Pit,
The balls are held in place by means of a "star" shaped part inside of a bearing cage. The force is applied by the star, to the balls, and then to a bell shaped housing which in turn spins the outer axle and your wheel. The balls work a slight groove into the inside of the cage and housing, and it is the balls popping into these grooves when the wheels are turned sharply that causes the clicking noise.
I frankly agree with you that a mall cruiser can continue to operate in this condition, albeit with a bit of noise, until the grooves get so deep that one day a ball does not slip into it quite fast enough and jams before doing so. Bang. Instant grenaded birf. Or, the grooves are not deep but the birf grease has dried up and one day a ball hangs up. Again - bang.
If the differential is constantly filled and the leaking gear oil bathes the birf, it will help, but once the leaking axle seal gets to a certain point, the oil will flow through quickly and the owner is driving on a very lightly lubed birf. More heat in there dries the gear lube more quickly than the owner's inspection cycle, and boom. So lots of possible scenarios.
How long will they last? - a long time. You could have a badly leaking birfield last for years because of good front diff fluid attention.
Rick,
The parts are heat treated by Mr. T and as you wear, you actually go through the surface treatment and into softer metal. These surfaces don't get work hardened as a high speed engine bearing might. I do agree that minor tolerances get matched during the break in phase, however. And reversing them causes the balls to work on the opposite faces of the star, cage and housing, which starts off again with much less slack on the drive side in terms of the ball groove thing. What's key is that you're again starting like it did at the factory with no groove to catch the balls and cause the clicking, though there will likely be a little still occuring as the balls can thump against the "coast" side of things (which used to be the worn "drive" side of things) when they pop. But it's not the destructive click/pop that was occuring before the birfs were swapped.
I also agree that if you disassemble the joint, it would be wise to mark them and replace them in the exact spot to minimize the potential that the largest ball happens to end up in the smallest star spot, etc. Best might be to see if new balls can be secured and someone did talk about it once. CDan - what say ye?.
As for Junk's comment. If true, I'd speculate it's simply because there are a lot of 80s that have grooves worn in their birfs now appearing with oversize tires, and hitting the trails. A birf that would run forever on the road with normal tires can indeed be blown on the trail. Remember, all it takes is ONE ball to stick instead of dropping in the groove and it will destroy the cage immediately.
It's a fine design - very tough. But like anything else mechanical it can be neglected and destroyed. There is nothing on this earth that is immune to that.
Doug
The balls are held in place by means of a "star" shaped part inside of a bearing cage. The force is applied by the star, to the balls, and then to a bell shaped housing which in turn spins the outer axle and your wheel. The balls work a slight groove into the inside of the cage and housing, and it is the balls popping into these grooves when the wheels are turned sharply that causes the clicking noise.
I frankly agree with you that a mall cruiser can continue to operate in this condition, albeit with a bit of noise, until the grooves get so deep that one day a ball does not slip into it quite fast enough and jams before doing so. Bang. Instant grenaded birf. Or, the grooves are not deep but the birf grease has dried up and one day a ball hangs up. Again - bang.
If the differential is constantly filled and the leaking gear oil bathes the birf, it will help, but once the leaking axle seal gets to a certain point, the oil will flow through quickly and the owner is driving on a very lightly lubed birf. More heat in there dries the gear lube more quickly than the owner's inspection cycle, and boom. So lots of possible scenarios.
How long will they last? - a long time. You could have a badly leaking birfield last for years because of good front diff fluid attention.
Rick,
The parts are heat treated by Mr. T and as you wear, you actually go through the surface treatment and into softer metal. These surfaces don't get work hardened as a high speed engine bearing might. I do agree that minor tolerances get matched during the break in phase, however. And reversing them causes the balls to work on the opposite faces of the star, cage and housing, which starts off again with much less slack on the drive side in terms of the ball groove thing. What's key is that you're again starting like it did at the factory with no groove to catch the balls and cause the clicking, though there will likely be a little still occuring as the balls can thump against the "coast" side of things (which used to be the worn "drive" side of things) when they pop. But it's not the destructive click/pop that was occuring before the birfs were swapped.
I also agree that if you disassemble the joint, it would be wise to mark them and replace them in the exact spot to minimize the potential that the largest ball happens to end up in the smallest star spot, etc. Best might be to see if new balls can be secured and someone did talk about it once. CDan - what say ye?.
As for Junk's comment. If true, I'd speculate it's simply because there are a lot of 80s that have grooves worn in their birfs now appearing with oversize tires, and hitting the trails. A birf that would run forever on the road with normal tires can indeed be blown on the trail. Remember, all it takes is ONE ball to stick instead of dropping in the groove and it will destroy the cage immediately.
It's a fine design - very tough. But like anything else mechanical it can be neglected and destroyed. There is nothing on this earth that is immune to that.
Doug
