Rear end noise! side to side clunking sound..C-clips broken?

**DaytonaBlues** · 10-29-2012, 09:44 AM

I wish i had a sound file of this but when i tried to diagnose a clunky noise from the car during driving over bumps I noticed something odd. I noticed that when the car is on the ground or in the air for that matter when you grab a rear wheel and move in in and out i hear a pretty loud clunky sound and the wheel you can feel move in and out a little bit..almost like the axle is moving in and out inside the differential. Im stumped as to what the hell is this. Im assuming maybe the bearings are worn or the C clips might be broken??? both sides do this and the in and out movement of the rear wheel is about the same on each side. With the car on the ground and you push the car side to side you can easily hear this clunky noise of the axles moving in and out inside the rear end..more so when the car is in the air and you do the same thing. the car has a stock rear end with the torsen in it (1999) and 112k miles. i did change the rear end oil to Castrol synthetic 75-90 and used the GM additive from the dealer.

is this a sign the rear end is about to barf on me? the rear end doesnt make any noise at all really driving slowly in a circle, and going around a corner its quiet. the only noise is this clunking sound from the rear end while driving. Note this car does have really worn rear shocks and the Panhard rod is BMR adjustable but one of the bolts loosened up and rounded out the hole in the bushing...which im trying to figure out how to find a replacement bushing for a BMR panhard rod...i dunno if i should be worried about this??????

thanks to all.....

***SMWS6TA*** · 10-29-2012, 10:04 AM

If your c clips were broken you'd know it by now, your axles would just come out. Checking the bearings is a good place to start for the rear. Now I'd be more worried if you were hearing grinding noise. That is one of the signs the rear is going. Clunking noise could be a bad CV joint, loose/broken suspension, etc.... It takes some investigation to find.

This is the car that was bought from an estate and just had the transmission replaced correct?

If so, you're going to keep finding issues till you get them all fixed. It may not feel like you got a good deal currently but don't get discourage. It's been sitting for a long time and stuff is going to go bad. Bushings, bearings and gasket/seals all go bad quick the longer a vehicle sits. Just take it with a grain of salt and work the issues of as you can, it will get back in shape in no time.

Some of the noise issues could be coming from loose bolts and bad bushings. Most aftermarket parts have replaceable bushings. Look at the BMR site or some of our sponsors for replacements.

**Smittro** · 10-29-2012, 10:52 AM

99 z28 has rear disks, if the c-clip is worn, fallen out or even broken the rotor and calipar will hold the axle in the housing.

No 4th gen f-body ever came with CV joints.

I do however agree to start with checking bearings.

**Smittro** · 10-29-2012, 11:17 AM

If you suspect it's within the differential pull your cover and have a look,

because if the calipars are holding things together that's not a good thing.

How much play are we talking about?

***SMWS6TA*** · 10-29-2012, 11:22 AM

Originally Posted by Smittro

99 z28 has rear disks, if the c-clip is worn, fallen out or even broken the rotor and calipar will hold the axle in the housing.

No 4th gen f-body ever came with CV joints.

I do however agree to start with checking bearings.

Meant U joint but defaulted to my Hummer days subconsciously

**DaytonaBlues** · 10-30-2012, 03:07 PM

Not much play. Maybe 1/8 inch or less in and out. You can barley see the wheel move in and out. I'd say 1/16th play. The car was sitting for a while but the guy hasn't beaten on the car since he's had since 60 k miles. So be just drove the car hiway until 100k miles. I'm suspicious that there are worn suspension and exhaust rattle too. Just the spinning of the wheel and play movement sounds worry me

**35th-ANV-SS** · 10-30-2012, 03:44 PM

Originally Posted by DaytonaBlues

The car was sitting for a while but the guy hasn't beaten on the car since he's had since 60 k miles. So be just drove the car hiway until 100k miles.

How do you know the car hasn't been beaten on? You're taking their word? Bad idea. I'm guessing that car was beat on plenty of times.

Start with the axle bearings. Like Smittro stated, if it were bad or broken c-clips, you would know. The wheel would be moving much more than that IMO.

Also, to fix your rounded out hole for the pan hard bar you can have a washer with the correct hole size welded on each side of the bracket. Or, drill the rounded hole out to a bigger size and do the same on the PHB (assuming there is enough material there) and use a larger bolt to secure it. Get that fixed pronto as your rear end will start walking quite a bit on you and the car will become dangerous to drive.

**DaytonaBlues** · 10-31-2012, 09:06 AM

Originally Posted by 35th-ANV-SS

How do you know the car hasn't been beaten on? You're taking their word? Bad idea. I'm guessing that car was beat on plenty of times.

Start with the axle bearings. Like Smittro stated, if it were bad or broken c-clips, you would know. The wheel would be moving much more than that IMO.

Also, to fix your rounded out hole for the pan hard bar you can have a washer with the correct hole size welded on each side of the bracket. Or, drill the rounded hole out to a bigger size and do the same on the PHB (assuming there is enough material there) and use a larger bolt to secure it. Get that fixed pronto as your rear end will start walking quite a bit on you and the car will become dangerous to drive.

oh your right about the car being beat on, i meant it was beat on a lot more way back when it had 60k miles on it, it has been neglected since the new owner took it over at 65K, now with 112k miles. anyways, the problem with the panhard rod bushing is that the bushing itself is rounded out inside i think The bolt that holds the p-rod to the bracket was loose, which allowed the p-rod to move around in the bracket, therefore causing the bolt to wear out the inside of the bushing. now i gotta find out how to find a replacement bushing. other thing is, DOES ANYONE KNOW the lenthg of a stock panhard rod??? this one is adjustable and i want to make sure the doofus who had this installed got the adjustment right.

as far as the rear end goes, i guess axle bearings starting to go would cause the in and out play of the wheels??
thanks again for all yous guys help

**35th-ANV-SS** · 10-31-2012, 02:39 PM

I can measure mine, but I adjusted it since I'm lowered a little. It would put you in the ballpark though.

Best way is to tape a string from the quarter panel right above the top of the wheel well with a weight tied to it and let it hang down. Let gravity make the string tight. Measure the distance from the string to the tire. Do this on each side and adjust accordingly.

**fbodlovr** · 11-10-2012, 07:43 PM

Originally Posted by DaytonaBlues

I wish i had a sound file of this but when i tried to diagnose a clunky noise from the car during driving over bumps I noticed something odd. I noticed that when the car is on the ground or in the air for that matter when you grab a rear wheel and move in in and out i hear a pretty loud clunky sound and the wheel you can feel move in and out a little bit..almost like the axle is moving in and out inside the differential. Im stumped as to what the hell is this. Im assuming maybe the bearings are worn or the C clips might be broken??? both sides do this and the in and out movement of the rear wheel is about the same on each side. With the car on the ground and you push the car side to side you can easily hear this clunky noise of the axles moving in and out inside the rear end..more so when the car is in the air and you do the same thing. the car has a stock rear end with the torsen in it (1999) and 112k miles. i did change the rear end oil to Castrol synthetic 75-90 and used the GM additive from the dealer.

is this a sign the rear end is about to barf on me? the rear end doesnt make any noise at all really driving slowly in a circle, and going around a corner its quiet. the only noise is this clunking sound from the rear end while driving. Note this car does have really worn rear shocks and the Panhard rod is BMR adjustable but one of the bolts loosened up and rounded out the hole in the bushing...which im trying to figure out how to find a replacement bushing for a BMR panhard rod...i dunno if i should be worried about this??????

thanks to all.....

Have you figured out anything with this? This sounds basically EXACTLY what I am going through. Shaking the car, and hearing the clunking, hearing it inside with every little bump in the road, etc. I've replaced, LCA bushings, shocks, sway bar end links, exhaust hangers, and it's not the spare. lol The shop said it was supposedly not the bearings beause the axles still look good. I'm really thinking there is something wrong inside the carrier.

**Too Fast** · 11-11-2012, 04:07 AM

OP, what you describe is perfectly normal about the axles having slight play axially when they are retained with a c-clip. It is very hard to diagnose noises over the 'net, and if the diff were going bad usually they make really horrble noises. You sure it's not any exhaust rattle?

**DaytonaBlues** · 11-14-2012, 02:16 PM

I measured everything and its all good. Thanx..still got the damn clunky sound going over bumps. No noise at all around corners etc. I dunno..I guess since c.clips hold the axles in maybe it is normal but I doubt how anyone else can literally hear the axles moving in and out just a Little but enough to hear it while driving. Aaaaaarrrrrgggggjhhh

**Too Fast** · 11-14-2012, 02:30 PM

^^^naw. If everyone could here the axle play then it would've been eliminated 40 years ago.

Your noise is something else, just gotta find it. Very frustrating sometimes until you finally do find the source.