New Departure D Snapping from Drive to Coast/Brake

Some New Departure hubs will "snap" when going from drive to coast/brake. Something inside is binding, not letting everything in there do it's thing.
So a snapper has been a-buggin' since I built these wheels and put them on Back in Black. When the hub was overhauled NOS disc set, cone, driver, cog, and new bearings were installed. One thing I suspected might be causing the prob was the clutch sleeve sticking in the drive shoulder from the sticky grease. I didn't really think this would be the cause as I don't tend to over-grease, but as an unscientific test I put a little oil on it. This has improved the action on other hubs I've overhauled so thought it might help here.



Back into the bike and back on the road...shoot: still a-snappin'.
Into the stand with Back in Black, wheel off and into the axle vise, open the D up.

So what would impede motion and cause snapping? There are 3 things that move left and right in there: disc pack, brake clutch, and clutch sleeve. Since the clutch sleeve wasn't being caught by the shell or driver, and the clutch was moving freely on the disc support sleeve, there had to be a problem with the motion of the discs.
If the ears on the discs are misshapen they might not slide in the keyways nicely....NOS discs tho: flat, smooth, pristine ears.
So the only things left were the keyways in the hub. Wipe out the grease, get some cotton-swabs in there...
Eureka:





There were 2 bad spots in 2 keyways. I could see and feel them sticking up enough to cause binding.
File, sand, repeat, clean, reassemble.
Back into the bike, back on the road.
Several good stands on the pedals, throw foot back to coast: silence...beautiful.
So the cause of snapping on this D was damaged keyways. I suppose an axle bent enough to misalign the driver and clutch sleeve could cause a similar problem, but I suspect that if the axle was bent that far out the hub wouldn't work anyway.
Note: In a pic above you'll see an arrow pointing to a rough spot outside of the keyways. This was not in the path of the clutch sleeve, but I left it alone anyway to test the keyway fix.
So if you have a snapper, check the ears on the discs, and look for burrs in the keyways and on the disc support sleeve. File & sand them down, might just fix you up.

Awesome observation & fix Scott! I have a couple "snappers" I'll be checking my next weekend off. Thanks for the write up & great pics!






Next Mission:The Infernal ND Brake Squeal

Great work Scott,glad you sorted it out. Thanks for sharing.

Very good info Scott. Thank you for posting.

Great stuff Scott,
I love how too's and detailed pics. Good reference material for down the road issues.

Great work Scott! Thanks for posting.

Good stuff Scott. Always nice to conquer something pesky like that. Thanks for the post.

I hadn't seen damage like that before. In the immortal words of Arlo Guthrie, "inspect inject and detect!"

My model D hub made kind of a grind changing from drive to coast after clean and relube (bike has been setting for 40 years).
Now after like three 5mi rides it has started refusing to coast and keeps spinning the pedals! Bike sat for couple minutes and I took it for another ride and its fine! do these hubs have some break in after cleaning and grease the bearings and oil the plates? or do you think my hub is worn like you show?

horsefarmer said:

My model D hub made kind of a grind changing from drive to coast after clean and relube (bike has been setting for 40 years).
Now after like three 5mi rides it has started refusing to coast and keeps spinning the pedals! Bike sat for couple minutes and I took it for another ride and its fine! do these hubs have some break in after cleaning and grease the bearings and oil the plates? or do you think my hub is worn like you show?

Click to expand...

Can't say w/o seeing it, but I'd first make sure the locknut on the brake arm is tight and that the drive-side locknut and cone are locked firmly together while checking the bearing adjustment in "coaster":
between drive and brake the wheel should spin (relatively) freely in hand or axle vise, if the cones are too tight the cog will rock/jump and/or turn with the hub shell. Too loose and there will be excessive bearing play. Just a bit of "loose" is good as that's usually taken up when axle nuts are tightened.
You'll need a thin "cone wrench" to hold the cone while locking it firmly against the locknut.
If the bearing adjustment is good, then it sounds like something is making the clutch sleeve stick in the shell or not release from the driver.