PDA

View Full Version : S&S Vibration


josepcedwards
02-16-2011, 11:33 PM
When I took mine out Sat. to me at full throttle it had some vibration. Is this caused form it having a 351 in 2200 lbs boat? It may just be me. I just want to make sure this boat is right. Around 35 it was smooth. Any input would help! Thanks!

thatsmrmastercraft
02-16-2011, 11:44 PM
Was the vibration you felt at full throttle in forward or in reverse? OK, seriously there are a lot of things that can cause a vibration. What is the condition of the prop? How about the engine? A slight miss can really show up under load. Engine alignment is another. How easy or hard is it to turn the prop while the boat is on the trailer? Those are probably the most likely sources.

josepcedwards
02-16-2011, 11:53 PM
Was the vibration you felt at full throttle in forward or in reverse? OK, seriously there are a lot of things that can cause a vibration. What is the condition of the prop? How about the engine? A slight miss can really show up under load. Engine alignment is another. How easy or hard is it to turn the prop while the boat is on the trailer? Those are probably the most likely sources.

Prop-good, Engine-seems to run really good, Prop is kinda hard to turn. What causes that?

cbryan70
02-16-2011, 11:56 PM
prop may be out of balance, shaft me out out of alignment or bent

josepcedwards
02-16-2011, 11:59 PM
prop may be out of balance, shaft me out out of alignment or bent

The owner before me did do some trans work. He changed the seals. Is this an easy fix? Something i could do?

thatsmrmastercraft
02-17-2011, 12:00 AM
Prop-good, Engine-seems to run really good, Prop is kinda hard to turn. What causes that?

Prop should be kind of hard to turn without the transmission running. Of course you don't want to get anywhere near the prop with the engine running. With good engine alignment you should be able to turn the prop with one hand. Not an expert on this yet. I know the boat is new to you. What are the condition of the plugs, wires, dist cap & rotor, fuel filter. Is the timing set to specs? Is the advance working smoothly? Even old gas can cause an issue at WOT that you may not notice at part throttle speeds. And it doesn't take much of a bend on a prop blade to cause a vibration.

cbryan70
02-17-2011, 12:00 AM
there are threads on here about alignment. Only way to tell if the shaft is bent is to pull it. Alignment there are measurments that I can not recall

Willski
02-17-2011, 12:04 AM
I'm not sure what your used to, but my friend that had an 86 Nautique always thought my boat shook more than his and was louder. I thought the same, but of course my wake was 3x better! We checked alignment of the engine/drive shaft and it was all good. Just a bit more vibration than he was used to. No prop issue either. In my opinion, that era MC has a bit of a vibration at certain RPM ranges.

As far as prop turning hard on the trailer, that may depend more on how recently you have operated the boat and how tight the packing nut is.

If the vibration is excessive, I would first check prop condition, then alignment to engine, then it is possible the shaft could be bent, but don't fret just yet. It could be all normal.

josepcedwards
02-17-2011, 12:08 AM
Prop should be kind of hard to turn without the transmission running. Of course you don't want to get anywhere near the prop with the engine running. With good engine alignment you should be able to turn the prop with one hand. Not an expert on this yet. I know the boat is new to you. What are the condition of the plugs, wires, dist cap & rotor, fuel filter. Is the timing set to specs? Is the advance working smoothly? Even old gas can cause an issue at WOT that you may not notice at part throttle speeds. And it doesn't take much of a bend on a prop blade to cause a vibration.

Im gonna do a tune up cause ill know I did it. Lets just say the prop doesn't turn as free as a wind mill, but can be turned with one hand. Im really new to these S&S and what i call a vibration may be nothing to someone that knows how they feel.

josepcedwards
02-17-2011, 12:11 AM
I'm not sure what your used to, but my friend that had an 86 Nautique always thought my boat shook more than his and was louder. I thought the same, but of course my wake was 3x better! We checked alignment of the engine/drive shaft and it was all good. Just a bit more vibration than he was used to. No prop issue either. In my opinion, that era MC has a bit of a vibration at certain RPM ranges.

As far as prop turning hard on the trailer, that may depend more on how recently you have operated the boat and how tight the packing nut is.

If the vibration is excessive, I would first check prop condition, then alignment to engine, then it is possible the shaft could be bent, but don't fret just yet. It could be all normal.

Im used to a 05' X10. I really think that is my problem. I agree with it being in an RPM range from what i can tell too.

When i tried turning the prop... it was before i put it in water from it siting all winter.

Willski
02-17-2011, 12:50 AM
I always had some vibration at certain rpms but definitely had some in the barefooting range above 4000 Rpm. You are probably okay but have someone take a ride that has had an older boat for a check! If my boat sat for a bit the prop turn would be a little tough and would chatter when turned.

josepcedwards
02-17-2011, 12:52 AM
I always had some vibration at certain rpms but definitely had some in the barefooting range above 4000 Rpm. You are probably okay but have someone take a ride that has had an older boat for a check! If my boat sat for a bit the prop turn would be a little tough and would chatter when turned.

Thanks for your advice!

03geetee
02-17-2011, 09:38 AM
I think most of what your describing is normal. Remember you have a flat bottom boat towards the rear and a prop sitting less then 10" underneath it. It will start to pulse from the prop no matter what you do, it is an older boat so these things are expected.

If it is severe then you may have an issue that needs correcting.

JTR

josepcedwards
02-17-2011, 11:56 AM
I think most of what your describing is normal. Remember you have a flat bottom boat towards the rear and a prop sitting less then 10" underneath it. It will start to pulse from the prop no matter what you do, it is an older boat so these things are expected.

If it is severe then you may have an issue that needs correcting.

JTR

Yea Just had to ask. I really had an idea that its the age of the boat.

thatsmrmastercraft
02-17-2011, 12:10 PM
Yea Just had to ask. I really had an idea that its the age of the boat.

This is the perfect opportunity to find someone on here near you with a similar boat to go for a ride in theirs as a comparison.

josepcedwards
02-17-2011, 12:20 PM
This is the perfect opportunity to find someone on here near you with a similar boat to go for a ride in theirs as a comparison.

Thats a good idea! Whos near me?? Calhoun, GA ... Carters Lake.

WilliM1940
02-17-2011, 01:57 PM
If it is a cause of boat age then something has worn or is misadjusted. Check your strut bushings and shaft for wear also. Just because the boat is an older design is no reason to accept vibration. My S&S has no vibration at any speed.

josepcedwards
02-17-2011, 02:36 PM
If it is a cause of boat age then something has worn or is misadjusted. Check your strut bushings and shaft for wear also. Just because the boat is an older design is no reason to accept vibration. My S&S has no vibration at any speed.

So your telling me that it should not have any vibration at all? How can i look for shaft wear? Do i need to pull the floor?

josepcedwards
02-17-2011, 08:59 PM
Ok so when I got home I got the boat out to look over some things you guys have suggested... I turned the prop with my hand and it was kinda stiff. It has a spot the sticks while your turning it. Some of the prop tips are turned up/ peeled back. You can only tell this by feeling it. Its not bad enough to see with your eyes. Maybe this will help narrow it down..

ctjahn
02-17-2011, 10:02 PM
Couldnt you use a dial indicator to evaluate the shaft? Thats what I would do...

Even if you didnt want to spend the money for a high end precision one you can get one from Northern Tool or Harbor Freight: http://www.harborfreight.com/1-inch-travel-machinists-dial-indicator-623.html

My 78 S&S has a vibration...but my prop was bent and its in the shop. When I get it back I am going to evaluate my prop shaft...

Cj

josepcedwards
02-17-2011, 10:35 PM
Would I have to pull The shaft? I think I will take it to the lake Sunday to get a better feel soni can explain better.

ctjahn
02-17-2011, 10:49 PM
Well, I am no expert in prop shaft measurement but, I am quite mechanically inclined and spend a great deal of time working on cars. (No I didnt stay at a holiday in last night either)

To me, it seems pretty logical to just spin the prop while attached to the boat and in place *(because you have a handle to turn it) while measuring the deflection with the dial indicator. (But, again, maybe I am over simplifying it)

I think the hardest part would be to figure out how to mount the dial indicator.
(again just my opinion)
cj

mayo93prostar
02-17-2011, 11:00 PM
there are threads on here on shaft alignment. you probably need to remove the rear floorboard to access the shaft coupling. best to get the prop balanced.

josepcedwards
02-17-2011, 11:11 PM
Well, I am no expert in prop shaft measurement but, I am quite mechanically inclined and spend a great deal of time working on cars. (No I didnt stay at a holiday in last night either)

To me, it seems pretty logical to just spin the prop while attached to the boat and in place *(because you have a handle to turn it) while measuring the deflection with the dial indicator. (But, again, maybe I am over simplifying it)

I think the hardest part would be to figure out how to mount the dial indicator.
(again just my opinion)
cj

Thanks CJ! I understand what your saying. I think that would be the simple thing to do too.

josepcedwards
02-17-2011, 11:12 PM
there are threads on here on shaft alignment. you probably need to remove the rear floorboard to access the shaft coupling. best to get the prop balanced.

I looked for those threads. Im sure im missing something..

grimsweeper
02-17-2011, 11:41 PM
I would check prop,especially if you can feel the edges bent. I hit a submerged tree with my previous boat-'84 s&s-actually bent strut,damaged prop and bent shaft. Replaced strut,had shaft straightened and prop rebuilt. Still vibrated until I replaced prop. Major difference-no more vibration. The local Correct Craft dealer let me take a new prop and puller to verify before buying.

EricB
02-18-2011, 12:03 AM
3 blade or 4 blade prop? I had the same on my 83 (with 3 blade) and switched to a 4 blade and issue was gone. Back in the "old Days" of glass stringers, they transmitted EVERY small vibration to the rest of the boat. That is one of the reasons they have changed mounts in newer designs to absorb the small vibrations.
Just a thought...

ctjahn
02-18-2011, 06:06 AM
there are threads on here on shaft alignment. you probably need to remove the rear floorboard to access the shaft coupling. best to get the prop balanced.

Yep! My idea was just for checking the shaft. havent checked alignment yet but it is a good idea. I havent checked that yet....

Cj

mayo93prostar
02-18-2011, 08:44 AM
josep,
the link below goes to a thread that has a word document on propshaft alignment in post #14. or try those two words in your search. hope this works.

http://www.mastercraft.com/teamtalk/showthread.php?t=37336&highlight=shaft+alignment&page=2

josepcedwards
02-18-2011, 09:56 AM
3 blade or 4 blade prop? I had the same on my 83 (with 3 blade) and switched to a 4 blade and issue was gone. Back in the "old Days" of glass stringers, they transmitted EVERY small vibration to the rest of the boat. That is one of the reasons they have changed mounts in newer designs to absorb the small vibrations.
Just a thought...

Its a 3 Blade. Its sounds like it a prop issue.

josepcedwards
02-18-2011, 09:57 AM
josep,
the link below goes to a thread that has a word document on propshaft alignment in post #14. or try those two words in your search. hope this works.

http://www.mastercraft.com/teamtalk/showthread.php?t=37336&highlight=shaft+alignment&page=2

Awesome! Thanks dude!!!!!