More on the water pump!

[Ian]

Chaps, Over the last two years I have had no less than five Oldham couplings fail.The first coincided with the pump seal self destructing but the others since have just broken. One split axially as if it was cut with a knife and the others have lost 'ears' resulting in noise, failure and in two cases, a run home courtesy of the RAC.One only managed about 70 miles and the best was about 500. It was getting to the stage where much bad language wasn't calming me down either.So, having kept the broken couplings (I am that sad) I had them metallurgically tested. Interesting to say the least. The one that split axially was cheap mild steel and unhardened. The second failure was the same but a tang had broken on that one and the other three were cheap grade mild steel also but were hardened but only to a depth of 1-3 microns. They were cheap parts and that's why they failed. What I needed was a tougher material.I then took a new, unused coupling to my friendly local machine shop who made up two couplings in aircraft grade stainless steel. Looked lovely!2000 miles later and all is still well. £20 well spent I think.Now the questions:Anyone else had this?Is weak material the problem, or am I disguising something else that's wrong?Am I doing any damage to my engine?Finally, if this is the answer I can probably get more made up, providing you're not in a rush. It was done 'between jobs'.Any comments or suggestions?Ian

[Richard Negus]

Ian,That must be a record!Difficult to comment without seeing one of the failed ones, but sounds very much like a manufacturing problem. Did any/all of them come from Shenstone or Rugeley? How about the pump spindle and eccentric shaft drive dog?Are the dowels in place to correctly locate the pump housing on the left hand end plate?R.

[Dell Boy]

Having bought in the last week two more sets from graham & having bought more than ten maybe as many as twenty sets over the years i am very interested in purchasing two stainless steel sets if they are available.Cheers,Derek Fox.

[Ian]

Derek, I've only had the Oldham coupling itself made in stainless; the other components remain as (I presume) Norton intended. I can organise some couplings if you still want them.Richard - I haven't kept the old couplings after testing but what I thought odd at the time was that all the other parts of the coupling assembly were in good order, no witness marks that I could see at all. I concluded that all was fine except for the coupling itself which was why I had two made.I got the failed ones from all four sources over a period of years tghough failures were relatively reent - Graham, Shenstone, Rugeley and indeed AN. Which one came from which source I don't know. Was there only ever one supplier of this coupling?I di a quick search. Apparently Oldham couplings were developed to connect the crankshaft of a paddle steamer to the paddle wheels. It avoided having to make a longer shaft straight as it took up misalignment and was a quick and cheap fix. In 1804!Ian

[Dell Boy]

Hello Ian,Ideally I would like the following parts: Drive Coupling 50-0676. Spindle. 50-0681. Drive dog. 50-0677.Two sets please if you can supply them.Let me know how to pay you.Many Thanks,Derek Fox.

[Ian]

Derek,I only had the coupling made, not all the parts, see post above.I paid £20 for two. I'm happy to ask for more but I'd like to gauge how many are really required. I would rather ask for ten in one go than five pairs for instance.If just the coupling is OK, please let me know and if anybody else wants some, please do likewise.Ian

[Dell Boy]

Hello Ian,After the 2,000 miles in service what do the contact services on the spindle & drive dog look like with the stainless coupling in use. Are they showing any signs of wear?All my failures have shown extensive wear on all three Oldham coupling components.Derek Fox.

[Ian]

I'll be honest Derek, I don't know!I'm working on the 'it's working now, leave it alone' basis.No doubt the bike will surprise me yet again...You're right though; I should check it.

[Dell Boy]

Hello Ian, I`ll risk 20 sqids on two stainless couplings if you want to get your mate to knock some more up.Cheers, Derek.

[Ian]

The parts are in hand, be about three weeks. Sadly for us his wife has just had a baby so it'll take a bit longer than usual.Ian

[Ian]

I got a PM about ordering some more but due to early onset incompetence I've deleted it.Yes. I've asked for two more for you.I'll post again when I have them.

[bodgerbloke52]

IanPut me down for one if I am not to late.Roger