Volvo Penta SX Drive vibration

[mikeneal]

I have 99 Volvo SX drive and have a very slight vibration while straight ahead and a fairly large one when the drive is turned right of left with power applied. The U joints are new and the gimble seems totally OK. When I did the Ujoints it actually seems to make it slightly worse. Yikes. I read a tech bulletin and I might have screwed up the orientation of the center yoke relative to the others. I might try to flip it and see if it changes anything. I have tried 2 props and have had one rebuilt so I am sure it is not prop related. I checked the alignment and it seems OK too. I can slide the tool in and out pretty easy and the grease from the coupler splines are uniform. I don't really have abaseline for what the alignment tool is suppose tro feel like though, since I just bought it. ( I don't think alignment can cause vibration anyhow......just kills couplers...correct?) I am replacing the gimble bearing anyhow since it apart and while doing that I noticed the drive shaft that engages the coupler has some wear where it slides through the gimble bearing. It looks like a typical surface hardened thing that has the upper layer hurt, slight pitting and granular looking. It looks worse as you get farther away from the o-rings. Is that where it rides thru the gimble bearing while you turn since the axis is rotation is outward? I measured it and it is about 1.3755 inch. My aligment tool is 1.3745 so I think the shaft is OK. One other piece of info, both the little o-rings were quite beat up. I assume that are for grease retention only and have no effect on side clearance. True? Anyone have any clue what might have caused the shaft to wear in the first place? Think this is the cause of my vibration? I hate to throw a 200 dollar part at it and have same issue. Am I just being too anal about the vibration and expecting it to be totaly vibe free while turning under power? Thoughts?

 

[nrladeere]

Re: Volvo Penta SX Drive vibration

I posted a similar topic recently you may want to do a search. Exact same symptoms. I installed a New SS Rapture prop and it is smooth as glass. FWIW I think the Sx drives index very far in the turns and you can feel the ujoints working at full turn. I would not worry too much as I think these are the best drives out there. I would also replace the o rings while you are in there. They may take out some of the play. Also put a dial indicator on the prop shaft and see if it has any run out. My money is on the prop or shaft.

 

[mikeneal]

Re: Volvo Penta SX Drive vibration

I read your post and there are lots of thing that are the same as yours. I doubt it is my prop though since it does the same thing with 2 differnt ones and one rebiult one that they said they balanced I figured the prop was out of the equation. I get the vibration long before full lock, so I don't think that is it. I am checking the prop shaft run out later tonight (if the rain quits). Thanks for your help.<br />Mike

 

[nrladeere]

Re: Volvo Penta SX Drive vibration

Let us know what you find.

 

[rodbolt]

Re: Volvo Penta SX Drive vibration

the orings sole porpose in life are to take up the slack in the bearing. they really dont seal much as there is not a lot to seal. if you doubt what I say install it with no orings and listen to the shaft chatter. if the slip fit was any tighter we would have issues removing the drive. its kinda like the rubber hub hype. while the prop rubber hub will absorb some shock the reason they are a pressed rubber hub fit is manufacturing costs. kinda like a freeze plug has nothing to do with cold. it allows the mold sand to be rinsed from the casting core. that is why lost foam blocks have no core plugs.<br /> good luck and keep posting

 

[mikeneal]

Re: Volvo Penta SX Drive vibration

The prop shaft has about .0015 inch run out. I cannot find a spec, but I gotta belive that is true enough. I switch the center yoke connector over to the same orientation as it was before I repalced U joints. I did screw up and I do not know if the same end is attached to the drive vs. the couple. I just maked a line down the 2 shafts if you follow me. Anyhow, it helped alot and now seems to be the way it was before I messed with it. I think at this point I am expecting too much froma I/O in regards to vibration free. I have had several people in the boat tell me I am crazy that there is no vibration, but I can feel it. But I am pretty anal about most mechanical things. Thanks for everyones support and let me say again that this type of forum is super cool. <br />Mike

 

[vinney]

Re: Volvo Penta SX Drive vibration

Props. There is very few shops who can do a good job on dp props. You need to have a pillow block for each props pitch and they are expensive. You need to try a new fresh set of props. I seen them come out of new boxes all beat up. If you chasing a vibration rebuilt props won't help you. Try a new set of wheels.

 

[nrladeere]

Re: Volvo Penta SX Drive vibration

I will second the prop recommendation again. Install a NEW prop and you will likely see your vibs go way down. I was ready to tear my outdrive down after having the same experience as you. A new stainless Rapture prop made it smooth as glass. If you are going to keep the boat you can keep yur existig ones as spares.

 

[rodbolt]

Re: Volvo Penta SX Drive vibration

the orings really dont seal anything. they mainly help take up the lateral slack on the shaft to bearing fit. if the fit was much tighter the slightes amount of rust would make the shaft weld to the bearing. your on the right track keep checking

 

[mikeneal]

Re: Volvo Penta SX Drive vibration

I have some updates. The new gimble bearing did nothing but aligning the yoke shaft to same orientation helped ALOT. It is basically liek ti was before I "fixed" it. I am looking for a deal ona new prop and will try that out. That is good to knowabout the rebiult ones. It sucks though i mean it is not rocket science, if they true them and ballance them they should be good as new. Oh well thanks for everyones input.

 

[Tad Griffin]

Did you figure this out?
Same problem here, replaced everything, except the prop.
volvo 5.7 GL volvo sx cobra outdrive
no vibrations in neutral, turning hard both ways, only at good plane and rpm's while turning.
Im new here so dont know how to start a new topic yet.

 

[GA_Boater]

Did you figure this out?
Same problem here, replaced everything, except the prop.
volvo 5.7 GL volvo sx cobra outdrive
no vibrations in neutral, turning hard both ways, only at good plane and rpm's while turning.
Im new here so dont know how to start a new topic yet.

Tad Griffin

This thread has been inactive for over 12 years old - Way outside of our 90 day rule. Take a look at the Help Tip on top of the page about starting a new thread. A new thread is the best to get help. Thanks.

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