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Dan in IL wrote:I changed the front wheel bearings in my ‘88 RT a few years ago. I borrowed a blind hole bearing puller from Autozone. As I remember, the bearing puller didn’t exactly fit but I did manage to get them out. The new ones just tapped into place, didn’t use any heat to get them in or out.
It’s a simple swap. There’s no magic, and it’s not rocket surgery.

If the hub is aluminum without a steel insert, then a steel bearing is a shrink fit and heat must be used. It is simple physics.

I have seen so many hubs ruined due to someone not understanding the coefficient of thermal expansion of the two different materials.

Here is what Wiki says about it. http://en.wikipedia.org/wiki/Thermal_expansion

+1 for Duane on that.
Aluminum hub and steel bearing = heat needed to do it right.
Freeze the bearing to do it even righter.
Yes, you CAN drag the bearing out of the alum. hub, but the hub won't be the same size when you are finished.

When were steel inserts introduced for snowflake wheels? I bought a rear wheel from Germany with an insert an thought it may have been sleeved due to a spun bearing, but now it seems sleeves were done by the bmw factory at some stage?

ME 109 wrote:When were steel inserts introduced for snowflake wheels? I bought a rear wheel from Germany with an insert an thought it may have been sleeved due to a spun bearing, but now it seems sleeves were done by the bmw factory at some stage?

I can't say for sure but I'm thinking that all snowflake wheels have steel inserts for the bearings. At least all of my snowflakes that I've actually looked at have them.


Ken

Ken in Oklahoma wrote:

ME 109 wrote:When were steel inserts introduced for snowflake wheels? I bought a rear wheel from Germany with an insert an thought it may have been sleeved due to a spun bearing, but now it seems sleeves were done by the bmw factory at some stage?

I can't say for sure but I'm thinking that all snowflake wheels have steel inserts for the bearings. At least all of my snowflakes that I've actually looked at have them.


Ken

Interesting Ken,the dodecagon rear snowflake that I recently swapped out on my RS had no steel insert.

ME 109 wrote: Interesting Ken,the dodecagon rear snowflake that I recently swapped out on my RS had no steel insert.

There ya go, then. All it takes is just one without the steel insert to make my supposition wrong. I'm away from my snowflakes right now so mercifully I don't have to go to the effort to check further, such as when the transition might have come about.


Ken

Ken in Oklahoma wrote:

ME 109 wrote: Interesting Ken,the dodecagon rear snowflake that I recently swapped out on my RS had no steel insert.

There ya go, then. All it takes is just one without the steel insert to make my supposition wrong. I'm away from my snowflakes right now so mercifully I don't have to go to the effort to check further, such as when the transition might have come about.


Ken

For further ponderings.... the wave washer shaped front flake that I swapped out, had no steel insert either.
Nor did the front wheel that I swapped in.

I checked my records and I’ve put 8000 miles on the RT since changing the front wheel bearings. The wheel still turns easily, there’s no play in anything, and the center hub is always cool when I check it after a ride. It doesn’t appear as I’ve destroyed anything?

I think I’d say it’s okay to try and replace those bearings without heat, but if they don’t move with light taps you should warm up the hub until they do move easily. As best as I recall the interference on those bearings were barely .001 inch. I didn’t measure it but I have enough mechanical experience to feel those things.

Maybe someone else destroyed the wheel hub before I got the bike? At any rate, the dang thing still works and that’s all that matters to me!

Dan in IL, If a bearing race will tap out easily, then the hub is probably already damaged and further tapping will not be good. That is a shrink fit and it can never be removed without heat, never. I made a lot of money from people who didn't know that, or thought that they knew what they were doing. I knew what they were doing, putting more money in my pocket.

One such regular customer brought his bike in because the rear wheel was loose. We found the axle torque to be well over 50 lbs. I told him the problem and said that there is no way in the world that anybody in my shop would have done that. He then confessed that he had a flat tire and since he lived in San Francisco and was only a couple of miles from the local dealer, he took it in for the repair. His excuse was that fixing a flat tire is super simple and anybody should be able to do it. The hub was destroyed and we sold him a new one. Within 6 months he was back with a loose rear wheel........... again. Again the axle nut was way over tight and the hub was ruined........... again. Yes, he took it back for the next flat tire to the same shop. Some people don't even learn from pain.

Ken, I was out of the biz after 80, so I won't bet a penny on this answer (guess) or any other. I think that the steel insert started being used by the factory in 1981.

Duane Ausherman wrote: Ken, I was out of the biz after 80, so I won't bet a penny on this answer (guess) or any other. I think that the steel insert started being used by the factory in 1981.

Duane, I just went out to my shop and looked at my '78 R100S (Touring). You saw that bike during this last (May) rally at my place. It was one of the two bikes that Randy and others kindly dragged out of deep storage in the dark scary dungeon at the end of my shop. It just dawned on me that I do have a snowflake wheel (or two) to look at. I'm the second owner of this '78S bike and it is original at 18.7K miles. The owner bought it for his honeymoon and then it spent most of it's life in a storage building. After the second time taking the bike to the shop to get the carbs de-varnished he decided it was time for him to sell it.

This bike has the original recalled front wheel that has never been been replaced.

I got down on my knees (not a usual position for me) with a flashlight, and examined the L/H side of the front wheel hub. I could clearly see a steel insert, turned dark with oxidation, next to the bearing/and seal. There was a slight step between the aluminum of the wheel and the steel insert.

Then I went to the other side of that same front wheel. There I saw something that I couldn't figure out. I saw traces of the steel insert and what looked something like aluminum bondo that had flaked away. Then I finally figured out what was happening. The "inserts" weren't inserted. Rather they were put in place as the wheel was cast. In the case of "flaked bondo" the aluminum over the step had broken away. Thus in some places I could see the insert and other places I was seeing the cast aluminum and parts of the insert.

Then I moved to the rear wheel. I only looked at the exposed L/H side of the wheel since the R/H side was hidden behind the final drive. And I wasn't willing to pull the axle and tire for a close look at the drive side. But the L/H side told the same story. I could see the grey oxidized "insert" and the bearing/seal inside of it. And I can't imagine that BMW would have two "styles" of snowflake wheels, with steel insert and without.

So we have a conundrum. You have me reporting that both the front and rear snowflake wheels have steel inserts in them--as of the '78 model year anyhow. And we have at least on person reporting that there is no steel insert. Perhaps a few people reading this topic could go out and take a hard look at their snowflake wheels and report back.

I could go buy a magnet and try it on the wheels, but due to the close proximity of the bearing/seal I'm not sure I would get a definitive result.

I don't like mysteries, even in books.


Ken