Volvo Penta SX-M Steering Vibration (Not what you think)

[stant1man]

Hi Guys,

The season has come around and i'm still trying to solve a vibration through my sterndrive...

Volvo Penta SX-M 1.79 coupled to 5.7 Vortec

My symptoms are as follows -

Cruise in a straight line and there is no noticeable vibration....
Turn left or right there is a vibration through the boat which gets worse with more steering applied.
Trim the outdrive up to optimal then I get vibration even in a straight line.

So far I have replaced -

Engine coupler
Gimbal bearing
UJoint Shaft (new from volvo complete unit)
Engine mounts (All four)
Propeller - tried 3, 4 and 5 blade all new.

Engine alignment 100% yet vibration under turning and trim load remains

I have removed the lower unit and inspected all gears and bearings, all are in perfect condition.
I have checked the bearings in the upper and again, all are smooth with no play or rumble.

I have some play in the steering... for example, if i hold the sterndrive and a friend turns the wheel there is around an inch of play... could this be the issue.... i'm totally bewildered!

Am I missing something simple here... this is driving me crazy!

Best wishes,

Stan

 

[stant1man]

Re: Volvo Penta SX-M Steering Vibration (Not what you think)

Anyone?

 

[Jammer864]

Re: Volvo Penta SX-M Steering Vibration (Not what you think)

What about the shims mounted on the lower unit. They shim the drive tight between the drive and the gimble ring. They are plastic pieces slightly smaller than a cigarette pack that are secured onto the lower unit. Is it possible there is excessive left to right play? Might account for the vibration in a straight line when trimmed up, as there is less shim surface being applied tilted up? Just a thought......

 

[stant1man]

Re: Volvo Penta SX-M Steering Vibration (Not what you think)

What about the shims mounted on the lower unit. They shim the drive tight between the drive and the gimble ring. They are plastic pieces slightly smaller than a cigarette pack that are secured onto the lower unit. Is it possible there is excessive left to right play? Might account for the vibration in a straight line when trimmed up, as there is less shim surface being applied tilted up? Just a thought......

Thanks for the reply Jammer, when I remove the lower unit I see no shims between the gimbal bearing and lower... Can you point me in the right direction here?

 

[dypcdiver]

Re: Volvo Penta SX-M Steering Vibration (Not what you think)

I get a slight vibration on turning and have put it down to slight cavitation, also get slight vibration when running at 5000rpm and trimmed up for max speed, again as the props are close to the surface and just on the point of cavitating.

Jammer864 means the shims between the gimbal ring and the piviot housing where the piviot pins are.

If you think about it the boat on a turn is effectively crabbing and the flow of water over the inside blades is different to the outside. I'm probably talking rubbish!

 

[jerryjerry05]

Re: Volvo Penta SX-M Steering Vibration (Not what you think)

Does your steering actuator(where the steering cable goes through)have a grease fitting? Try greasing that.
The shaft need lubrication?

 

[Jammer864]

Re: Volvo Penta SX-M Steering Vibration (Not what you think)

Id post a pic but cant do that for a few days. The shims are flat plastic pieces on the left and right of the drive. They rub along the gimble ring.

 

[Pete104]

Re: Volvo Penta SX-M Steering Vibration (Not what you think)

It sounds like the power assist assembly is trying to work against itself. No real way to isolate it but if the boat has hit a submerged object, you can count on replacing it eventually. Same thing jj05 is talking about but a little deeper.

You never mention what year it is. That helps a lot!!! Specifically, I had this issue on an '04 Chapparal.

 

[Tail_Gunner]

Re: Volvo Penta SX-M Steering Vibration (Not what you think)

I get a slight vibration on turning and have put it down to slight cavitation, also get slight vibration when running at 5000rpm and trimmed up for max speed, again as the props are close to the surface and just on the point of cavitating.

Jammer864 means the shims between the gimbal ring and the piviot housing where the piviot pins are.

If you think about it the boat on a turn is effectively crabbing and the flow of water over the inside blades is different to the outside. I'm probably talking rubbish!

No rubbish as good as the Volvo outdrive is this is a common problem. I have the same vibration at wake speeds when turning left to right and the same slop in the steering. Does one crab the drive at high rpm yes and you will lose some effeciency that way. For 6 yrs ive watched for a solution as of today there still is none.

If you run across something that will end the vibration plz post the solution