NS70A Shifting Problem

[mccarlej]

I have a Nissan NS70A and took it on the water today to discover this problem. She runs like a top and goes into reverse perfectly. When I shift into fwd nothing. I took it out of the water and tested with muffs on and prop spins perfectly in fwd and reverse as it should. Put it back in the water and this time I disconnected the shifter cables and viola, I can shift by hand into Fwd,N, and Rev just fine (fwd I have to move the shifter quickly to get it to engage otherwise it's as if the cable is connected). So before everyone says "your cables need adjusted, understand that the shifter is moving the full range of travel. I am thinking there may be excessive play in the shifter cable but without being in the water I do not know the best way to test the adjustment. Any ideas?

 

[pvanv]

Assuming the shift rod and mechanism on the motor is not bent, and roll pin is not missing from the rod coupler, then adjust the shift cables as indicated in your owners manual, available online from nissanmarine.com. Essentially, you pull the clevis off of the motor, shift the motor to N, shift the RC box to N, and make sure the clevis fits the pin perfectly; if not, shorten/lengthen the clevis on the cable until it slips on perfectly.

 

[mccarlej]

Thank you Paul, nothing is bent and the pin is in the coupler. The real issue is not being able to test the adjustment out of the water. On muffs, everything works as it should but putting it the water (under load is where I assume the issue starts) starts the trouble of not engaging in Fwd. I can hear the teeth of the clutch dog but it's not fully seating. If I disconnect the cable I can shift by hand. Is there a way to test this out of the water (simulate load on the prop) so I'm not the jerk at the dock taking up an entire lane all day trying to solve this? Thank you again for the input. Oh, also I drained the LU hear oil and it was very dirty/black and thick. Do you think this could effect the clutch?

 

[mccarlej]

Update: after changing gear oil I was able to get it into gear. I had to quickly throw it forward and the gear would catch but if I gave it more throttle it would slip out of gear. I'm still hoping it's bad throttle cables/adjustment but I'm becoming more worried it's the clutch since it has no issues going into N or R.

 

[pvanv]

I suppose if the old lube was very gooey, it might restrict the clutch dog travel, slowing it down. Yes, you are supposed to shift Briskly; "easing" into gear has damaged a lot of clutches over the years. You can adjust the RC cable to favor the F engagement, but it's possible that you will need a clutch dog; if so, you may also need the A bevel gear, because if the clutch dog is really worn, the engagement ears in the A gear may also be worn. At issue is that your motor is very obsolete, and the clutch, etc., is NLA from Tohatsu, so if you do need a clutch dog, you will be searching for used parts. Very few parts are available new for this model, so, as Elvin would note, beware the money pit.

 

[mccarlej]

You are right, the guy I got the boat from said he never had this issue so time will tell how honest he was. I'm going back out today and I'm going to disconnect the cable and see if it will shift and hold gear under load by hand. If it jumps out of gear when I shift by hand then I know it's time to do some machining on the clutch dog but if it holds then back to the PITA adjustments.

 

[mccarlej]

Update: today I took her back to the water and disconnected the shift cable. I shifted by hand and had the same problem, she slipped out of gear under load. This weekend I am going to pull the gears out of the LU and see what the damage is. I'm suspecting the dog clutch. If so I'll be looking for a machine shop or for anyone here with a good LU to sell... I think I got swindled on this boat

 

[pvanv]

Unfortunately, the dog is difficult to replicate; you would need to start with good high-carbon steel, then machine it, and have it heat treated. But a used LU may possibly be available. Or, you may want to part-out the 70A to someone else.

 

[mccarlej]

I'm going to start pulling the the gears today. If the teeth on dog clutch are rounded and the corresponding bevel gear why couldn't the teeth be machined back in order to seat? Also, I think this model has a spring for Fwd and if that spring is worn or is weak it may not have enough pressure to go into Fwd. the last owner said it never grounded into Fwd so I still have hope the gear is good. If it is the spring then that is one of the few parts that are still available. I'll start taking pics when I start tearing it down. I'm not much for giving up!

 

[mccarlej]

No Title

So, dog clutch teeth are pretty rounded as you can see in the photo. I'm at the machine shop the get the angles cut back to 90 degrees. I'll update to let anyone know if this works out or not.

 

[mccarlej]

Part number 3a364-2151m if anyone has one laying around!

 

[mccarlej]

No Title

Well got my clutch back and here is the finished product. Mig (or Tig) welded teeth that are hardened and tempered. Cost was $60. I've attached pics and reinstalling tonight. Taking her out Saturday to see if my problems are solved.

 

[mccarlej]

It's solved all the issues! Anyone who needs clutch dog work, this is good to go. Boat is doing great! Now I'm going to start the decks and just finished my live wells last night!

 

[mccarlej]

No Title

Ran great for hours yesterday. What is this? Do I have a bad seal?

 

[pvanv]

If it's clear (it seems to be), you have a leak in the lower unit. I would install a new seal kit if available. Could be a drive shaft seal or a cam rod o-ring, since the prop area seems dry. The fill/drain plugs are on the other side.

 

[mccarlej]

It's definitely gear oil. Looks clean since I just put new oil in with clutch dog. Seal kits are not available so I'll just have to keep an eye out keep oil changed until I find a kit or have time to pull gears to see if the o rings maybe slipped off when I installed the gears with the clutch dog