top hat

[Zombie Master]

1984 R100

Do I have to remove the wheel bearing seals to replace the top hat spacer on my rear drum brake rear wheel.

If so, does the seal need to be replaced?

Thanx!

[melville]

Left or right?

Left you can take off the five bolted seal holder and probably reuse the seal.

Right, you've either got to remove the stack or destroy the seal.

[Rob Frankham]

No 5 bolt seal holder on a '84 snowflake (assuming that's what you have...) the seal just taps into the cast wheel. Not easy to get the seals out without damaging them.

You might get away with one side by removing the other side bearing inner race, spacer tube, wedding band and supports then knocking out the outer bearing out from the other side (after prying out that grease seal) pushing the seal with it but, unless you're desperate, it's a lot of work for little gain.

Rob

[gspd]

Replacing the 'stack' with sealed bearings would be ideal.
My front wheel has them, as do all modern bikes.
Maintenance-free and they virtually last forever.
I'm not sure what's readily available and exactly what that job would entail.

[Zombie Master]

Not long ago I repacked the rear wheel bearings and installed new seals. I had shimmed the wheel over to make room for the larger tire. The tire was still pretty close to the swing arm. If I leave it shimmed the way it is, is that a problem using the 4:00 18 tire?

[barryh]

When BMW introduced the 1.5mm wider spacer to facilitate the fitting of wider tyres, they stipulated that the maximum wheel offset should not exceed 4mm. If you can meet that spec I would leave it in.

[Zombie Master]

When BMW introduced the 1.5mm wider spacer to facilitate the fitting of wider tyres, they stipulated that the maximum wheel offset should not exceed 4mm. If you can meet that spec I would leave it in.

The offset wouldn't really change with the smaller tires? Where is the offset measured?

[barryh]

The offset wouldn't really change with the smaller tires? Where is the offset measured?

No it wouldn't change with a smaller tyre. The offset is how far the center line of the front and rear tyres are from being in a straight line. Hard to measure accurately without a jig but you can do a string check as described here by Duane Ausherman. It doesn't matter that he's talking about a /2.

https://w6rec.com/bent-2-frame/

[Rob Frankham]

Replacing the 'stack' with sealed bearings would be ideal.
My front wheel has them, as do all modern bikes.
Maintenance-free and they virtually last forever.
I'm not sure what's readily available and exactly what that job would entail.

Relevant sized deep groove ball bearings are made (that is to say the same nominal sizes as the taper bearings used by BMW i.e.40 x 17 x 14) however they don't seem to be commonly available and all of the listed suppliers seem to come from Russia. If they could be sourced, I would think the only other thing you'd have to do would be to adjust the spacer and wedding band so that they run central in the groove.

As a matter of interest, the R65LS does use a 40x17x12 ball bearing on it's from wheel.

I do wonder what their life would be though, they are substantially smaller that the 47x25x12 bearing fitted to your bike and the Mono range... and they certainly don't last forever.

Rob

[gspd]

.... deep groove ball bearings ..... don't last forever.

I agree +1
Nothing lasts forever. And size matters.
However I said "virtually forever".
540,000 maintenance free kms and counting on mine.
If they didn't spin as smoothly as when they were brand new or if they exhibited even the slightest play, you know me, I'd have replaced them by now.

"I intend to live forever, or die trying". -Groucho Marx