F R- Can you answer this one?

[bktheking]

I wouldn't normally single someone out but F R , you seem to be a pretty good at this stuff so i'll try you.

In another post I had asked about my 7.5, 1955 model.

The shift detents are missing so I found a set, I plan on installing them. I shift the motor in forward or reverse with the motor off, I move the prop by hand and the flywheel turns. I fire up the motor , move the gear selector and nothing happens, no clunk, no drop in rpm, no prop wash. I understand these motors have a shock absorber in the leg, would this be the problem?

Thanks for looking at my post, I figured you might know.

 

[1946Zephyr]

Re: F R- Can you answer this one?

I'm not F_R but yes it could have an affect.

 

[bktheking]

Re: F R- Can you answer this one?

Appreciate it zeph, like I said I don't mean to single anyone out. I posted the same question before and didn't get a reply on the shifting issue. Why then will it spin while the engine isn't running, is it simply a load issue? I don't undertand the old vs the new, split shafts and shock absorbers, seems like the 50's were more complicated than the 80's.

 

[1946Zephyr]

Re: F R- Can you answer this one?

Well it seems that it does turn the flywheel when you turn it by hand but won't engage, while the engine is running, so that is the only thing it could be. The load is reversed, when you turn the prop by hand, versus the powerhead doing the work. The prop could have hit a rock and broke it.

I actually found the older ones to be simpler. I truthfully don't know why the shock absorber was put in only the 5 1/2's and 7 1/2's in that time frame, but I would start with replacing that and see if it changes the issue. I have seen some broke, in the past. If you try the AOMCI website, you might find someone who could sell you a good one.

 

[F_R]

Re: F R- Can you answer this one?

Appreciate it zeph, like I said I don't mean to single anyone out. I posted the same question before and didn't get a reply on the shifting issue. Why then will it spin while the engine isn't running, is it simply a load issue? I don't undertand the old vs the new, split shafts and shock absorbers, seems like the 50's were more complicated than the 80's.

A broken shock absorber usually locks up the lower unit, but I suppose that might not always be the case.

I don't know what is wrong with your motor without an inspection, but this will explain the shock absorber operation: EDIT: picture got lost, retrying...

 

[bktheking]

Re: F R- Can you answer this one?

That's all i've read about the shock absorber, if it's indeed broken it will screetch the motor to a grinding halt. I'm going to pull it apart tomorrow, it's like anything mechanical that doesn't work right, it drives me nutz! Looking at the diagram that might explain it, I guess one could have the 2 shafts welded together eliminating that spring and replace the prop pin with a softer shear pin.


Thanks for replying guys.

 

[samo_ott]

Re: F R- Can you answer this one?

When the engine is running it does not shift into any gear? That's odd. Thus as the driveshaft has to turn if the engine is turning, the answer can only be, broken drive shaft/shock absorber, stripped gear(s) or shifter not connected/shifting.

 

[bktheking]

Re: F R- Can you answer this one?

Nothing, no change in rpm, no prop wash, no clunk, nadda. Yet when it's not running I can shift it into neutral- the prop freewheels, move into forward, turn the prop by hand and watch the flywheel move. Move it into reverse, and it does the same thing, the flywheel turns. Something has to be broken in the gear case.

 

[samo_ott]

Re: F R- Can you answer this one?

When not running. Can you turn the flywheel manually the right way and put in neutral and the prop will spin freely, put in forward and the prop turns the right way and put into reverse and the prop turns backwards? If that works manually and not when running, something is real weird... It's too bad it's such a pain to drop the LU's on the 5.5 and 7.5. That's why most of mine sit in the shed! I stick to the 10's and 18's. Much easier to work on It's sounds like you have to open up the LU.

 

[Chinewalker]

Re: F R- Can you answer this one?

Is it pumping water while it's running? That would tell you that the driveshaft is in fact turning. I've seen a couple that were improperly serviced, resulting in the crankshaft splines rusting out. Might be enough friction there to turn as you tested at the prop, but not enough when running... Check for wear on the top driveshaft splines.

 

[bktheking]

Re: F R- Can you answer this one?

Yes the water pump is pumping so I know the shaft is turning.

 

[F_R]

Re: F R- Can you answer this one?

Yes the water pump is pumping so I know the shaft is turning.

You also know that the gearshift is functioning because it shifts in and out of gear on land. Let us know what you find.

 

[bktheking]

Re: F R- Can you answer this one?

Yes, so very strange. I know the motor has been dropped, there is a dent in the cowl from the shifter but I can't see how that would have anything to do with it. I hope to tear into it today and find out what is going on, it's very strange to have it shift and turn on land and not in a barrel.

 

[bktheking]

Re: F R- Can you answer this one?

Here is the answer to the mystery

Something broke and split the lower unit. I guess it's lower unit replacement time? Or can I completely strip this lower unit down to the housing , figure out why this happened (suspect that shock absorber) and have it welded by a guy I know in town who can weld aluminum?

 

[stingertrey]

Re: F R- Can you answer this one?

Yes im pretty sure you can strip this lower unit down to the housing. My 5.5 was locking up bad about 2 weeks ago F_R called it out instantly as the shock absorber.. had another lower unit at my disposal so I stripped them both down and switched them. Remove the shaft, water pump base plate, seals, and the shock absorber sits below it and I reached in and pulled it out with plyers and the drive shaft is slotted to fit into it. You can probably just replace what is broken.. laingsoutboards.com sales a shock absorber spring and pinion shaft for 75 bucks.. there not made anymore but they still have them apparently. And welding that shaft and putting a softer shear pin doesnt sound like a bad alternative to the 75 bucks if your tight on cash in the economy lol

 

[bktheking]

Re: F R- Can you answer this one?

So I figured out after looking at a diagram that is a bearing plate. After digging into the lower unit a little deeper I made some discoveries. The shift detents are both in tact, the shift rod was bent so I bent it back. All good now, the gears and dog look good so no gear worries. The shock absorber is indeed broken.

So I guess whoever owner this motor in a frustrated state hit a rock, shock broke , came up and hit the bearing plate and probably bent this shift rod all at the same time or after it broke tried shifting it. No wonder it wouldn't "go" anywhere.

 

[bktheking]

Re: F R- Can you answer this one?

I found a guy off of the old outboards site the has a pile of parts motors, his price for a good one is $30.


I'm gonna say this and probably get jumped on but this is the STUPIDEST design I have ever seen. How about a solid shaft and a shear pin, problem solved. Could imagine using this on snowblower and hitting a rock, $1 shear bolt vs a shock absorber, thank god they did away with this design.

 

[coolguy147]

Re: F R- Can you answer this one?

what engines have this? hope my motors dont oh and how would you know it was broken?

 

[bktheking]

Re: F R- Can you answer this one?

1955 Evinrude 7.5, the 5.5's do to as stingertrey pointed out, wouldn't be surprised if the 15 does as well, anything in the era it seems had this thing. Seems like the 9.5 shared parts with the 7.5 , shift detents are the same part number but I guess OMC got smarter and went with a better design, no shock absorber in the diagram.

Thank god I have a 9.9 as well!

 

[F_R]

Re: F R- Can you answer this one?

1955 Evinrude 7.5, the 5.5's do to as stingertrey pointed out, wouldn't be surprised if the 15 does as well, anything in the era it seems had this thing. Seems like the 9.5 shared parts with the 7.5 , shift detents are the same part number but I guess OMC got smarter and went with a better design, no shock absorber in the diagram.

Thank god I have a 9.9 as well!

OK you guys, the shock absorber is used on all 5.5 and the first couple of years of the 6hp. It is also used on the 7.5hp. And the 5hp Gales that have a gearshift. That's all. Oh, and the TN Johnson 5 had one similar but different.

As for stupid design, well I don't know about that. They made tons of motors using it. Hitting rocks doesn't break it, in fact that is what it is in there for-to release the drive and protect the rest of the motor when you hit something. What does seem to be breaking a lot of them all of a sudden is just plain old age. You have a piece of spring steel sitting there under conctant stress for 50 years and it gets tired. Water in the gearcase will cause it to break too, by causing rust.

The system was replaced by the rubber hub in the propeller on newer motors. They aren't exactly foolproof either.