How to Tell if Rear Axle Bearings are Worn - S-10 Forum
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How to Tell if Rear Axle Bearings are Worn

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Old 08-01-2009, 08:09 PM   #1
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How to Tell if Rear Axle Bearings are Worn

How to Tell if Rear Axle Bearings are Worn
I was wondering if anyone knows how to tell if the rear axle bearings in a 2002 Z-R2 are worn and need replacing. I have noticed a bit of a clunky noise in my Z when I am reversing/driving forward while turning at low speeds. It is not constant, but noticeable when the rear wheels go over uneven areas such as dips/ruts/bumps. Never while straight driving, or straight driving over bumps. If I stand beside the box and shake it side to side, I can get the noise or a similar one, but I am not sure if it is the same. I need to shake it quite substantially to get a noise. I am having the rear u-joint replaced this week since it is squeaking, and perhaps this is the cause of the clunk noise. I will see but I fear it is time for rear axle bearings. Any help out there. Thanks everyone!
-Shawn
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Old 08-01-2009, 09:50 PM   #2
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Re: How to Tell if Rear Axle Bearings are Worn

The rear axle bearings run directly on the axles, so if you need to replace the bearings then the axles will have to be replaced too. The noise that you hear when you shake it from side to side is jut the axle end play. There are c clips that hold the axles in. These c clips have a little bit of clearance and don't hold the axle perfectly still. You can push and pull on the axles and they will move a little bit. This is completely normal. The noise that you are hearing when driving is probably the u joint.
Old 08-03-2009, 01:06 AM   #3
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Re: How to Tell if Rear Axle Bearings are Worn

Quote: Originally Posted by big gear head
The rear axle bearings run directly on the axles, so if you need to replace the bearings then the axles will have to be replaced too.
What?
Old 08-03-2009, 01:00 PM   #4
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Re: How to Tell if Rear Axle Bearings are Worn

The axle bearings don't have an inner race. The rollers run directly on the axle shaft. When the bearings wear out they also wear the axles. When the bearings need to be replaced then the axles need to be replaced too.
Old 08-03-2009, 07:56 PM   #5
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Re: How to Tell if Rear Axle Bearings are Worn

Quote: Originally Posted by big gear head
The axle bearings don't have an inner race. The rollers run directly on the axle shaft. When the bearings wear out they also wear the axles. When the bearings need to be replaced then the axles need to be replaced too.
Never heard of such. I highly doubt it.
That would defeat the purposed of using a bearing roller system that can be replaced if it wore out all your other parts along with it.
Old 08-03-2009, 10:52 PM   #6
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Re: How to Tell if Rear Axle Bearings are Worn

Have you ever had an axle out of a GM rear end? All 7.5, 8.2 and 8.5 10 bolt rear ends and all car and truck 12 bolt rear ends have this kind of alxe and bearing set up. The 7.5 and 8.8 Ford also uses this arrangement. If the bearing wears out the axle is also worn out. The 8.2 BOP 10 bolt and 8 and 9 inch Ford and 8 3/4 Chrysler use a press on axle bearing that can be replaced without replacing the axle. Any c clip axle uses a bearing that runs directly on the axle and wears the axle along with the bearing.


Two examples of worn c clip axles.
Old 08-03-2009, 10:58 PM   #7
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Re: How to Tell if Rear Axle Bearings are Worn

Quote: Originally Posted by big gear head
Have you ever had an axle out of a GM rear end?
Yes, I have one sitting in the basement with the axle shafts pulled and they look just fine. That is the reason for being confused.

Do you mean if the bearing wears out while driving it often tears up the axle shaft or that every time you replace a bearing you have to replace the axle shaft?
Old 08-04-2009, 12:14 AM   #8
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Re: How to Tell if Rear Axle Bearings are Worn

The tolerance on the axial where the bearing was riding is worn down.
Think of a front spindle.

I have seen bearing replaced and not the axial and got away with it.
But thats not a proper repair.
Old 08-04-2009, 12:19 AM   #9
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Re: How to Tell if Rear Axle Bearings are Worn

Quote: Originally Posted by Lowl!f3
The tolerance on the axial where the bearing was riding is worn down.
Think of a front spindle.

I have seen bearing replaced and not the axial and got away with it.
But thats not a proper repair.
But you're referring to the front of a vehicle.
And you're referring to a spun bearing, which is different than one just worn out.
Old 08-04-2009, 12:46 AM   #10
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Re: How to Tell if Rear Axle Bearings are Worn

Quote: Originally Posted by big gear head
Have you ever had an axle out of a GM rear end? All 7.5, 8.2 and 8.5 10 bolt rear ends and all car and truck 12 bolt rear ends have this kind of alxe and bearing set up.
A GM 8.5 with bolt-in axles also has press-on bearings.
Old 08-04-2009, 01:17 AM   #11
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Re: How to Tell if Rear Axle Bearings are Worn

You don't have to replace the axle if you are replacing a bearing as long as the axle is still good. If the bearing went bad then it will wipe out the axle too. I've put in many new bearings on axles that were still good, but I have had to replace a truck load of bad axles because the bearing wore out the axle.


OK, there are very few 8.5 rear ends that have bolt in axles. Most have c clip axles. The only 8.5 rear ends that I know of that have bolt in axles are the '71 and '72 A body rear ends.
Old 08-04-2009, 01:20 AM   #12
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Re: How to Tell if Rear Axle Bearings are Worn

Quote: Originally Posted by big gear head
You don't have to replace the axle if you are replacing a bearing as long as the axle is still good. If the bearing went bad then it will wipe out the axle too. I've put in many new bearings on axles that were still good, but I have had to replace a truck load of bad axles because the bearing wore out the axle.
Sounds like you are referring to spinning a bearing.
Correct?

If so, I was simply referring to replacing a bearing that is wearing out before it has spun. Clearly, if you spin a bearing on anything, you are going to want to contemplate replacing the item that seats the bearing.
Old 08-04-2009, 11:35 AM   #13
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Re: How to Tell if Rear Axle Bearings are Worn

It's very rare that a axle bearing from a c clip rear end will spin, and if it does then it will wipe out the housing end too. Go to your basement and look in the housing at the axle bearings. You will see that the rollers in the bearings have no inner race. The rollers run directly on the axle shaft. Look at the axles and you will see where the bearings run on them. If they have no wear on them then you will just see a darker area. If you see where there has been any metal removal from this area then the axles are worn. Click on the pictures that I posted above. Sometimes it is only pits like the first picture and sometimes there is a strip of metal gone all the way around the axle shaft like the second picture. You will also see where the axle seal runs on the axle shaft. This is usually not a problem area.
Old 08-04-2009, 11:43 AM   #14
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Re: How to Tell if Rear Axle Bearings are Worn

Quote: Originally Posted by big gear head
OK, there are very few 8.5 rear ends that have bolt in axles. Most have c clip axles. The only 8.5 rear ends that I know of that have bolt in axles are the '71 and '72 A body rear ends.
73-77 A-body as well, BOP cars might have one. Chevy is C-clip.
Old 08-04-2009, 12:06 PM   #15
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Re: How to Tell if Rear Axle Bearings are Worn

The '73 to '77 Olds Buick and Pontiac 8.5 might have had the bolt in axles. I haven't built many of these years. I have a few of the Chevy 8.5 rear ends from these years, but they have c clip axles in them. I see that you are into dirt track racing, so you have probebly seen more of these than I have.

Last edited by big gear head; 08-04-2009 at 12:07 PM.
Old 08-04-2009, 01:38 PM   #16
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Re: How to Tell if Rear Axle Bearings are Worn

Yup, I have a 76 Cutlass rear w/ bolt-ins that is going under my next Impala.
Old 08-04-2009, 03:46 PM   #17
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Re: How to Tell if Rear Axle Bearings are Worn

Quote: Originally Posted by big gear head
It's very rare that a axle bearing from a c clip rear end will spin, and if it does then it will wipe out the housing end too. Go to your basement and look in the housing at the axle bearings. You will see that the rollers in the bearings have no inner race. The rollers run directly on the axle shaft. Look at the axles and you will see where the bearings run on them. If they have no wear on them then you will just see a darker area. If you see where there has been any metal removal from this area then the axles are worn. Click on the pictures that I posted above. Sometimes it is only pits like the first picture and sometimes there is a strip of metal gone all the way around the axle shaft like the second picture. You will also see where the axle seal runs on the axle shaft. This is usually not a problem area.
I see what you mean. I've just never had a problem with it.

Anyone want to buy spare shafts then?
Old 08-04-2009, 04:17 PM   #18
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Re: How to Tell if Rear Axle Bearings are Worn

Quote:
Yup, I have a 76 Cutlass rear w/ bolt-ins that is going under my next Impala.
How do you keep the bearing on the left axle? The 9 inch Ford rear ends will pull the left axle out of the bearing after a few races. I use to put 3 or 4 spot welds on the axle retainer ring to keep the bearing from pulling off. Some axles come with threaded retainers for dirt track racing.
Old 08-05-2009, 02:49 PM   #19
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Re: How to Tell if Rear Axle Bearings are Worn

Quote: Originally Posted by big gear head
How do you keep the bearing on the left axle? The 9 inch Ford rear ends will pull the left axle out of the bearing after a few races. I use to put 3 or 4 spot welds on the axle retainer ring to keep the bearing from pulling off. Some axles come with threaded retainers for dirt track racing.
I haven't run one yet, I'm upgrading from a 7.5 to an 8.5.

One of the rears that I got does have some tack welds on the ring.

I have talked to a couple people about it, and they advised that a) I should make and use a thicker axle retainer plate than the stock one and b) put a snap ring in to take up some of the slack so the axle doesn't have so much motion in and out of the housing.

A couple guys in the division run bolt-in axle 8.5's, one of them being the division leaders for the past 5 years (family of racers) and had no problems. Another guy hates them. I guess he was having problems breaking stock axles on the flange across the access holes. I'm planning on running a race axle on the right side as allowed per rules. I never had a problem before with my 7.5 breaking axles, but I never went as fast as the division is now.

We'll see how it goes, I originally wanted it for asphalt racing but the track went bankrupt before completion. Asphalt rules allowed a Ford 9", but I wanted the 8.5" for less rotating weight than a 9 but better gear selection than a 7.5. I have no need to change gears quickly, so the 9" wasn't something I had to have.

Last edited by ka_jd7and1; 08-05-2009 at 02:54 PM.
Old 08-05-2009, 08:21 PM   #20
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Re: How to Tell if Rear Axle Bearings are Worn

It's been my experience that c clip axles stay in better for this type of racing. I've seen the 9 inch Ford axles pull out of the bearings and push all of the ball bearings out. The left axle is the one that always comes out. Just keep an eye on that axle and bearing.
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