A10 oil pump

[Jhg1958]

Just started on my 1961 A10 restoration. It had been roughly reassembled for sale but a right dog.

I have taken off the oil pump. The worm drive is slightly worn. How worn is ok?  Can I get a replacement? See photo.

Also the pump does not turn easily. I am tempted to take some fine wet and dry and ease off the tight points. Is this a bad idea?

John

[peterg123]

I had to rebuild a SH pump I got from USA as my 59 A7SS project came without any pump at all. If you intend to refurbish your oil pump the first thing you need at a sheet of FLOAT glass 1/4" minimum thick, slightly shorter than a sheet of emery paper, so you can wrap a sheet on against a flat surface.. This is because float glass (i.e. that used in counter tops) is for weird reasons almost 100% dead true flat. Any glass merchant should be able to cut a piece for you.

Such a sheet will have innumerable uses in restoration, including rubbing down carb flanges and rocker boxes, gearbox casings and more. It stands between you and oil leaks!

You also need maybe a magnifying glass. This oil pump repays VERY CAREFUL attention.

Engineers Blue is recommended highly.

Then you need some 600 or  800 grit good emery paper and maybe a sheet of 1000 grit to boot.

The 67-1389 you pictured is available from Dragonfly, new and cheap.  I will remark of the other  issues. These could be  three

1) Your PUMP FACE where it mates to the crankcase could be scored, pitted and rough. The remedy is using the 600 or emery on the floats glass rubdown plate, a few strokes in the direction, then turn 90 degrees, a few more strokes, then turn again etc.... and with oil on the emery paper...to remove and flatten those imperfections. If you don't rotate every say 5 strokes, you could "vee" your pump face and be in real probs.

2) Your pump is BINDING and does not turn freely. This needs to be traced down to whether your 67-1389 is binding in the long nose housing( could be rust or debris/dirt) or the same dirt  and/or rusted/deformed  or problematic oil pump gears.

3) More likely the pump is too LOOSE..there has to be (a) a very good, clean pair of oil pump gears (b) an almost imperceptible clearance between the gears and the end plate 67-1391 and 67-1388 "nose". . First check the steel end plate for scarring, rotation marks and etc. Again the emery paper and float sheet treatment applies.

However, with the pump BODY 67-1382, be very careful. It's Mazak "monkey metal", soft. If you rub down the body on any side  to take up any slack or clearance ( correct is when the pump turns by hand with  very slight stiffness or resistance resistance) without care on your emery sheet, you can end up with BINDING.

With all that I ended up emery glassing one of my gears a minimal amount. In the end I got a pump that when oiled spun with very slight resistance. On startup, it pumped like a Dutch windmill.

Why did I do all this? I have time and I saved about 300 Sterling.

[Jhg1958]

Nice to hear that they can work well. I was almost ready to buy a new one from SRM.  I suspect it is stiff as it has been run without oil then left dry for a long time.  I worked each part with Brasso until it turned freely. I will get a new Driving spindle.

The float glass is an event essential part for any old Brit bike.  I must admit to using valve grinding paste rather than emery paper.

My only problem now is that when I tighten the whole thing up it stops turning. I will flatten off the the nose casing and the end plate to see if this helps.  If not I will use the engineers blue to identify the tight piece and get rubbing.

The monkey metal is very alarming. There are small bits spoiled of the casting.  Probably best to smooth these off to prevent additional bits crumbling into the oil. 

Anyway like you I am not pressed for time.  Thanks for the advice