A rear drive theory... - BMW Luxury Touring Community
 
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post #1 of 5 Old Sep 14th, 2006, 10:36 am Thread Starter
 
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A rear drive theory...

Am in the process of having my spare drive inductive sensor slotted ring re-affixed to the crown gear. To pull the black cover plate one has to heat up the rubber gasket/seal to pull the plate off the crown gear hub.

Anyhow, the heat needed to expand the gasket is only around 80-100 degrees. "IF" the gasket and it's inner spring got warm enough and worn enough, there is the possibility that contaminants could get past the gasket and have access directly to the 19 ball bearing. This could be further enhanced with rain water carrying contaminants past the gasket.

My point is that I believe that the LT rear drive runs warmer due to the weight it has to support and that gives the gasket a chance to get very warm and expand during a ride. This would permit some dirt/grit to get past and down in the bearing and wear the components over time.
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post #2 of 5 Old Sep 14th, 2006, 12:38 pm
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Quote:
Originally Posted by hoodoodrum
Am in the process of having my spare drive inductive sensor slotted ring re-affixed to the crown gear. To pull the black cover plate one has to heat up the rubber gasket/seal to pull the plate off the crown gear hub.

Anyhow, the heat needed to expand the gasket is only around 80-100 degrees. "IF" the gasket and it's inner spring got warm enough and worn enough, there is the possibility that contaminants could get past the gasket and have access directly to the 19 ball bearing. This could be further enhanced with rain water carrying contaminants past the gasket.

My point is that I believe that the LT rear drive runs warmer due to the weight it has to support and that gives the gasket a chance to get very warm and expand during a ride. This would permit some dirt/grit to get past and down in the bearing and wear the components over time.
I think you are misunderstanding what the heat does. Heating the housing cover is to expand it slightly, making it less of an interference fit to the outside of the final drive bearing to allow it to come off of the bearing. Heat does not loosen the seal, as that will slip on or off the hub of the crown bearing easily without heat. It is pliable rubber, and the "garter" spring inside the seal keeps it in contact with the hub no matter the temperature or slight wear it sees over time.

If you do not heat the housing cover, it "may" be difficult to get off the bearing, depending on how much interference fit there is. Mine did not need heat, light tapping with a plastic mallet removed it easily.

I don't want to achieve immortality through my work...I want to achieve it through not dying.

David Shealey
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EX: '01 Black LT, BAT BYKE (Totaled at 110,000 miles)
IBA SS, BB, BBG, 10/10ths.
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post #3 of 5 Old Sep 14th, 2006, 1:47 pm Thread Starter
 
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Quote:
Originally Posted by dshealey
Heating the housing cover is to expand it slightly, making it less of an interference fit to the outside of the final drive bearing to allow it to come off of the bearing. Heat does not loosen the seal, as that will slip on or off the hub of the crown bearing easily without heat. It is pliable rubber, and the "garter" spring inside the seal keeps it in contact with the hub no matter the temperature or slight wear it sees over time.

If you do not heat the housing cover, it "may" be difficult to get off the bearing, depending on how much interference fit there is. Mine did not need heat, light tapping with a plastic mallet removed it easily.
I guess I was just pondering what would happen if it expanded too much.
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post #4 of 5 Old Sep 14th, 2006, 1:59 pm
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Quote:
Originally Posted by hoodoodrum
I guess I was just pondering what would happen if it expanded too much.
It is clamped hard to the bearing face by the bolts holding the cover on, and is also sealed with an "O" ring. No way to get the cover hot enough to allow anything in without destructive temps. The only way dust can enter the drive is through the little vent on top. That "breathes" as the final drive alternately heats and cools.

I don't want to achieve immortality through my work...I want to achieve it through not dying.

David Shealey
Dandridge, TN
EX: '01 Black LT, BAT BYKE (Totaled at 110,000 miles)
IBA SS, BB, BBG, 10/10ths.
No bike now, but maybe in the future.
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post #5 of 5 Old Sep 14th, 2006, 2:14 pm Thread Starter
 
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Good points David. Thanks
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