mark III primary cover removal

Have removed all 11 cover bolts and knocked all round the cover with a rubber mallet but it seems stuck on the gasket/ dowels. i really don't want to start trying to drive something in the joint. any bright ideas how to get it off without damage - a big search effort hasn't shown anything up but i can't believe I'm the only mark111 owner with this problem. perhaps some kind of gasket sealant has been used. thinking about rigging up some kind of extractor thru the clutch adjustment aperture ? thanks for any advice

davidcumbria said:

Have removed all 11 cover bolts and knocked all round the cover with a rubber mallet but it seems stuck on the gasket/ dowels. i really don't want to start trying to drive something in the joint.

Click to expand...

The Mk3 primary cases are quite thick so you can use a hide mallet or a hammer and a block of wood to break the joint.

Owners often use gasket sealant in addition to the Mk3 primary case gasket which is usually unnecessary and it makes the joint difficult to separate.

L.A.B. said:

davidcumbria said:

Have removed all 11 cover bolts and knocked all round the cover with a rubber mallet but it seems stuck on the gasket/ dowels. i really don't want to start trying to drive something in the joint.

Click to expand...

The Mk3 primary cases are quite thick so you can use a hide mallet or a hammer and a block of wood to break the joint.

Owners often use gasket sealant in addition to the Mk3 primary case gasket which is usually unnecessary and it makes the joint difficult to separate.

Click to expand...

thanks - there is nothing to hammer against in the 'off direction' away from the bike. am i right to keep hammering the case in the up and down direction or are you suggesting I try to hammer a sliver of wood into the joint ?

davidcumbria said:

there is nothing to hammer against in the 'off direction' away from the bike. am i right to keep hammering it in the up and down direction ?

Click to expand...

Just keep knocking all around the case as you pull the gear lever towards you (the lever and shaft can be removed still attached to the outer case). If sealant has been used, then it may be necessary to use enough force to actually split the gasket. If it still won't budge then you could try levering as you suggested, or try to carefully split the gasket joint with a Stanley knife blade?

As L.A.B. has indicated, pulling on the gear lever is the trick here. It's nice and centrally located and is attached with a pinion on the inside so it can't pull through.

This is a very hefty casting and won't even be bruised if thumped quite hard with a good well broken-in hide mallet.

Don't however try it too close to a wall or with anything sharp or dangerous behind you because if it gives way suddenly, you'll launch yourself into orbit.

If the gasket has been glued on, you can look forward to an afternoon getting the remains off before reassembling.

I had exactly the same problem. There was a grey silicone applied to the cover by the PO.
I tapped as much as I thought safe to do and stopped and went to bed before I broke anything. It was late and I was flaked out.
The next day fresh and alert I tapped again to no avail.
The cure was to take a single edge razor blade and very carefully cut into between the cases by hand as deep as I could.
Then I resorted to tapping the razor blade into the gap made previously all along the top joint figuring it would be less likely to leak up there.
Then I resorted to prying at the upper part of the Z plate figuring the damage would be less noticeable.
Whala the cover came loose immediately, the razor blade must have helped.
Here is a view of the dowel locations just in case you are unsure of where they are.



The dowels inhibit any sliding when you are hammering on the cover.
I didn't know at time the shift lever was robust enough to use as an aid. That is a good tip from the boys there.
I found evidence of the PO having used pry bars through the clutch adjustment access hole and against the clutch diaphragm hub. Not pretty, avoid levering blindly.
With the cover removed you should cover the internals very well with some rags before you begin cleaning the gasket surface. Little bits of debris will be on everything otherwise and they are a bugger to get off.
All the best

Recommend a good old clam knife. These are not usually sharp enough to hurt the metal.

thanks for all the advice . it came off with a little very gentle persuasion into the seam with a hammer and blade but no damage done. hope i haven't bruised the casing with all my hammering. discovered the clutch centre nut was loose so hopefully that explains the clutch drag.I 'm enjoying taking bikes apart again after a very long break . thanks again.

I've just taken mine off. It was "glued" on with the gasket and threebond. I got a small pinch bar (jemmy bar or crow bar depending where you are from) and very carefully using the angle end levered up through the clutch adjuster inspection hole. Just wiggled it putting pressure on the outer case from inside was enough to "pop" the seal. Sticking a blade in between the faces is a last resort.