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Old 08 April 2012, 08:09   #1
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Yamaha Hydradrive loose steering

Our boat with twin Yamaha diesel sterndrives was behaving erratically when accelerating or decelerating. On close inspection we found the steering connections between the drives had over a foot in free play. That is, when we grabbed both drives and pushed them together by hand and then apart, there was over 30 cm of free play.

On closer inspection we found that the steering arm that comes out of the gimbal housing has a bolt that clamps it tight onto the steering shaft. The problem is the seal of the steering shaft eventually leaks and corrosion and wear make the steering arm loose in the shaft. You cannot tighten the bolt any further as it has a ridge on it where the thread ends that prevents it getting any tighter. As a matter of fact even loosening it was extremely difficult as it was rusted in and access is tight from inside the engine bay through the transom. A 6 point 19mm socket, a short extension, a very long bar and lots of patience was required.

Alex's solution to tighten up the steering was to machine off the ridge using a lathe. Of course Alex has a lathe at home and perhaps not everyone has, so I guess the option is to get someone else to do it or get a bolt without a ridge. We thought it best to use the lathe and only take a few millimetres off as we didn't want to over stress the steering arm clamp and risk a fracture by over tightening.

The photo shows the difference between the standard bolt and the machined bolt. Machined version on right and below.

The steering is now much better.
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Old 08 April 2012, 08:52   #2
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There's a thread somewhere on Ribnet from a while ago where one of these bolts sheared off. Like you have found, you can't see the corrosion until it's too late.
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Old 08 April 2012, 13:40   #3
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There is a nut on the top of the steering shaft it is not easy to get at if the transom is not cut right. Need a short 27 mm spanner like 3 to 4 inch and a lot of hard work. Or take the engines out and t/shields !!!!!
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Old 08 April 2012, 17:40   #4
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Quote:
Originally Posted by Joshv6
There is a nut on the top of the steering shaft it is not easy to get at if the transom is not cut right. Need a short 27 mm spanner like 3 to 4 inch and a lot of hard work. Or take the engines out and t/shields !!!!!
With this bolt modification there is no play any more. I guess if it gets sloppy again we will have to look at this 27mm bolt. I am guessing it is the one that the steering arm attaches to.
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Old 08 April 2012, 17:48   #5
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Quote:
Originally Posted by Erin
There's a thread somewhere on Ribnet from a while ago where one of these bolts sheared off. Like you have found, you can't see the corrosion until it's too late.

Are we talking the bolt pictured above?

As they do corrode and the logical thing to do is to attempt to tighten it, I can see how threads could be stripped as the ridge stops the bolt tightening any further. But I think what you are saying is they shear while in use.

I searched 'Yamaha' and 'steering' and can't seem to find it.

Would love to know more.
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Old 09 April 2012, 03:35   #6
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I'm going to check this on our boat. The steering is fine on it but its another worthwhile thing to look at before the season starts
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Old 05 November 2013, 02:40   #7
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Just an update at about 200 hours.

Starboard steering was loose. Took bolt out, cleaned it up and it is all back yo the way it should be.

Port is fine.

They get pretty rusty in there. I need to pay more attention to the transom shields when rinsing the boat down after a day out.
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Old 05 November 2013, 03:33   #8
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Quote:
Originally Posted by kubcat View Post
Just an update at about 200 hours. Starboard steering was loose. Took bolt out, cleaned it up and it is all back yo the way it should be. Port is fine. They get pretty rusty in there. I need to pay more attention to the transom shields when rinsing the boat down after a day out.
The reason the arm gets loose is because the lip seal that seals the steering pin fails . Which then water enters an under the steering arm were thrust washer sits , then it stars to corrode shield and the arm is not supported making the gimble ring drop putting pressure on the arm .
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Old 05 November 2013, 06:14   #9
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Originally Posted by yam man View Post
The reason the arm gets loose is because the lip seal that seals the steering pin fails . Which then water enters an under the steering arm were thrust washer sits , then it stars to corrode shield and the arm is not supported making the gimble ring drop putting pressure on the arm .
Not sure I understand. It is a difficult spot to have a look inside.

So what you are saying is that I need to replace the lip seal and the thrust washer or more to it?
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Old 05 November 2013, 06:46   #10
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the steering pin that arm is clamp to via the 17mm pinch bolt and the 30mm nut on top has as seal which stops sea water from entering.the seal ( where the grease nipple is located on top of shield )after time the seal starts to get hard a doesn't seal which then let's water in causing it sit under the steering arm which starts to corrode underneath the arm it's self . The arm has thrust washer underneath which stops it binding against the shield the material that arm an thrust washer sits on to corrode away allowing the pin to drop an all the wight of the sheild is on the arm making come loose . Inside boat were the arm is any corrosion wight deposits /rust ?
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