Sign in to follow this  
VeloceSailing

Rudder bushing question

Recommended Posts

Hi,

I have taken down the rudder from my Sun Fast 32i and its delrin top and bottom bushings because the rudder had quite some friction. 

The delrin bushings are in good condition, but they rotate difficulty on the shaft, even after polishing. The problem I see is that the bushing has a track with an o-ring that create a lot of friction. I cannot really understand the meaning of the o-ring as water should freely move through the bushing. Some googling shows also that most rudder bushings do not have any o-ring except Jeanneau.

 

Can you see any problem with simply removing the o-ring?

 

The picture shows the rubber o-ring inside the low friction bearing (rubber and low friction in the same sentence?). The same applies for the top bearing.

 

Could it be that Jeanneau uses this system to reduce dirt in the bearing and lengthen its life?

2.jpg

Share this post


Link to post
Share on other sites

Delrin plastic absorbs water ands swells.  I don't think the o-ring is the source of ALL the friction, I think the bearings are a bit to tight on the rudder shaft. Go ahead & remove the o ring then test for friction again.

Share this post


Link to post
Share on other sites

I tried it without the o-ring and the bushing rotates very smoothly around the rudder shaft. Unfortunately I do not have the possibility to try the rudder on the boat at the moment.

I am only wandering why there is an o-ring and if it actually does anything good to the overall system

Share this post


Link to post
Share on other sites

The o ring is likely to stop water from pumping up the stock and spraying about the cockpit.

The delrin is a lousy choice of materials and swelling is the most likely culprit unless the rudder stock is bent.

Share this post


Link to post
Share on other sites

UHMW-PE water absorption is a bit better than Delrin (almost zero for UHMW versus 1% for Delrin) BUT...

- it's compressive strength is a LOT lower (~5x lower).  So don't be replacing Delrin with UHMW without thinking about it carefully.

- it doesn't take much swelling for a bearing to get tight. For example for a 2" shaft you're looking at 0.001-0.003" tolerance on the clearance for a nice rotating fit.

I'd be inclined to hone the Delrin bearing very very slightly.

Share this post


Link to post
Share on other sites

Could be temperature.  I replaced my delrine  bushings last year in the spring and had a hell of a time getting them on one morning.  But by early afternoon after sitting in the sun I found the slipped right on.  I did this over the course of a few days when I had the rudder out and was prepping the rudder to go back in.  Later that evening when things cooled off and the bushings were in the shade tried they were hard to slip on so I took a hairdryer to them and wouldn’t  you know, they slipped right on.  
 

I noticed that  in cooler weather, 50 degrees and colder that the bushings get stiff.  Warm days over the summer and they are fine.  To honed them out I got a cylinder honing tool at Harbor Freight. 

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this