One of the wheels on my ST4000 decided to take a holiday. The silly things are held in place with a screw into a plastic post. I have seen several with the top wheel ( the one that broke) repaired by replacing the post with a bolt. However this repair kit seems to resolve the design issues. I suspect the top post carries more load relative to the other wheels as the broken wheels I have seen are all top ones.
FWIW, I replaced the wheels on my ST4000 yesterday. The ring would vibrate so loud when it was disengaged that it was really embarrassing, although it worked just fine.
I was skeptical that replacing the wheels would fix the problem, but reached out to i3DGear to find out if they would. They emailed me right back and said that 90% of the vibration issues would be fixed by replacing the wheels. For $89, they better! Raymarine no longer makes replacements for the ‘black’ ST4000, so no real competitive choice.
I was delighted when I took her out for a spin that the vibration was completely gone, at any revs. It’s nice to just hear the engine humming along. Thanks for the lead on the resource!
Here’s his explanation:
When the rollers wear down, that is exactly what happens. The rollers are what keep the 2 halves of the wheel together - the interference over the sloped edge of the wheel. 9 times out 10, this is the problem. New rollers. They’re our second most popular product.
It’s the internal diameter of the rollers that wears out, so they’re loose on the posts. The internal diameter is subject to more friction that the outer edges. Even 1/64th inch wear doubles from the roller on each side and you’ve got 1/32 inch slop in the fit.
Order new rollers here:
https://www.i3dgear.com/online-store/Roller-Wheel-Autohelm-4000-ST4000-Wheel-Pilot-Set-of-7-A18058-p92001167
Bob Gehrman
NS30U #396 “Quickbeam”
Baltimore, Maryland
I have that annoying rattle as well. Unfortunately mine is the grey version so these parts won’t be of any use. A quick Internet check isn’t turning up any parts for mine but knowing the source of the problem is half the battle I guess. A small wear issue might be repairable. I’m thinking maybe a “bushing” of scotch tape or packing tape …
I do love a challenge.
Thanks for the information.
Paul M
NS30U, Sandpiper
Cowichan Bay,B.C.
Paul,
Check with Raymarine. I think they still supply the parts for yours. Mine are out of production.
Good luck!
I’ll look harder. 
From Raymarine support:
Are your ST4000 drive unit the new light gray version ? For this drive unit there are spares available. Can be the gear that are
tired, or the belt inside. For the old black drive unit that was obsolete in 2003/4 there are no spares available
Best to contact an local dealer for more information regarding spares and repair of the unit.
Link to find an local dealer on our web page https://www.raymarine.eu/buy/find-a-dealer.html
I have the newer one and it does need a belt replacement. The bearings are totally different though so I’m not sure if replacing them would stop the rattle. Maybe when I replace the belt it will stop. It works now but slips sometimes even when adjusted properly.