scout-j-m
Chief Petty Officer
- Joined
- Jul 31, 2009
- Messages
- 636
Subject motor is a 1988 Yamaha 30hp 3 cylinder long shaft. I bought it last summer with a non-working lower unit. The lower had a broken shift rod and after tearing into it found that the forward gear has one tooth completely broken off. There was also a crack and subsequent very questionable weld repair to the upper threads where the bearing housing is held in by the gland nut. I was able to find a used lower unit not long after purchasing the motor so fixing this one hasn't been real high priority. I'm thinking I may give it a shot though....I just need to price parts and tools and see if it makes sense to invest the time and money in it vs selling it for parts since the drive shaft and prop shaft are for sure good parts.
I will for sure need a new forward gear which is about $100. I know the recommendation when replacing one gear is to replace both plus the pinion...plus the clutch dog. With the reverse gear being $100, pinion $80, and clutch dog being $50 that totals $330 not including shipping/tax. Moving on to bearings, new roller and needle bearings throughout add up to about $180 before taxes/shipping. So total becomes a little over $500 for just parts.
On to the labor - I do have the factory service manual which is a huge help. The job itself is not that intimidating. The issue is the number of special tools required to properly shim it and achieve proper backlash. Is it possible to rebuild without these tools? I believe it would require initial guessing on the shims and then full assembly followed by backlash measurement which would require total teardown and reassembly each time a new shim was required. I have found that the fwd/reverse gear shimming gauge is available used for $50 and the pinion gear gauge for $100. A gland nut tool would also cost me about $50 but I will need to buy that no matter what.
Questions I have:
-Would just a new forward gear and clutch dog suffice? Assuming backlash is set correctly between the pinion and forward gear it seems that the forward gear operation would be fine which is used 99% of the time.
-Is total bearing replacement also required? The roller and needle bearings in the bearing carrier are still very smooth. I haven't tore in enough to inspect the other bearings though. One would imagine losing a whole tooth would really mess bearings up but I am not seeing that. I wonder if a previous owner/mechanic repaired it and reused a broken forward gear for whatever reason.:noidea: It doesn't make much sense. FWIW, when I got the lower it was already drained so I don't have any data from the oil to go off of.
I will for sure need a new forward gear which is about $100. I know the recommendation when replacing one gear is to replace both plus the pinion...plus the clutch dog. With the reverse gear being $100, pinion $80, and clutch dog being $50 that totals $330 not including shipping/tax. Moving on to bearings, new roller and needle bearings throughout add up to about $180 before taxes/shipping. So total becomes a little over $500 for just parts.
On to the labor - I do have the factory service manual which is a huge help. The job itself is not that intimidating. The issue is the number of special tools required to properly shim it and achieve proper backlash. Is it possible to rebuild without these tools? I believe it would require initial guessing on the shims and then full assembly followed by backlash measurement which would require total teardown and reassembly each time a new shim was required. I have found that the fwd/reverse gear shimming gauge is available used for $50 and the pinion gear gauge for $100. A gland nut tool would also cost me about $50 but I will need to buy that no matter what.
Questions I have:
-Would just a new forward gear and clutch dog suffice? Assuming backlash is set correctly between the pinion and forward gear it seems that the forward gear operation would be fine which is used 99% of the time.
-Is total bearing replacement also required? The roller and needle bearings in the bearing carrier are still very smooth. I haven't tore in enough to inspect the other bearings though. One would imagine losing a whole tooth would really mess bearings up but I am not seeing that. I wonder if a previous owner/mechanic repaired it and reused a broken forward gear for whatever reason.:noidea: It doesn't make much sense. FWIW, when I got the lower it was already drained so I don't have any data from the oil to go off of.
