Separating a Stuck Coupler

79nautique wrote: to play it safe and They also need to be grade 5 or better

???? A 3/8 stainless bolt has a shear strength of around 10,000 lbs x 4 is 40,000!!! Even Billy's or Joe's engines would shear them!!!

I just wanted to replace them because they were a bit rusty. Not too bad, but a bit.

Because they are rusty, maybe they are not stainless.

Jared

Stainless is fine....

Unless you plan on putting a carbide prop on your machine.

Thanks man for the answer on the stainless.

Next question. I think I have the side to side aligned well enough. But now it is pretty clear that the top has a larger gap than the bottom. May .006.

So I am thinking I need to raise the front of the engine. So my best guess is that I need to loosen the lock nuts, and then turn the big silver bolts clockwise just a bit. See the pictures below, I think I need to turn that bolt clockwise to raise the front. And then retighten the lock bolt.

Sound like the right plan?

Thanks again guys

Some brass nuts on your stainless bolts work good :)

GottaSki wrote: I may see '79's point on this one.. Stainless tends to gall up and sieze a bit easier than grade 5 likes to rust.

Never-seize on SS threads.

I remember when I first saw the stuff. A saleman came into the shop with a piece of SS threaded rod, smashed the threads with a hammer, put the never seize on and then ran the nut off over the damaged threads. The nut was smoking but it came off! It actually re rolled the threads!

I got it done. And I just reused the old bolts. Thanks for all the help.

Jared

79nautique wrote: sjpitts wrote: Thanks man for the answer on the stainless. Next question. I think I have the side to side aligned well enough. But now it is pretty clear that the top has a larger gap than the bottom. May .006. So I am thinking I need to raise the front of the engine. i would be dropping the rear mounts to close the top gap.

Why is that?   Why would you chose one or the other? I thought about lowering the back, but the front seemed a little easier to do. I guess you would have to move it less using the back. Is that it?

Jared

Both are correct. Front or rear mount adjustment may be needed to keep the shaft centered in the shaft log and maintain alignment to the strut.

Jared,
A true drive train alignment starts at the strut and then goes forward because the strut is the fixed position. Now's the time for you to check to be sure the strut is ok and not bent. What I do and suggest, is with the coupling halves disconnected, make a wood V block to rest the forward end of the prop shaft on. Make it so you can move it around in different positions. When turning the prop shaft you should find the "sweet" spot where the shaft turns the easiest. Hopefully this is when the shaft is roughly centered in the shaft log. If it turns freely, then you know the strut position is good. Clamp off the V block to maintain the position and align the engine to it.

Make sure the pinch bolts are completely loose so you can move them with your hand. Put some PB Blaster on the shanks from the trunions and let it soak in real good. Then try moving it again.

Marcus,
The pinch bolts are the small fasteners that clamp (squeeze) the mount down onto the horizontal shank (round rod - not threaded). These can be stubborn as they do rust up inside. Sometimes the mount needs to be removed and loosened up on the bench or in the vise.

the "pinch bolts"
what i do is take the nut all the way to the end of the threads and tap it thru with my brass hammer...i think this is being overlooked. if the mount does not have a split, it is the tapered type mount, so the more you tighten the nut the tighter the trunion. you will notice on the opposite end that there are no means to hold the other end of the bolt.....this is the tapered type. if the mount is split and you see a bolt head at both ends this is the clamp type.
simply by loosening the tapered type will not move the trunion, you have to tap it out and release the taper

                                                           This is a picture of what i'm looking at. What do I need to tap through.

Please read again - slowly.

8122pbrainard wrote: Marcus, The pinch bolts are the small fasteners that clamp (squeeze) the mount down onto the horizontal shank (round rod - not threaded). These can be stubborn as they do rust up inside. Sometimes the mount needs to be removed and loosened up on the bench or in the vise.

From your picture, it looks like you have moved the engine sideways. See the shiny spot on the round (NOT THREADED, HORIZONTAL) rod.