Damaged transmission flange

[a64pilot]

Get grade eight bolts if your worried and “torque stripe” them so an easy visual check can ensure nothing has moved. Torque stripe is an “anti sabotage lacquer” made for the job, but any thick paint will do, model airplane paint is fine.

[Warby12]

Thanks a64, great tip, I'll be able to tell without having to lift a spanner. I'll do it. (but I'll still lift the spanner).

Ok, it's on! I couldn't take any picks because my wife disappeared with the makeup mirror I was using.

I am happy. The file was very effective for showing the high spots and knocking them down. It was around the bolt holes. I also hit the area around the bolts with the flapper disk, just to ensure they would give no further grief. I did a lot of turning, measuring and comparing, couple of hours, as I aligned it and I'm satisfied it good. Good enough for me anyway.

The test will be when we launch. We are going to tie up at the jetty here and do some power tests. If it is no good, I will be very surprised (and cranky). But it is worth I try I reckon. I'll try and take a movie.

Thanks again all

[boden36]

I hesitate to suggest this, as it has an element of danger. I would use a new file with a good handle.
Idle the engine in gear and apply the file carefully to the face of the flange. Wear nothing that could get tangled in the workings. Work extremely carefully. It should not take too much to true the thing up.


Regards,
Richard.

[Dymaxion]

Originally Posted by boden36

I hesitate to suggest this, as it has an element of danger. I would use a new file with a good handle.
Idle the engine in gear and apply the file carefully to the face of the flange. Wear nothing that could get tangled in the workings. Work extremely carefully. It should not take too much to true the thing up.


Regards,
Richard.

Make sure if you try this that should the file grab/catch it is pulled out of you hands, not driven into them. If you have sufficient room you could do the same using an angle grinder braced against something to keep it dead steady.

[Warby12]

I wondered if something like that was realistic....... scary though, anyway ours on now, so I'm happy for now.

[Steven UK]

, but The area circled in red is weird but it is a depression, like chipped off

I wouldn’t worry about that depression it could easily have been a void in the casting that was uncovered as it was machined. It’s not a highly stressed part. As long as all your ‘irregularities’ are below the machined surface the mating flanges will be true. Just keep the majority of the machined surface as it left the factory and you’ll be just fine.

All the best...

[Steven UK]

I also like the paint idea we use it all the time when testing. the product mentioned earlier the anti sabotage paint looks good, but we just use a white paint marker on our heavy machines no chance of sabotage in MN...

So note to self:- put paint marker in toolbox along with grinder and Loctite...

[Sailing Drummer]

Re: post #17
I've been told to check and possibly realign about a week AFTER the boat goes back in the water.

[Warby12]

Yep, we're going to run it up and down in the pen and realign it. Makes sense as the engine mounts have to settle.

[jimbunyard]

Originally Posted by Steven UK

, but The area circled in red is weird but it is a depression, like chipped off

I wouldn’t worry about that depression it could easily have been a void in the casting that was uncovered as it was machined. It’s not a highly stressed part. As long as all your ‘irregularities’ are below the machined surface the mating flanges will be true. Just keep the majority of the machined surface as it left the factory and you’ll be just fine.

All the best...

Just to be clear, the point wasn't that the circled area was a depression or a high spot; it looks like an impact to me and thus a low spot or depression.

The point was that the impact looked like it distorted the metal around the recess, causing a lack of concentricity and the slight intrusion of metal into the area that the radius or 'spigot' on the companion flange is supposed to fit into.

See the exaggerated drawing below.

Of course, pictures can be deceiving and optical illusions are common, so my suggestion may be meaningless.


As far as 'dishing out' the area around the bolt holes, while this is better than having high ridges or halos around them, if carried too far, when the bolts are torqued they can cause distortion that upsets your careful alignment. Far better to maintain the entire surface of the flange as 'flat'.

[Warby12]

Just wanted to say, it's been a total success. Very low vibration, improved 200%, Have done 500 miles on it and everything is shipshape.

Thanks again for all of your help guys!

[pcmm]

Originally Posted by Warby12

Just wanted to say, it's been a total success. Very low vibration, improved 200%, Have done 500 miles on it and everything is shipshape.

Thanks again for all of your help guys!

what was the fix?

[Warby12]

New hard coupling (fitted and faced), replacing old flexible one. Straightened shaft and some hand file work on the damaged gearbox flange where the bolt holes had been dished out by what must have been in the past by a loose coupling.

All great fun