Chrysler 65hp clutch dog problem

[las]

Hi folks, took the old Selco and Chrysler 65hp out sailing for the first time in 5 years after getting interested in boating again.
I had just received a NOS SS propeller, a 10x14 cupped Michigan wheels and mounted it up and went for a test.
Out of the harbour and accelerating the whole engine jolted and it seemed like a severe backfire. I thought it might needed to run and heat up a little but then i continued and i headed back.
The last few hundred meters it actually got worse even though I hardly gave it any throttle, to the point were it wouldn't move forward. And it was at that point I knew it wasn't a misfire, but a gear issue.
I continued to adjust the gear linkage and play in the system for the rest of the day, but I already knew what had happened and the damage had already been done.
Today I decided to open the gearcase up and see what it looked like, and if it was possible to fix or even to dismantle it without destroying the engine.
I think there's a rather fine line with these engines when to call it quits. And after the last outing I knew I wouldn't trust it not to skip gears on the water unless i opened it up and fixed it or killed it trying.
But at the end of the day I managed to dismantle it without to much damage, or so it seems!
I can tell you right away that it's not a job for the average DIY'er.
At this point there's still hope for the engine.... But the next few days will show i guess!
Tomorrow I will get some pictures uploaded and share some thoughts and maybe get a few pieces of advice.
Well actually I already have some thoughts regarding the lower leg. Before going sailing I gave the gear some fresh gear oil and after disassembling it I saw there was some bronze bushings in there and I know newer gear oil will damage them! I can't remember right now how it is, but it's worth having in mind when it's time to put it back together.

 

[jerryjerry05]

That old it's might be hard to find the dog.
Try Franz Marine?? They seem to be able to find something that old???
That said, Dremmel and cut down the edges or a machine shop.
In some cases the dog can be flipped around and used if not in too bad of shape???

 

[las]

It is hard to find anything for this old engine, but for some reason I have fallen in love with it over it's design, and it also have a history to tell.
I already ordered some new seals, o-rings and what else in stock at the dealer, including the famous spacer and looong cone. The cone was not cheap! But neither is shipping and import tax to Denmark, so might as well order a bit extra.
I've heard Franz mentioned before and will inquire with him if I need any more.
I took some pictures, maybe it's hard to see on these, and it appears that the forward gear have less damage than the dog. Gears must be a bit harder thank god.
It also seems like the dog should be able to be reversed and that would most likely solve the problem. See what you all think and give me your thoughts!
If I decide to clean up the edges, it would be the dremmel method and some engineers blue to check. But it's a tough job I think, to achieve the desired accuracy with a dremmel!
But then again I would like the forward gears to be back cut or what it's called, so that they pull towards each other. You see, there is no spring assist in this dog clutch assembly. The shift yoke is what's holding it in forward gear. I thinks that a bit of a design fault.

The disassembly was a real pain and I DO NOT recommend you do it yourself if you don't know what your doing, and even then?
First I had to make a puller for the outer bearing carrier and it had some corrosion and took quite an effort to free.
Next was the inner gear carrier which was held in place with two halfmoon retaining rings/half-rings. After tapping the carrier and the rings they eventually moved and i then used the prop shaft assembly as a glide hammer to get the shaft, reverse gear and dog out.
Then on to the pinion gear. And I can tell you that gear is almost impossible to get at, besides that, the nut and the conical splines / pinion gear was green Loctite glued to the driveshaft.
The lower leg is so small on these one piece legs that it's almost impossible to work inside them and the gearcase is not that thick that you just go at it with full force. Round the pinion nut and your done for!
The nut is recessed inside the pinion, and that is recessed inside the gearcase leg. A normal 1/2" socket and ratchet will not fit! It's that tight and close to the forward gear.
I tried to heat it with a small torch but there was no oxygen inside the gearcase and the flame went out. I then heated it with a heat gun as best I could and eventually got the nut off (I did order a new one).
Then I hammered the lower leg with the driveshaft in a wise as per the Seloc manual, but it took some serious effort to free a conical splined shaft that was glued together..... OMG.
As you can see in the pictures the driveshaft did take some abuse from the wise, there was simply no way to avoid it with the amount of force required.
I did fixate in in the middle of the shaft so that I can smooth it out later and not damage the oil and waterpump seals when they go on.
The manual then says to put your hand inside and retrieve the forward gear, my hands are not that big but they would not fit inside. Luckily the gear just fell out when turned around.
This is turning out to be quite a novel, but maybe it benefits someone one day, or maybe even myself later on.
What caused the gears to slip besides what I consider a bad design?
Well in 2016 I must have had some problems with the gears apparently! I remember moving the shifter cable a hole down on the shift lever to give it some more throw. The problem with that is that the stiff cable will bind when the shift linkage is moved to far forward because of the angle and therefore restricting the travel.

 

[Nordin]

Las I have made the same journey with my 1977 65Hp in this summer.
The gear started to jump out of gear at almost WOT and WOT and I did not countinued to run it.
I disassembled it and found the edges at the forward gear rounded.
The clutch dog edges was also a bit rounded so I flipped it 180 dgr.
Luckily there was three forward gear (two different seller) for sale at Ebay in the US.
I bought all three for a fair good price. The forward gear is about 150-200 dollars (Franz Marine).
Now I am in order to put everything back, but have to check if I have to shim the pinjong gear and the adjust the prop shaft end play.
I have the tools to check the pinjong gear but have to buy the shim and the thrust washer for the prop shaft.
Luckily we have a workshop with a toolmaker at my work, so he will try to mill the rounded edges at the bad forward gear.
Hopefully it will work as a third spare forward gear.
I have investigated why the gear have started to jump out of gear and I found that the throw of the forward and reverse gear was not equal adjusted and the lower shift shaft rod ahve to be turn out about two turns from seated to give a good throw for the forward gear.
Maybe I will adjust the forward/reverse gear throw with some bias for the forward throw.
BTW I had a spare LU for this engine so it was up and running fairly fast.
Now the bad LU will be for spare when I have checked and maybe adjust the pinjong and prop shaft.

 

[las]

Hi Nordin, did you also notice the bad design regarding the forward gear? The clutch dog is simply just located forward when gear is engaged and there is no continued pressure applied to keep it in gear. Any play in the system along the line will add up and locate the dog at that point, not fully forward or allow it to slide a bit back putting strain on the corners of the dog and gear.
I was thinking about drilling the prop shaft and dog shaft arm for a spring to put a tiny amount of pressure on the forward gear and take the load of the shift yoke. Or maybe undercut the gears and dog in some way.
The thinking goes on.

I was hoping not to have to change the gears and re-shim the leg this time around.

Like I wrote I made the mistake of introducing a bind in the system because of the angle of the gear cable in the lower hole and too much forward throw of the linkage.
When I came back after my last outing I adjusted the shift rod itself and got so much forward bias that it couldn't go in reverse. I still found that the setup did not apply any positive holding power on the shifting yoke and clutch dog and that's why I'm hesitant to just put it back together without a spring or undercut gears.

 

[Nordin]

Las, my experience is that all lager Chrysler and Force engine do not have any spring to hold the clutch dog/shift shaft in place when engage.
It is just the shift cable ,shift shaft, gear pivo pin and yoke that hold it in gear.
I suggest you to mount a small spring at the shift lever to give the shift cable some support to hold the gear in place at forward.
As you say when there are some play (it will occure after years of working) in the cable/linkage the force from the prop will help the clutch dog to jump out of gear.

 

[las]

The only problem with adding a spring anywhere in the linkage system is that the yoke will be engaged with the clutch dog shaft at all times and that can't be good either.
Well I'll keep thinking about what way to go but at the moment I'm leaning towards undercutting the gear and dog.

 

[jerryjerry05]

From the looks of the dog and gear, they both don't look bad????

 

[Nordin]

Jerryjerry, the edges at my forward gear looked about the same and my thought was as you, it do not look so bad!
As I had the LU disassembled I suggested to change the forward gear BUT I found that an adjustment of the lower shift shaft might have fixed it.
I had a spare LU and put it on the engine but still had problem with jumping out of gear. The lower shift rod was screw all in. Did the adjustment of the upper shift shaft under the carbs (similar as the 3 and 4 cylinder Chrysler/Force) by the OEM service manual and it did not fixed the problem.
Then I turn the lower shift shaft out two turns from seated and it fixed the problem.
The OEM service manual do not mention anything about the lower shift rod if it should be screwed all way down or not!
So my thought is in this case, the clutch dog and forward gear may work if you adjust the linkage/cable and shift rod right.
BUT it is not fun if you have to disassemble the LU again if it not work.
The throw of the shift rod is only about 0,08 in (2 millimeter) from neutral (gear start to engage) to fully engage!
Not so much to play with.

 

[las]

Jerryjerry, no they don't look that bad but you really never know before you take it apart. It's hard to tell from the pictures but it appears the dog is worn the most, and that's a good thing in my book.
I don't remember, but maybe from the Seloc manual, they mentioned that the shift rod be screwed all the way in to the shift rod coupler and it makes sense since the real adjustment should me made under the carbs, 35mm from center eye to steering arm base if I remember correct. Also, if you by accident screw it all the way out, you have a problem and it's big one.....
In another thread I found from Frank he mentions taking the lower rubber mount covers of, remove the cotter pin, rotate the square block on the shift rod just like you did.
I'm quite sure this is not the correct way to do the adjustment, but a quick fix to give more forward bias. To do it correct IS under the carbs, you'd have to disassemble quite a lot on the engine though and the other method makes more sense for a quick fix.
After the trip I adjusted shift rod eye to approx. 37-38mm and even though I could no longer go in reverse, I was not satisfied like I mentioned before.

Yes it did work when new but how well really?

 

[Nordin]

Las, I do not know if I misunderstand you but the clutch shift rod will always be engage to the yoke even if you have a spring connected to the shift lever or not.
This have no disadvantages for the function in my opinion.
As I mentioned before all lager Chrysler/Force engines has this typ of shift system.
From my experience with OBs LU no matter of brand, less rounded edges at the gear or clutch dog has big effect of the function.
The lager engine the function will fail if rounded edges.
The force from the prop will help the cluch dog to jump out.

 

[las]

I think that if you were to apply positive pressure from a spring anywhere in the linkage system to the yoke, thus applying a positive force on the forward gear and yoke at all times when forward gear is selected, you would wear it down pretty quick.
The yoke grabs a pretty thin axle with a large head and there's no bearing surface.
Right now the yoke doesn't provide any holding force.
When I adjusted forward bias well beyond specs it was still "just" situated forward and I could still wiggle it when in gear.
The Seloc manual even showed a picture of a badly worn yoke.

A spring inside the prop axle on the other hand would only apply pressure on the yoke in reverse as the prop wouldn't spin in neutral. In forward the spring would assist the dog, keeping a light pressure on it and not the yoke.
The problem with the spring in shaft I think, is that one would have to drill both the prop shaft and the clutch dog shaft to act as a guide for the spring, so it doesn't jump out the side of the prop shaft and destroy everything.
Still a spring wouldn't supply much holding force I think, it would rather just position the dog as far forward as possible without loading the yoke.
But it's a design I've seen used on newer OB's.

I've found that many motorcycles suffer the same problem, especially the old English ones, and it has been the norm to undercut those problem gears.
From what I can see it derived from these engines being upgrades to double the HP but still use the old gearbox.
From what I can see online it's not a cheap thing to get machined and I think 200-400 dollars would be quite a lot to throw at it given all the other things in need of attention.
Right now I'm leaning in the direction of the dremmel and engineers blue method.

I think there has been an evolution and today most motorcycle boxes , if not all, are undercut.
The undercut does provide a self enhancing positive holding force, even to the point where if the undercut is at a large angle and throttle is applied you bent the shift forks trying to get it out of gear.
A solid gearlock would be nice,,,,

 

[Nordin]

Yes, you are right in your theory, good.
You can try to resurface the clutch dog and gear and se what happens.
Would be a good information for me too as I have one gear with rounded edges too.

 

[las]

Yes I think many could benefit if it's a success.
I'll try to remember some pictures along the way.

 

[las]

I'm grinding the dog and gear right now and it's not easy.
I have settled for a contact patch somewhere in the middle of the gear and dog and then I believe it will wear itself a bit more even over time.

Getting an uniform contact patch with a dremel is close to impossible, for me at least. From another forum I've read about a guy with the same problem and he reported that gears actually meshed better after some use. Guess the high's would wear pretty fast compared to the rest, until other dog/gear tooth took more load again.

But I might have discovered an issue with the reverse gear when I tested how much holding power the straight cut gears had vs the undercut ones.
Apparently there is no bronze bushing in my reverse gear! And I can't seem to find a picture of one.
There is a thrust bearing and a roller bearing inside the carrier, but no bushing against the prop shaft.
Is there supposed to be a bushing?

 

[las]

Just took some valve lapping compound and worked the dog and gear a bit.
It's easier to see the contact patch on the dog now. All three are roughly similar.
I smeared some lapping compound on the three dog teeth and then just barely engaging the teeth and twisting so they pulled together. Rotated a lot of times, I think it's acceptable for now.

 

[las]

Does any of you guys know if I miss a bronze bushing in the reverse gear or if it's meant to be like this?

 

[Nordin]

Looks like there is no bronze bushing in the reverse gear.
I did not notice that when I pull my LU apart.
If you have miss it the prop shaft should have wiggle a lot.

 

[las]

There is actually quite a bit of play against the prop shaft and that bothers me. The propshaft does not wiggle because it is guided from the carrier all the way back to forward gear's bushing.
But looking online I can't find a reverse gear for this gearcase with bushing in it, only other models.... Hmmm
Nordin do you have any gears disassembled that you could look at?

 

[Nordin]

I have no reverse gears at the shelf only in my spare gear case.
Maybe I will pull my old spare LU apart this weekend because I have to check the drive shaft/pinion lash (shiming pinion) and the prop shaft end play is to large. If there is no other more importent thing to do.
I did not checked it when I reassembled it when I changed the forward gear!!!!
My mistake, I just put the spare LU in the engine and reassembled the other not measuring the pinion and prop end play, cause I was worried to loose some parts if it was apart in my garage with all other projects.
Have about 0,04 in (1mm) in end play and it should be 0,01 plus/minus 0,001 in (0,25mm).
Have to check the thickness of the thrust washer and order a thicker to reach the right play.
I will check the reverse gear.