WANTED Banjo axle diff

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Ian Fozzard
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Re: WANTED Banjo axle diff

Post by Ian Fozzard » Thu Feb 27, 2020 7:17 pm

[attachment=0]s-l400 (1).jpg[/attachment]

I think this is the sort of stamping you should be able to see on the diff case?

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B Faiers
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Re: WANTED Banjo axle diff

Post by B Faiers » Fri Feb 28, 2020 12:26 am

Thanks Ian I'll have a look tomorrow, if not it will have to come down into the light and get stored in my overcrowded garage.
1964 MGB Roadster
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Michael Barclay
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Re: WANTED Banjo axle diff

Post by Michael Barclay » Fri Feb 28, 2020 8:36 am

Hi Guys
The crown wheel should be stamped on it outer perimeter. Should read something like 11/43 if it is a 3.9 ratio. Alternatively you could put a mark on the crown wheel and count the number of turms of the propshaft flange to work out the ratio.
Hope This helps.
Mike Barclay

Ian Fozzard
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Re: WANTED Banjo axle diff

Post by Ian Fozzard » Fri Feb 28, 2020 8:46 am

Thanks Mike. I guess the stamping on the crown wheel is 100% reliable, whereas any stamping on the case may be misleading if the ratio has been changed?

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Paul Hollingworth
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Re: WANTED Banjo axle diff

Post by Paul Hollingworth » Fri Feb 28, 2020 4:43 pm

If the axle has half shafts in then you could do one turn on the halfshaft (remembering to lock the other one) and see how many turns the input flange does. With the banjo type it looks like you would have to remove the halfshafts to get it apart and even then you might not be able to see the pinion that well. However if you count the teeth on the crown wheel and divide by 3.9 or 4.2 and it should give an integer number.
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Peter Cresswell
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Re: WANTED Banjo axle diff

Post by Peter Cresswell » Fri Feb 28, 2020 6:51 pm

I'd forgotten I had this!
I think I mostly got it from the Magnette Register.
Most likely the Marathon car has a 4.3:1 ratio as there isn't a 4.2:1 in the list. This would be an ideal choice for a rally car which would need to keep up quite high speeds. I seem to remember that Gerry Brown's FIA car had a 4.875:1 ratio. It was geared for 105mph at 6,500rpm! He said it was tiring on Autoroutes!!!
[attachment=0]BMC axle ratios.pdf[/attachment]
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B Faiers
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Re: WANTED Banjo axle diff

Post by B Faiers » Tue Mar 03, 2020 5:37 pm

Well after another excursion into the loft I'm no wiser. Can't find any relevant markings on the edge of the crown wheel or the case.

Thanks Peter for posting the BMC axle ratios table, most interesting.

Would it be reasonable to assume that the item I have is standard, and that only any non-standard items would have been marked? Perhaps the non standard ratios would have only been available through the old 'Special Tuning' or 'comps' departments as specials and got nowhere near the production line?
1964 MGB Roadster
1958 MGA Coupe
1926 MG 14/28 Bullnose
2012 MG 6TSE
2003 MG ZS180

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