clutch dog trick on newer 25/35 gearcases?

[johnyrude200]

Going through the service manual, it states that the clutch dog need to be installed with the grooved edge toward forward gear.

What is the importance of this? Can the old clutch dog reversal trick be used on these gearcases?

When I look at the CD, I would be darned to see what difference there is on either side less this groove. Granted the teeth are staggered, but the rest of the CD looks symmetrical.

[chris-p]

Yes can be flipped. Our older clutch dogs, well some of them, have the same groove.
The mark is to simply mark it to go towards forward gear.

[fleetwin]

I’m not sure if these clutch dogs can be flipped around, I always assumed that groove was there for a reason. If you are going to attempt to flip the clutch dog, assemble the gearcase "dry" first/no orings or sealer, then check for full clutch dog engagement in both forward and reverse as well as a clean neutral.

[chris-p]

Yeah, Ive done it Don. I spend some time with a mic, and could not find a single difference between sides, other than the groove.

The older big twins have the groove as well, I always just pick the better side for forward, if im not putting a NOS one in.

The groove is simply to mark forward gear so ive been told by some of my older mechanic friends that worked for OMC in the 50s. I haven’t seen it ever referenced in manuals? Or is it somewhere, not sure.

[frankr]

It is referenced in many manuals. I suppose there may be some difference between forward and reverse in some newer motors, but the main reason for the marking in the old ones is so you can tell which way it was (originally) and put it back the same way—or flipped if you are so inclined.

[frankr]

From 1972 Evinrude factory service manual, 40hp

[johnyrude200]

OK, sounds as if that groove is just to aid in re-installation. Using the OMC sleeve tool to hold those detent balls and spring in place seem easy enough either way.

I rather ask you folks than destroy an otherwise good gearcase through needless experimentation.

On a side note, it seems as if these 3 tooth clutches/gears are much more rugged than the older 2-tooth ones. Opinions?

The few gearcases I’ve opened up so far this winter (using the newer 3-tooth clutch/gearset) all seem to have very minimal wear on any of the teeth. Obviously, 3-teeth vs 2-teeth means force being applied over a greater area = less wear.

Your experiences with this?

[frankr]

The more ears, the less space between them. Less space means less time to get it in there as it goes by. In other words, it is more important to have it it down to slow idle and shift snappy. The detent balls help.

[dan-in-tn]

The three lug clutch dog was the final fix for the 25/35 motor gearcases for jumping out of gear. The third lug did spread the load over all three lugs. There is a kit for older 25s, but it is expensive! You can make the special tool for loading the propshaft in the gearcase with an old clutch dog and piece of tubing. Actually works better than the special tool of old (plastic).
BTW: If I remember correctly the V-4/V-6 clutch dog orientation is with the grove toward the reverse gear. Good old OMC/BRP always did want to keep things consistent. And that one did make a difference!

Dan in TN

[johnyrude200]

Good to know the special tool is plastic (won’t buy), and even better heads up on how to fabricate one from an old clutch dog. A retired mechanic who I have become good friends with fabricated one out of thin brass tube for the older 2-tooth dogs. I modified the opposite end to hold 1 of the detent balls and used a large flat head screw driver to hold the other one in as I guided the prop shaft into the forward bearing.

The service manuals recommend using some grease to hold the detent balls in place, I used that to keep it there until it was butting up against the CD surface, then just used the flat head screwdriver to recess it into the prop shaft orifice. The trick is to have a rubber mallet close by to drive the prop shaft down into the orifice/forward bearing. There is a moment where you push the guide tool and prop shaft as far as it will go, balance for a moment while holding the flat head screw driver against the detent ball, and then need to give the prop shaft a whack with the rubber hammer. Then you’re home free. There is a ‘click’ as things go to where they’re supposed to, and the rest is pretty much clockwork.

I’m more fascinated with how many trials it must have took by the engineers to set this thing up. How many hours and hundreds of thousands of dollars did the R&D department blow through in revisions before they got their glob of clay molded enough to be practical…?

A little bit of a finesse job, but after a few dozen I’m sure it’ll get easier!

I will say that the single housing gearcases sure don’t seem to spring many seal leaks. With the 2-piece gearcases I pretty much assume I will be changing the shift shaft seal on every one I deal with. Saves me the time of boat testing the motor because obviously opening it up, I get to see how the internals are. Of course, all of the units I’m dealing with are at least "40 years of age" with original seals. But they still run great after necessary servicework!

So I guess I’ll have to wait another 5-10 years to see what is the common failure point for the 80’s/90’s motors.

OUT OF LEFT FIELD: used some truarc pliers on one of these gearcases and WOW, talk about reminding how nice it is to use the right tool for the right job. Took literally 5 seconds to do something that had taken me 20 minutes last time, and a lot of cussing.

[Author]

Posts