Front gearbox driveshaft output play

[willg54]

So I've been trying to diagnose a front end rattle,sound like it was in the middle of the car. Eliminated any suspension and then felt some play through the front diff on the driveshaft outputs, sounded pretty noisy and knocky.

First thought was probably cv joints. Just dropped the lh driveshaft off and it's definitely not them. The LH driveshaft cup can move in and out a few mm and has a good knock. Also a few degrees of backlash. Reckon this is the culprit.

Before I start delving further, can anyone else confirm if the is correct or just wrong... And also any other ideas?

Gearbox itself hasn't been any trouble.

[mcandmar]

So I've been trying to diagnose a front end rattle,sound like it was in the middle of the car. Eliminated any suspension and then felt some play through the front diff on the driveshaft outputs, sounded pretty noisy and knocky.

First thought was probably cv joints. Just dropped the lh driveshaft off and it's definitely not them. The LH driveshaft cup can move in and out a few mm and has a good knock. Also a few degrees of backlash. Reckon this is the culprit.

Before I start delving further, can anyone else confirm if the is correct or just wrong... And also any other ideas?

Gearbox itself hasn't been any trouble.

Check the prop shaft CV joints. I wouldn't worry about play when rotating as there is normally a lot there inside the differentials. If you can wiggle the drive shafts up and down, then the CV joint is ******ed.

[willg54]

This is with the driveshafts off. There's about 3-4mm of axial play in the output flanges. No vertical or lateral movement. Rocking them back and forwards is quick knocky
I've got new cv joints to go on as that's what I thought it was initially.

[Dynasty]

I have lot of play in the front diff in one of my Audis. Get a clunking sound when I let off the throttle (engine braking) and the gearbox/diff "meets" the decelerating engine/torque converter. Annoying AF... Worn ring and/or pinion gear? Time to open it up i guess... *sigh*

[mcandmar]

Most of the play will be in the center torsen diff as it wears, not much you can do about that.

[willg54]

Diff is out..

You can see the movement I'm on about here. It seems to be play in the sun wheels to the output flange.

https://youtu.be/aJkZ5p07CQ0

looking at the assembly diagrams, it does show a small gap between the flange and the diff housing which is obviously needed but you wouldn't think they could knock around when installed.

[Error404]

You can shim those, but i don't think that's your problem, its normal to have some axial play on the output flanges.
Are you using a single mass flywheel?

[willg54]

Yea I didn't think it was an issue so all gone back together.
I don't think it's single mass no.

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[Error404]

Cool, the single mass flywheels do tend to cause some gear rattle on low load, but if you are on the original ABY DM unit then shouldn't be any problems there.
As per Mark's suggestion, I would look at the prop first - CVs and centre bearing

[willg54]

Got new CVs going on, prop shaft doesn't appear to have any play in it so hopefully that can stay on.
Will have to wait a few weeks now!

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[Vauhtiveikko]

Did you find culprint for your problem?