Installation angle limits??????

BobT · Mar 13, 2013

Is your new strut a different length from the old one?
Did you raise the motor mount supports evenly fore and aft?
What's the angle of the old motor mount bed rails?
Is there a reference drawing of the two engines to compare offset between mount & output shaft?
Is the transmission different?
Maybe it's daylight slaving time messing with us yet again.

tommays · Mar 14, 2013

Well they mostly do a REALLY bad job at the factory as it takes a LONG time to do it right
When my stern tube failed and I replaced it was pretty clear any semblance of aliment was by accident
If i had not used and aliment shaft to set the strut up correctly it would have never been any good
The strut was off abot .090 which does not sound like much BUT it changes the height of the motor 1 INCH at the front of it

Ron20324 · Mar 14, 2013

Well, considering the engine angle off horizontal when the boat pitches into waves....

tkanzler · Mar 14, 2013

The Yanmar manual says 8 deg. is ideal, and 15 is the max. The only way to change the engine angle that I can see is to change the angle of the shaft, being that it uses a rigid coupling. Where that leaves you, I couldn't begin to guess.

Anonymous 121765 · Mar 14, 2013

Wood,

When I installed my Universal M320A, I had to make brackets for the engine alignment off my stringers.

I made a drawing looking at the engine from the side view. I then made brackets based on the drawing. Look at the attachments to give you a better idea for reference.

I made the weldment drawings and had them fabricated from stainless steel plate. Your situation will decide the correct design for you.

Maybe the brackets are a better way to go to get the angle you want.

Good luck......

CR

Don12364 · Mar 14, 2013

Some engine manufacturers, including Yanmar, offer a gearbox with the output shaft at a downward angle so that the engine is level in the boat.
Any chance the old engine was like this? If so could the gearboxes be exchanged?

Also the angle you need to know is, with the rubber stuffing box support tube removed, measure from the centre of the inboard end of the log tube to the centre of the cutless bearing. Everything else follows from the line between these two points and, short of installing an angled gearbox or a universal joint, the position of the engine is already decided and there is little else one can do.

Anonymous 121765 · Mar 14, 2013

Or,

Run your shaft thru the cutlass bearing and put the coupling flange on the end.
Push it up close to the engine flange and see what the difference is.

Maybe you can adjust the engine mounts to get the angle you want.
One good thing is the matching circular keyway built into the flange faces. If you can get your flanges to EASILY slip together, you might have it.

Do a temporary fit-up and then check the shaft at the cutlass bearing to see it's not cocked out. It's trial & error until it's right.

CR

redhead78 · Mar 14, 2013

engine bed work

Wood, with my repower I had similar problems, the width of the engine mounts was ok, the stringers in my bed were 2 different heights, the old Renault engine rear mounts were like 4 inches lower I had to get them all to the same height, and as it turned out I had to rip approx 2" of height off both of them. This was not fun as they were about 4" wide and almost 4' long, laying sideways upside down trying to get push on a sawzall. This is where the plywood engine template with the motormounts attached and front and rear shaft positions that held a 1"metal conduit mock shaft at the exact angle and placement in relation to the engine. My engine supplier gave me dimensions for this, off the tech sheet prints.sounds like you may have to maybe make wedges for stringers to alter the angle?? Maybe step cut the stringers to get correct angle?? Make sure u leave enough room for your oil pan if you alter stringers, I ordered what they called shallow sump oil pan...Remember if your finish stringers are off make sure u err on the low side, u can always shim up, then glass...I really enjoyed the entire experience, you are at a critical stage, take your time and get it right, any questions I will be happy to help you out if I can, happy motoring...Red

redhead78 · Mar 14, 2013

I think they make a couple of different trans offset angles. I originally shopped Yanmar, beta and volvo, and I seem to remember 7 and 15 degree offsets on trans. Red

tommays · Mar 14, 2013

Its good to see somebody else use a dummy motor

As i said before IMHP most OEM jobs are marginal at best

IN having to change Seafevers sterntube because of shaft rub the first that that became apparent besides the horrible angle worn into the cutlass bearing was there was NO WAY it was ever right

It was not even remotely imposable to pass a shaft through a set of alignment bushings placed in the sterntube and strut

It may seem overkill but the blisters inside the tube and shaft run has dam near sunk the boat and there was some kind of bad marine-tex job between the boat and sinking

I have to do alignments on machines all the time so a dummy A4 motor was as simple for me as picking out some of my stuff that would sit 3.5 inches high on the engine bed

You have to love Cal and all fiberglass engine bed in 1970

I come form a mindset that your doing a WAG if there is a rubber part like a cutlass in place and always use bronze bushings as it does not allow any cheating

After wasting far more time than the repair took trying to NOT do the repair i now have a sterntube and strut that are in as perfect alignment as it gets

You can walk right up to my boat and turn everything with ONE finger and look at a shaft going dead straight into the tube

FWIW my homemade pilot-drill and the big azz hole i had to make

Stu Jackson · Mar 14, 2013

Woody, there are two "parts" to the new strut: it's length and the angle of the shaft into the strut, right? If they are different than your old one, you are going to get something different inside. If either of these was different, then I can't imagine how you got anything lined up at all. I think you're on the right track. Good luck with your alignment.

tommays · Mar 14, 2013

Woody

Remember what i said .090 or about 3/32 at the strut will change a motors height about 1 INCH

The .090 X the 6 some odd feet to the front of the motor is a big deal

I had to put wax paper on the hull and mold a fiber reinforced epoxy shim between the hull and strut

This allowed the strut to then be bedded in compound and tightened correctly with silicon bronze hardware

tomgrigsby · Mar 14, 2013

woodster said:
and after correcting the answer i gave you last night i think maybe i see my problem...i had to shim the strut down about 3/8 to 7/16 of an inch to make the shaft center in the stern tube...so haveing said that i may have to go back and raise the strut thighter to the hull and even drill out the old stern tube and install a new one.....oh well better now than later in the water......

regards

woody

I think you've found the problem. Shimming the strut down increases the angle between the shaft and the hull, and drives the other end (engine) higher. I'm not convinced you have a problem with centering the shaft in the stern tube. Think of the stern tube as the pivot point - strut goes up, shaft still centered in stern tube, engine goes down. Your thoughts?

Installation angle limits??????

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