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Discussion Starter #1
Hi guys. I use a Yamaha 9.9 High Thrust (T9.9EXH2 to be specific) and broke the shift cable a few weeks ago while trying to get into reverse. I thought the cable just went bad so I replaced it. Now, it shifts just fine from neutral to forward, forward to neutral, but it's almost impossible to get into reverse. HOWEVER - if you manually spin the prop in the reverse direction and THEN shift to reverse, it will shift perfectly from neutral to reverse and reverse to neutral.

I feel like I have heard of cars having "synchros" or something in the gear boxes but I'm probably way off here.

Any suggestions on what to investigate next would be very appreciated.
 

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Hi guys. I use a Yamaha 9.9 High Thrust (T9.9EXH2 to be specific) and broke the shift cable a few weeks ago while trying to get into reverse. I thought the cable just went bad so I replaced it. Now, it shifts just fine from neutral to forward, forward to neutral, but it's almost impossible to get into reverse. HOWEVER - if you manually spin the prop in the reverse direction and THEN shift to reverse, it will shift perfectly from neutral to reverse and reverse to neutral.

I feel like I have heard of cars having "synchros" or something in the gear boxes but I'm probably way off here.

Any suggestions on what to investigate next would be very appreciated.
If it binds when not running, assuming all the linkage component are properly aligned and lubed, it may be due to the cogs on the gears not being lined up.

On all the outboards and motorcycles I have had, all the gearboxes had cogs, not slip or synchro rings. We had a Volvo outdrive on a Skipjack 20 that did have "slip" or "compression" rings in addition to cogs, IIRC.

If it binds when running, it may be in the linkage, or possibly the gears themselves not being properly shimmed?

Was there any work done prior to the problem?

Paul T
 

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Discussion Starter #3
Thanks for the input.

The only service that has been done in the past year was replacing the gear oil about a month ago. Therefore, I don't want to disconnect the lower unit until I get that far of the troubleshooting.

I suppose that maybe I was always forcing it to reverse which caused the old shift cable to fail and I really do have a problem in the lower unit?
 

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Sounds like the lower unit needs to be worked on could be a bad shim on the reverse gear not allowing the cog to float properly gear oil is cheaper than new lower unit. What did the old her oil look like?
Oil condition could indicate possible problems.
 

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Discussion Starter #5
Thank you all for the help.

The oil seemed fine. I had my hand running though the oil as it poured into the pan and there didn't seem to be out of the ordinary.
 

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Thanks for the input.

The only service that has been done in the past year was replacing the gear oil about a month ago. Therefore, I don't want to disconnect the lower unit until I get that far of the troubleshooting.

I suppose that maybe I was always forcing it to reverse which caused the old shift cable to fail and I really do have a problem in the lower unit?
Forgot to ask, how long has it been a problem, and did it come on suddenly or over a period of time? Not familiar with your particular motor, but those I have owned or operated have an interlock system to prevent the motor from being started when in gear or shifted when the throttle is beyond idle.

A shop manual, sometimes available on line, would probably show the alignment specs. Suggest you try the easy things before tearing into the gearbox. If you do, resist the temptation of removing the drive shaft from the gear clusters. Getting it back in can be difficult as the gears might fall into each other, very frustrating.

I have a 6HP 4 stroke Tohatsu. The gear selector has to be in exactely the right spot to be able to start it.

Paul T
 

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Before you start rebuilding the gearbox, I suggest eliminating some of the simple (and inexpensive) things that could be causing the issue.

The first and most obvious would be a misadjusted shift mechanism. I had precisely the symptoms you describe on my Yamaha 8, when the shift rod was not properly adjusted.

The second would be an issue with the reverse shift / tilt interlock adjustment.
 

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Before you start rebuilding the gearbox, I suggest eliminating some of the simple (and inexpensive) things that could be causing the issue.

The first and most obvious would be a misadjusted shift mechanism. I had precisely the symptoms you describe on my Yamaha 8, when the shift rod was not properly adjusted.

The second would be an issue with the reverse shift / tilt interlock adjustment.
I'll second this. Was a certified Yamahammer outboard tech... the shifting rod adjusted one way or the other too far and shifting to that gear will not work properly (if at all).
 

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Hello Dave_E,

Today I helped a friend replace the impeller in his Yamaha 9.9 4-stroke. When we finished, the engine wouldn't go into reverse even with the shift shaft adjusted all the way out. (We tried all the way in as well, and many adjustments in between.) At the extreme "long" adjustment, with the engine running & the shift lever held all the way back in "Reverse", we get the rapid clicking of the dog bouncing off the face of the reverse gear, but it never actually engages.
This adjustment also puts the actual Neutral position of the shifter where Reverse should be, and any position from Neutral to Forward puts the gearbox in forward.
There were no problems shifting into reverse before we replaced the impeller, so it shouldn't be a matter of chewed-up cogs refusing to engage, but I can't figure out any other possibilities.
I wondered if you could think of any damage we might have done by trying to pull the lower unit off without removing the jamnut from the shift shaft first. (I did flatten the shift shaft seal retainer out, which we bent during disassembly, before bolting it back in.) We did have the shift shaft coupler disconnected though, and we didn't pull very hard on the lower unit.
 
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