Problem removing driveshaft from 1924 Johnson BNL gearbox.

I’m dismantling the above to give it a good clean out prior to repacking with grease and cant remove the drive shaft. Its a fresh water motor to the best of my knowledge, as there is no corrosion visible and all the screws and bolts have come out easily. The problem is how to remove the gear off the shaft. I have tried holding the drive shaft in a padded vice and then tried driving the gearbox off with a plastic hammer, but no sign of movement ………..needless to say I don’t want to do any damage.

Again, thanks in advance for any help.

Monte NZ

Thanks crosbyman and Tubs once again for your much appreciated input……..Mr Mohat’s  article and the You Tube on expansion and contraction are very interesting.

I am pleased to report that I have spark…….one side has a bigger spark than the other. I swapt the spark plus around and installed new HT leads, but it didn’t make any difference…….what that indicates I’m not sure. Maybe I will wait until and see how the motor runs.

Regarding the dismantling of the gearbox and pump, I got that apart ok. I found that by lowering the drive shaft with the gear, that there was a steel ring round the top of the gear and by sliding the ring up it exposed a steel drive pin, which slid out easily…….simple but very effective.    I managed to get the pump apart. All appeared ok and worked well later when tested in our it laundry tub. One point I would like to make though, is to be very careful undoing the top valve which has a the thin hexagonal section with the adjustment screw in the middle.

It is  easy to have  the spanner slip and damage the hexagonal end of the valve so I mounted the pump body (which goes into the gearbox) in my lathe, making sure it was tight in the chuck and using an  on old car inlet/exhaust valve, fitted into the tailstock  chuck, I then brought the face of the valve up to the hexagonal section, so that it was just touching and  locked the tailstock from moving. I then fitted the spanner and gave it a gentle smack with a hammer, which broke it loose…….”Hey Presto” …… no damage !……….Hope this helps someone dealing with similar problem.

Thanks again

Monte NZ