New Departure rear hub discs

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jd56

Riding a '38 Autocycle Deluxe
Mar 26, 2011
6,875
63
Norfolk Va / Va. Beach va.
On a model D, how many steel disc's and how many brass discs should there be?
 

jd56

Riding a '38 Autocycle Deluxe
Mar 26, 2011
6,875
63
Norfolk Va / Va. Beach va.
I posted this earlier in another thread that had this ND mod D diagram.

yvu3etu4.jpg


As it states in this diagram, there a 23 count on the disc pack.
I have a mod D that had 26 discs. One extra steel disc's from what can guess.
Removed the extra and then started reassembly. The brake clutch with the spring won't fit onto the shaft. I never took this section apart in fact I greased that ends bearing with it all assembled as I don't have the spanner wrench to remove the hub sprocket.

8e4yry7u.jpg


e2eqemu3.jpg


So I took out 6 more discs and now it fits onto the spline.
tubeveze.jpg


So can this work?
I'm guessing someone must have serviced this hub and added the extra disc by accident but I can't see how or why an additional 6 would be added.

Let me also mention this hub was never tested before it's breakdown. It was very tight though (not free spinning as one would expect).

I am stuck at this point with this rear wheel resto....help me guys and gals!!
 
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dougfisk

Cruisin' on my Bluebird
Jun 24, 2008
3,008
under a rock
There are a couple different versions. The most common (in my experience) has 17 discs. These discs would be noticably thicker than the version with 23. Measure the height of the stack and compare to others in your posession... or I can measure some later this evening. What is the approximate vintage of the hub you are working on?
 
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jd56

Riding a '38 Autocycle Deluxe
Mar 26, 2011
6,875
63
Norfolk Va / Va. Beach va.
Don't have another that ai can breakdown to measure. The discs seem to be the seem thickness as all the other D's I've done in the past.
The bike is a 1938 Hawthorne. Have no idea if it is the correct rear hub. The brake arm as pictured above appears to be from th eff prewar 30s era. With the model D stamping on the arm with 2 hash marks
Doug if you can measure what your stacks are, maybe that will help.
I guess my concern is if it all fits together with the removed discs, will it work?
 

dougfisk

Cruisin' on my Bluebird
Jun 24, 2008
3,008
under a rock
I counted and measured the discs in 4 older ND hubs. I found: 20 at .690, 20 at .714, 23 at .723, 21 at .79 and 21 at .751. I have seen hubs with different thicknesses mixed together. My (2) 20's would not be original as OEM would always have been an odd number.

I ran out of time tonight, but tomorrow I can open some boxes and measure the height of new replacement sets. I think I remember doing that before, and I think .750 is it. If you need to wrap it up now, I would start with whatever odd number stacks up to .750. If you do not like the action, you can add or subtract as needed.
 

jd56

Riding a '38 Autocycle Deluxe
Mar 26, 2011
6,875
63
Norfolk Va / Va. Beach va.
3/4" high

Thanks Doug.
Obi Wan mentioned he thought it was 3/4" high as well in my other thread about the discs number.
I agree that it should be an odd number so 19 to 21 will be the number I go with.
Not sure if I have the thick discs vs the thinner discs on this setup.
but do recall that it should start with steel and end with steel discs.

I also brass brushed the discs to try to remove the glazing that accumulates after years of used. Hopefully that it the correct proceedure to do.
Brushed 30 weight motor oil on the discs to lubricate as well.

Just don't understand why so many extra discs were in the hub when I disassembled. They just don't all fit on the spline (#22 in the pictured diagram above) as to allow the clutch (#6) with the spring (#12) to fit on the squared splined end.
 
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dougfisk

Cruisin' on my Bluebird
Jun 24, 2008
3,008
under a rock
My new-in-the-box replacement sets have 17 discs and measure .750 inch. So, again, I would use whatever odd number it takes of yours to equal three quarters of an inch.
 
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jd56

Riding a '38 Autocycle Deluxe
Mar 26, 2011
6,875
63
Norfolk Va / Va. Beach va.
My discs seem to be thicker than I've seen before.
But, I did install 19 on this application. And the stack was about 3/4". We'll see how it works.
 

Miq

Wore out three sets of tires already!
Jan 12, 2019
799
49
Arizona
I was looking at this today. My 1941 Schwinn's ND Model D came with 23 discs. Similar to what's called out in this dwg:
newdepartures ND Assy Dwg.jpg



But clearly this changed over time. Dropping to 21 discs called out in step 4 of this dwg:
NEW DEPARTURE SALES AND SERVICE MANUAL.jpg



And down to the now default number of 17 discs per set (D278).
ND Model D 1.jpg



The Schwinn Repair Manual that @rustjunkie provided here has a great section on coaster brakes. This page has some info on the disc sets, and the note at the bottom in Step 7 pretty much sums it all up:
Schwinn Coaster Service Pg 201.png

1574002263111.png


Having a higher number of thinner discs would give the brake slightly more braking surface area rubbing together but I doubt it makes much of a difference if you can lock the brakes up with 17 thicker discs.
1574004131842.png


I also thought this note at the bottom of step 4 on assembling the disc sets was interesting and have never heard this before. I thought you HAD TO start and end with Steel discs:
1574002528387.png




The other thing that I've been following, is the many methods of lubricating the ND coaster brake. I hadn't noticed that the recommendations from ND changed over time. It has always been grease on the bearings and oil on the discs, but I imagine as people realized that light motor oil was too thin and could work its way out through the grease, they started to increase the weight of the oil. Thicker oil sticks to the discs better and doesn't mix with the bearing grease and work its way out as easy.

Old 20 weight oil call out:
1574003259030.png


Here they are calling out Hypoid (gear) Oil:
1574003423495.png


And the Schwinn Repair Manual says Hypoid or Castor Oil:
1574003563164.png


I hope this post can help others unravel the differences in number of discs seen in these hubs and how to lubricate them correctly. Fast forwarding to the Schwinn Repair Manual advice is probably the best IMHO.

3/4" total disc stack height and thick gear oil on the discs
 
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pedalpower17

Finally riding a big boys bike
Oct 20, 2010
312
Michigan
A related question.... I'm overhauling my second ND Model D hub. Unlike the first one, on this one, some of the flanges on each copper disc have taken some serious force that has slightly damaged the ends of some of the flanges. See pic. The result are little spurs that stick up slightly, perpendicular to the plane of the disc. I'm thinking of taking the time to gently sand these down so that the disc is again smooth. I did not test the function of the hub before disassembly, so don't know if this damage had any effect on the function of the brake. Anyone have any experience to share?

1099176
 
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gkeep

Wore out three sets of tires already!
Jun 11, 2014
641
Alameda, CA
Those burrs may cause brake "snap" when you stop pedaling. No expert but my guess is it causes the ears to bind when they slide in the keyway of the hub. There are some great threads about this topic with comments by much more qualified people than me.;)
 
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piercer_99

I live for the CABE
Dec 27, 2015
1,661
59
Sanger, TX
A related question.... I'm overhauling my second ND Model D hub. Unlike the first one, on this one, some of the flanges on each copper disc have taken some serious force that has slightly damaged the ends of some of the flanges. See pic. The result are little spurs that stick up slightly, perpendicular to the plane of the disc. I'm thinking of taking the time to gently sand these down so that the disc is again smooth. I did not test the function of the hub before disassembly, so don't know if this damage had any effect on the function of the brake. Anyone have any experience to share?

ND Model D Discs.jpg
I would replace the discs, they are available.


Also Scott sells them, @sm2501

It is worth it. The flanges are the key to solid braking, they will start to wear with the chink like that, the it shears off and scores the hub.

I have had that happen to a hub and the results are not pretty.

Although, depending on how much you ride, and how hard, sanding the discs down will work for a while.
 

pedalpower17

Finally riding a big boys bike
Oct 20, 2010
312
Michigan
I would replace the discs, they are available.


Also Scott sells them, @sm2501

It is worth it. The flanges are the key to solid braking, they will start to wear with the chink like that, the it shears off and scores the hub.
Piercer, sounds like a solid idea. I wasn't looking forward to the tedium of sanding down 30+ burrs of soft copper without wearing too much into the surrounding disc. I've reached out to Scott. Thanks
 
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pedalpower17

Finally riding a big boys bike
Oct 20, 2010
312
Michigan
I ordered this set from eBay recently. I contacted @rustjunkie a few days ago and he does not have any replacement sets in stock at the moment but thought the NK set on eBay was worthy and priced correctly under $20
Miq, thanks for the suggestion. I just saw them on ebay, but notice that this is a 17 disc set, 8 flanged and 9 regular. My hub has a 23-disc set. Did you use your NK set to replace an ND 23-disc set? If so, I'm guessing that these discs must be thicker, but that the total stack height is the same.
 

Rivnut

Wore out three sets of tires already!
Nov 24, 2012
997
Shawnee, United States
I think you'll be okay as long as the stack is .750" tall and you have a steel disk on each end. I've rebuilt a couple of these and I lay a piece of 400 grit wet/dry paper on the work bench with a little water on it which has a dab of Dawn detergent on it. Slide each side of each disk around in a circular motion. Just enough to smooth the up. Doesn't take all that long. Rinse. Reassemble putting grease on each side of each disk.
 

Andrew Gorman

Cruisin' on my Bluebird
Jun 15, 2008
2,892
Pasadena (Hastings Ranch), United States
Nankai and Mattatuck discs work fine in the ND, along with SOME other parts. Definitely not the retarder spring. Mattatucks were used a lot on little kids bikes.
 
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