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Clunk when changing gear

3969 Views 35 Replies 7 Participants Last post by  thiagaraj87
My W123 has a manual 5 speed. When pulling away in 1st, if I don't release the clutch gently I get a slight clunk.
This also happens when changing to 2nd and to a lesser extent 3rd.
There's obviously some play somewhere but I'd like advice where to look first.
If I grab the prop shaft, should there be any rotational play at the diff end? What about the gearbox end?
I read somewhere it could be engine mounts, but these have been changed recently along with gearbox mount and diff mount.
Could this be a sign the clutch needs changing?
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The centre bearing and support were changed last year too.
Hi, thanks.
Just to be clear, the centre bearing and support have been changed, but neither of the flex discs.
They both appear OK but I realise it's better to examine when off the car.
Could worn flex discs cause the symptoms I'm getting. I assumed they would have to look pretty knackered on the car if they got to the point of making a clunk.
Just about only happens in 1st and 2nd.
Replaced those last year too.

Forgot to mention I can reduce or even stop the clunk if I release the clutch very slowly.
That's what I'm thinking too.
I do sometimes get some clutch judder when cold, but that seems to be less frequent now that I use the car every day
sway bar bushes replaced a few months ago and the problem has been present before and after.
Upper control arms, rear subframe mounts, shocks and all steering arms changed recently.
Car only has 107000miles so I was hoping gear box and diff will be OK.
No apparent play in lower ball joints.
I managed to have a good look under the car today.

Does this flex disc look OK?

If I hold the flex disc and turn the prop shaft, I can close the gap marked a little.
Should I be able to compress the flex disc like that by hand.

Theres a small amount of radial play when I turn the prop shaft and I can hear a clunk.
Difficult to tell if it's from the flex disc or inside the gearbox.
The car was in first gear when I did the above.

There's very slight rotational play in the u joint as well, perhaps 3mm.
Is that normal?

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I started replacing the rear flex disc today.
It was pretty easy to remove all the bolts but a nightmare to push the drive shaft forwards to give space to get the old disc out.

I managed it eventually, but there's no way I'll get the new disc in. Centring bush is stuck in drive shaft so it's going to be regreased and stay.

I now realise that I should have loosened the 2 bolts that secure the centre bearing mount.

Does doing that allow the driveshaft to be moved forward better? It just keeps springing back and not giving enough space at present.

I could see the rear portion of the drive shaft sliding forward and I haven't loosened the 46mm clamping nut. I'm thinking it shouldn't be able to move like that?
I managed to replace the rear flex disc but still have the clunk.
I mentioned the play in other posts but here's a vid of the noise from the diff end when I rotate the prop shaft. Wheels on the ground and car in neutral.
Is this amount of play normal and if not, what could be the cause?
It's a manual, so not that.
I changed the front flex disc and the noise has pretty much gone.

Can't believe how well the car drives now!

I used to get a large clunk going over bumps as if a ball joint had worn....that's gone too.

It didn't take much to undo the bolts on the gearbox support plate. I reckon there was some movement there sometimes.

Probably some issues with axles/diff, but happy for now.
OK, so the clunk returned after a few weeks.
I checked the bolts for the gearbox support and they are tight.
Going to change the drive shafts next.
Is SKF a good brand? Can't get mine refurbed in the UK.
Drive shafts ordered. Not sure if that's going to fix it to be honest. Can someone confirm whether the play at the diff is excessive?
I changed the axle shafts and it has improved some more, but not gone completely I think there has been excessive play in each bit of the drive train. I have removed the flex disc and axle shafts from the suspect list by changing them. Both were past their best. The U joint appears fine. The only other areas are the diff and the gearbox.
What is the mileage of your car?
I convince myself that each thing I did made the clunk go, but I think I was kidding myself :) I currently have all the rear suspension and subframe off and I'll reassess when back together with new bushes.
From what I've read, I think it's rare to get differential wear unless it's lost oil or has been used for loads of towing.
Hmm. Mine has a little clutch judder when cold. My car has about 120000 miles which is why I don't think it's the diff.
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