Wheel/Hub bearing and 10-bolt Question

[FlyingDutchman]

This is for my 1997 Z28. Has just over 90K on the clock. Stock T56 with stock 10-bolt 3.42s in it.


Case 1:
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I have been noticing a 'knocking' that I thought was in the front end every time I hit a bump. It has progressively gotten worse. When turning slowly into parking spaces (low speed, neutral) I can hear a clunk/metallic grind.

I assumed the knock was from the sway bar. So I replaced the front sway bar and end links after noticing a piece had broken off (look at the picture).



I thought the rear end might be grinding so I spun the wheels by hand and it seemed to be quiet. I also noticed the rear end has become a bit of a whiny PITA (literally). No play up and down by the rear or tail shaft. Only play is rotational which I believe is normal (right?).

That did not seem to solve the problem. So today I jacked up the car, shook the front wheels up and down, side to side etc. and could not replicate the 'knocking' I was experiencing while driving. Figured it could be a ball joint or something. Only noise I got was the brake pads shifting a bit. So, with the car resting on all four wheels, I grabbed the front passenger wheel with both hands and proceeded to shake the car back and forth. I hit a frequency in which I heard a not so healthy noise coming from the rear passenger wheel. Proceed to shake the rear wheel and find out there is play there. I assumed I was negligent in tightening my wheels and maybe had loosened and wrecked the wheel. When taking off the wheel none of the lugs were loose (in fact it took some muscle to loosen them). It appears the bearing may be shot. I can pull the wheel in-and-out maybe 1/16th or so? The moving part seems to be the rusted hub in the center. Below is a shot video so you can hear the noise and see what I am shaking.

This is the front (didn't have a picture of the rear on file), the rusty part im talking about is dead center of the rotor.


This is the rear wheel I am shaking. Not the best video, but the noise is audible.


To verify the rear end wasn't shot, I removed the other wheel which is nice and tight with no play anywhere.

So the question is ... what exactly is moving around? Wheel bearing? Something worse? What parts will I need to replace? Is it an entire assembly? Procedure for replacing bearing?



Case 2:
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My other question is pretty easy. While inspecting the rear, it appears the torque arm and front of the differential is covered in oil/dirt. One of the torque arm bolts had a drop of oil hanging off. I am assuming the pinion seal is leaking. Easy job to do myself? I need to get back to NJ from PA, I may just add enough fluid and do it over Thanksgiving break. What kind/type of oil/additive do I need? Is the fill hole the square drive bolt located maybe 3/4 up from the base of the differential?



Sorry for the lengthy read, prompt answers are greatly appreciated as I would like to tackle it this week.

Thanks in advance,

- Josh

[MyFirstZ]

The Pinion seal can definitely be done your self. Just make sure it goes in square. I did mine not to long ago you also have a breather at the top of the pumpkin. So see if you can trace any gear oil up to it.

I actually experienced the same noise coming from my ten bolt. I have heard from two different GM techs a few things. One it was normal. Second the C-clips for the axles wear out.

Maybe because my car is freaking loud I cant hear it now but before when i had the magnaflows I never heard that actually causing any type of noise while driving.

I would recommend replacing the c-clips and change the diff fluid. While your in there check for any wear on the axles or on the gears.

As far as additive GM sells a little 3oz or something like that bottle for 10$, then you need two quarts of either tGM's synthetic fluid (27$) or you can use mobil one. (75w-90) I know people that have used royal purple also. As far as filling, normally I will fill until it comes out the fill hole.

As far as knocking over bumps, when you shook the wheel you grabbed at 12 and 6, 3 and 9?
You may not always hear the noise but will feel any play. I know the rear shocks could make a hell of a noise when they start going bad.

[FlyingDutchman]

Ok thanks for the reply, going to check it out today and figure out what is moving and where. Do I have to go to a GM dealer for the additive? That may be a bit of a problem, not many out by me.

[MyFirstZ]

I haven't seen many other places that carry them. You might get lucky at a part store.

[FlyingDutchman]

Went outside and jacked up the passenger side again. Put my hands at 3/9 6/12, tried to shake side to side and I got nothing. There is no howling indicating a bad bearing. Only howling I get is gear whine on deceleration. The wheel/rotor assembly seems to move in-and-out as a unit. The axle housing didn't shift, no play in the shock/spring assembly either. I would also say its not really a 1/16th of play, less than that. Seems like a worn c-clip according to you description.

There is a Chevrolet dealer just down the street ha. They said one bottle of LSD additive is $20.84, gear lube (85w-90) is $35.80 per quart. They didn't have any c-clips in stock but they are just over $8.18 each (may have to have them order one). AAP has Mobile 75W-90 for $11 per quart, probably go with that.

I am thinking of ordering c-clips off of rockauto but they didn't have them listed under my car... The only c-clips came up for older Camaros using 8.5" 10-bolt and Pickup/Suburban as part #81050. They are listed for $2.21, far cheaper to order online instead of driving 2hrs to a dealer that has them. Are they the same for all 10-bolts?

Thanks.

[MyFirstZ]

I would imagine you need to go by your vin for axle diameter. Not exactly sure where the c clip is located in there. Seems like a lot for the additive though. But yeah I went with mobil 1 for that reason.

When I said to grab those places on the tire I was referring to the front.

Also take a peak at your lower control arm bushings in the rear. They can cause a rattle/knocking.

[FlyingDutchman]

Well there's definitely something wrong in the diff which I will address when I get home. I think it will be fine so long as I take it easy. The LCA bushings were ok, they are newer non-adj BMRs; less then 10k on them.

I took your advice and checked the shocks by pushing/lifting repeatedly on the car to see if I could find the knock. Seems like something in the driver side suspension is worn. Ive heard it could be the shock...

So many issues, so little time lol

[FlyingDutchman]

Used my FlipHD video camera and took a ride around the block. Its clearly pronounced whenever I hit a bump as you can hear. I doesn't do it on acceleration/braking. Doesn't occur when I shift. Doesn't matter if its in gear or neutral. Im going to change the oil on Saturday, so while Im under I will see if I can find anything loose ...

link to video
http://www.youtube.com/watch?v=WjxaXA530is

[MyFirstZ]

The knock noise is what you hear in the start of the video right ? You can always peel back the carpet in the trunk and expose the shock tops see if is more pronounced.

[BigAls87Z28]

Once you get the front end in the air, grab the front tire at the 9 and 3 o'clock position and alternate pushing.
If it shakes side to side, you could have possible outer/inner tie rod problem.
If you grab the front tire at 12 and 6 position of the tire and alternate pushing , there should also be no movement. If there is movement, it would be related to ball joints.
That clunking sound could either be the shock mounts in the front worn out, or a bad ball joint.

[MyFirstZ]

Grabbing those spots will also find any play if any in the front wheel bearing assembly.

Any luck with the diff ?
Is it coming from the front or rear the noise ?

[FlyingDutchman]

Originally Posted by BigAls87Z28

Once you get the front end in the air, grab the front tire at the 9 and 3 o'clock position and alternate pushing.
If it shakes side to side, you could have possible outer/inner tie rod problem.
If you grab the front tire at 12 and 6 position of the tire and alternate pushing , there should also be no movement. If there is movement, it would be related to ball joints.
That clunking sound could either be the shock mounts in the front worn out, or a bad ball joint.

Tried that, everything seems tight without play. No play in the steering wheel or weaving back and forth. At 90K miles it could possibly be the shocks. If memory serves me right, I recall hitting a sizable pot hole on the passenger side not too long ago. Whatever it is, its coming from the front somewhere and only makes noise over bumps, usually when the passenger side hits a bump.

Originally Posted by MyFirstZ

Grabbing those spots will also find any play if any in the front wheel bearing assembly.

Any luck with the diff ?
Is it coming from the front or rear the noise ?

Not going to play with the diff until I get home tmr. Im having a mechanic do the front crank seal (leaking over my sway bar), Ill have him do the pinon seal (also leaking) while he is at it and take a look at the play in the axle while Im at work.


Appreciate the advice/opinions. Will let you know what I find out.

[MyFirstZ]

Sounds good buddy, Good luck !

[FlyingDutchman]

Dropped it off, had my mechanic do the pinion seal and crank seal in the front plus look into whatever is knocking. I also asked about a groan/pop coming from the rear.

He checked over the front end, every thing was nice and tight. Checked the bushings and joints, all was good. His best guess was possibly the piston within the shock. As for the rear I was told the end of the axle shaft tends to wear against the spider gear pin so its nothing really serious at this point, but I will have to replace it at some point. As for the groan/pop, I thought maybe the diff was going but apparently the rear coil spring was the culprit; so he greased it and now all is well.

[MyFirstZ]

Very nice, sounds like you have a pretty GM knowledgeable mechanic. Sometimes you can't replace experience.

Thats kind of what i figured it was, just in the rear. Wasnt certain if the front did that since the springs are mounted on them.