linkage trouble

rcwjona1

Cadet
Joined
Aug 15, 2009
Messages
25
I have a mer cruiser 305 1981. I'm a new boater, and am having trouble getting boat to work. We got the motor running great. Now we are having trouble switching gears. When we put it into forward the prop grinds and than kicks in. Then we put it back into neutral or revers the motor stops. I was told it might be something in the linkage or micro chips?. Any thoughts or advice would be appreciated. If you know an easy way to adjust the micro?whatever there called? or a tool we might need that would be great. :D Getting there slowly.
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
71,095
Re: linkage trouble

any other time it means the lower shift cable is going bad and needs replacement.

Ayuh,... No doubt....
 

proxyx

Banned
Joined
Aug 28, 2009
Messages
135
Re: linkage trouble

what shall I say... adjust the linkage (shift line) as per manual, eventually replace the shift cable


http://forums.iboats.com/showthread.php?t=158082


I/O Shift Cutout Switch Adjustment, Submitted by AChris.

--------------------------------------------------------------------------------

Mercruiser MC-1, R, MR, Alpha One, Gen II shift system

Many people ask about the shift cable setup and the shift cutout switch. Here is an explanation of how it all works and how to set them up. This will assume that there are no ongoing problems, like stiff cables or excess slack in the shift system.

Theory of operation
(Courtesy of "Qystan")
The shift cutout switch "can" work in both going into gear and out. Let me explain.

If you study the intermediate shift plate and the linkage. The function it performs is for the upper shift cable to move the lower (both directions) and allow one to move independently of the other. When independent movements occur, the shift cutout switch will sense this and cause the ignition to be cutoff, ignition is restored when the cables synchronize.

So how does this work? The gear design allows shifting into gear quite easily, hence engaging gears is usually not a problem and the 2 cable movements stay synchronized during the engagement cycle, the switch is never actuated. If you have a sticky lower cable, the upper cable movement will result in an out of sync situation if the lower cable does not move. The switch will be actuated and kills the engine.
Shifting out is slightly different, due to the gear undercut, the gears do not disengage easily. This will always result in non-movement of the lower cable and actuating the switch. When the engine 'dies' the torque on the gears which holds them together is removed, allowing the gears to disengage. In disengaging, the lower cable moves and synchronizes with the upper cable, resets the switch, restores ignition.

Bad cable adjustments which misaligns the upper and lower cable neutral position will cause engine dying during engaging shifts. The misalignment gives an upper cable 'overtravel' which the lower cable cannot synchronize due to its limited travel. Symptoms would be engine dying going into gear in one direction but the other is OK.

Adjustment of the cables
1. Remove both the shift cable (to leg) and the control cable (from control box) from the shift plate.
2. Push in on the end of the cable and have someone turn the prop slowly Counter clockwise at the same time. When the prop stops the unit is in Forward gear.
3. Adjust the brass barrel until the distance between the centre line of the brass barrel and the cable end guide mounting hole is EXACTLY 6 inches. (pre-1974, 5-7/8")
4. Re-install the shift cable onto the shift plate. DO NOT change this adjustment again.
5. With the control lever at full throttle in forward adjust the brass barrel to line up with the guides on the plate. DO NOT install the cable at this point.
6. Turn the brass barrel AWAY from the cable end guide 4 turns. Install the cable on the shift plate.
7. Move the control lever to the full reverse position, as the helper turns the prop slowly clockwise until it stops.
8. Check the shift cutout switch roller position. If is has moved from the centre position, adjust the brass barrel on the control cable, one turn at a time (maximum 4 turns) until the roller is in the centre position.
9. Secure the cables with the nyloc nuts. DO NOT tighten them onto the barrels.

Cutout switch
The cutout switch should also be checked. The correct adjustment for the switch is to activate when the switch arm has moved 1/8". Check this with a 1/8" drill and a multimeter. With the key 'OFF' put the multimeter across the switch (points ignitions will have to have the points open for this) and start moving the switch arm. When the meter shows that the switch has closed, check the gap between the switch arm and the actuating lever, it should be 1/8". Bend the arm of the switch to achieve the dimension.
 

Don S

Honorary Moderator Emeritus
Joined
Aug 31, 2004
Messages
62,321
Re: linkage trouble

Theory of operation
(Courtesy of "Qystan")
The shift cutout switch "can" work in both going into gear and out. Let me explain.

This was before he learned how the system really worked. He just thought his worked right and explained it from his perspective.

Go up to the adults only sticky and look at the thread on how the shift interrupt system works.
Proxys, if you want to quote something, make sure it's correct. Times have changed and correct information is available. But doing a copy and past of OLD posts, isn't the way to go.
 
Top