Hello David,

My Myford S 7 of similar vintage became noisy about 30 years ago. It turned out to be the needle bearings on the clutchshaft. Replaced with the then current standard "Oilite" bushes and has been OK ever since.

Even when the back gear is locked by the lever there can be sufficientt clearance to allow the back gear to rock a little, hence noise. Goes away when the item being turned places a firm load.

Face the fact, spur gears will be noisy, even in good condition, with correct backlash and accurately centre distanced. Otherwise helical gears would probably not been invented.

Listen to a Bedford OB or Austin K2 in the lower ratios to hear characteristic spur gear noise, or any spur gear transmission.. When automotive gearboxes started to use helical gears, before the days of synchromesh,, the selling point often was "Silent Third"

So, OP, resign yourself to some noise when using backgear or changewheels.

The smoother the drive input, the less noise will be evident Which is why 3 phase drive motors produce less noise than single phase

Back gear centre distances usually cannot be adjusted, but changewheels can, and should be.

By adjusting the banjo, and the position of the gears carried on it, the meshing can be improved.

Too little or too much backlash will increase noise, and probably, wear

The normal technique is to run a sheet of paper ( About 0.003" – 0.075 mm thick ) between the gear on the Leadscrew (Since that cannot be moved about ) and the Idler gear meshing with it. That will provide a little backlash

Then set the backlash between that Idler and the next gear in the train, and repeat for any others by positioning the studs on the Banjo.

To set the backlash on the final mesh between first Idler and the drive gear (Below the Tumbler reverse ) the Banjo will need to be rotated about the housing surrounding the Leadscrew..

Once all the backlashes have been optimised, (Check again after everything has been clamped in place ) noise should be reduced, but not probably entirely eliminated.

Sorry if this is teaching Granny to suck eggs.but if your changewheel drive is noisy, better setting of backlash ought to improve matters.

Howard

Looks like your are running the lathe on the highest speed (circa 2,000rpm on the S7) and it sounds like the tumbler reverse gears are whizzing around good and fast. The super 7 should have two Tufnol gears on the tumbler reverse mechanism, that is a brown fibrous material, non-metalic. In later years perhaps a plastic substitute like Delrin etc. Yours sounds suspiciously like steel gears at high speed.

Would be worth taking the gear cover off and having a look under there at what you have. You might lubricate the gears and their spindles while you are at it. I use motorcycle clear teflon no-fling chain lube for this purpose. Much tidier than oil. (Don't use the black graphite off-road chain lube!!) Or you can use the same general oil you lubricate the rest of the lathe with and live with the mess.

Could be motor bearings, belts rubbing, pulley rubbing, pulley loose, clutch bearing rattling, or something else. Best way is to eliminate it one step at a time. Take the motor belt off and run the motor. If no noise, the motor is not the cause. Then try with belt on and look and listen for where it is coming from. Common cause of noisy clutches in general is the clutch centre bearing that allows the clutch outer housing (pulley in this case) to spin when the clutch is disengaged and the shaft stops rotating. But belts rubbing on guards is awfully common too.

I had a noisy countershaft, needed to replace the 2 Deep Groove ball bearings in the Mk2 clutch assembly, noise reduced significantly.

Peter