Transmission removal

[skipperdude]

Max, Perfect that is just how I invisioned it.
Thanks for the picture.

Sd

 

[Bugmon]

SD-- whenever you remove and replace any component of the drivetrain-- engine, transmission, shaft, cutless bearing(s)-- the engine-propshaft alignment must be checked and corrected. We're talking fractions of an inch here. IIRC the yard we use and our diesel shop use an allowable misalignment of one ten thousandth of an inch. Anything more than that and they say it must be corrected out by adjusting the motor mounts to bring the alignment back to no more than one ten thousandth of an inch.

The alignment is checked by separating the two halves of the shaft coupler and measuring the gap around the circumference of the coupler with a feeler gauge. The engine mounts are then adjusted to tilt or yaw the engine relative to the shaft until the gap is the same measurement all the way around.

As was said previously, while it is a mechanically simple process, adjusting the engine mouts for proper alignment is something of an art form.

The penalties for running with an out-of-alignment drive train are shaft vibration at best and shaft bending and premature wear on things like cutless bearings at worst.

"and shaft bending and premature wear on things like cutless bearings at worst"

You will Not bend your shaft from an out-of-alignment shaft. Statements like this are why you should take comments from 'backyard mechanics' with a grain of salt ( and shot of rum).

 

[Marin]

Our boat bent its shaft and wore out its cutless bearings fom a bad alignment from the previous owner. Cure was a new shaft and a proper alignment job.

Situation was analyzed and repaired by one of the best yards in the area, not "backyard mechanics.". Since this work was done several years ago there have been no problems since.

Not a good idea to second guess the pros. They will generally prove you wrong, which you are in this case.

 

[psneeld]

"and shaft bending and premature wear on things like cutless bearings at worst"

You will Not bend your shaft from an out-of-alignment shaft. Statements like this are why you should take comments from 'backyard mechanics' with a grain of salt ( and shot of rum).

Not sure where you heard that you can't bend a shaft from misalignment....BUT...this seems to be the consensus...

Here's a short list of the problems that can be caused by engine/shaft alignment faults:

• Rapid cutlass bearing wear.
• Misaligned strut galls shaft, requiring shaft replacement.
• Causes stuffing boxes to wear out and leak, not infrequently sinking the boat.
• Bent or broken shafts

While I agree a bent/broken shaft seems unlikely...it may be possible based on the number of documented writings of "experts" that say it is so.

While I agree that the amount of misalignment would have to be extreme or the vessel have an unusual shaft alignment to begin with...and you may have to be a rock to miss the symptoms before damage occurs....I can't say that it is out of the question..

 

[Max Simmons]

I spent a good portion of a day trying to align the motor myself. On paper, it seems straight forward. Finally gave up and hired a pro and $300 later it was aligned. I do question the tolerances though. Can it really get to 1/1000 of an inch? With rubber engine mounts and any small amount of flexing in the shaft, or the engine torque throughout the RPM range seems that it would be unrealistic.

 

[skipperdude]

I am hard mounted to the stringers, no rubber motor mounts at all. From what I can see the only adjustments I can make are port and starboard. There may be adjustments for up and down but I am hoping that I can remove the tranny without removing or tampering with the adjustments at all.
If I look at replacing the rear seal I will have to unbolt the mounts.
I think I have to remove the fly wheel to get to the rear seal. I am not sure the tranny housing will have to come off or not as the tranny housing is where the mounts are located.
I will have to stand on my head and try to learn how to drink a beer in that position untill I can get this all figured out.

Sd

 

[Marin]

[*]Bent or broken shafts

As it was explained to us, a potential for bending a shaft can arise if the boat with an out-of-alignment shaft sits for quite awhile without being run. Months was the measurement I recall they used. The uneven loading on the shaft from the misalignment can, over time, put a "set" in the shaft. While it won't be an obvious visible bend this "set" will nevertheless be there and can not only contribute to making it difficult to align properly but will contribute to vibration and the potential damage it can cause to struts, bearings, etc. until the shaft is either straightened or replaced.

 

[psneeld]

As it was explained to us, a potential for bending a shaft can arise if the boat with an out-of-alignment shaft sits for quite awhile without being run. Months was the measurement I recall they used. The uneven loading on the shaft from the misalignment can, over time, put a "set" in the shaft. While it won't be an obvious visible bend this "set" will nevertheless be there and can not only contribute to making it difficult to align properly but will contribute to vibration and the potential damage it can cause to struts, bearings, etc. until the shaft is either straightened or replaced.

I agree...I wasn't ruling out the possibility...as you have posted...ANTHING that can happen...just might.

Given the right parameters I can see a shaft taking a set....although I think in many cases the size and length of the shaft are such the engine would have to be so out of line it would be terrible to run by anyone but the complete newbie...on some boats the shafts are so long how they don't bend is beyond me.

 

[psneeld]

I spent a good portion of a day trying to align the motor myself. On paper, it seems straight forward. Finally gave up and hired a pro and $300 later it was aligned. I do question the tolerances though. Can it really get to 1/1000 of an inch? With rubber engine mounts and any small amount of flexing in the shaft, or the engine torque throughout the RPM range seems that it would be unrealistic.

That's almost the joke about shaft alignment...there are other issues with some boats when they are running, alignment changes from the at rest situation.

 

[jleonard]

That's almost the joke about shaft alignment...there are other issues with some boats when they are running, alignment changes from the at rest situation.

Yes the dynamics do change things. However, you might as well start off statically as close in alignment as you can get.
I was able to get my Mainship to about .0015" near as I could tell.

 

[skipperdude]

One thing leads to another. this started as a starter issue.
Thanks Chrisis: and Swampu: for giving me more work. As stated. As long as the tranny is off may as well do the rear seal.

Not a big job if you have the right tool. I don't, and can't seem to find one to rent.
The Cat dealer will do it for about $800.00 on a special trip.
$200.00 if they have to go to the harbor anyway.
The tool is around $350.00.
Still looking for the tool. I can't see buying a use one time tool.
So she may set for a week or so.
Ticks me off the Salmon and Halibut are running.

I plan on taking lots of pics as I do this repair.
Watch for it.

SD

 

[skipperdude]

This is what I could see looking into the port for the starter.
The first is what it is supposed to look like.
The second is what I could see after using a screw driver and rotating the fly wheel.

The Aluminum was breaking off in chunks and getting into the starter.

Third is a little better shot to the left you can see where a crack is develkoping. Top center is where it has broken off.

 

[Capn Chuck]

Just a follow up. The mechanic just left and it took him about an hour to block the engine, unbolt the coupler, drain the water and fluids and get the transmission out of the boat. No problems at all with the dripless, it slid back to remove the transmission and slid forward again to sit where it was until the tranny goes back in. Never leaked a drop. I don't have the equipment or the desire to do this project which is why the mechanic is doing it. We are also replacing the damper plate and engine mounts while all of this is being done. I have done all of this myself in the past but the back doesn't like it much anymore. Now it needs to be checked over, new seals and reinstalled. Chuck

 

[skipperdude]

I have no desire to do this job either, but finding as mechanic in my area is like finding a fishy smell you know it is there but tracking one down ain't easy.

A question on the rear main seal. How do you tell if it is leaking or not. I think I can see the seal.Not sure. Will I have to remove the Fly wheel housing to inspect it? The fly wheel is off and all I see is rusty dust.
SD

 

[skipperdude]

Has anyone had to replace the rubber blocks on a Twin Disc tranny on a Cat 3208?
I have the model 506

These look Ok but when I took one off and pinched it I could see some small cracks.

SD

 

[RickB]

They should be replaced whenever the gear is pulled. They just slip off the "tooth" and new ones slip back on.

 

[skipperdude]

Thanks Rick,
Someone suggested the same about the rear seal.
Luck would have it it is not leaking.
Really hard to find the tool to replace it.
The only one I could find was in Fairbanks. The local Cat dealer had the other one and wouldn't let it out of there sight.

Ahh, boating or working on boats in Alaska.
Do it yourself because there is no one you can hire to get it done.

Sd

 

[RickB]

Ah, so ... may as well wait until the seal starts leaking then.

Why not buy the tool and then rent it out if they are so scarce up your way? That might be cheaper than having to repeat the entire process in a year or two.

 

[skipperdude]

Well unless I want to have the boat out of service for the rest of our short summer.
I'm gonna have to.

I'm 3 weeks out for Cat to come to the boat and a good 4 weeks for the tool to get back from Fairbanks.

It is not leaking now.

I have now the knowledge and equipment to pull the tranny and replace it at a future date.

So that's it. I will wait till it starts leaking.

Sd

 

[swampu]

dude my trannys been in the shop since your thread started. I almost don't want it back because I will no doubt be broke when the bill is due,,,,, but hurricane season is here and I've got to get this thing going. No offence but the inside of that thing looks not so shiny. What gives, water leak, underwater? Mine burned up and it was shiny new looking, just broken. Good luck. Paul

 

[skipperdude]

Under water.
She sank in 92 down to her lines at the dock.
The motor was pickled and the top end rebuilt.
That is why I have been having this problem.
sometimes it is remarkable the darn thing still runs at all.

SD

 

[ancora]

Does Twin Disc still supply customer support, i.e., parts, for that transmission? I have 26 year old Volvo transmissions and am SOL for parts.

 

[skipperdude]

Google Twin disc.
In alaska the closest dealer is Mill Log Marine in Seattle.
1-425-251-3434.

SD

 

[skipperdude]

Well, I rigged a sawhorse and used a come-along to lower the tranny back into the ER.
A little trouble getting things to line up but the suggestion from Rick B and Marin to use guide bolts worked like a charm.

I use longer bolts to get the bottom of the transmission to suck in as I had to draw the new rubber blocks into there slots on the drive ring.

Once the tranny was in the rest was just bolting everything back up.

Turned the key and no more starter problems. It also seems to have gotten rid of my vibration problem.

All in all a sucessful reinstall.
I forgot my camera so no pics.

Thanks for all the advice.

Sd

 

[Cold Shot]

Well, I rigged a sawhorse and used a come-along to lower the tranny back into the ER.
A little trouble getting things to line up but the suggestion from Rick B and Marin to use guide bolts worked like a charm.

I use longer bolts to get the bottom of the transmission to suck in as I had to draw the new rubber blocks into there slots on the drive ring.

Once the tranny was in the rest was just bolting everything back up.

Turned the key and no more starter problems. It also seems to have gotten rid of my vibration problem.

All in all a sucessful reinstall.
I forgot my camera so no pics.

Thanks for all the advice.

Sd

What was the special tool you needed? I’m about to tackle this job.

 

[C lectric]

Cold Shot,
It has been almost 9 years since Skipperdude posted this. He has been inactive for many years now.

If you Email him through this site and his Email address is still active he may answer.

Click on his name "skipperdude" and a drop down box will appear. One of the boxes will be send a message or similar. Fill in the message and also copy the thread link from above so he knows what you refer to.

At least just contact him hopefully.

Then you can either go through the site or exchange Email addresses.

 

[Cold Shot]

Will do Thanks