Cutless bearing size

[Sean]

Is there a cutless bearing model that would allow me to move up to a 1-1/4″ prop shaft from a 1-1/8″ shaft?

My strut bore ID/ cutless bearing OD is 1-5/8″. Strut bore is just over 5″ long. Bronze

I am using a “BELT” size brass sleeve bearing (1-1/4 shaft, 1-5/8 OD) and running 1/2″ gap between rear of cutless bearing and front of prop hub.

I see there is a “BIND” slimline bearing with 1-1/2″ OD and a “BIRD” with 1-3/4″ OD; both with 1-1/4″ shafting. No stock 1-5/8″ OD bearing listed by Duramax/ Johnson.

If not commercially available could the BIRD (1-3/4″ OD) bearing be machined down to 1-5/8″ OD?

Could the strut bore be machined 1/8″ larger to accept the 1-3/4″ OD bearing…minimum strut bore wall thickness? Strut is bronze.

Boat Specs: 25 Farallon, Gas GM 5.7L V8-260hp, velvet drive transmission 1.52, prop shaft length 62-5/16″, prop 16×13-3B bronze

Trying to get by until I can afford a real powertrain from you guys.

Topic

[Tony Athens]

In an ideal world, all properly fitted prop shaft couplings should have a degree of interreference fit and are machined true to the shaft turning on its own center,  and the shaft is straight  itself   to .001″ per ft of length or better .  

Moving on, you needed to find a qualified machinist to help you from  here if you are gong to make changes to what you have currently.. 

1 user thanked author for this post.

Sean

[Sean]

split hub clamp fitment

For the split hub to prop shaft; is this supposed to be an interference fit?

I can slide my hub over my prop shaft by hand with slight wiggle room.

I have seen Frank on the youtube videos using little wedges to split the hub gap open so he can manipulate the shaft as needed.

Is this something I should worry about or like you said I have high RPM engine and small prop so not a significant risk of shaft slipping in the hub? Maybe like I read in another post a dolop of rector seal will help it tack and clamp in the hub bore.

[Tony Athens]

This all depends on your BUDGET– If I was to go with a new shaft,  then go bigger but that will cost  few 1000 by the time the dust settles  do all that would be involved to do it right.   

IMO, maybe just stay with what you have as it was working OK, right?  You have small props and high rpm gas engines.. You need a custom stepped washer behind the prop. 

NEVER BORE a split hub clamp-fit coupling unless there is no other choice.

[Sean]

Shaft any good?

Thank Tony.

So how would you proceed?

Would you run on this shaft in this condition or just move up to 1.25″ gear?

I have used boat a few times, but am I running the edge of safety factor on this shaft?

Attached are pics and measurements of current 1.125″ shaft, transmission coupler, stuffing box clearance, etc.

Mahalo, Sean

Also, after lapping the prop to the shaft and making sure the key rode free seated hub with rector seal/ WD40 then set the big nut on with epoxy per your article…awesome lock nut! Came off “easy” like a tight lock nut. 

 

[Tony Athens]

We custom sleeve up quite often in a case like yours..

Plus, we also have a expandable reamer tool that we use to bore struts in place ( up to about 1/8″ total)

[Author]

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