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Need engine coupler for Ford 5.8L to King Cobra

Corsair

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I have a 93 Four Winns with a 5.8L, 360 HP connected to a King Cobra I/O drive. The splined sleeve spun leaving no splines. I need an OMC engine coupler P/N 987528 or suitable substitute. I have been scouring every on-line marine salvage site for this part. Anyone have any ideas? The boat is in excellent shape, the engine runs strong and the lower unit is excellent. The coupler, however is required! Thanks...
 
I will try the coupler you listed. The U-joints and gimbal bearing were replaced about 2-3 years ago when I could feel, at low speed, a vibration that was not normal. At that time the coupler was not examined.

Where did you research that this coupler will possibly work? I have been working on this since early August and no one has suggested that this may work. Just curious.

Thank you.
 
I would wait for word from Ricardo. I cross referenced the yoke and gimbal bearing for the 1994 supersede I could not confirm the bolt pattern for the flywheel bolts tho. Yea I am surprised OMC does not give you numbers the original number was only for two years for the king cobra drives 93-94. I just checked the numbers I gave you are the same for the 1991 5.8.
 
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I would wait for word from Ricardo. I cross referenced the yoke and gimbal bearing for the 1994 supersede I could not confirm the bolt pattern for the flywheel bolts tho. Yea I am surprised OMC does not give you numbers the original number was only for two years for the king cobra drives 93-94. I just checked the numbers I gave you are the same for the 1991 5.8.

I assume Ricardo is another contributor to this site and will eventually read my question.
 
I had ordered the OMC 3853862/Sierra 18-21753 prior to starting this string. There is a 5/8" difference in height where the flange for connecting to the flywheel is. Also the"sleeve" that slides through the bell housing is shorter. The technician at my marina is concerned that the additional height will not allow the lower unit to fit tight against the transom.

Anyone have any other possible substitutions for an OMC 987528 coupler?

Thanks...
 

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Do you have the drive off of the transom plate? Put the couplers on the yoke and measure from the flange where it bolts to the flywheel to the flat spot on the yoke.
 
Unfortunately at noon I dropped the replacement coupler in the mail to return. I know the drive shaft on the lower unit from the end of the shaft to the base of the yoke on the shaft is 9". If you measure from the end of the shaft to the C/L of the yoke it is 12 inches. I believe, not sure, that I have the shorter shaft of the two.
 
I wish someone who know would chime have you measured how far in the coupler the splines are stripped? Are there any good splines left in the coupler?
 
The coupler spines are completely gone. There is not a spine left. I was very surprised when I saw this as it was a complete catastrophic failure. I would have expected the splined sleeve to spin in the rubber before sheering all of the splines away. The splines on the drive shaft are perfect. I assume that there is a difference in material composition. When the lower unit was pulled all of the shavings, full length of the spline dropped out.
 
Faztbullet, thank you for the suggestion. The concern remains that the new coupler's flange that attaches to the flywheel is 5/8" taller than the original. Thus it will either not allow the engine to fit back in or will hit/rub the transom. It does not appear that the shaft it the concern as it is the shorter shaft available.
 
Considering the shaft assembly is a Mercruiser type a short shaft is available. The same for the U joints and gimbal bearing. So considering a Mercruiser coupler would work all you need to do is have a flywheel accept the bolt pattern for a Bravo coupler to handel the horsepower
 
Doctur, Faztbullet and kimbrwct1, I did a lot of research on which Merc coupler(s) would be the correct substitute based on your advice. The Sierra P/N # appears to be 18-21752-1. It is a replacement for OMC #'s 986120, 984290 and 3853917. How do I determine which is the correct shaft to match this coupler? I assume that all shafts do not have the same spline design so I will not be able to use the current shaft.
 
I assume that all shafts do not have the same spline design

Ayuh,.... I'm guessin' yer assumin' wrong,....

Just as gimbel bearin's, 'n alignment tools are all the same, every drive spline I've run across are also the same,....
 
I have continued to search for the correct coupler. During my search I found another string where the engine and sterndrive are the same P/N's as mine. The difference is that it is in a 92 Liberator not a 93 Horizon. I am now wondering if that it the cause for having such difficulty in locating the correct coupler. I was wondering why I could not find my engine in 93 listings. This answers that question.

Does this help in finding the right coupler?

Engine: P/N 584DPEAMK S/N 1242537
Sterndrive: P/N 987526 S/N T0756893
 
Your engine uses a flywheel just like a Merc .Your coupler bolts to the crankshaft where Merc bolt the coupler to the flywheel .The Bravo coupler will take the horespower of your motor . If your flywheel can accept a autoclutch and pressure plate it will also accept a Bravo coupler
 
I had the marina install the Sierra part (18-21753) and it hits the transom as was the original concern. there was several suggestions to use a Merc replacement coupler. It was suggested that the Merc 59826A3 (BPI11510 replacement) may work. Once again it appears the difference may be the height from the mounting flange. The Merc coupler is approximately .75" shorter. With a 9 inch drive shaft I believe I will have enough engagement at all trim angles. Does anyone know for sure? Everyone's help is greatly appreciated.
 
I was thinking of adding a spacer between the coupler and fly wheel but the mechanic said that the flywheel has studs not bolts thus the studs will be too short. I assume studs can be removed and longer studs installed. (?). If so then I was going to have a machine shop make a 5/8" aluminum spacer. That would add 5/8" engagement resulting in 2 5/8" to 3 1/8". Is this a plausible solution?
 
I did not see this thread back in August of 2017.

(for some reason these quotes are not in order)

Will a VP coupler work? # 3853862 or 3850520 Ricardo may know or have one?
Kim, while I was active I did Volvo Penta AQ series service. I did very little with the VP gimbal suspension SX or DP-S drives, and rarely did any OMC work.


From my research the coupler #3853862 or sierra 18-21753 is the ticket from a 1994 OMC 5.8l
By 1994 Volvo Penta was producing their version of the Volvo Penta Cone Clutch drives.

I have a 93 Four Winns with a 5.8L, 360 HP connected to a King Cobra I/O drive.
Curious..... how do you get 360 HP from a Marine 5.8L Ford engine? (is this a possible Typ-O ?)

The splined sleeve spun leaving no splines. I need an OMC engine coupler P/N 987528 or suitable substitute. I have been scouring every on-line marine salvage site for this part. Anyone have any ideas? The boat is in excellent shape, the engine runs strong and the lower unit is excellent. The coupler, however is required! Thanks...
The OMC 460 w/ King Cobra parts are also very difficult to find these days.
460 King Cobra drive couplers and exhaust manifolds are among this list.

I would wait for word from Ricardo. I cross referenced the yoke and gimbal bearing for the 1994 supersede I could not confirm the bolt pattern for the flywheel bolts tho. Yea I am surprised OMC does not give you numbers the original number was only for two years for the king cobra drives 93-94. I just checked the numbers I gave you are the same for the 1991 5.8.

I assume Ricardo is another contributor to this site and will eventually read my question.
I just now saw your thread.
I was involved primarily with the Volvo Penta AQ series. I wish that I could offer some OMC help.
As Bill suggested, I do believe that all of the shaft splines are the same.

I was thinking of adding a spacer between the coupler and fly wheel but the mechanic said that the flywheel has studs not bolts thus the studs will be too short. I assume studs can be removed and longer studs installed. (?). If so then I was going to have a machine shop make a 5/8" aluminum spacer. That would add 5/8" engagement resulting in 2 5/8" to 3 1/8". Is this a plausible solution?
Even with longer studs, the coupler flange would now no longer be mated to the flywheel's surface.
By doing this it may cause an increased shear issue...... especially if the 360 HP rating is accurate.

OK..... it would appear that the Ford 5.8L crankshaft flange bolt pattern is the issue re; finding a drive coupler.
Most all flywheels offer multiple outer bolt patterns (for automotive clutch pressure plate mounting).
I've not done this..... but what if this style Merc drive coupler would work?
These do not rely on the crankshaft flange bolt pattern...... instead they use the outer flywheel bolt pattern for mounting.

merc drive coupler.jpg


Just a thought!




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