Lower Unit issues '77 65 hp chrysler

[LostCoastDreamin]

I just took apart the lower unit in my 1977 65 hp Chrysler, and found a mess of metal in the gear housing. Forward gear has large chunks missing from, or cracks in, all the teeth, so it needs repair or replaced. Is it even possible to repair teeth on a spiral bevel gear such as this? Can a machine shop handle it? I have a nice arc welder (up to 180 amps) but my metal machining tools are limited to bench and hand grinders, drill press and rotary tools. No metal lathe here.
I have only had this on the water three times, and it was hard to engage forward from the start. Now I know why. The third time out, I felt something "let go" while under way, followed by a COMPLETE loss of all power. Had to get the tow of shame. This would be the last bit of grip between the drive shaft and the pinion gear shearing off/pinion nut loosening. I am more and more sure the drive shaft-to-pinion teeth were already stripped, and the last owner just tightened the nut back on and sold it to me. My fault for not testing out the lower unit before buying it. Surprisingly, the pinion gear itself looks pretty good inside and out. So does reverse.
After taking apart the unit, I discovered the reason for the total loss of power. The nut on the pinion gear backed its way out enough to stop holding the drive shaft, but the main issue is that the drive shaft teeth are stripped. Turns out they are so completely stripped that no amount of pinion nut tightening would fix it. I'm pretty sure I can weld enough metal to the drive shaft to grind the teeth back into it, and have a solid grip there again.
The clutch dogs are slightly rounded, but I am sure I can repair that. Fairly simple welding and grinding on square dogs. That means two out of three problems solved if I'm right about being able to fix them.
Is it even possible to repair teeth on a spiral bevel gear such as this? Can a machine shop handle it? Does anyone else have a forward gear that would work for me? I've heard that several years of 55, 60, and 65 Chryslers have the same lower unit, something like '73-'78 for years. Please PM me if you might have a replacement for me.

 

[Frank Acampora]

Re: Lower Unit issues '77 65 hp chrysler

Chrysler made these series of engines for a number of years and made them with two different lower units: Earlier and later.

Your engine year and lower unit description do not seem to match as you seem to be describing a one piece lower unit. A couple of photos would definitely help.

On to the meat: NO! It is not possible to repair this small a gear adequately. Oh, you could hardface weld and grind but the accuracy would not be sufficient AND it would cost more than a new gear (which is not avaiable at any price.) It takes special tooling and there is a reason why companies specialize in making gears only.
The same can probably be said for the drive shaft. BUT: While the drivew shaft did have splines, the pinion is also on a locking taper. Tighten the nut adequately (I'm guessing around 50 FOOT pounds) and the gear should stay on the shaft.
The drive dogs do not need to be welded and squared, there is enough meat on them that you can simply grind back to square. However, if the forward gear is as bad as you say, you really need to replace all three gears and probably some of the bearings.

These engines were VERY torquey. They developed gobs of power at low speed and the lower unit gears were too small for the output. IF you did a hole shot with a low pitch prop on a light boat, the engine would rev-up into max torque range and overload the gear teet. It would sometimes strip out the forward gear. Accelerate slowly and everything would be OK.

You would be best to simply buy a complete, used lower unit. If it is indeed a one piece lower, they can be difficult to find. However, believe it or not, I have a couple in my garage.

I am a bit curious: What did you pay for the engine? And, is it worth it to you or how much do you want to put into repairs.

 

[fucawi]

Re: Lower Unit issues '77 65 hp chrysler

Frank are you saying the early and late lower units are interchangable as a whole unit or not ? Gearbox and pump ..?

 

[Frank Acampora]

Re: Lower Unit issues '77 65 hp chrysler

No! Nothing is swappable. They are completely different in design. exterior, earlier lower units were similar to the 35,45,55 engines However, i have not had the pleasure of opening one. Later model one piece lowers were mini-me's of the one piece 75-150 lowers.

Since he seemed to be describing the one piece lower unit, I directed my comments to that particular model.

 

[LostCoastDreamin]

Re: Lower Unit issues '77 65 hp chrysler

Thanks for the quick reply. Frank, I PM'd you about buying parts (or I guess a complete LU) but just gonna post it here so respond to one or the other.
http://forums.iboats.com/showthread.php?t=517735 Is the first thread I started and has pics for identification purposes. I have been able to locate some forward gears online, both part numbers are the same part, F2A522023 is Chrysler and 819292A2 is Force. They are all in the $200 ballpark and available, which is not outside my price range to fix this outboard. Once I fix it I will baby the gears, to make sure they last.

I paid just $850 for a 1971 Starcraft trihull in fair-to-good condition (no leaks, solid hull), a trailer, two batteries (one new @$200), this outboard, a fish finder and 4-speaker stereo, new seats, deck, etc. I can sink a couple (maybe three) hundred into it and not feel too bad. I can afford more but not wanting to. I feel like once it gets fixed it will get me across the water reliably for years afterward. I've already spent more than that on boat accessories like VHF, GPS, etc.

Not sure what you'd sell a complete lower unit for, but I sure am interested in finding out how much it would be. Do you know the condition of the gears inside your spare lower units? I just want to make sure they are in good enough condition.

As for tightening the nut on the pinion gear, yeah I could do that, but that is what left me stranded on the water last time and I don't want to repeat that if I don't have to. A used lower unit with a non-stripped drive shaft would be awesome, one less worry/concern on the water. If not that I still plan to weld enough steel to grind new splines on it. Crude or not the extra friction will help the parts to not disengage again and leave me stranded.

As for the drive dogs, the simpler the fix the better, only about 1/16th inch of metal to remove from each dog, twelve rounded corners to sharpen. Straightforward enough for me.

Looking forward to hearing more from you Frank. Thanks again.

 

[LostCoastDreamin]

Re: Lower Unit issues '77 65 hp chrysler

Just quitting the laziness and posting pics here.

 

[fucawi]

Re: Lower Unit issues '77 65 hp chrysler

photos attached like that never show ..you need to go to ... advanced ..attachments ( paper clip symbol) and follow the instructions ..no hosting required ....

 

[LostCoastDreamin]

Re: Lower Unit issues '77 65 hp chrysler

Just an update, Frank I'm sure you saw this coming if you already read my post. All sorts of marine parts dealers list the forward gear, but not many of them actually carry it. There are one or two that actually have it tho. Forget what I said about how much I'd spend on fixing this lower unit, I just want to get back out on the water and I'm ready to spend what it takes, so if you could let me know what one of your lower units would cost me, I'm bracing myself. I just went down to the local boat launch and it made me sad to see bunches of people getting out there when I can't. If I don't hear from you in the next few days I'm gonna order a replacement gear and make the best of the drive shaft. Thanks once more for advice and all.

 

[Frank Acampora]

Re: Lower Unit issues '77 65 hp chrysler

Reply to me in the email address I gave in the private message. I will send photos of a lower unit that is installed on a RUNNING engine. As a matter of fact, I ran this engine and lower unit on a 16 foot bass boat and while the engine ran perfectly, it was just too little for the boat weight. 16 footer, 3 batteries, 3 trolling motors live well, 2 swivel pedestal seats fore and aft, 2 bilge pumps, fishing gear, ropes and anchor. Really a lot of weight. The customer was unhappy with the performance and really, I couldn't blame him, so was I. 60 just wasn't going to cut it, so I replaced it with a 90--that kept him happy.