Atlas Rear Wheel Fitting and Dimensions

Guys, help me out with this, or someone take all the razor blades away from me.

This may also apply to early bolt -up Cdo wheels as well as Atlas.

After rebuilding the rear wheel (new bearings both sides) and new brake shoes, I am missing 0.140 inch. It is curious because I have had personal communication with two other guys on this Forum who also were missing 1/8 inch +/- when refitting the rear wheel (both early Cdo). The other guys just spread the swing-arms and forced the last spacer (pt # 18235 - G19 below) into place. I can swear that I never had to force that spacer anytime I had the wheel off before this rebuild.

Here are the dimensions that are stumping me. If anyone can verify these dimensions, I would appreciate it.

Inside distance between swing arm flanges where axle (spindle) fits: 7.75 inches
width of left side spacer (pt # 19268 - G29 below): 0.590 in.
More dimensions: When the brake plate is snugged up using the stub axle, and spacer G29 in position between the left swing-arm and brake plate, the distance from the nose of the stub axle (the part furthest right that butts up to the double row bearing) to the inside of right swing arm flange is 6.28 inches. See below. I know the scale cannot be read....trust me, I've read the scale a dozen times.



Now the wheel hub:
Distance from outside of double row bearing (on left) to outside of top hat spacer (pt # 18234 - G9 below) on right (all assembled with speedo drive lock ring tightened) - 5.25 inch

Speedo gearbox and top hat (#18 below) thickness: 0.170 in.
Spacer (18235 - G19): 1.0 inch

Now add it up - Wheel (bearing to bearing with top hat bush) + speedo GB + spacer = 5.25 + 0.17 + 1.0 = 6.42 inches.

But I only have 6.28 inches, or short 6.42 - 6.28 = 0.14
I just don't believe one should have a 0.14 inch interference fit!

I have driven out the new bearings to measure and verify they are proper width (16 and 12 mm), the single row bearing seats until it hits the shoulder in the hub, then the distance piece (G16 below), then the double row bearing seats on the distance piece....this fixes the 5.25 dimension...no way to drive the bearings deeper to reduce the 5.25 distance.

Are wheel hubs like entropy? i.e. ...always expand when worked?

Parts Assy below:



Going crazy in Texas
Slick

Sounds like you have to cuss the PO for that one !

Sorry, can't help otherwise.
Other than closely comparing old parts and new parts, there has to be a difference somewhere.
Bearings wider perhaps, or don't fully go into housings ?

Rohan said:

Sounds like you have to cuss the PO for that one !

Sorry, can't help otherwise.
Other than closely comparing old parts and new parts, there has to be a difference somewhere.
Bearings wider perhaps, or don't fully go into housings ?

Click to expand...

I am the ORIGINAL owner!!! Never have any parts been changed out until this rebuild. No wrecks to have buggered the swing arm!

Re: Bearings .... I have addressed these issues.

Slick

texasSlick said:

I am the ORIGINAL owner!!!

Click to expand...

We know !!

If everything is the same, it can't be wider, can it...
Maybe the swingarm shrank while the wheel was out of it ?

I measured my stock parts etc, not all that you have measured but it may be a start.
I'll put my measurements after yours
Inside swing arm 7.75" 7.85"
width of right spacer 1" 1.062"
width of left spacer .590" .670"
speedo gearbox and top hat spacer .170" .180"
bearing face on stub axle to inside swingarm right side 6.28" 6.330"
compare these and see what you think
Don

using my parts above , the wheel slips perfectly in the swingarm

Perhaps a bearing that is not driven home could account for some of your lost clearance.

Stephen Hill

Re: “After rebuilding the rear wheel (new bearings both sides) and new brake shoes”
Perhaps the clue is in the question :?:

@Don and anyone who may have knowledge of this:

The dimensions of the left side spacer , mine .590 - yours .670, blows me away. That is an 80 thou difference and will affect chain alignment. This makes me wonder if Norton used an assortment of left/ right side spacers to account for assembly differences in the frame mounts, side plates, gearbox, and final drive sprocket. Following this line of reasoning, should chain alignment require a plus 50 thou wider than nominal left spacer, they would compensate by using a minus 50 thou on the right spacer.....can anyone verify this? This has profound consequences for Norton restorers who may have to supplement missing parts of a basket case....just picking up a left or right spacer from somewhere, may result in chain misalignment. OTOH, this method of chain alignment would upset the wheel centering.

If I were to substitute your left spacer (+80 thou), and your right spacer (+62 thou), I would lose an additional 142 thou, or have over 1/4 inch of interference!

The main difference which I see in your data, to account for my missing 0.140 inch, is the swing arm inside dimension....yours will give me 0.100 of it.

I failed to mention, in my first post, that all my parts are original, except the speedo gearbox. Thus left/right spacers should be matched if the chain alignment premise above is correct.

Thanks for the data. I welcome input from others.

Slick

I just found this
19268 SPACER N/A 13/16"x1-1/4"x15MM
15mm is .590" so yours is correct

and
18235 SPACER N/A 9/16"x1"

This is the inside width of my 3 slim featherbed SA are 7.830, 7.860 and 7.990"
Yours seems narrow :roll:
I've got two more but the wheels are currently mounted on the bikes.

Added:
made excuse to exchange two rear tires
LH spacers 2 plus spare- .590"
RH spacers both bikes 1.00"
swing arm on 63 7.965" sprung "open" about .08-.10 when I loosened axle
swing arm on 66 7.875"

yep looks like your swingarm is squashed about .100"

Thanks guys.

Your SA average 7.895 for reference. Then, 7.895 minus 7.75 (mine) = 0.145 or bingo! what I am missing. The left and right spacers all being 0.59 and 1.0 resp. rules out notion of Norton using spacer width to align chain.

Now to figure out why mine got squashed, and how to spread it.

Slick