Mystery Noise

[GOFAST]

I need some assistance in identifying the source of a mystery noise on my '95 (4500 miles). When I back out of my garage or a parking place, I hear a loud "pop" coming from the left rear wheel area. I'm wondering if it could be the ride control system.

Any ideas?

Thanks.

[mike100]

Not ZR-1 specific and most likely the half shaft splines going into the hub are sticking and pop when they move.

Try tightening the axle nut to see if it goes away. You can also take the half-shafts out, wire brush the splines and put a little bit of synth. grease on them. There is also a teflon coated washer that is recommended to replace if it is not in good shape, but I have never had to get new ones to fix this noise on any C4 I have worked on.

[GOFAST]

I have not removed a half shaft on a C4. Does the half shaft have splined drive shaft that goes through the hub assembly? It never makes noise moving forward. Why not?

Thanks.

[GOLDCYLON]

Not ZR-1 specific and most likely the half shaft splines going into the hub are sticking and pop when they move.

Try tightening the axle nut to see if it goes away. You can also take the half-shafts out, wire brush the splines and put a little bit of synth. grease on them. There is also a teflon coated washer that is recommended to replace if it is not in good shape, but I have never had to get new ones to fix this noise on any C4 I have worked on.

This is not a ZR-1 specific problem however a C4 specific problem. The teflon washers always seem to be the problem as they get chewed up due to inproper lubrication. Mike is right.

[mike100]

I have not removed a half shaft on a C4. Does the half shaft have splined drive shaft that goes through the hub assembly? It never makes noise moving forward. Why not?

Thanks.

I don't know, but if I had to guess, it may be pulling out of the hub (toward center) in one direction, but not the other due to anti-squat diff torque loading and unloading the rear suspension. in other words the pinion gear is trying to crawl up the ring gear but it can't so the diff twists against the c-beam and suspension itself. Going in reverse it torques the other way and the suspension loads the other way too.

You will have a 97% chance of fixing this noise by just taking your rear wheels off, pulling the cap and cotter pin on the axle nut and tightening it to the next spot where the lock cap will let the cotter pin re-insert.

Just do that for now. If you service or repair the rear of the car later, the half shaft splines can be cleaned and lubed then.

[GOFAST]

Thanks. I'll keep you posted.