B46 2005 Upper Rudder Bearing

[SYJetzt]

My upper rudder bearing has loose in the four mounting screws. See attached foto.
The four screws (M8) are stuck, and i cant tighten or untighten them.
The loose rudder bearing causes a bang, if the rudder get pressure after tacking when going upwind.

I consider untightening with an impact wrench, and replace screws with hex socket head screws.

Any suggestions?!?

[Yngmar]

Yes, stop. Those four aren't screwed into the GRP, they're bolted through, with a nyloc nut on the inside of the boat. You need to gain access to those nuts and then you can tighten them up properly (needs two people, one inside one outside).

Also, I have no idea why you have elongated holes on that fitting or why there are two extra screws in addition to the four bolts, seems odd, but if you tighten the bolts up it should be okay.

[SYJetzt]

sorry, forgot to attach the photo from inside hull. Seems to be a solid aluminium ring.
i think, the elongated holes are for adjusting the  correct vertical positioning of the rudder shaft.

[Yngmar]

I see. Looks like you had a leak there and significant corrosion - there's pitting on the aluminium ring even outside. Once you get the bolts out (using release spray or ATF+Acetone and probably some force - impact driver will help), you should drop the rudder sufficiently to rebed the upper bearing housing and stop the water leak. Inspect the housing and clean up any pitting - you can fill and fair it with epoxy. The threads in the housing are probably gone, but you can just add nuts instead.

There is also normally a cover over the outside, I think on the aft cockpit boats it's just a plastic lid though. This should prevent any water even getting there, I think (our CC boat has a longer shaft and different cover, and the housing it stainless, but functionally the same).

[Mirror45184]

The slotted screws are to enable the rudder to be adjusted and the two single bolts are to lock it in place. Same system on the Cruiser 40 2009 build. I have used a tight fitting through bolt to replace the single bolts. These are all hex head machine screws too. photo attached

[SYJetzt]

Thank you all!
So i try to loosen the screws and replace it.
Hope to get the play out of the rudder shaft.

Robert

[dawntreader]

When changing my rudder bearings I couldn't release all the bolts on the rudder shaft clamp as they were corroded in place. However, if you can get two on one side loose it is possible to gently tap the clamp upwards whilst dropping the shaft down - lubricant will help. Once out it was easy to clean and remove the remaining screws on the clamp 

[Ziffius]

My bav39 has exactly the same arrangement and I also experienced the same banging when under load sometimes. I tried for ages to see what was happening - expecting it to be the mounting sliding along those elongated holes. It wasn’t, it was the whole mounting moving slightly under load and tightening the bolts was not the solution. I believe it’s wear in the plywood that’s glassed in that the bearing mount is fitted in.

[SYJetzt]

fixed the problem! 
I couldnt  loosen the existing bolts, so i applied new ones (the hex socket head screws). Drilled the holes through deck and the inner aluminium ring and tightened it with nyloc nuts in the lazarette. There was no need to lift out the boat!
When tighening the whole construction, the old bolts where lifted out about 1mm, so i could turn the existing washers beneath the philips-head screws with my fingers. I think, the whole construction  (GRP with glassed in plywood) has set down in the years.
After the first hard upwind sailing the boring "bang" is gone.   

[kavok]

Re: What is your best improvement on the boat and why?
« Reply #53 on: August 14 2019, 21:58 »
QuoteModifyRemove
Modified rudder top bearing plate.


Due to a banging noise from rudder on my Cruiser 40 2008 twin wheels. The  upper rudder bearing aluminium plate slip sideways due to the elongate holes. The two stop screws are not efficient when movements came from rudder (when load was reversed on the rudder.), I changed these two Parker little screws with through 6 mm bolts and nuts. Also I  add up an down two big aluminum custom washers  8 mm thickness, bolted whith six 6 mm bolts ad nut. All side movements are now impossible. I also changed the two bearings with new Jefa roller bearings and adjusted chains tension not too loose not too tight. Now sensibility and lightness windward are excellent.
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[kavok]

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