For quite a while now, I've heard an occasional knocking/clunking sound coming from the passenger side axle - it is most noticable during deceleration. It has been getting progressively worse. I assumed one of the CV joints were giving out, so I'm rebuilding a half shaft to put it.

While getting ready to remove the old half-shaft, I took a closer look. I don't think it is bad CV joint anymore. The play seems to be in the transmission itself. It's on the passenger side, inboard. When I twist the axle, there is a lot of play in the transmission and it makes a knocking sound. The drivers side doesn't have this play in it.

What is going on? Am I looking at a transmission rebuild or is this something that can be fixed without a full rebuild?

Here is a video:

https://www.youtube.com/watch?v=9nbvEPOZKiQ...eature=youtu.be

for Bob.

My car will probably be up in the air later today and I could compare to mine, but I recall at least some play in mine as well. I'll go ahead and ask: you've inspected the trailing arm bushings? Does the wheel itself have any play side to side or up and down? Engine mounts? You say it's during deceleration only?

Maybe Dr Evil will chime in but on the good bad scale, I would have to say that much play is bad!

If the trans was in gear what ever is worn and causing that will get hammered back and forth on accel and decelerations. Eventually something will break.

Look up Dr Evil and ask him to look at the video.

That's not good.
Best case scenario is worn splines on drive flange.
Which would be unusual.
If so you'll only buy time by replacing the worn one.
Remove both sides and compare condition.
Try good one on worn side to evaluate interior condition.

Hi, I just tried it on my 1973 that is on jackstands now. When I do that on my driverside rear wheel I do not have that clonk as in your video.

Ya, that doesnt look good. Assuming that the other side of the diff is not moving when you do that, you are checking backlash in a crude matter and it is HUGE. Pinion likely worn, or something is not well inside causing large opening of backlash. Back lash should be 0.12-0.18mm and is measured with the diff locked. Other option is that the diff internals or splines on the output shaft are kaput. Those are more simple/inexpensive to fix. You wont have the special tools to set all the parameters, tho, if/when diff is changed or pinion and ring is changed.

Thank you for the responses. The sound in the video is the sound I've been hearing (only louder), so I think it's got to be in the transmission.

The excessive backlash is only on the passenger side.

I'm pulling the tranny out today and taking it to Steve Limbert @ Aircooled Racing to investigate. He took a look at the video and agreed to take a look at the transmission.

Epstein was kind enough to give me an old tailshift that I can cannibalize parts from.

Will post what we find out.

I continue to appreciate the incredible knowledge resource that is 914world.com.

You guys & gals are awesome!

I just realized I never followed up with this post after fixing this a few weeks back.

I pulled the tranny and took it to Aircooled Racing. Steve went over it and didn't see any problems.

I replaced the passenger side half shaft with a rebuilt one and the problem was solved.

Its great to be back on the road again.

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Wow

Well, glad you’re back up and running.

Glad you got that resolved, Bob!