Timing drive removal bolt 25016

Hello Gary!

There is a special slide hammer available for this operation.

Remove the center bolt, screw in the slide hammer and pull out the advance mechanism.

It is a taper fit.

I use this tool for my Commando and Navigator , don´t know if the threads are the same but it worked.

Available here: https://andover-norton.co.uk/en/shop-details/16315

A/NORTON

#06.4298 SLIDE HAMMER (06.4615) £13.80 

RGM

SLIDE HAMMER (AUTO ADVANCE) Part No 064298 £9.95. THIS SLIDE HAMMER HAS TWO THREADS ON THE SPINDLE WHICH ARE 1" LONG, ONE END IS 5/16" UNF AND THE OTHER END IS 5/16" BSF

NORVIL

064298                  EXTRACTOR - ROCKER SPINDLE - CYCLE THREAD £10.50

064615 TOOL - ROCKER SPINDLE EXTRACTOR - 26 THREADS PER INCH £10.50

All + P&P/VAT....

The thread is, most likely, 5/16" UNF.  Lucas recommended a tool like those in the attached photo.  They screw in to the ATD, the plain extension bottoms out in the camshaft and pushes the ATD off its taper. 

These tools do not need to be one-piece, a short length steel rod cut to the right length and a suitable bolt work just as well.

I don't like the idea of using a hammer to remove the ATD, (or anything else!), much better to have the "feel" of the recommended tool.

Why not give it a clump? perhaps with an ally or copper drift. The taper fit soon breaks. and you are going to throw the ATD away and fit electronic anyway!

Hi Gary,

You ask Alan for a reply. Sorry to butt in Alan.

Gary, the shim has probably been put there to try to get the points cam to run more centrally.

So, either the camshaft has been made with a non-central taper (unlikely)

Or the taper has been damaged by some energetic cam pinion removal (more likely)

Or the auto advance central cam carrier post was bent (possible)

Or the whole thing was assembled with burrs, dirt, and a piece of drinks can.

I would suggest you need to check if the taper is in good condition and concentric to the camshaft bearing. This will ensure your electronic magnet carrier runs nice and true, without swash, so that the magnets run an even distance from the pick-up plate.

If this doesn't make sense, probably best to take it to someone who can check things out for you. Or just buy a new Jubilee inlet camshaft from the club.

Definitely go for electronic ignition.

Peter

Cam nuts are RH thread.

Hi Gary,

There are very few BSF threads on the lightweight engine and gearbox assembly.

The thread will generally be either cycle (26 threads per inch) or Whitworth.

There are enough bolts in your box to try. The cap screws holding the rocker box are 1/4 Whitworth. All the 1/4 ins studs on the engine like crankcase, gearbox, sump etc at threaded Whitworth at the end that screws in. And Cycle at the end that takes the nut.

At the time Lightweights were designed (Post War) the general move was away from BSF threads. One of the first thread forms to become (non preferred) as NATO sought to get rid of the spanner and bolt mix-ups that dogged the allied mechanics in WW2 battlefields.

But we still have 1/2 BSF for the stud in the drive end of the crankshaft.

Peter

Gary,

The cam pinions are threaded 1/4" BSF. 

I looked for a puller but couldn't find one so a friend modified my engine sprocket puller by slotting the holes for the attachment screws. But I had to buy some 1/4" BSF cap screws. 

My friend also cut a bolt for me so that it would fit into the taper on the end of the inlet camshaft to provide a surface for the puller to push on.

The engine sprocket puller could so easily have been used for both purposes if the draftsmen had talked to each other. Not the only instance of this occurring on the lightweights!

David

Hi Gary,

The confusion comes because some screws of one type will screw into another nut.

So when Dave says with certainty that the thread for extraction of the cam pinions is BSF. I accept that a BSF threaded bolt will fit into the camwheel. And fit very well. But the thread is probably tapped 1/4 ins cycle and has 26 threads per inch. Guess what, 1/4 ins BSF thread also has 26 threads per inch. Differences are miniscule. I don't think cap screws are available with cycle threads, so Gary definitely did the best thing.

You can also screw a metric M6 bolt into a 26 tpi nut or tapped hole and think it 'fits'. Try an M6 nut on a 1/4 inch bolt and for sure it won't fit.

1/4 UNC is similar to 1/4 Whitworth. Cap screw sets for brit bikes are often UNC thread where Whitworth is the proper fit.

All these thread ranges are very confusing. I couldn't manage without a thread gauge a set of measuring calipers, and thread data charts. 

I don't believe there is a list of all the thread types used on a Norton Jubilee.

Peter