AJS & Matchless Owners Club

Having finally got the crank case halves apart for inspection. on my 1949 basket case model 18. Oh dear a tale of woe. The gear teeth on the oil pump plunger and the timing side axle were shot. Some teeth had broken off and chewed up the pump and axle gears. Some of the debri had got into the timing side bush and scored it, Other bits of broken teeth were found in the oil pump plunger cavity. So now I need a new oil pump plunger and timing side axle as well as the timing side bush. My question is this, is the replacent of the timing side bush a job for an engineer's workshop, ie does it require reaming by a machine after fitting to ensure that it is in line with the axle ? Or could I get away with reaming the bush by hand?

I replaced the timing side bush myself but did have it line reamed as per the expert printed advice. I understand some have not done this and all was well; I'd spent so much money (timing and drive axles, new bigend - both Alpha bearings, rebore - T&L, etc.) I was taking no chances.

I would check the oil pump plunger bore wear/damage. There was some light damage from my failure and I was advised by an expert (Ken de Groome, who also did the line reaming and sorted out the drive side bearings that I'd fitted correctly but were tight) that it would be OK as would the plunger. I had planned to replace the plunger but the new replacement was as sound as the old one in overall dimensions. I'm at least 2k on and all is well.

If the plunger bore is badly scored you may be better to source a replacement crankcase as I'm informed that sleeving is a heck of a job, see videos by The RideNut. I'd post a link but my mouse is playing up.

Good luck.

Johnny B

I had a problem with the bronze timing side bush on my 350cc Triumph 90. I'd got about 20 thou up and down movement on the crankshaft. The crankshaft journal was very badly worn and worn eccentrically. Patrick Seager at Seager Engineering made a beautiful job of the repair. He ground the crankshaft and made a new aluminium bronze bush which was honed to give the correct clearance on the crankshaft after it was fitted into the crankcase.
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