Saving Old Seagulls

Calling all engineers - what is the best way of getting the big screw between the exhaust and the drive shaft (the one that holds the gearbox on) out ?- I cant seem to find any way of getting any purchase on it - it seems pretty well stuck. thanks for your help-my knuckles await skinning!

I clamp the skeg in the vice, using soft jaws.

Then I heat the gearbox up - around the upper part where the screw thread engages - and use an impact driver to get it turning. It is without a doubt the worst fastener on a Seagull.

It is important that the impact driver bit is big enough, and that you use lots of heat.

Hello Clive - my method is: first ensure that the screw slot is as clean from corrosion etc as possible - this is to get maximum contact/purchase from a screwdriver.
Find a screwdriver with a fairly long shaft - say 8-10 inches or so, as the screwdriver has to lean a bit, and the longer the driver, the less acute the angle of the tip is in relation to the slot.
Make sure - possibly by grinding the tip if necessary - that the screwdriver tip is a snug fit in the screw slot - width and depth-wise.
Have a relatively small Stilson wrench (like plumbers use) that will grip onto the screwdriver shank to give you the necessary leverage to undo the screw.
Before things get serious, check that you have the Stilsons set to a position where they will grip the screwdriver shank.
Mount the engine somewhere with a firm grip against the turning motion you are about to impart - eg a workmate or suitably protected vice jaws, but leaving yourself access for your skill and artistry with the screwdriver and wrench.
Get the area around the screwhead, and where you can imagine it is threaded into the opposing part very hot (gas blowlamp or similar) and give a liitle while for some expansion to occur, keeping the area hot all the time.
When ready, put the screwdriver in the screwslot. As above, you will have to incline the screwdriver slightly for access between the drive tube and exhaust.
Keep as much pressure as possible on the end of the screwdriver with one hand - hopefully the position of the slot will be kind to you so that you can get full contact between screw and driver tip. Find a good position to get the Stilsons to grip on the screwdriver shank as high up as possible (to minimise the angle of lean), and apply force to Stilsons. If the process is going on too long, re-heat the gear casing occasionally.
You may be lucky and have a screwdriver of suitable size with a hexagon below the handle on which you can get a spanner, but usually the spanner that fits doesn't give enough leverage.
Don't bother spraying the screw with so called release agents - they just can't get where they need to -but for reassembly, wire brush the screwthread, and run a tap (BSF) into the female thread if you have one, and grease (I like copperslip) the screwthread.
Good luck, and let us know how you get on. The above works on quite seriously corroded parts - yours may not be that bad. Rick.

Charles and Rick have given you the method for getting this awful fixing out but if you use a standard metalworking vice with soft jaws always check that you have sufficient clearance in the throat of the vice to avoid clamping up against the skeg and bending it as you close the vice........ You see an awful lot of gearboxes with bent skegs and this is the main cause.


Good luck!


Peter

As others have stated, these can be a pig to remove.You may find it easier to work on if you can remove the powerhead, exhaust and drive tube first.

I use a carpenters brace with a screwdriver bit in the chuck,you can exert quite a lot of force this way and can bear down on the brace to prevent the screwdriver jumping out of the screw slot.

It is quite possible to shear the head off this screw if you are not careful so use loads of heat and initially just try to get some movement then wind the screw to and fro,each time trying to extend the amount of rotation.It is worth trying some sort of penetrating oil once movement can be felt.

Best of luck.
Steve

This is great guys - thanks for all your advice - I will let you know how I get on!!