flywheel thread specs Merc 850

[MercMark]

I'm having a flywheel puller combination lifting eye made by a local machinist becasue it's cheaper that buying the two separate mercury parts.<br /><br />On my mercury 850 I measure the threads of the flywheel and I get 1-7/16"-(16 thread) to the face of the threads. The machinist informs me that it is risky to be out by more than a couple of thousandths of an inch because the threads might pull out and wreck both the tool and the flywheel thread.<br /><br />I noticed that a couple of guys made their own lifting eyes from bolts and whatnot. I was hoping someone could confirm the thread spec on this flywheel.<br /><br />The local hardware bolt specialty shop only has one bolt of that diameter and the thread isn't even close. It's for like a dumptruck or something. We were hoping to find a standard size to be sure that we're not off in our measurement.<br /><br />I don't want to pay the labour to cut a large thread, then trim it down to fit. It's $45 each time I trim it down. I want to get it right the first time.<br /><br />Any help would be apreciated.

 

[Hooty]

Re: flywheel thread specs Merc 850

My puller/lifting eye doesn't use the crankshaft for lifting. Mine lifts using the three 1/4"-28 (or what ever threads they are in a Mercury flywheel) bolt holes where the puller fastens to the flywheel. Here's a foto of my lifting eye using the harmonic balance puller and a bolt in the center with a couple of flat washers welded to it for lifting. Hope this helps.<br /><br />

<br /><br />c/6<br /><br />Hooty

 

[MercMark]

Re: flywheel thread specs Merc 850

My flywheel doesn't have three bolt holes for a puller. I'll post a photo of it. Are you refering to the ring of bolts (about twelve) that encircle the hole in the middle of the flywheel? I guess I could pull three of those. It seems to me that Mercury are dinks when it comes to making tools and parts that you have get from only them to to be able to fix your own motor.<br /><br />I read in a topic not to remove those bolts, because they were balanced in there. I suppose if I mark them and put them back in the same holes that it won't throw anything off.<br /><br />I guess by experience you could say that it is safe to lift by those bolt holes. Do you know of anything that can go wrong if everything doesn't go as planned?<br /><br />So far I'm still planning on using the replica of a merc puller.

 

[Hooty]

Re: flywheel thread specs Merc 850

It's true, I'm not familiar with how your Merc flywheel pulls (I know it's not the bolts on the circumference of the flywheel) so what does the puller "pull" on if not drilled and tapped holes about two or three inches out from the center of the crankshaft? <br /><br />c/6<br /><br />Hooty

 

[MercMark]

Re: flywheel thread specs Merc 850

Merc pullers thread into the hole around the crankshaft. You put a little cap on the end of the crank then thread teh puller in, then there's a pin down the middle that pushes on the crank.<br /><br />Do a search for JSRE merc felywheel puller. This guy has photos of the merc puller and his own high end one with a thrust bearing in it in place of the little brass cap that merc supplies.

 

[Hooty]

Re: flywheel thread specs Merc 850

O-k,<br />Now I understand how the Merc flywheel pulls. I think I'd go ahead and spring for one of Jay's puller / lifting tools.<br /><br />c/6<br /><br />Hooty