Crankshaft bearings

[derekn]

Hi Chris, many thanks for your help.  I think it was an undersize bearing that had been put on.  It was a tight fit when we took it off and when I measured the inside diameter, it was slightly less than 1.25 inches .  I have had the crankshaft crank tested, so it is a good one, apart from the problem with the end of it.  I will have to consider ways of raising the surface or trying to find another crankshaft.  I think it would be better if I could do this and use a standard size bearing, which would help with long term future use.
Derek

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Hi Howard, yes, I’ve had the crankshaft tested, and it was sound.  It’s a pity it has this bearing problem.
Derek

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Hi Robert, your suggestion of nickel plating the crankshaft sounds interesting, this would increase the diameter of the shaft, and then I could have it ground to the correct size to take the 1.25 inch bearing.  I’m having all the chrome parts on the car replated at the moment, and I will talk to the metal plating company about this idea. Many thanks.
Derek

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Derek are you sure the rear bearing is undersize, or has the bearing simply been spinning on the shaft and worn it down?

It's a not uncommon situation. The traditional fix was to dot-punch the shaft all over the mating area and this would raise spots locally to provide some measure of grip. A more modern solution is to build up the shaft by metal spraying, though this generally entails machining off some material to provide enough thickness. Another possibility is to machine a little off and sleeve the shaft. Some just slap it together with some Loctite - depends just how loose it is.

If you choose to follow the latter course, for heaven's sake make sure you are able to remove the bearing from the shaft again! Keeping in mind that you may have to do so with it in the crankcase where it's very hard to apply much force. 

Before doing any such thing or spending more money I would suggest crack testing the shaft and inspecting it carefully for any other defects. You might very well do better just to find another shaft, they are not usually much money.

Hi Chris, many thanks for your help.  I think it was an undersize bearing that had been put on.  It was a tight fit when we took it off and when I measured the inside diameter, it was slightly less than 1.25 inches .  I have had the crankshaft crank tested, so it is a good one, apart from the problem with the end of it.  I will have to consider ways of raising the surface or trying to find another crankshaft.  I think it would be better if I could do this and use a standard size bearing, which would help with long term future use.

Derek

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Hi Derek

I would echo what Chris has said.  These cranks are around 90 years old and most have had a hard life. Failures are not uncommon and may render the whole engine scrap. So crack test and check the journals carefully.

Cheers

Howard

Hi Howard, yes, I’ve had the crankshaft tested, and it was sound.  It’s a pity it has this bearing problem.

Derek

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Many years ago I had the rear journal fairly heavily nickel plated, which is something you can do at home with a relatively cheap kit. It may be that if you follow that course of action you will need to get the plating on the journal ground down slightly to give the tight bearing fit which you should have.

Hi Robert, your suggestion of nickel plating the crankshaft sounds interesting, this would increase the diameter of the shaft, and then I could have it ground to the correct size to take the 1.25 inch bearing.  I’m having all the chrome parts on the car replated at the moment, and I will talk to the metal plating company about this idea. Many thanks.

Derek