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Subject: Gearbox Drive Plate

Hello Tony,

May I pick your brains a little?

I recently had my second-hand BMC 2.52 rebuilt by Peter Atkinson and unfortunately he died two weeks ago. Fortunately for me he had rebuilt the engine and bench tested it before that sad day, so things could have been far worse.

However, the gearbox, a Newage Coventry Ser No: 24-14565 is still off the engine. I can't find a type plate on the box, but it is one of the bigger ones about 25 years old [though hardly used, like the engine.]

There is a circular aluminium drive plate that bolts on to the engine flywheel. It has three shaped lugs on it facing back towards the gearbox. On the gearbox shaft is a similar circular plate made of steel, also with shaped lugs projecting forward. When Peter stripped the engine he told me that 'rubber biscuits should have been fitted between the lugs, but they were never there! However, as the engine had only done about 30-40 hours running, no real wear had taken place on the lugs.

Having spoken to his son, he thinks he remembers his Dad saying that he had ordered these 'biscuits', but we don't know where from! They certainly haven''t tuned up in the post.

Having inspected the drive coupling myself, I don't see how loose rubber 'biscuits' could be located on assembly. After all, the coupling is inside the bell housing, so on assembly you couldn't get at it.

I am now wondering if these two plates, one on the engine, and one on the gearbox shaft are in fact two halves of a coupling assembly that has broken apart when Peter took the gearbox off. The only other gearbox drives I have seen were splines that fit into a shock-absorbing assembly or clutch.

I suspect I will have to find a new coupling from somewhere.

Can you shed any light?

Much appreciated.

Tony H



Hi Tony

I have been following the saga.

I have seen many variations on flywheel - gearbox drive plates, so it comes down to who made it, and I am afraid I do not recognise it from your description. I think the box is probably a PRM, especially if its is mounted at an angle and is sort of heart shaped.

It could be Centa transmissions. As long as the plate matches the splines on the gearbox input shaft I do not think it matters much whose plate you use.

When we fitted them at the hire fleet we used an ordinary clutch-aligning tool to centre the plate for drilling the flywheel.

Hope this helps - but I suspect not much. If you have not already done so, ask the news group uk.rec.waterways.

Tony Brooks


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