C-Drive Input Shaft Bearing end-play Adjustment


Tony Elliott
 

Hi all again,

I have a another question related to the C-drive and since it is of a different topic, I have started a new thread for future search simplicity.

I am re-working the engine/coupler/c-drive/engine mount structure on my SM after significant vibration was noted during our last passage. I have new engine mounts, C-drive mounts and will also replace the fairly badly torn up Vetus coupler as soon as I can get a response from Amel.

During disassembly, I have noted a larger play in the input shaft of the C-drive than would be acceptable longer term.

The C-Drive is a simple structure with opposing tapered roller bearings on each shaft as you would find on a truck wheel and as with truck wheels, the lock ring on the outside of the C-Drive next to the coupler is likely the adjustment point for the clearance or preload for the bearings.

My intent is to remove the C-Drive input shaft assembly complete and inspect the bearings for wear and if necessary will replace the cones and cups accordingly (the bearings are SKF 33211 and 32011X on the input shaft, 33210's on the vertical transmission shaft) assuming there is no damage to the shaft itself. If there is damage to the shaft, then I will need to weigh the possibility of a new shaft being machined as well. Obviously the lip seal will also be replaced also.

In general, most manufacturers recommend a clearance fit for these types of bearings of 0.001 to 0.005" although there are applications with a preload (which generally shortens bearing life substantially).

So to my question: Does anyone have the specifications from Amel as to how the bearings for both the input shaft and the vertical transmission shaft that goes down to the prop shaft are adjusted/set up? Are they assembled with a clearance fit or are they assembled with preload and in whichever case, what those values are (inches in clearance, foot/lb in preload)?

Thanks in advance,
Tony
SM#443-Grand Cru


Tony Elliott
 
Edited

Hi all,

So, after a little hiatus on SM work, I have successfully removed the C-Drive input shaft assembly.. A very easy thing to do.

There are mylar shims between the casing of the assembly and the main c-drive casing totaling about 0.032". There is also about an additional 0.04" end float on the shaft which seems a little excessive. Has anyone got any experience on what this end float should be for the C-Drive input shaft assembly on its own and for the end float after it is assembled to the C-drive main case? If not, is there anyone who can point me to a contact in Amel that can answer these questions?

Thanks in advance,
Tony
SM#443-Grand Cru