What's this clonk?

[HoraceM22]

As I slowly reverse my UK '74 TCS off my downward sloping drive with a bit of rh down lock on there is a slight clonk from what I think is the rh rear of the car, but not too sure. I'm in the process of checking all the bolts on the undersidefrom back to front.  (They're all "new" as the car has been TOTALLY restored) So far everything has been tight as expected and the two long suspension arms where I thought the issue might be are all fine. I also think I may have heard the odd clunk whilst driving.
Any ideas?

[gideon]

Is there any play between the driveshaft U joints and the driveshafts?  George Karellas did a nice explainer on his youtube channel about driveshaft U joints.  I didn't know this before, but apparently the retaining clips come in different thicknesses and if you get the wrong ones then you can get a clonk.  Here's the relevant bit

https://youtu.be/t45cp1hY2C4?t=710

[4129R]

You, as the author of this thread, can edit the title from "clock" to "clonk".

[314159td]

Make sure to empty out the trunks before you start tearing things apart.
Many suspension clunks can be found by strategically jacking under the control arms/uprights and giving the wheels a yank through every axis. If you let everything go to full droop, that isn't representative of driving conditions.

For a recent restoration, readjusting the front hub tapered wheel bearings comes to mind. They're difficult to set correctly with that silly felt ring in the way.

[GavinT]

Apart from the items mentioned, the first thing I'd be checking is the rear stub axle nuts.

[HoraceM22]

Ahh, sorry about the "clock instead of clonk" bit.

Anyway thanks for the suggestions. I hadn't thought that it could be the driveshafts as they, along with everything else, has been either reconditioned or replaced, but after ensuring every nut and bolt from the front engine pulley backwards is tight, I was thinking that they were all that's left to consider. A couple of engine mounts were just tight but not TIGHT, but that was down to me anyway.

I have jacked under the rear uprights and given the wheels a "top-to-bottom and front-to-back" tug, MOT style, without success, but not in the in-and-out direction, so that will be my job for today.
Thanks guys.

[Dilkris]

As I slowly reverse my UK '74 TCS off my downward sloping drive with a bit of rh down lock on there is a slight clonk from what I think is the rh rear of the car, but not too sure.
Any ideas?

Can you identify whether it is caused by reversing or the rh lock? ie: if you reverse without lock, any noise?
Also are you free wheeling down your sloping drive or driving under power ?
You need to positively identify what promotes the noise so as we can (hopefully) identify the cause. 

[BDA]

It appears not to be your problem but stub axles are always worth checking out. I rebuilt my car using the original 10,000 miles old stub axles and after probably another 15,000 miles my driver's side stub axle was toast (see picture). The nut was tight, I didn't track or otherwise abuse overly stress my car. It's unusual but stuff sometimes happens and those stub axles are a huge weak point. They aren't even hardened!

[HoraceM22]

Dilkris, I'm about to get my nephew over to be able to find (if poss) where the noise actually is emanating from. As we all know, a noise can seem to be come from "A", but it actually from "B".

Anyway with two of us we can look into the engine bay and as one twists, turns, pulls and pushed the other can actually see if there is any corresponding noise from within.

Similarly, when I gentry reverse down my drive he can be closely looking at the wheel /engine bay etc. although I suppose this won't make the noise on command eh?

[4129R]

I had a mysterious sound which I thought was from a front wheel/brake disc, it was road speed related, and it turned out to be a new speedo cable that I had just put in.

Sometimes the noise can come from unusual places.

[Dilkris]

Dilkris, I'm about to get my nephew over to be able to find (if poss) where the noise actually is emanating from. As we all know, a noise can seem to be come from "A", but it actually from "B".

Anyway with two of us we can look into the engine bay and as one twists, turns, pulls and pushed the other can actually see if there is any corresponding noise from within.

Similarly, when I gentry reverse down my drive he can be closely looking at the wheel /engine bay etc. although I suppose this won't make the noise on command eh?

Any progress with this? I'm curious to know what was the source of the noise. 

[Pfreen]

I had a clonk which turned out to be the radiator bolts at the bottom.  The fiberglass nose of the Europa is not supported very well.

[Kendo]

Yes, it really needs that closing plate. I drove mine around for a very short while without the plate. And the nose porpoised a lot. I quickly reattached the plate.

[HoraceM22]

Needless to say, when my nephew came and we tried replicating this,  it didn't do it. More grrrrrr.

[69merc]

Mine had a “similar”  clunking noise rolling in the driveway after I got it back on the road.  After I put the rear drive shafts back together, I forgot to “release” the ujoints after I installed them.  I good hammer thwack on the unjoints solved my mysterious clunking.  Just something to try.