Green Bearings v OEM

momoparman said
Been running sealed bearings (green) for over 8 years on the street with never a problem. I have a MOSER 60 diff and 3:55 gears. Have the same bearing setup in 2 other cars. NEVER an issue in a straight line or a corner.

Here is some info from a similar post I responded to last year, good reading material for you straight from Dr. Diff

The guy selling green bearings? Say it ain't so.

momoparman said
Why Green Bearings?

Drawbacks of the OEM design

An OEM adjustable, Set 7 (A7) tapered wheel bearing is definitely strong but it is has a few drawbacks.

The bearing is flipped around backward, so the race is captive between it and the axle flange. This means the bearing must float in the housing end and requires an adjuster, thrust block or thrust pin. Of course, an adjuster, thrust block or thrust pin must pass through the center of the differential. A hole drilled in the cross shaft of a 4 pinion carrier creates a stress riser that is prone to breaking. A 2 pinion carrier allows the thrust block to pass around it unobstructed, but the 2 pinion design also limits the differentials strength.

The bearings are certainly not backwards. The corning load is carried by the opposite side bearing.

momoparman said
Axle spline engagement also suffers because the width of the thrust block (which must have room to slide side to side) protrudes into the splined area of the side gears. This limits spline engagement in differentials with a 2 piece cone or clutch-hub/side gear arrangement.

Show me a stack of ruined 8 3/4 splines due to limited spline engagement, and I can probably find you a bigger stack of ruined 8 3/4 housings due to green bearing failure.

momoparman said
Beaded steel and foam gaskets dont keep water from running into the housing end and into the non-sealed wheel bearing. Dont forget to check your pickups A7 wheel bearings if you ever back a boat into the water.

True, foam seals don't keep water out. Taken from Dr. Diff's own web site:

I don't know if I want bearing advice from a guy that says his rears are unsealed, but sells the seals and doesn't seem to know where they go.....

momoparman said
Axle flange stand-out is not held constant unless you blueprint the axle lengths. Measure the axle flange stand-out on both sides of any stock 8 3/4″ rearend. Because of production tolerances, a single adjuster causes the axle flange to stick out farther on 1 side than the other.

The length of both axles, and the housing width is critically dependent on each other. Because everyone uses tape measurements to specify axle and housing lengths, making a set of axles with adjustable set 7 wheel bearings for a custom application is very hard. Axle flange standout varies greatly unless the axles are cut long, installed then blue printed to length.

Axle flange standout/side variance (due to end play) measured in thousandths (0.00x") of an inch, in a car with axle location production tolerance at an eighth of an inch (or more)? Sure thing.

momoparman said

The need for non-adjustable wheel bearings

Click to expand...

momoparman said
Most of these problems can be avoided by installing non-adjustable sealed ball Green wheel bearings. The name comes from the Green Bearing Company which first produced them. The company has since been purchased by Bearing Technologies.

Unfortunately, the original Mopar Green wheel bearing design has 2 problems.

Agreed. What was the design flaw with stock, again?

momoparman said
First generation (RP-400) Green bearings, still sold by Mopar Performance and others, are problematic because the crimped-on flange will not allow the bearing to wiggle around inside a housing that is not perfectly straight (none are).

Because these bearings are not designed to accommodate side loads. Wiggle inside the housing? You mean, like you're (Dr. Diff) saying the bearing is supposed to wiggle in there? Uh, no....Stock bearings don't wiggle, and neither should green bearings. That's probably why there's not a single provision for "wiggle".

momoparman said
In addition, the design causes the axle to be inserted DEEPER into the housing than necessary. This results in pre-loading against the differential thrust block and early bearing failure.

Uh, what? The axle is pre-loaded against the thrust block (proving: no side load capability), and the bearings fail? If only there was some way to prevent preloading....some way to keep end play in there....some method, an adjuster of sorts, that allows endplay so we don't preload stuff.....

momoparman said

Second generation (MO-400) snap-ring style Green bearings are forgiving because they can move around inside the housing and they do not preload the differential thrust block in a stock application.

Click to expand...

momoparman said
Most guys who have problems with Green bearings are running the RP-400 first generation version or incorrectly made aftermarket axles or housings or poorly designed rear disc brake kits, all of which cause pre-loading and premature bearing failure.

I have several customers running MO-400 snap-ring Green bearings in daily drivers. The design is no different than what came stock in millions of other vehicles, including 60s era Mopar 7.25″ and Ford 9″ rears. (For example, see here) I do not stock, nor do I recommend the first generation RP-400 Green bearing with the crimped-on 5 hole retainer. I only carry the loose fit, snap ring style second generation MO-400 design.

Yup, because the axle side loads are carried where? somewhere else. Apples: Meet oranges.

Snap ring? What's the snap ring do? I hope it's not carrying cornering loads.

momoparman said
Mopar Green Bearings for 8 3/4" (8.75) and Dana 60

Mopar Housing Gasket+Seal Kit for 8 3/4" (8.75) or Dana 60 for reference above. Sounds like the new bearing is a dual-taper/angular-contact cartridge style.

moper said
A customer's Cuda weighs 4100lbs and he road races it. It's been past 150 on the highway, and on Watkin's Glen. Car has huge Baer brakes, low aspect ratio wide sticky tires, etc. After 10 years of abuse, the gears gave up, but the Green bearings have never been an issue. I'd like to have some examples of them "failing" due to corners. They fail due to incorrect installation, not design or capacity.

And what, pray tell, is the correct way to install them that so many people (including the folks at Mopar Performance, who recommended you not install them for anything other than drag racing), are failing at?

RustyRatRod said
Most all modern cars have hub assemblies with green style bearings. They run for hundreds of thousands of miles with zero issues in millions of vehicles. We have an 04 Escape 4WD. It has 146K plus on it and still sports the original hub assemblies. No noise, no nuthin. In fact, it's the best car we have ever owned, PERIOD. I think you're safe.

The hub assemblies don't use a green-style bearing (Edit, I'm considering this in reference to the old-style green bearings. No comment on the "new n' improved" ones). They're angular contact ball bearings. Using angular-contact balls instead of tapered rollers, they absorb thrust just like a Mopar 8 3/4; there's no diff in the middle and the end play is controlled via fixed spacer.

RustyRatRod said
How many miles does the average five year old car have nowadays compared to 40 years ago? A damned shitload. Hub bearings last. It's a fact.

There's always one in every crowd that will argue with a signpost.

I won't dispute either point. After a quarter million miles on my neon, I failed one. I suspect the others will start growling on the way to work this morning.

Of course, there's more maintenance involved, but factory 8 3/4 bearings will last as long too. Green bearings (Gen 1? Gen 2? beats me) maybe not so much.