Custom Runout Thingamajig

[racclarkson@gmail.com]

Getting ready to bust my port shaft loose from the ZF gear check out some vibration. I'm kinda pleased with this. I made extensions that'll allow measurements to be taken at the coupling, hub and the shaft all the way back to the dripless seal.

I use a C-clamp to secure the legs to the transverse stringer.

This seems to work better than the vice-grip type mounts because it's rigid.

 

[kelpy]

I don't think you will get any useful data with that setup on the OD of the coupler. What I would want to know is if the bore thru the coupler is straight and that the bore centerline is square to the mounting face.

 

[racclarkson@gmail.com]

Well I think I will. I’m looking for a new vibration. Unless the hub nut has come loose, it’s centerline bore is a given.

 

[kelpy]

I don't see how indicating a painted non-precision surface such as the OD of a shaft coupler can provide any useful info but perhaps I don't understand what you are looking for.

 

[racclarkson@gmail.com]

I don't see how indicating a painted non-precision surface such as the OD of a shaft coupler can provide any useful info but perhaps I don't understand what you are looking for.

It ain’t painted no mo. Anyway, the paint wouldn’t matter. I’m looking for significant variation. Noted the output flange of the ZF indicated 0.000 as expected. Also got data on prop shaft. Just looking. When I break the coupling I’ll have another set of numbers before checking alignment. The vibration has developed from somewhere.

 

[kelpy]

Well, best of luck and I hope you find the cause quickly. Driveline vibrations that appear out of nowhere are really tough to track down.

 

[cenger]

I am having the cutlassbearings replaced on my 55c before spring launch. The marina did a runout on the shafts while they were at it. Stbd was .006, and Port was.003. I wanted to check if these were acceptable tolerances.

 

[Captain Ralph]

I think what Kelpy was trying to say, The cast coupler is trued at the flange face and the shaft bore. The OD of the coupler is not in the precision machining of these mating surfaces.

Also, you may not detect the correct run out that close to the clutch. If there is an alignment or whipping of the shaft, it will be better detected away from the clutch and support bearings. Just think D bend, more error away from the ends (top or bottom).

I do like your rig. Beats the 5" of rail iron I used to use.

 

[Captain Ralph]

I am having the cutlassbearings replaced on my 55c before spring launch. The marina did a runout on the shafts while they were at it. Stbd was .006, and Port was.003. I wanted to check if these were acceptable tolerances.

IMO, 0.003 & 0.006 are very good.
Now 0.03 or 0.05 would raise an eyebrow,,
Are you sure of the decimal and zeros to the right of it?

 

[cenger]

Thank you for the fast response, .003 & .006 iscorrect. The yard said they were good, but I wanted a 2nd opinion. Weare chasing down a vibration. I sent the props out, and new cutlassbearings are being installed. Hopefully, that will solve the issue.

 

[cenger]

While the shafts were out for new cutlass bearings, I sent them to be straightened, and the port shaft turned out to have a crack at the keyway. Does anyone have a good source for a new prop shaft? I know I have seen threads on this but came up blank in my search.

 

[Captain Ralph]

Getting 0.003" out could be fun for that tech. The error less than a sheet of typing papers thickness.
But, you found a crack, then whew,,, Good thing you were a perfectionist.

I found the shops that will machine the shafts and couplers, prefers it to be a shaft they sold you.
Kind of like bringing in your own eggs and bacon to a Waffle House.

Ensure they do clean up and resurface the coupler and while they have all the parts, lap on and check the propellers connect.

 

[Captain Ralph]

Well I think I will. I’m looking for a new vibration. Unless the hub nut has come loose, it’s centerline bore is a given.

Well, it's your thread, Lets get back to you.
Any results yet? Find that new vibration?

 

[cenger]

The three things I did to chase the vibrations were; send the props out for balancing (I think this was the problem), check/true the shafts, and replace the cutlass bearings.