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BMC 1.5 Crankshaft Bolt


MrC

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Hi All

 

New to both this forum and forum's in general and need a little advise if I may please.

 

Have got a leaking front crank seal that I need to replace and am unsure of the correct size for the bolt holding the pulley on.

 

Also is the bolt right or left hand thread?

 

Many thanks in advance

 

MrC

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Thank you all - esp MtB - I did search prior to posting this question

 

Now searched again and found it - 32mm

 

Right hand thread - Thanks Flyboy

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The hex size can vary, (assuming you want to know the size of socket or spanner to use, rather than the thread dimensions). Mine has a dog for a starting handle so might well be different to one without. By memory it's 1 1/8", but I'll double check later tonight when I get back to the boat.

 

Rob

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Thank you all - esp MtB - I did search prior to posting this question

 

Now searched again and found it - 32mm

 

Right hand thread - Thanks Flyboy

1.1/4'' AF then, sounds big.

Edited by bizzard
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Hmmm - 33mm - that's 1 5/16" AF then? - so a google (other search engines are available) search tells me - from what I can find out 1.5 and 1.8's are the same

 

Thank you for checking - I'm no where near mine at the moment

 

hernia gauge smile.png

Edited by MrC
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Hmmm - 33mm - that's 1 5/16" AF then? - so a google (other search engines are available) search tells me - from what I can find out 1.5 and 1.8's are the same

 

hernia gauge smile.png

Vernier gauge but Hernia is what I call it when I have to measure something like that bolt (by feel,blind) deep down in the bilge and close up against the bulkhead. ouch!

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Go with 1.1/4" AF

 

33 mm AF is an uncommon size.

 

If I remember correctly the BMC A series used 1.1/4" AF on the transverse engines but may have used a different size on the inline engine ie. A35 or Morris 1000 which had starter dogs.

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Go with 1.1/4" AF

 

33 mm AF is an uncommon size.

 

If I remember correctly the BMC A series used 1.1/4" AF on the transverse engines but may have used a different size on the inline engine ie. A35 or Morris 1000 which had starter dogs.

As well as measuring I just tried an 1.1/4'' socket on it also and it was too small.

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I'm confident that it was 33mm=1.5/16''. The 1.1/4'' socket is the biggest in my 1/2'' drive set. I have 1.5/16'' and much larger sockets in my commercial 3/4'' drive set but that's locked away in my shed and hassle to get out.

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As well as measuring I just tried an 1.1/4'' socket on it also and it was too small.

I was wrong. You are correct in that it is 1.5/16" AF. That is what I have just found on Google for the MGB.

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Bizzard, Flyboy - What can I say apart from a massive Thank you for your time and trouble

 

Orf to get a 1 5/16" socket to get it done this weekend

Edited by MrC
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Can't remember, its been a long time but it will be AF so if you have a good 1/2'' drive socket set. 11/16'' - 3/4'' maybe. A lock tab could also be there which will need knocking back first.

I think you are right about the tab, petrol ones did I know.

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Go with 1.1/4" AF

 

33 mm AF is an uncommon size.

 

If I remember correctly the BMC A series used 1.1/4" AF on the transverse engines but may have used a different size on the inline engine ie. A35 or Morris 1000 which had starter dogs.

 

The 1500 and 1800 are based on the B Series petrol engine...

 

:)

 

This bolt head size has been discussed in detail here too, long long ago, and the conclusion was it is a bloody awkward size for which no-one ever has a socket to fit. 1 1/4" AF is far too easy.

 

MtB

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The 1500 and 1800 are based on the B Series petrol engine...

 

smile.png

 

This bolt head size has been discussed in detail here too, long long ago, and the conclusion was it is a bloody awkward size for which no-one ever has a socket to fit. 1 1/4" AF is far too easy.

 

MtB

I think the A & B series shared the same size bolt. The thread is 5/8" UNF but the hexagon is an odd size at 1.5/16" AF

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  • 5 years later...
11 minutes ago, Gilsteamin said:

Hi Guys. On this subject, how do you remove the nut? The manual mentions the tool but it’s not illustrated in the manual tools section. Need to stop the pulley moving so it can be removed. ??‍♂️

B1D6ECD1-76CE-4F3B-A9B2-3D0263CEFA84.jpeg

I posted this qustion not long ago,and although I didn't remove the nut(I sold the boat) the answer from one of CWF members,was to wedge a tyre lever or similar piece of metal in the starter ring.

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19 minutes ago, Gilsteamin said:

Hi Guys. On this subject, how do you remove the nut? The manual mentions the tool but it’s not illustrated in the manual tools section. Need to stop the pulley moving so it can be removed. ??‍♂️

B1D6ECD1-76CE-4F3B-A9B2-3D0263CEFA84.jpeg

The usual proceedure to remove a tight nut from something that wants to rotate  is to hold the socket on the nut and give the wrench a smart strike with a hammer (Avoiding hands etc) It may require several attempts before the nut is loosened, but that is how I got mine off.

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