H: Hubs, Wheels and Tyres Bearings

[vibrac]

The wheel bearings in a BMW air head rear wheel (tapered) spin as well, not only that but one of them is at the other end of a long tunnel and locktite is the recommended fix there and I guess the BMW guys are at least (No No more , especially the US ones ) myopic about engineering than we are....

 

[timetraveller]

For those of us who were not there could someone describe what happened to Graham's bike. I recall that Russ Kemp had a similar event on his way back from a rally in Belgium (if I recall correctly). This was after he and Peter Appleton had just done lots of mile on poor roads in a long distance round Europe road trip. They will both remember the details better than I can but I believe that Russ's rear wheel collapsed and threw him and passenger down the road among large lorries and they were lucky to survive. Whether the causes of the failure were the same could be of interest to the rest of us.

 

[Vincent Brake]

Wasn't it heavy overloaded?

 

[oexing]

In the matter of keeping bearings seated in alu cases you are ignoring the mix of materials. Loctiting all steel components is an obvious action, no temperature problems here, as long as max. temperature is below 150 to 200 degrees when common Loctite products keep strength to half or more of their cold numbers. Now when you want to fix a steel race in an alu hub or engine case you have to do a little calculation before:
When operating temperature of the bearing in the engine case is around 80 to 100 degrees you will get two or three thou growth and the steel race will drop out - provided you did not allow for that amount of shrink fit before in a good case.
So when you apply Loctite on the alu seat and steel race and fit that while on cold room temperature you might think - great - - till you heat to operating temperature 80 to 100 degree and the race will beloose again. You cannot possibly expect the thin Loctite film to grow one thou in the gap, it will lift from one side during expansion by heat. This is NOT the effect of falling strength of Loctite with heat, but exclusively due to heat growth of aluminium relative to the steel race.
I am quite sure some will not accept any advice from continentals so please do your own tests. No doubt will you have some stock of aluminium component with loose bearing fit.
First test: Glue the bearing at room temperture into the case - test - great seating. Now heat up to 100 degrees - test - easy to unseat - Loctite lifted from faces due to heat growth.
Second test: Heat the alu case to higher than operating temperature, say 120 degrees , cold steel race! Apply Loctite to alu seat plus onto the cold bearing race as well and quickly drop the bearing into the hot case. Wait an hour like with the first test. Then heat the hot glued assembly to operating temperature of 80 degrees and do same strength test. The Loctite did its chemical reaction in the expanded alu case so at a lower temperature the bearing will still have some minor preload and will stay put safely.
So conclusion: Heat the alu hub to 80 to 100 degrees , apply Loctite to hub faces and bearing race and drop it in a swift action else it will be stuck somewhere higher.
The BMW hubs of more modern types, meaing /5 series and later were aluminium and - I am sorry to say - they did not keep good old industry standards and allow a proper shrink fit of steel races in the hubs. The Earles types, which were about the only real great sidecar machines in more than one aspect, had cast iron hub centres so did not have that problem, being all iron bearing environment.
I had this aspect in my mind for a while and did the heat seating test with a very sloppy gearshaft ball bearing Loctited into the gearbox cover. Cold glued failed as described at 100 degrees, hot glued was allright at high temps, so that confirmed a theory.
As to the recent cathastrophic failure of the wheel bearing I´d be very intersted to see components and what led to this outcome. Pictures may speak louder than many words - sometimes.

Vic

 

[Vincent Brake]

In the matter of keeping bearings seated in alu cases you are ignoring the mix of materials. Loctiting all steel components is an obvious action, no temperature problems here, as long as max. temperature is below 150 to 200 degrees when common Loctite products keep strength to half or more of their cold numbers. Now when you want to fix a steel race in an alu hub or engine case you have to do a little calculation before:
When operating temperature of the bearing in the engine case is around 80 to 100 degrees you will get two or three thou growth and the steel race will drop out - provided you did not allow for that amount of shrink fit before in a good case.
So when you apply Loctite on the alu seat and steel race and fit that while on cold room temperature you might think - great - - till you heat to operating temperature 80 to 100 degree and the race will beloose again. You cannot possibly expect the thin Loctite film to grow one thou in the gap, it will lift from one side during expansion by heat. This is NOT the effect of falling strength of Loctite with heat, but exclusively due to heat growth of aluminium relative to the steel race.
I am quite sure some will not accept any advice from continentals so please do your own tests. No doubt will you have some stock of aluminium component with loose bearing fit.
First test: Glue the bearing at room temperture into the case - test - great seating. Now heat up to 100 degrees - test - easy to unseat - Loctite lifted from faces due to heat growth.
Second test: Heat the alu case to higher than operating temperature, say 120 degrees , cold steel race! Apply Loctite to alu seat plus onto the cold bearing race as well and quickly drop the bearing into the hot case. Wait an hour like with the first test. Then heat the hot glued assembly to operating temperature of 80 degrees and do same strength test. The Loctite did its chemical reaction in the expanded alu case so at a lower temperature the bearing will still have some minor preload and will stay put safely.
So conclusion: Heat the alu hub to 80 to 100 degrees , apply Loctite to hub faces and bearing race and drop it in a swift action else it will be stuck somewhere higher.
The BMW hubs of more modern types, meaing /5 series and later were aluminium and - I am sorry to say - they did not keep good old industry standards and allow a proper shrink fit of steel races in the hubs. The Earles types, which were about the only real great sidecar machines in more than one aspect, had cast iron hub centres so did not have that problem, being all iron bearing environment.
I had this aspect in my mind for a while and did the heat seating test with a very sloppy gearshaft ball bearing Loctited into the gearbox cover. Cold glued failed as described at 100 degrees, hot glued was allright at high temps, so that confirmed a theory.
As to the recent cathastrophic failure of the wheel bearing I´d be very intersted to see components and what led to this outcome. Pictures may speak louder than many words - sometimes.

Vic

View attachment 28589

Hi Vic,
Some continentals would say that if one puts a bearing in a heated up casing or so.
The chemical reactions become very Very rapid indeed and thus curing the locktite in a rather quick way in an bigger seating than when at normal temp.
So it might run heavily.
But its sure fix in the seat

 

[oexing]

Salü Vincent,
Yes, a preload is just what you want at operating temperatures. The amount of preload is controlled by the temperature when you drop the loctited components. So when you expect 80 degrees engine cases on the road I´d heat the cases to 100- 120 degrees and assemble with Loctite. So you just get a preload from 20-40 degrees heat shrink - no deal. But you definitely have to be quick in this action, but then you are going to fix a sloppy fit so dropping the race is easy with all that wear as long as you don´t jam the lot ham-fistedly .

Vic

 

[Peter Holmes]

Looking at the picture that Graham posted in MPH it is hard to draw any accurate conclusions, it looks like the solid axle some how started to rotate with the wheel and then worked like a rotary file, neatly removing the metal that lies between the rear frame bolt and the lifting handle bolt, but how can this happen, the solid axle must have picked up internally in the hollow axle and the taper rollers must have picked up on the hollow axle, presumedly the taper rollers picked up on the bearing cups and the bearing cups held bloody tight in the hubs (wish mine did) I shouldn't really guess about Grahams actions but I would imagine the homing instinct got the better of him, I am sure he must of been aware that something was not quite as it should be long before he literally ground to halt. Aren't we lucky we ride Vincents, if that was a modern bike you only have to trash a couple of plastic panels and they write them off.

 

[oexing]

What amazes me is that the solid axle made it till home obviously - without getting parted off by the frame lug ??? Unbelievable !!

Vic

 

[greg brillus]

Only bike i know of that the hollow axle seized to the solid axle, resulted in both rear frame lugs split in two. I treat wheel hubs just like the crank assembly..........Do it once, do it right, as the pain of a complete disassembly to repair is too much trouble.......It might seem a bit of a "Hard nose" approach, but I'd rather have that than a wheel strip down to fix..........its just too much trouble to do it again.

 

[vibrac]

Two things
1 do we think a wheel bearing properly set up in a Vincent hub will reach 100 degrees?
2 I had a rear axel seize on me years ago on my first egli due to insufficient lubrication of the rollers they simply welded the outer race and the axel together luckily the race turned in the hub and the axel stayed still till I noticed the drag so perhaps locktite letting go at higher than normal temperatures is a good thing!