I am in the process of fitting a new primary chain to a '71 A65, but having big trouble getting the clutch drum to separate from the main shaft. I bought the correct service tool to screw into the centre of the clutch drum, but when i tightened the central bolt, instead of the drum coming off the taper, it pulled the threads off the service tool. The tool was a pattern one
I bought from a reputable supplier, but it isn't great quality admittedly.
Does anyone have any ideas? I've tried heating the centre but its so awkward to get a blowtorch in there.
It sounds as though you didn't screw the puller far enough into the clutch centre and, the few threads that were engaged, were not strong enough to take the load. It does take quite a bit of force to pull the centre off the tapered gearbox main shaft and therefore it's important to screw the puller fully home.
If you heat the clutch centre you will be looking at replacing the rubbers inside.
As spaceman said, tighten the the part that threads into the hub and use a spanner. Then tighten the centre bolt of the tool as much as you can. Then get a 2lb hammer (not a dead blow hammer) and give that centre bolt one decent solid rap! If you've done it right the basket and hub will fall off. This technique is known as "shocking" and it does work well if done right.
I too had similar problems and consulted the vast knowledge known as the forum on which we now consult! I found out that there were 2 thread types depending on year of machine but a far more useful tip perhaps was whenever a chance arises to purchase old school tooling often far superior to the modern overseas monkey metal so readily vailable today! Not a solution as such but good luck.
Dave.
The earlier clutch extractor for the 4-spring clutches was 1" x 26 tpi while the later 3-spring clutches used a 1" x 20 tpi extractor and many venders get them mixed up. It would be worth checking the thread on this extractor - if an earlier extractor, it could well screw into the clutch centre slightly but it will not hold.