One for those in the know......

[Denis Sweeney]

Hi folks a question to those in the know.....

I have had a clunk or knock on my Ruby from the drive train ever since she has been on the road which normally appears in reverse gear and again back in first gear when moving off again.

However I have noticed that it also clunks when changing down from 4th to 3rd especially if I do not get the revs of the engine to match the rotation of the prop shaft and similarly 3rd to 2nd.  

I have attached a link to a very short video which shows the play on the train below. This is with the gearbox in neutral.

Is this something I should be concerned about or is this simply what is to be expected on a car nearly 90 years old.

Any assistance would be greatly appreciated   

https://youtu.be/DxSk5UQy4P4

Cheers Denis S

[John Cornforth]

Hi

My suspicion would be that you might have some play in a half shaft/hub interface, which re-settles every time the drive torque changes direction. As a first step I suggest you check that the hub nuts are adequately tight.

[stuartu]

Likewise, check the pinion shaft drive flange nut. More annoying to get at I’m afraid. Often these end up having no lock tab after intervention by others.

Regards,

Stuart

[Denis Sweeney]

When I originally put Ruby back on the road the rear axle had been rebuilt using “new” half shafts purchased from A7 Services, Kirby Wiske yonks ago but I could never get the original hubs locked and these were always an issue there was also constant leaking of oil into the hubs, having used original style felt seals soaked in tallow.
And so these were replaced with new half shafts and new rear hubs and modern lip seals from A7C.
The rear axle was stripped and totally rebuilt again.
Since then I have had no issues with the hubs coming loose, despite this the clunk still persists.
I did check all the fixings from gearbox to the diff and all tab washers are in place and I cannot find any movement in these fixtures. I also checked the paintwork that has been applied on these fixings and cannot detect any signs of cracking in the paintwork that would suggest movement, but the clunk is still there.
Cheers

[Tony Press]

The rear big ball joint at the top of the torque tube is loose either at the top or the bottom.

[John Mason]

Yes I agree with Tony and a check of this first is much easier as a first step.

Jogs Mason.

[Denis Sweeney]

With the weather being a tad on the warm side I decided to spend the afternoon in the shade lying under Ruby. As advised above, I have checked the ball joint once again and I really cannot detect any signs of any movement at all of the mountings, cross member or anywhere else. It really does feel very stable.
In my original post I noted that the video was taken with the gearbox in neutral and so I checked the rotation on the prop shaft with the first gear engaged, the slack in the prop shaft virtually disappeared, yes I could feel movement but it would be difficult for this to show up on a video.
I checked the reaction on the rear axle and there is no discernible slack there, the rear wheels begin to rotate in either direction with the just the slightest rotation of the prop shaft.
I can only conclude that what slack there is, is at the gearbox when in neutral which is not present when in gear.
I think this would account for the clunk in changing direction, forward/reverse, and again when changing down when the engine revs have not been synchronised with the revs of the prop shaft.
Now whether this is a correct assessment or not and whether it is an issue that needs rectification, I look to more knowledgeable folk than myself for guidance.
Best regards for now
Denis S