Deep Six "Shift Assist"

[Arminius]

What a piece of crap! I took a while to disconnect it as an experiment as it had a helpful name. Mine's a 305 MPI if anyone wants to tell me my decision was a rash one. Imagine the cautious boater trying to dock at the Club when someone sneaks a party trick into his throttle cable causing it to blip on every shift into either gear!

3/4" long by 5/16" ID barrel spacer and a 1" long 1/4" clevis pin is all it took!

Comments invited: The correct way to shift a marine engine is "smartly" in the sense that you move the lever continuously, without hesitation, so as to avoid that grinding noise. Timid boat drivers were grinding the gears and putting metal flakes in the outdrive oil so MercCruiser engineers invented the snap-action "shift assist" cylinder which binds the throttle movement slightly before engaging and then releases with a snap into gear, incidentally blipping the throttle at the worst moment. This only lasted a few model years including 2003.

 

[Arminius]

For the record, the "shift interrupt system" (the wired "Y" switch on throttle plate") is totally different and designed to ease the shifter out of gear: https://forums.iboats.com/forum/eng...3-how-to-how-the-shift-interrupt-system-works
Some claim that this only kills half the cylinders on my mpi engine but so what.

Trying to do more research on removal of shift assist cylinder, I find one old posting by a mechanic:
"jerryd,81 Posts:
The spring loaded “ Shift assist cylinder “ letter A in
above diagram, was only used a couple of years.
It caused problems, and was not used after 1999 ?
Remove it - fill spaces with plastic bushings -
adjust shift - and go.
I have a 5 gallon bucket filled with these that I removed over the years -
have never been asked to put one on."

 

[Scott06]

What problem was it causing?my 2004 has one shifts no issue

and yes on any dog clutch system like and alpha one you have to shift into gear like you mean it no screwing around. Everybody bags on this but it’s simple technology that works for years.

 

[scoflaw]

That device works to get the boat out of gear not into gear

 

[Arminius]

My shifter/throttle operated with higher effort and difficulty at lowest speed as I jockied the boat up to the dock. I had already determined that the "gear" cable from the shift plate to the outdrive worked smoothly and had rerouted the "shift" cable from the shifter/throttle "binnacle" to the shift plate to ease one bend. I also reduced friction at the binnacle. It was only when I removed the "shift assist" cylinder that I got a dramatic reduction in effort and increase in fine control. See also: http://www.clubsearay.com/index.php?threads/shifter-maintenance-2003-alpha-1.97819/
Maybe a new shift assist cylinder for $35 would have helped but the concept seemed wrong and all comments and advice were negative while the result of my experimental removal was very positive. I have posted for better than a week without any contrary postings.

 

[Bt Doctur]

the spring loaded assist also wears out the control cables faster

 

[Arminius]

Here's the shift plate with the also pictured cylinder removed.