to the stuffing."
 
"One add to Dave's inputs:

"One add to Dave's inputs: Use T-Bolt clamps on the hose.

I know Buck offers pre-cut stuffing box hose. I think is worth the extra $$ for it has extra plies and comes pre-cut - no fuss.

Sometimes, you can get the flange off the shaft using longer bolts and a socket to 'press' it off. make sure the set screw comes free, too, or you'll have a helluva time and marr the shaft.

Seating the packing is the standard break-in and adjustment process. I've see lots of articles on repacking, all with their variations. I think the teflon or GFO material is the way to go. I'd also say count the rings in there and replace with the same number."
 
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