Just general questions-Speedometer and Lower Unit shifting

[NJCoastFlyFish]

I replaced my waterpump and noticed a few things along the way, I am curious, how does the speedo and the gear shift work?<br /><br />The speedometer has hosing that goes to the lowerunit, how exactly is the engine reading speed? I assumed there was some type of wheel somewhere like my depthfinder but how does it read water speed when it is going through all that tubing, wouldn't it mess it up?<br /><br />My next question is, I put the engine in forward before I took the lower unit off so I figured once the lower unit was off the prop would only spin forward, but it doesn't it spins both ways even when shifted to forward. This even caused me to assume I knocked it into neutral so I put the engine in neutral when I put the lower unit on, but it wouldn't go, so I tried forward and bingo, it slid right on, so how does the shifting work?<br /><br />By the way, the engine is a 95 yam 200

 

[rodbolt]

Re: Just general questions-Speedometer and Lower Unit shifting

the speedo is water pressure operated from a tiny hole called a pitot at the leading edge of the gearcase, faster the leading edge goes the more pressure, mathmatics does the rest<br /> the shift has a cam that when rotated CCW or CW pulls a pin thats attached to a clutch that is splined to the propshaft, sticking off each gear face are 3 to 6 lugs the clutch has 3 to 6 coresponding lugs that lock to whichever gear is selected or no gear for neutral.<br /> its a mechanical slam shift arrangement which is why it goes clunk when engaged, but never ease it into gear as it wears rapidly that way.

 

[NJCoastFlyFish]

Re: Just general questions-Speedometer and Lower Unit shifting

Thanks!

 

[wvstriper]

Re: Just general questions-Speedometer and Lower Unit shifting

rodbolt, my speedo doesn't work. It is connected to my C115. I pulled the tube off of the back of the speedo and tried blowing in it and it seems to be clogged. I even tried to suck on it, but all I got was a little taste of saltwater! I looked at the hole on the lower unit. The opening on the housing is clear, I stuck a small drill bit through the opening and it went in a little ways and then I hit something solid. I stopped fooling with it then. My question is how small is the opening for the pitot? Does the opening face forward or down? My Seloc manual doesn't even reference the pitot let alone have a pic of it. Thanks in advance.

 

[rodbolt]

Re: Just general questions-Speedometer and Lower Unit shifting

it faces fwd about 4 inches down from the ventalation plate, its rather small.<br /> its a steel tube pressed into the leading edge of the housing and is prone to clogging with wood/weed debris.<br /> unplug the tube just above the gearcase and try blowing from the tube back down through the pitot tube.<br /> the pitot tube is an inch or so deep but I always use a drill bit in my fingers to clear it, I am not an oil baron and try NOT to strike it.

 

[wvstriper]

Re: Just general questions-Speedometer and Lower Unit shifting

Thanks, I'll check it tonight.