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Old 10 June 2008, 17:12   #1
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Seastar Pro bolt failure

We have had the coupling bolt between the tiller arm and the steering yoke sheer off on a seastar pro steering.

This has occured twice now on two different set ups Honda 150 and DF300 and is exciting when it happens!

Is there anyway of preventing this (apart from changing the bolts every few month!)

The bolt in question is a fine thread (a 14mm spanner fits the head?)

Any suggestions / comments
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Old 10 June 2008, 17:21   #2
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Is it a stainless steel bolt? Perhaps you could replace it with a High tensile steel one?
If its metric use one with 12.9 stamped on the head, imperial six radial lines or a letter T show a high tensile bolt.
I think most stainless steel bolts are relitevley low tensile strength compared to HT bolts.
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Old 11 June 2008, 02:33   #3
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I was talking to a chap who runs 2 charter RIBs with Suzuki 300s on the back, who was worried about this happening as I think it's happened once with him. Suzuki's advice was simply to check the bolt regularly and change if you suspect anything dodgy. It's something I've become paranoid about now.
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Old 11 June 2008, 05:47   #4
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Quote:
Originally Posted by doggypaddle View Post
Is it a stainless steel bolt? Perhaps you could replace it with a High tensile steel one?
If its metric use one with 12.9 stamped on the head, imperial six radial lines or a letter T show a high tensile bolt.
I think most stainless steel bolts are relitevley low tensile strength compared to HT bolts.
These are stainless with a very fine thread - the thread has to be the same as it is tapped into the tiller arm
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Old 11 June 2008, 05:50   #5
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Quote:
Originally Posted by Tim M View Post
I was talking to a chap who runs 2 charter RIBs with Suzuki 300s on the back, who was worried about this happening as I think it's happened once with him. Suzuki's advice was simply to check the bolt regularly and change if you suspect anything dodgy. It's something I've become paranoid about now.
Tim

How do you check the bolt? Isnt it either OK (and looks fine) or broken

Did Jimbo tell you I have got a hydrolic steering in my garage for your new boat by the way?
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Old 11 June 2008, 05:56   #6
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Quote:
Originally Posted by Trailer Bloke View Post
The bolt in question is a fine thread (a 14mm spanner fits the head?)
by my reckoning you're holding the steering torque of a 300 HP engine by a single M8 bolt in shear........ if it's a screw (threaded all the way to the head) then the actual diameter doing the work is probably nearer 6.5mm!

I'd suggest make sure its a "proper" bolt with a non threaded section in the hole (pack it with washers if you have to) and if possible, go up a size of bolt.
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Old 11 June 2008, 07:18   #7
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Originally Posted by 9D280 View Post
by my reckoning you're holding the steering torque of a 300 HP engine by a single M8 bolt in shear........ if it's a screw (threaded all the way to the head) then the actual diameter doing the work is probably nearer 6.5mm!

I'd suggest make sure its a "proper" bolt with a non threaded section in the hole (pack it with washers if you have to) and if possible, go up a size of bolt.
Good suggestion and yes you are right about the amount of 'meat' actually in the bolt.

There is however the restriction is the seastar yoke has a bearing in it that cannot be enlarged so I will drill the engine tiller arm out and then put as large HT bolt through as the bearing will take- M8 or maybe even slightly larger imperial size- it looks as though I will be off to the bolt shop!
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Old 11 June 2008, 08:24   #8
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just changing to a HT bolt will make all the difference, stainless are as soft as the proverbial assuming its 6mm diameter fine its probably m6x.75 or 1mm pitch.
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Old 11 June 2008, 09:29   #9
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errrrr that depends on your grade of stainless!

Trailerbloke,
if you are planning to drill the arm out for a bigger bolt, but can't drill out the yoke 'coz of the bearing, was the fastener you had in there "rattling" in the yoke?

I assume from your response it was a "threaded all the way" bolt? - Got any pics of the break? I have a theory, but if I post it now the thread will fill with discussions based on a guess!
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Old 11 June 2008, 10:17   #10
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we have the same setup, SS Pro with DF300, a pic would be helpful, better go and have a look asp
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