Cutless bearing - acceptable play

[surekandoo]

What's the maximum acceptable play (if any) beteween prop shaft & cutless bearing?

Have searched threads and not found this info.

FYI Boat is a Feeling 720 with Vire 12hp & Gori folding prop.

Thanks

 

[30boat]

Idealy none or only barely perceptible.Basically what you can live with.The more play there is the faster it'll wear out.

 

[PeterGibbs]

What's the maximum acceptable play (if any) beteween prop shaft & cutless bearing?

Have searched threads and not found this info.

FYI Boat is a Feeling 720 with Vire 12hp & Gori folding prop.

Thanks

There is always slight "give" when pressing the shaft left and right in the cutless bearing, even when newly installed. This is required to ensure good water circulation for lubrication.

When give descends to distinct movement, the life of the bearing is almost shot. Nothing desperate will happen by pressing on a bit when the bearing is worn this much, but vibration will be apparent and accelerated cutless wear will set in.

This is a pretty reliable system with built-in scope for abuse, even neglect, but excessive movement and vibration will transfer back up the power train with consequences.

PWG

 

[doug748]

I measured mine this year before fitting a new one, so:

Old 0.5mm
New 0.2mm

This was total vertical play (ditto horizontal) measured at the shaft where it exits from the deadwood. 1" shaft & 1 1/4" cutless.

When I removed the old tube the brass carrier was starting to break up at the inboard end, although the rubber was in fairly good shape.

 

[PCUK]

5mm is about the maximum before replacement.

Doug, how can you measure fractions of a mm with such accuracy?

My Cutless bearings go in new with more than 0.5mm play and last for ten years.

 

[doug748]

...

Doug, how can you measure fractions of a mm with such accuracy?

My Cutless bearings go in new with more than 0.5mm play and last for ten years.

I clamped a DTI (dial gauge) to the skeg. This question has come up in the past and It struck me I sould measure it for my own future reference.

I guess the actual figures vary according to each installation. You will notice that my wall thickness is only 1/8" including rubber and brass tube, so I need to keep an eye on it. The original builder fitted a tufnol bearing.

 

[PCUK]

I always use composite housings as there is no fear of them corroding into place.

 

[Neil_Y]

Shaft bearings are made with a new clearance (running + thermal + moisture) and an advised replacament clearance. These will be different for different shaft sizes/bearing wall thickness.
We have a calculator here that you put in your shaft and carrier and then get all the clearances.
http://www.h4marine.com/Downloads/Maritex AQUARIUS General Calculator REV 20100519.xls
38.10 shaft 50.00 carrier
New clearance 38.23 - 38.33
Replace when it approaches 39.00

 

[surekandoo]

Thanks everyone.

There is about 0.5mm play as a guesstimate. Noticed some vibration under certain conditions (engine revs, boat speed etc.) but not serious at the end of last season.

Too late to replace now - boat goes in next week. Job for next spring then.