Transmission knocking - guidance sought

[Phil D]

As a bit of a novice, I'd be glad of advice, please. Driving my 1930 Box this morning developed a knocking on overrun. Knocking slows as car slows. Same noise irrespective of clutch engagement. Seems to be midway in car but hard to tell. Noise is there under slight load but less pronounced.
Where's best to start?   Thanks

[Ian Dunford]

As a bit of a novice, I'd be glad of advice, please. Driving my 1930 Box this morning developed a knocking on overrun. Knocking slows as car slows. Same noise irrespective of clutch engagement. Seems to be midway in car but hard to tell. Noise is there under slight load but less pronounced.
Where's best to start?   Thanks

Sounds like a loose flywheel or front main bearing lip disintergrating I'mafraid.

[Mark McKibbin]

As a bit of a novice, I'd be glad of advice, please. Driving my 1930 Box this morning developed a knocking on overrun. Knocking slows as car slows. Same noise irrespective of clutch engagement. Seems to be midway in car but hard to tell. Noise is there under slight load but less pronounced.
Where's best to start?   Thanks

As you say "Same noise irrespective of clutch engagement" it sounds like a dodgy tailshaft joint.

[Dave Wortley]

Phil,
Have you any A7 owner nearby to help? It is very difficult to analyse a noise without being in the car.
Hope you can find someone.

[John Raeburn]

Phil,
Check the tightness of the torque tube anchor on the rear cross member.
J

[Timothy P]

I'd back up Mark's post, worth checking the fabric coupling.
I had the same symptoms recently of knocking on over run, and with clutch dipped, road speed dependant, but mine went away on application of the handbrake. I found one of the nuts on the fabric coupling completely loose (Incorrect type). meaning the fabric coupling was flailing, and rubbing on the handbrake in its 'home' position. Nuts tightened and the noise went, but i'll be replacing the fabric coupling anyway, and replacing the incorrect fixings, which are causing the fabric to crush and push out, thus causing the loosening.

Hope it's nothing too serious for you.

[Phil D]

Thank you all. I hope to have time this week to get underneath. It's evidently worth looking at prop shaft couplings etc, ... in hope!

[Steve Jones]

Thank you all. I hope to have time this week to get underneath. It's evidently worth looking at prop shaft couplings etc, ... in hope!

Yes, always check the easy things first. In this case working forwards from the prop shaft/pinion connection. Eliminate all other possibilities before looking for a loose flywheel (although given your description of the symptoms, that's where you might end up  ). 

I think I've told the story before of a friend competing on a trial who immediately put the lack of performance of his new engine down to him having assembled the timing gears a tooth or two out. When Malcolm and I came across him (in the middle of a damp forest) he was starting to remove the radiator prior to dismantling the front of his engine to re-set the gears. 

We spent a couple of minutes re-timing the distributor for him. Problem solved!

Steve

[John Raeburn]

Phil,
Does the knocking go when you depress the clutch pedal?
if it does then it is most likely to be a loose flywheel, if not then my bet would be, as Timothy suggests,  
the fabric coupling, or the torque tube anchor on the rear cross member both are easy to check.
J

[Phil D]

Thank you John, - no it doesn't go away upon depressing clutch. I've been thinking it may have been worth trying it downhill with engine off, clutch depressed. I shall try simply pushing it on the flat when I can next go to it. I imagine that if it clonks then I can eliminate an engine issue.