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J/28 Rudder Bearing Update
We've completed the overhaul of the rudder bearing on my J/28. This project certainly was a trial and error process, especially when it came to machining the new bushing.
As I explained in an earleir post, we found in the course of the removal that the bearing is in reality, a bushing, made of plastic/Delrin. The bushing is press fit into the hull and secured with set screws via the rudder tube. It did not appear to have any type of adhesive/sealant (5200, etc).
There is a 5" dia stainless collar affixed to the rudder shaft, which turns inside the bushing. My collar was slightly out of round. The yard deemed it serviceable and did not replace or machine the collar.
The new bushing material is a plastic called Vesconite. It shipped from Tennessee, so there is a US distributor. The bushing stock was machined to final demensions through a yard sub-contractor.
The first time the bushing was installed, the rudder would not easily go back into the hull. After 5 trips to the machine shop, each time taking off a couple more .002"....the rudder was aligned enough to be re-installed. It's important to point out that the rudder, old bushing and new bushing material were sent to the machine shop for the initial machine of the Vesconite bushing, but I don't know how or if measurements were made (this is my fault, I should have been more inquisitive...but I was trying to not piss off the yard folk).
J/boats uses a flax sealing system, that functions similarly to an over sized stuffing box. The yard used two layers of 1/2" packing to seal. I beleive the original was 3/8", but apparently the yard wasn't comfortable with the initial seal using 3/8".
The boat was launched Friday, and I have about 600 yards on the new bushing....moved from the yard to my slip. Overall, I think we chose the right materials, but the jury is still out on whether the stainless collar should have been replaced.
Of note, I am not happy with how much effort is required to turn the wheel. I don't have to manhandle it, but it doesn't spin as freely as before. The wheel pilot will turn the wheel (no load, done in the slip)...but to my ear, it is straining. Bottom line: it's 'pretty stiff'.
There are a couple possible issues: 1. The top sealing ring is torqued down too tightly on the (maybe) oversized flax packing, which is turn is creating too much friction against the stainless collar. 2. The tolerences between the Vesconite bushing and stainless collar are too narrow. 3. There is an alignment issue of the collar top to bottom within the bushing, creating friction.
I will report again after a proper sea trial under sail and power. The trip to the slip under power was short and I now know I have to get the engine aligned. While the rudder was out, I had the shaft and prop trued, then added a new split half coupling and a flex coupling (both by R&D marine / PYI) and a PSS shaft seal. I kinda knew it was going to need an alignment, but I was hoping it wasn't going to be as bad as it was.
Last edited by jason3317; 05-18-2009 at 04:04 PM.