FRONT ENGINE SPROCKET MK3

Hello all,

I am looking for thoughts on removing a very stubborn front engine sprocket from my 1975 MK3 (26,000 miles) .. I need to replace the primary chain and So far I have tried the factory manual method of a puller under tension (a lot) and hitting the side of the sprocket with a soft metal drift, nothing.. Next I heated up the sprocket drum (hot) and gave the end of the puller several short sharp hits with a hammer, still no movement, WD 40 with heat and all of the above, still it just will not let go !

Is it normal for this sprocket drum to be so tight, I would swear it is welded to this shaft.. Any ideas or tricks to remove would be greatly appreciated..

Cheers
Paul ...

Tighten the puller as much as you can, obviously without stripping any threads. Then use a suitable dia. steel punch on the side of the sprocket and hit it. The sprocket should then come of with a loud bang. 26,000 isn't much for the primary chain - check sprocket and shaft alignment on reassembly.

I agree that is low mileage for a primary, expect double that.

If the chain has been changed however it may be of lesser quality
than the original "old" Renold. Even the new Renold is not the beast
it once was.

If you must change look at the iwis Merc diesel cam chain.

Works wonders on Laverdas just ask Redax in OZ.


Andy

Ugh, yes for my 2 Combats I've had 2 pullers break, one cheap steering wheel type and a quinine Norton robust factory puller, cracked just before I got to give it a tap after heating to oil vapor frying pan HOT like 450'F++. So add more heat and tighten puller to max and repeat and repeat till something breaks. After facing the trauma's of my 2 Combat the rest of life is rather less stressful.

You should soak that primary area for about a year in WD 40 or similar release agent. MK 111 Puller has longer bolts. Tighten down puller until you feel it's so tight you start to think it might start stripping the threads. Apply heat to sprocket and lots of it. Smack the end of the tool with a 5 lb. sledge ,not a hammer. There should be an audible bang - snap or pop, followed by happiness. Punch tapping side-strikes hot should help too. This is age related fusion. :|

A big thanks to all for the advise and tricks.. After having another go with more heat and the use of Al-otment's steel punch idea to the side of the sprocket it gave up the fight with a loud bang ***** finally it's OFF ! .. To answer questions on chain renewal at only 26,000 miles: my Sprag had blown to pieces and some of its apears to have damaged one or two of the rollers .. Now I have to decide on how many of the Sprag items I need to replace :shock:

Cheers to all
Paul ...

Sprague is the weak link. Will someone build a beefier cage please.

Rollers are the weak link in the current crop of triplex, indeed most chains.

Just because a roller looks solid it may be a seamless tube construction and
not deep drawn. Look at the roller and if it has a slight rounded edge at one end
avoid.

I know I bang on about the Merc chain but it does have no rollers, its a bush chain.

Andy

andychain said:

Rollers are the weak link in the current crop of triplex, indeed most chains.

Just because a roller looks solid it may be a seamless tube construction and
not deep drawn. Look at the roller and if it has a slight rounded edge at one end
avoid.

I know I bang on about the Merc chain but it does have no rollers, its a bush chain.

Andy

Click to expand...

Just to clarify - is the Merc chain triplex or duplex?

Duplex but it runs happily on the triplex sprockets just using 2 rows of teeth.

Its difficult to explain the advantages but your close enough to pop over and
see for yourself.

It is really odd that my advice on cam and starter chains is used, an order for
another 25 today from the USA, but the really good advice on the primary and
rear is only liked in Belgium.

Andy

PS It is common for Laverdas to use the big pin Merc duplex instead of the
triplex and for those running 2 single chains, the big pin simplex. I cant see
that a Commando would be any more demanding than a triple Laverda, such
is life.........Ring if you come over and I will get the coffee on.