I have a nasty knocking when under accelerating under load on my MK1. It occurs only when putting power on, or sometimes when giving it a rev on stand. It was present a while back and seemed to abate away, and I've since done 400 miles, but assumed it was the clutch contacting casings.
I decided to nail the problem and have tried every possible clutch and outside cover shimming and position option, but sadly the noise has returned with a vengeance......and I just cant pinpoint where it's coming from. In a attempt to contain the clutch movement I reduced the BA gearbox input shaft float to .010, and replaced gearbox grease. I've looked at the BA drawings (and Mr Moore's YouTube video,) and struggle to to see where in the BA such a noise could propagate. I wondered if it was drum wobble ( also attached video), but attempted to lock drum movement by jamming drum tight against inner ...but sound remained.
It kinda sounds like a big end but not......sounds more like a cyclical contact. I checked to see if the big ends had run doing screwdriver test, and they are tight. The shock absorber spring / cam are also new.
I can make the noise by revving the engine stationary and out of gear (video also attached) but the noise is much much harsher when taking off in gear.
Apologies for the rambling email, but I'm just attempting (badly, I know) to outline the problem.