Lower Unit Questions

[dabowhunter]

Hi,
I have a 50 HP Johnson. Last season the lower unit went out on it. I found a used lower unit that I bought from a private party. I paid a dealer to install it. When I picked it up he said it worked fine in Forward gear, neutrat was fine. It would shift into revese but made a vibration and clicking noise in the shift lever like it wanted to jump out of gear. So I stop in by the dealer a few weeks ago and he gives me a deal on another complete 50 HP Johnson for parts. So I have him put the new lower unit on my engine. It works fine in forward and reverse, but I notice if I shift slowly into reverse it makes the same clicking and vibrating till in engages fully. Than it is fine. So I am wondering if this is a problem with the shifter lilnkage or the lower unit? Is there a way of testing a lower unit when it is off the power head?

Model # J50TLCUD SN G 7429015

 

[kjdunne]

Re: Lower Unit Questions

May be shifter cable needs adjusting. Or shift rod into gear case needs adjusting. Once engaged in reverse, does it stay in gear and the clicking stop? You should not shift into gear slowly. Do it with authority. The gearcase does not any clutch mechanism, so slowly engaging gears causes wear and tear that is expensive to fix.

 

[kjdunne]

Re: Lower Unit Questions

Sorry, didn't read your post fully before first reply. You can do a basic test of the lower unit when it's off the engine. Clamp to the edge of a bench by the cavitation plate using wood blocks between the plate and the clamps. While rotating the driveshaft clockwise looking from the top, pull up sharply on the shift rod, this will engage a gear, reverse I think, and the prop shaft will turn. Push the shift rod down one "click" for neutral. Hold the prop shaft while rotating the driveshaft to verify, as the prop shaft will sometimes turn if you don't hold onto it. Still rotating the driveshaft, push sharply down on the shift rod to engage the other gear and the prop shaft should turn in the opposite direction. This is only a basic test for the shift rod pivot, clevis and clutch dog. When under power, worn gears or clutch dog can still pop out of gear. The height of the shift rod is critical, +/- 1/32 inch according to specs. This can only be checked and set with the lower unit off the engine. See your manual for your height. You can build a gage for this if you're handy, or have a dealer do it.

If, as you say, it is fine when fully engaged in gear, shift sharply into gear and don't worry about it. They're not designed to be put into gear slowly and they don't like it.

 

[dabowhunter]

Re: Lower Unit Questions

Thanks for the reply. Yes it seems as though the new lower unit is ok. But I was wondering if the one I pulled off was ok as well. But it was doing the clicking even when shifted fully into reverse. When testing it like you explained, it seemed to work alright. Seems odd to me that the reverse gear would be worn, seeing as it does not get used nearly as much as the forward gear.

 

[mstrud]

Re: Lower Unit Questions

Jesus GOD man!!! its normal for gears to grind if you shift them slowly, dont shift gears slowly!!!!! makes shifts quick as possible, your just grinding your clutch dog when you hear that noise wearing it out way prematurly. Just dont do it.

 

[5150abf]

Re: Lower Unit Questions

When you shift a boat you should do it in a quick deliberate fashion.
You want it to engage as fast as possible, boats don't have syncronizers like cars do, so shift quickly.

 

[dabowhunter]

Re: Lower Unit Questions

Okay, I got the part about shifting slowly. My main question now is on the first lower unit that had the reverse problem from when it was first installed used. Is there a chance the problem was in the shifting linkage? Does it need to be taken apart to surmise any damage? Thanks guys

 

[tashasdaddy]

Re: Lower Unit Questions

the unit is probably good, forward is usually the first to go. how old are you control cables. when the get old they start to fail. shifting to forward is pulling action, shifting to reverse is a pushing action, if the cables are failing the will bunch up and not push the linkage as far as they are suppose to.