Monty V

I, by accident, found this thread regarding what looks like a very tired Brunton gearbox. I also had one in similar condition until I rebuilt it while I was doing the same with my recently completed National engine. The problems I found were not only wear and tear but poor assembly at some time, probably war time when it was done just to keep it running. For example, Bronze thrust washers with hand cut steel shims behind them, finger tight nuts holding bearings in place, taper roller bearings worn to the point where the rollers dropped out of their cages and so on. As to what I did to rebuild would probably run me beyond my allowed space here but some observations I made might be of help. The timing cover on my engine had no location dowels to centralise it round the crankshaft. This is important as the gearbox mounts on it. The female forward clutch cone is mounted on a keyed taper with a ball thrust race and necessary shim between it and the timing cover. If the shim is too thick the clutch cone will not tighten on the taper and the crankshaft will be pull hard against the centre main bearing face. Shim too thin will cause the other main bearing face to be used as a thrust bearing went engaging forward. The centre main bearing should only be maintaining the crankshaft alignment to the cylinders. It is important that the key between the crankshaft taper and forward clutch has a small clearance at the top when assembled. Oil in the reduction gearbox, according the instruction pages states 'Good quality gear oil'. I've used EP90. I've read about return pipes being fitted between the reduction box oil level plug and engine. This means that the reduction box can only have engine oil it which is probably too light for the job it has to do. The reason this was done was due to engine oil passing through the bearings and felt seals on the forward/reverse selector. I've modified this to lip seals which should reduce the quantity of oil reaching the reduction box, some will pass as there is unsealed clearance between the sliding selector and its bore in the casting. I had new reduction gears made by a company near me. Sovereign Gears Ltd. Hill Lane 1, Markfield, Leicestershire. LE67 9PN. To reduce cost (very little) I reduced the width of the gears as I felt that now my engine is in a forty five foot boat and not likely to tow a butty it didn't need such hefty gears. I did look at standard gears from HPC who were very helpful but beware there is only just enough clearance to get the small pinion out of the box and standard HPC gears wouldn't have fitted. Attached is an assembly drawing of a Brunton reduction gearbox which may be of some use. I'm willing to chat further ( bore you to tears) on the subject if you wish.