Green Axle Bearings: Replace or Leave 'em Alone??

[bill440rt]

Well, I managed to drop & disassemble the rear suspension today on Project '69. I pulled out the rear axles (8-3/4 rear), & noticed that someone had been in the rear-end before as the bearings were replaced with the sealed Green-type. That's OK, as I have previously purchased a new set of Green bearings to replace them, anyway.

My question is, should I go ahead & replace them while the rear is disassembled, or leave them alone & just replace the large O-ring when I put it back together? What is the life-expectancy of these bearings?

I have them on both my other cars, maybe in my '68 there is about 2000 miles on them. I have no idea when they were replaced in this '69 or how many miles are on them, the car was a roller when I got it. They look OK, any way to check if there is play? The axles did not seem to move side-to-side at all. The drum area was dirty & full of crud, but the axle insides seem OK. That kind of leads me to believe they were replaced a while ago.

Sorry if this is a redundant post, but I did a search here & did not find the answer I was looking for. I did see some mentions of removing the center thrust block?? 
Please excuse my lack of mechanic skills, I'm more of a body guy, but can someone explain to me how this is done & why it's important to remove it? I don't think I removed it on my other cars, I just installed the bearings & went. No problems at all, both are street driven cars but I don't whip around corners with them. I will be removing the center section to replace the gasket & inspect the gears soon. Car has 3:91 Sure-Grip.
Any help or input is greatly appreciated.

[firefighter3931]

Bill, leave the green bearings in there....they will last for several years and many thousands of miles. 

The thrust block is not required (green bearings) because as you know there is no preload adjustment with the green bearing assemblies. With oem style bearings there is a procedure for setting preload so the block is required to make up the space between the axle shafts (so pre-load can be adjusted).


Ron

[471_Magnum]

 

Leave them in there until they start to howl.

No major disassembly is required to replace them later (w/ green bearings, anyway). Takes only a few minutes to pull the axles, then a trip down your local machine shop to have the old ones removed and new ones pressed on.

[Just 6T9 CHGR]

As per our phone convo

[bill440rt]

Thanks for ALL the input, guys! 

I figured, I guess since I had it apart I might as well change them now, even though a set of "unknown age" green bearings are already installed. If they last that long, I could then get by with what I have, right? They should last a long time. I can always replace the O-ring to ensure no leaks.

Can someone please tell me what this thrust block looks like, & where to find it? Is it in the center section? How do you remove it, any special tools? Do I need to disassemble that or rebuild that to remove it? Maybe someone removed it already since the green bearing swap was already performed?? 

[Chatt69chgr]

Thrust block pushes into the differential on each side (Mopar part number 2881313).  They look sort of like tappets out of a briggs and stratton lawn mower.  They are inch long rods about 1/8 inch dia with a flat holeless washer welded on the end maybe 3/4 inch across.  The end of the axle shaft pushes against these on each side making the whole axle assemble and differential a solid piece allowing the adjuster on the right wheel to set the preload on the tapered Timken bearings on the axles.  These bearings were used to absorb side loading (ie, going around curves) on the rear end.  These bearings are lubricated with the differential oil.  The green bearings are sealed ball bearings and are not really designed to deal with side loads.  They work quite well for drag racing where you are going in a straight line as well as for the kind of driving most do just taking the car out on sunday or to a show.  So if you have green bearings, you don't need the thrust blocks.  Least ways, that's my understanding of this.  But I certainly won't mind folks correcting anything I have misstated.  I am still learning. 

[Just 6T9 CHGR]

Thrust buttons.....

[smasherofall]

Thrust block pushes into the differential on each side (Mopar part number 2881313).  They look sort of like tappets out of a briggs and stratton lawn mower.  They are inch long rods about 1/8 inch dia with a flat holeless washer welded on the end maybe 3/4 inch across.  The end of the axle shaft pushes against these on each side making the whole axle assemble and differential a solid piece allowing the adjuster on the right wheel to set the preload on the tapered Timken bearings on the axles.  These bearings were used to absorb side loading (ie, going around curves) on the rear end.  These bearings are lubricated with the differential oil.  The green bearings are sealed ball bearings and are not really designed to deal with side loads.  They work quite well for drag racing where you are going in a straight line as well as for the kind of driving most do just taking the car out on sunday or to a show.  So if you have green bearings, you don't need the thrust blocks.  Least ways, that's my understanding of this.  But I certainly won't mind folks correcting anything I have misstated.  I am still learning. 

pretty accurate except for the tapered bearings aren't lubed by differential oil, they are packed with grease and sealed from it

[bill440rt]

Chris, THANKS for the pic of the thrust buttons! 
At least now I know what to look for. Maybe/hopefully they have already been removed.

Well, after further inspection I decided to replace the bearings anyway. They were a lot easier to spin than the new ones, which may have signified higher mileage. The amount of crud & crap built up around the seals verified this. The new ones were very hard to turn by hand. Also, my replacement bearings were twice as beefy looking than the ones that are on the axles now. The mount flanges on my replacements are at LEAST twice as thick. Maybe the ones that were on there were an inferior type, not sure. I just figured it's apart NOW, why take a chance later when it's back together?

Dropped 'em off at a mechanic friend's garage, they should be ready tomorrow. I'll let you know when I remove the center section if the thrust buttons are in place.

[471_Magnum]

Noticed something really interesting when watching Dream Car Garage last night.

They were rebuilding the 8 3/4 axle for an XV Motorsports car. Anybody want to guess what type of axle bearings they were using? Sure looked like "inferior" green bearings. Did my eyes deceive me?

Don't get me wrong. I don't want to start a debate. I've always considered green bearings to be perfectly adequate on a street car. At the same time, I appreciate the additional capacity the tapered bearings offer.

I just found it interesting that they would "settle" for green bearings on a car being upgraded for extreme handling.

[GMachineDartGT]

Here we go, the great axle bearing debate...I have had greens since they became available in the 90's. I just replaced my first set after 50-60K miles. True, they don't last 200K or more like the originals, but they are absolutely fine.

[tricky lugnuts]

   Sorry to stir up the Great Bearing Debate, but I was just wondering... The green bearings are non-tapered bearings that bolt onto the rear end housing -- if I'm not mistaken. Is it true that they are primarily for straight-line racing? I ask because my 71 Charger with an 8 3/4 rear end needed two new wheel bearings last summer. (My they can get noisy!) What a joy the tapered factory style is to replace -- with the need to cut off the old race and press all the crap together and then set the endplay -- it's really a chore.
     I went with the original style bearing because they were a little cheaper, it's true -- $35 each -- but also because a friend of mine said the non-tapered bearings go to hell real quick if you're doing a lot of cornering or unfortunate enough to hit a curb or pothole -- though they are supposed to be a thousand times easier to install.
     But if the green bearings just bolt on and will last for 50 to 60K miles, I think I might do that next time...

[tan top]

  Sorry to stir up the Great Bearing Debate, but I was just wondering... The green bearings are non-tapered bearings that bolt onto the rear end housing -- if I'm not mistaken. Is it true that they are primarily for straight-line racing? I ask because my 71 Charger with an 8 3/4 rear end needed two new wheel bearings last summer. (My they can get noisy!) What a joy the tapered factory style is to replace -- with the need to cut off the old race and press all the crap together and then set the endplay -- it's really a chore.
     I went with the original style bearing because they were a little cheaper, it's true -- $35 each -- but also because a friend of mine said the non-tapered bearings go to hell real quick if you're doing a lot of cornering or unfortunate enough to hit a curb or pothole -- though they are supposed to be a thousand times easier to install.
     But if the green bearings just bolt on and will last for 50 to 60K miles, I think I might do that next time...

thats what i thought  green bearings ( ball bearings) were really for straight line action &  were not as good as withstanding the force of hard cornering compared to the stock taper rollers

[471_Magnum]

I too have put many thousands of miles on green bearings. I run them on my Charger.

The tapered needle bearings inherently have more side load capacity than tapered bearings. No debating that.

Do you need the extra capacity? That's the debate.

[rcannon440]

I'm replacing my green bearings with the original adjusted bearings, problem is I need to find the adjusters and the thrust block, does anyone know where to find these?