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Old 16 July 2012, 11:07   #1
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Engine bolts.

Do mercury do an engine mounting kit? IE a bolt set. Metric fine 12mm. About 100mm long.
Usual sources proving unsuccessful.
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Old 16 July 2012, 11:11   #2
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I replaced the bolts on my opti and found Mercury just sell them as individual bolts (and nuts) seperately in differing lengths to suit the set up and thickness of boat. Stupidly expensive however . I added a couple of extra large washers to the bottom and a support bar between the two top bolts to spread the load - worth doing IMO...

I managed to drop one in the river ..but found RIBSMARINE & Marinautic had them on the shelf.
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Old 16 July 2012, 11:19   #3
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Quote:
Originally Posted by PeterM
I replaced the bolts on my opti and found Mercury just sell them as individual bolts (and nuts) seperately in differing lengths to suit the set up and thickness of boat. Stupidly expensive however . I added a couple of extra large washers to the bottom and a support bar between the two top bolts to spread the load - worth doing IMO...

I managed to drop one in the river ..but found RIBSMARINE & Marinautic had them on the shelf.
Cheers Pete. Had a look on ribs marine website, couldn't see them.
Do you remember how much they were?
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Old 16 July 2012, 12:07   #4
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Do you remember how much they were?
Recently bought new bolts from Rob @ Blackdog.
Pretty expensive, but seem to be the job well...
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Old 17 July 2012, 01:16   #5
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if you look on RIBSMARINE web site look at a 75hp transom brackets you should see them there ,I think you should go to maybe about mid-range serial number
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Old 17 July 2012, 02:18   #6
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I don't know if this is any use, but when I was looking for some stainless bolts to mount my engine I got them from here, price seemed OK and deilvery was fast.

Stainless Nuts and Bolts, Screws, Fasteners, and Hose Clips - Westfield Fasteners Limited
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Old 17 July 2012, 02:46   #7
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Thanks al I'll try that.

Yes seen the Westfield website but it's a fine pitch I need. Ta.
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Old 17 July 2012, 04:14   #8
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I would've thought merc bolts were 1/2" UNF

The ones that came with my mariner 50hp were high tensile, not stainless

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Old 17 July 2012, 09:19   #9
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Quote:
Originally Posted by Jizm View Post
Thanks al I'll try that.

Yes seen the Westfield website but it's a fine pitch I need. Ta.
Try Mark at MB Marine in Ocean Quay, He has 100s of all size mounting bolts
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Old 19 July 2012, 14:49   #10
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I would've thought merc bolts were 1/2" UNF

The ones that came with my mariner 50hp were high tensile, not stainless

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Yes they are, There not metric bolts.
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Old 19 July 2012, 14:54   #11
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Ok I need four turboD. What's the damage?
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Old 19 July 2012, 16:35   #12
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M12 x 90 Stainless Sets

I have a few M12 x 90 Bolts (Hex Sets actually as they are fully threaded ie no plain shoulder). Complete with full nuts and washers. They are standard iso coarse thread 1.75mm. PM me if you want 4 of them.
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Old 20 July 2012, 12:06   #13
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Cheers. Got loads of those. Need a fine pitch thread.
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Old 20 July 2012, 13:19   #14
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Ok I need four turboD. What's the damage?

Expensive!!!. Even with your discount, £18.15 each inc vat.
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Old 23 July 2012, 00:34   #15
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This is always a interesting subject. On the pictures, starting from the top( All factory original)Yam 90, Tohatsu 90 and the third looks ordinary SS or acid proof... But they are original bolts from a CMC transom jack, rated for 300 HP. The Japanese bolts are unmarked, Tohatsu looks like galvanized.

The CMC bolt is marked F593C. Don't know what that means, but threads look pretty standard.

Makes me wonder, as the forces are pretty bad on a lift(with a 300 hp lupmp hangin on it), do You really need fine threads in this application as coarse is OK for CMC? Believe that finer pitch is better due to getting the correct torque on the bolts, but most transoms have a core that flexes slightly( plywood or other) so that is not an issue on boats(?).

Not that I would recommend taking any risks on such a vital equipment, but still as the originals are made of gold(price wise anyway ) would be nice to fully understand the black magic of transom bolts ...for sure there must be industrial applications with close to same requirements.
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Old 23 July 2012, 06:48   #16
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This is always a interesting subject. On the pictures, starting from the top( All factory original)Yam 90, Tohatsu 90 and the third looks ordinary SS or acid proof... But they are original bolts from a CMC transom jack, rated for 300 HP. The Japanese bolts are unmarked, Tohatsu looks like galvanized.

The CMC bolt is marked F593C. Don't know what that means, but threads look pretty standard.
That would be an ASTM graded bolt also known as stainless steel type 304 or A2. Threads could be metric, UNC or UNF.
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Old 23 July 2012, 07:26   #17
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Quote:
Originally Posted by C-NUMB View Post
This is always a interesting subject. On the pictures, starting from the top( All factory original)Yam 90, Tohatsu 90 and the third looks ordinary SS or acid proof... But they are original bolts from a CMC transom jack, rated for 300 HP. The Japanese bolts are unmarked, Tohatsu looks like galvanized.
Small correction, the galvanized looking bolt on top is the Tohatsu, not Yam.
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Old 23 July 2012, 07:46   #18
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On the BananaShark race rib, engine was double bolted to the bracket with standard metric bolts plain full nuts locked with nylocs. We never had any break or stretch thou they were replaced every time we broke a saddle.
I always thought more important than the bolts(within reason) was the washers on the inside of the transom.
Imho merc shot themselves in te foot with the "you can't tighten a standard metric thread to the same level as unf cause it is too coarse" argument, when they replaced ss nuts with brass because people who didn't know what they were doing were complaining that they were gaulling (welding themselves solid) not entirly sure of the clamping presure of a brass unf nut compaired to ss metric at fail, but I'm sure it aint that far out.
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Old 23 July 2012, 08:22   #19
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Expensive!!!. Even with your discount, £18.15 each inc vat.
Oh yes - that'll be why I was in such bad mood when I dropped one !

On the subject is it possible to over tighten the fine threaded ones and crush the transom structure ( Guess Kitten will know more ?) . It was always a concern on airframe structure so I guess its similar on GRP transoms ?

I know I still have a couple of very nice alloy washers that I never got round to fitting when I fitted the brace across the top bolts on my opti.
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