Shifting Woes

marksa1458

Petty Officer 3rd Class
Joined
Apr 6, 2009
Messages
93
Have a 1968 Mercury 500 s/n 2479530 short shaft. The problem is it would stay in forward gear - dropped the lower unit, realigned the gear shaft splines bolted everything back up - Forward/Neutral/Reverse all works great. Tilt the engine up shift forward, shift back to neutral and reverse and bam the lower unit will not shift out of forward anymore.

The linkage at the powerhead looks ok, movement is good, adjustments look right. I am thinking there is a problem in the upper shift shaft slipping somewhere. My question is - is there a common place where these shafts can slip and how difficult is it to replace with a new shaft.

Also, anyone have an idea where I can find a good shift shaft?

Thanks,
 

marksa1458

Petty Officer 3rd Class
Joined
Apr 6, 2009
Messages
93
Re: Shifting Woes

In looking into further - there is a threaded rod that has a coupler attached to. The coupler was locked in place by a set screw that was badly corroded.

This doesn't look like the original factory design:

UpperShiftShaft_ThreadedRod.jpg


and here is the coupler with the set screw

UpperShiftShaft_Coupler.jpg


Is this the original design? there doesn't appear to be any threads in the coupler..
 
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