Cascade Crew

83Z28BlackBetty · Posted: Thu Jun 28, 2007 12:41 pm Post subject: knock knock knock goes the rear

So i've been hearing a knocking sound coming from my back right. It is definitely varying with speed and turns to a slight vibration when at speed. Nothing violent but annoying. What do you all think it may be. Sorry this isn't more specific but I am still new to the suspension on these cars. any help?

~JAKE

blue89 · Posted: Thu Jun 28, 2007 1:03 pm Post subject:

Could be a bearing. They make a fast knock/click sound that goes up and down with speed.

83Z28BlackBetty · Posted: Thu Jun 28, 2007 3:54 pm Post subject:

its a really deep pitch knocking sound and it seems to be from the rear right side? I'm confused and I don't want to go replacing parts that don't need replacing.

~JAKE

Twilightoptics · Posted: Thu Jun 28, 2007 4:58 pm Post subject:

I'd start by jacking it up and turning the wheels by hand and seeing if I hear anything. Also checking to make sure nothing is touching anything spinning... IE wheel & driveline.

Sellmanb · Member Joined: 30 Nov 2004 Posts: 727 Location: Tigard, OR

Paul pretty much hit it on the head. If you can hear anything when the car is in the air and you spin the tires, you'll need to pop the diff cover off.

Make sure your torque arm bushing isnt worn, struts arent bottoming out, things of that nature.

If it does this sound constantly I'd expect that once the car's in the air it should be very obvious.

83Z28BlackBetty · Posted: Thu Jun 28, 2007 9:17 pm Post subject:

cool, good call guys. I may try that this weekend.

~JAKE

83Z28BlackBetty · Posted: Sun Jul 01, 2007 1:23 pm Post subject:

So i jacked it up yesterday and its not the drive line, it makes that sound when i pull on the wheels. there is about a half an inch of play in and out and it makes a clunking sound. there is no vertical play or twisting so i don't think its wheel bearings.

something wrong with the spider gears maybe? I'm clueless. any help would be great.

~JAKE

Twilightoptics · Posted: Sun Jul 01, 2007 9:46 pm Post subject:

It will have some in and out play because we have C-Clip axles on our rears.

1/2" seems like it might be much, but I don't remember off hand.

Where is the clunking coming from?

Does it clunk when you TURN the wheels?

Xophertony · Posted: Sun Jul 01, 2007 11:26 pm Post subject:

you have a drum rear correct? if you have drums those C-clips are the ONLY thing holding your tire/wheel/axle to the car, without them they will fly off. if you have discs the caliper will hold the axle/wheel/tire/rotor on the car. if you have discs it may be that those c-clips have failed, allowing more axle play then usual since only your discs are holding the axle in.

9 bolts are bearing retained, so there is little to no axle play. you gotta get one. they are awesome.

83Z28BlackBetty · Posted: Mon Jul 02, 2007 6:51 am Post subject:

Its a non posi drum rear-end. I doubt its the C clip cuz the wheels are still there. also there is no sound when i rotate the tires, only when i push/pull on them. When i push/pull i can hear the clunk from in the differential. I didn't want to pull the cover that day cuz it was getting late and i needed to drive the next day.

~JAKE

blue89 · Posted: Mon Jul 02, 2007 6:59 am Post subject:

Sounds like the c-clips might be worn. Take the diff cover off and take a look. Usually you cannot here the slop from the clips.

When you were hearing the original "knock", when did it make the noise?

83Z28BlackBetty · Posted: Mon Jul 02, 2007 7:25 am Post subject:

Twilightoptics · Posted: Mon Jul 02, 2007 8:25 am Post subject:

There is always alot of play in the c-clip axles period.

Tony, with Discs, they wont move at all. The caliper holds them in place.

IF you pull the diff cover you'll need two bottles of 85w90 gear oil and maybe a gasket for the cover.

And it's going to make a clunk sound when you move the axle in and out by hand. You're smacking metal on metal.

rjmcgee · The Hammer Joined: 08 Jan 2004 Posts: 2328

blue89 · Posted: Mon Jul 02, 2007 8:34 am Post subject:

Still sounds to me like its the bearing, not the c-clips. Axle end play is not supposed to be more than 1/8" I believe. More won't really kill it but could be an indication that the clips are getting worn. When I did my 4.11's on my disk rear (converted from drum) the c-clips were worn about half the original thickness. They would almost FALL OUT! As in, you didn't have to take the pinion shaft out to pull the axle!

If you are going to take the cover off, go get new bearings, axle end seals, new c-clips, gear oil, and a cover gasket. Do it all at once. It sucks to take it apart more than once just because you didn't want to replace a $10 part. Go now and do.

83Z28BlackBetty · Posted: Fri Jul 20, 2007 7:35 am Post subject:

A little more info:

So i replaced the u-joints and the sound is still there, but while it was up in the air i messed around with it a little.

Clunks when i drive in a straight line that varies with speed.

I can rotate the wheels back and forth about 5* freely before i feel they catch and actually start turning the driveline. feels like a steering wheel when you have shot tie rods. Confused

I think it is in the dif then. but I'm also pretty sure that my rear end is not worth trying to salvage anyways, considering it is a non posi, drum brake, with a ratio of 2.93 (came standard on my car).

~JAKE

blue89 · Posted: Fri Jul 20, 2007 9:54 am Post subject:

Thats normal. Open rears have to turn the spiders, which spin on pinion shafts, that turn the carrier, that turn the pinion gear, which turns the driveline. 5* isn't bad. Hell, even my Auburn has that much play.

Still sounds like the problem is the bearing. The more you drive it, the more damaged the axle shaft can get. You should take it apart and figure it out. Just get new bearings, axle seals, gear oil, pumpkin gasket, and have at it!