Heavy popping in left rear (U's? Half shafts?)

[Schrade]

I got a new sound in the drivetrain - a heavy 'clunking' in the left rear, as I roll up and down the driveway.

The speed shop that did the auto conversion had the wheels in the air, testing the speedo link. I said, "Isn't that bad for the U-joints?"

They said no. They spun it up to 50 - 55 on the speedo.

Car only has 32k on it here.

Thoughts? Opinions?

[mike100]

Its loose axle nuts. The best solution will be to pull out the 1/2 shafts and grease the hub splines. Seems to happen to most C4's at some point.

[Schrade]

Thank you Sir...

Any special tools / hardware necessary?

[scottfab]

You say up and down the driveway.
Does the noise happen going forward only ?
or backward only ?
or both?

[mike100]

he said driveway- usually while turning or maybe transitioning a grade change. It is the dry, rusty axle stub splines popping against the loosened axle nut. I think it is a 34 or 35mm nut. I took my rear tires off, but i know on some vettes you can pop the center cap off to acess the axle nut for a quick tightness check.

the permanent solution involves R&R of the half shaft to get a brush and wd-40 into the splined hub for a good cleaning and then a little synthetic grease upon reassembly. There is also a teflon coated washer (it is mounted inboard and the axle has to come out) that is recommended to be replaced (along with a fresh axle nut probably), but I never had to buy those parts for a low mileage car.

Even the C5's and c6's do the same thing- pretty much all labor and no parts kind of a job. you may choose to do new u-joints while the axles are on the table- if so, use genuine Spicer parts, not the imported ones...they fit sooo much better.

[Schrade]

Originally Posted by scottfab

You say up and down the driveway.
Does the noise happen going forward only ?
or backward only ?
or both?

Both.

No mention by the guy who drove it for me, following me, on the 60 mile trip home last week, at around 65mph...

It DOES resemble the clunking of a 4WD vehicle, with FRONT hubs locked, on pavement in a turn (something you're not supposed to do)...

[scottfab]

Originally Posted by Schrade

Both.

No mention by the guy who drove it for me, following me, on the 60 mile trip home last week, at around 65mph...

It DOES resemble the clunking of a 4WD vehicle, with FRONT hubs locked, on pavement in a turn (something you're not supposed to do)...

Does not sound like a hub. Easy enough to rock the half shaft back and forth to check for slop in the U-joint. You'd want to lift such that the full weight in on the tire (ramp it up or lower it onto some wood)

[Schrade]

I found 2 of these in my driveway in the recent past - look like needle bearings, spec @ 10.63mm...

Any of them in the rear hub / half-shaft assemblies???

[Bearly Flying]

Looks like a needle bearing from a U joint.

[Schrade]

Originally Posted by Bearly Flying

Looks like a needle bearing from a U joint.

Sounds good there BF; now if only one other would concur - I'd think it too good to be true (depending on how accessible the U-joint is)..........................