Sprocket shaft wear

Just did my annual maintenance on the mirage drive and noticed a lot of wear on the sprocket shaft. As usual, I just clean it off, re-lube and re-install good side down. How much wear is normal and a what point should shaft be replaced?

I think it is highly dependent on the water the boat is used in. We had a guy do a trip on the Mississippi and that drive saw accelerated wear from the muddy abrasive water.

I don't think a worn shaft will actually cause any real issues for quite some time though. May allow the chains to loosen on the sprockets.

_________________
Matt Miller
Former - Director of Parts and Accessory Sales
Warranty and Technical Support
Hobie Cat USA
(Retired 11/7/2022)

Thanks Matt, the drive is used almost exclusively in salt water.

Replaced all my shafts a year ago after 18 months of solid use in Saltwater.
I mainly fish in shallow water so sand is always an issue.


Idler shaft


Drum (cross) shaft


Sprocket shaft middle


Ends


I always use too lube the shafts after each outing but have decided to not lube the new ones so sand doesn't have anything to cling to.
The drive just gets a wash after each time out now and so far there has been less wear.

I wonder if you could grind a new flat on the shafts and reinstall them the other way up?

The shafts can be re-used very easily.

Drum shaft: Mark the shaft, pound it out, reverse or flip and reinstall for a new wear surface.

Sprocket shaft: Pound it out, flip it, mark the ends denoting the hidden flat spot and reinsert for a new surface. Use existing flat spot. Use Loctite Blue to secure Alanhead. Snug but do not over-tighten or you can crack the spine.

Idler shaft: Pound it out, file a small flat surface on the opposite side and reinsert as per Sprocket shaft.

Very interesting and nice documentation. In my use, I get slightly less wear on the sprocket shaft than the drum shaft and almost no wear on the idler shaft. IMO, your excessive wear on both the sprocket and idler shafts indicates an overtightened Drive (possibly from the factory) to a greater extent than sand intrusion. If sand were causing the erosion on your sprocket shaft, your (properly lubed) idler shaft (not normally exposed to water or sand) would not show much wear. Your more recent reduced wear may well be due to your more relaxed cable settings.

Incidentally, the nylon surfaces wear at about the same rate as the shafts. I have a tendency to replace the plastic parts when turning the shafts (especially the drums) for peak performance, but this is not really necessary. Actually, as long as everything is functioning well and you can still make the proper adjustments, you don't really need to replace anything.

I totally agree with the over tightening of the cables causing excessive wear, very good point.

I wound up replacing the spine as there was a crack in the middle support under the set screw. I did notice the replacement spine has a semi-circular cutout in the composite where the idler pulley is located.

On the pre-'09 drives the composite is solid there, but a groove has been worn into the material. Obviously Hobie has redesigned the spines to take into account the wear in this area. I've since filed out some of the composite on the older spines to match the shape of the newer spines, to eliminate any friction or problems in this area.

What is the cause of this wear in this area?

_________________
Bob
Proud member Kayak Fishing Association of New York

Excellent observation. Hobie used a different style idler pulley years ago. It appears when they changed to the current pulleys they allowed only minimal clearance (left, below). Overtightening the idler cable could wear the idler shaft and eventually bring the pulley in contact with the spine. Hobie evidently corrected this as you noticed when they also incorporated the hole for the tether mount.

As always, thanks for the feedback and solving the mystery!

_________________
Bob
Proud member Kayak Fishing Association of New York

Just a quick clarification for anybody else trying to pound out their sprocket shaft for the first time. Before trying to pound out the shaft, remove the set screw that secures the sprocket shaft in place. That makes the shaft MUCH easier to pound out.

You'd think mentioning not to over-tighten that screw at the end of the quote above would've been enough to let a noob know the screw needed to be removed first…but it didn't click here until after a handful of futile attempts. I brought up the picture of all three shafts from earlier in this thread and finally noticed the big flat spot in the middle of the sprocket shaft.

Also, once you get the shaft pushed out enough to remove one sprocket, you can probably grab the extended part with a rag (it'll be greasy so you want something to boost your grip) and twist while pulling to remove it the rest of the way. Twisting breaks friction which allows pulling to work better than if you only pulled.

Thanks to the great info in this thread, I was able to replace a cracked spine tonight (being very careful not to crack the new spine while seating the set screw for the sprocket shaft and the one for the idler shaft).

I looked for a spine teardown but didn't find one. This thread was close enough (along with staring at the pictures from the manual and having two other mirage drives on hand to consult with).

Thanks for the info!