1962 - 1970 Repair Tips Regarding Lower Unit Electric Type Shifting That Jumps/Slips Out Of Forward Gear On Select 40, V4 75, 80, 85, 90, 100 HP.

[Driftwood Jim]

1962 - 1970 Repair Tips Regarding Lower Unit Electric Type Shifting That Jumps/Slips Out Of Forward Gear On Select 40, V4 75, 80, 85, 90, 100 HP.

Hi all,
1968 Evinrude Lark X 40hp
I have replaced wiring & switches and reconditioned all parts and connections except the bottom of the lower unit where the gears and magnet coils are. Symptoms: jumps out of forward sometimes. Sometimes it goes right back in gear and other times it takes a couple of tries to go in gear. Back and forth from neutral . I am not sure if the coil(which tests in working order every time I have checked it, dozen or more times) or the gear is failing. If it is the gear can the teeth be reground and if so how, or switched with the reverse gear since they are the same part. I am a very experience mechanic with only a little OB experience. Looking for advise on how to and any other feed back from those with experience in this problem

 

[jimmbo]

Welcome to iboats
Is there any pattern as to when it jumps out of gear? Rough water? Upon acceleration?
The unit is very simple and reliable. Oil is critical for this gearcase/shift system. BRP Premium Blend is the correct oil for this unit. Anything else can cause issues. Premium Blend used to be marketed by OMC as Type C gear oil. There are some oils being marketed as Type C but are not compatible with the Electric Shift, so beware. The gears themselves wear very little if at all over the like of the engine, and while they are the same part for forward and reverse, they do use different bearings.
You said you replaced the pushbutton switch in the control box? What condition is the wire that goes down into the gearcase? These sometimes get damaged and can short out or break continuity. Have you tried bypassing the swiches and harnesses and connected the unit directly to the battery? If you are using the right oil, and everything electrical checks out then you have to pull the unit apart.

Here is a video that sort of shows what goes on inside that unit
https://www.youtube.com/watch?v=ee7Yd1w-vuY

 

[F_R]

Disconnect the two wires leading to the lower unit, and insulate the blue one so it can't touch anything. Now connect a wire between the green one and directly to battery positive. Make sure it can't come loose or ground out. Doing this will lock it into forward gear, so be careful and don't run into anything or anybody. Run the motor and see if it stays in gear. If it does, the trouble is not in the lower unit. Warning! Do not allow battery voltage to touch both green and blue wires at the same time. Doing so will cause serious damage because that would put it in forward and reverse at the same time.

FYI, the push button shift switch is notorious for causing erratic shifting and/or clutch engagement.

 

[racerone]

The jumping out of forward gear has nothing to do with gear teeth at all.---What is happening is the clutch spring is not " holding " on to the forward drum properly.

 

[Driftwood Jim]

Thanks for the quick responses.

Does the tang on the end of the spring need to be reshaped? I am assuming it has been rounded due to wear.
I am using premium Type C oil and the NOS switch tests out good.
Thanks in advance as I have gone through this old baby and replaced bearings, oil seals and drive shaft to get it good order. It is mounted on a 16' tinny and is a pleasure to run. The boat handles like a dream.

 

[racerone]

Nothing to do with the tang on the spring !

 

[Driftwood Jim]

Then what is the cause and how do I fix it. Could you explain please? I am a very good mechanic with good fabrication skills...Thanks.

 

[F_R]

Don't worry about the lower unit fix, till you have proved the problem is down there---as I explained above.

 

[Joe Reeves]

An actual cure is to replace the spring and hub, both of which are quite difficult to find and are overly expensive.

 

[Driftwood Jim]

Thank you for the responses F_R & Joe.

The same thing happens(jumps out) after every fix, test or replacement. Therefore the lower unit is suspect. I will take it apart and see for myself. (back at square one again as I have not gained any knowledge from this post that I did not know already)
When I figure it out I post the solution for all to learn from.

I have been reading this and other forums and all offer free advise to solve common problems. ( I have seen the same problem asked about here and other forums and there is no further posting as to the solution or outcome).
I thought the forum was to help each other out.

 

[F_R]

We ARE trying to help you. If you want the official fix as according to the service manual, see post #10. What happens is the spring looses it's grip on the hub. You won't be able to tell anything by looking at it. My wild guess is that he is either sand blasting the hub or knurling it to improve the co-efficient of friction. Just guessing.

I'm trying to save you from getting yourself into trouble. I tell you again, hot wire it to make sure that is where the trouble is before tearing into it. If you do go into it, be careful. Many novices rip the coil wires in two by letting the upper and lower sections fall apart. Furthermore, if it has ever been used in salt water, it may be extremely difficult or even impossible to get it apart. Same thing goes for fresh water, just takes longer. Almost 50 years ought to do it.

 

[Driftwood Jim]

F_R
I have the service manual and am aware of what it states. It was the first thing I bought. I always buy one for any newly acquired vehicle. Only makes sense when one works on their own stuff. Saves money in the long run too.
I have already taken apart and replaced the drive shaft bearing and seals, water impeller and seal on the top portion of the LU to make it leak free. Tested both of the coils/ magnets while I was there and every step afterward. The bottom half has had a recent seal replacement by PO that is in good order as the LU does not leak. Did not open it up as all was good, but will now.
Thanks for clarifying the mechanical process as how it actually works. Never read anything from anybody to describe it and only found one video of the magnet pulling the spring. The manual only has a picture with no mechanical explanation as you described. Now that you have provided a clear picture I can figure it out prior to opening it up and fixing it.

Has anyone compared an old and new hub side by side as to how much and what type of texture the spring needs?

Thanks again and you have helped. I will let you know how it turns out. Can?t work on it for a couple of days though due other commitments

 

[Driftwood Jim]

Well, Well Well,
Is this is a forum, or is this a forum
Thanks for the support from all of you, very much

When I first posted I thought that the spring tang moved due to the magnet and engaged a grove or something to tighten the spring(not) . Well from your combined wisdom I have pieced together the mystery of the ?Selectric Shift?.
It is rather simple relying on only friction for such high torque forces. The spring provides the perfect adjustable tightening device as it spreads the load over a larger surface for strength and durability, but with anything mechanical it will wear. The mating surfaces of the hub and spring slip and wear from going in and out of gear (like a car clutch wears). When the surface becomes too smooth this causes it to slip and come out of gear. After searching I found a detailed photo of the inside surface of the spring and the roughness of the surface of the spring on the inside. Also found a good photo of the hub mating surface.

So without taking it apart yet and relying on my depth of knowledge in other mechanical and fabrication areas as well my experience in working in a marina long ago. I will surmise that the mating surface of the hub/spring is now not rough enough to provide the proper friction required for lock up of the spring/hub interface. (AKA- slipping out of gear)

So the solution as previously stated ? is simple? (thus the mystery). Just roughen up the inside of the spring with something like a cylinder hone, SS wire wheel or other abrasive method. Will be able to determine the exact method once I can visually inspect in hand and determine the hardness of the steel.
Surface of the inside of the spring appeared pretty rough in the photo.

As for the hub: the mating surface it has a sheen to it and indicates to me it is only lightly roughen up on the cut surface mating area, so depending on the hardness of the metal I will use emery or wet paper to abrade the surface sufficiently.

This should provide the surface textures needed on the mating surfaces to provide the friction required for lock up.(For comparison I will check the reverse spring/hub for wear and surface texture while I am in there.) Due to usage of the spring, a machined exactness is not required here for excellent mating of the 2 surfaces. This simple solution should not be revealed as it will awaken the Kraken and is forbidden (only kidding These items we have already in our tool boxes and if you can take apart the LU then you could make this repair .

I would like to Thank all of you, as each through bits and pieces contributed to the solution. As I am now able to see exactly how the parts interface with each other providing the solution for the failure.
Almost had it right as described in the beginning. (Still don?t know how the tang hooks up, but I will see this when I open it up.)

Will update and verify methods and materials when the work is completed and tested.

So can my hypothesis of ?The Mystery of Selectric Shift? be verified by any and all

 

[jimmbo]

By your earlier post you have probably figured out how the mechanism works, but on page 57 there is a brief description
http://www.fiberglassics.com/library/images/a/a7/Evinrudeservice002.pdf

 

[Driftwood Jim]

Yes the magnet causes the spring to stretch over the cross hatched area of the hub. This stretching causes the inside diameter of the spring to get smaller. Like a snake constricting around its prey (the hub) tightly gripping the hub as long as there is enough friction between the spring and hub. The problem comes from not enough friction between these parts. So to repair this condition the inside surface of the spring and the cross hatched area of the hub need to be roughened up to produce a coefficient of friction sufficient enough for the parts to lock up. Like the snake squeezes its prey and there is no movement between them. So roughening up the surface mating areas on the 2 parts should prevent the slippage and engage the prop.

To this I say Release the Kraken of knowledge for all to share. To this I think Poseidon would agree

 

[Driftwood Jim]

FYI I have found the spring and hub on Ebay for $12 and $10 respectively so the parts are not that expensive anymore. Not that I'll need them now
Once again thanks for the help

 

[Joe Reeves]

FYI I have found the spring and hub on Ebay for $12 and $10 respectively so the parts are not that expensive anymore. Not that I'll need them now. Once again thanks for the help

Yeah, I saw that also.... Very strange that they should be popping up now for such a low price. I'd like to know the story behind that!

 

[Driftwood Jim]

Thanks for the service manual. My service manual for the 40hp does not include the info you pointed out and some addition info as I continue to read.. Surprised its not in there, but I have the service manual for my 6hp Evinrude and it contains pertinent info not include in the 40hp manual. The additional info is important to service the motors. Example my 6hp manual describes pressure testing procedures for the LU where the 40hp manual has no such reference. I wonder why.

 

[jimmbo]

FYI I have found the spring and hub on Ebay for $12 and $10 respectively so the parts are not that expensive anymore. Not that I'll need them now
Once again thanks for the help

Hope you got the ones for the 40hp, the ones for the 75, 80, 85, and 90hp look very similar

 

[Joe Reeves]

Hope you got the ones for the 40hp, the ones for the 75, 80, 85, and 90hp look very similar

Jimmbo.... the spring and hub are identical (2 & 4 cyl)..., it is the actual gear that is different.