Chasing a noise in rear end

[AA-ron]

Good morning everyone,

I'm still chasing this noise down in my rear end. I have about 1500 miles on my car and the noise is getting worse. I have an IRS rear end (new from FFR).
This noise is a thunking kind of sound and it relates to bumps in the road. I originally thought it was related to my suspension and I thought perhaps it was a sticky bushing. It almost has that rubber tacking against metal sound. However, I've ruled this out as I was able to flex the suspension and not hear the noise. I also greased all the fittings again to just be on the safe side and nothing I do gets rid of the noise. It happens over small bumps and can be heard next to and behind the car. Well... I believe I found the source of it and it seems to be related to the CV shaft input to the pumpkin. With the car in the air, I can push up and down directly on the CV shaft (not rotating it) and I seem to be getting the clunking sound I'm hearing while I'm driving. The sound is coming from where the CV inserts into the dif. I can feel play at this point-- again, not rotational but vertical. I've attached a picture of this connection and I'm wondering if any of you see anything wrong with this joint?
I'm not nitpicking here, as even my wife has mentioned the noise on our last drive, and my neighbor says he hears it as I pull and out of the driveway.
Any help would be greatly appreciated.

[cc2Arider]

Hi AA-ron!

Something no one else has mentioned so far...double-check your upper suspension and toe-link jam nuts.

I surprised myself to observe rotational play in my IRS knuckles as I was torqueing down my Wilwood brakebrackets last night -- it was simply the adjustment jam-nuts loose.

Craig C

[Hoooper]

You shouldnt have any up and down play with the CV at the diff. Can you take a video? If its loose at the diff I would expect you to be losing oil out of the diff but it doesnt look like any is coming out

[Mastertech5]

There will be some slight amount of up/down play in the inner CV joints. It should be very minimal. I don't think that is the root cause of your noise. I've seen them much worse and not make noise but they'll leak. Suspension noises are some of the hardest to find because the forces involved can't be readily duplicated when not driving the car. I would usually prod and pry control arms and bushings the check for excess play. A through bolt for a bushing can cause that if it's not tight enough as well as shock bolts on your coilovers. If you have sway bars with ball socket ends they are infamous for that type of noise.

[Railroad]

If you have anti roll, (sway bars), disconnect one end and see if it helps.