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100-4 Clutch BN-1 or BN-2 ???

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britcardoc Avatar
britcardoc Dan Dougherty
Marietta, GA, USA   USA
Is this clutch plate a BN-1 or BN-2 ?

10 splines

Thanks in advance, guys

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Trevor Parker Avatar
Trevor Parker Silver Member Trevor Parker W
Sidney, BC, Canada   CAN
1954 Austin-Healey 100 "Healey Beep Beep"
1955 Austin-Healey 100
I just counted the splines on my spare three speed and it has ten splines . I am taking the gearbox out of my BN2 next week if you don't have an answer by then I'll let you know. Cheers Trevor

Michael S Avatar
Michael S Michael Salter
Dwight, ON, Canada   CAN
From memory they both have the same number of splines but the shaft diameter of the BN1 is smaller 1" as opposed to 1 1/8" from memory.



Michael Salter
Technical Chairman (Big Healeys)
Austin Healey Concours Committee

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fts2 Raf S
Munich, Bavaria, Germany   DEU
@ Michael S

I'm about to rebuild a BN1 drivetrain and I'd like to lighten the flywheel and to use the BJ8 diaphragm type clutch cover. Do you maybe know if it will fit the BN1 3-speed gearbox?

Michael S Avatar
Michael S Michael Salter
Dwight, ON, Canada   CAN
Don't do it!!!

http://www.netbug.net/blogmichael/2017/01/03/austin-healey-100-crank-failures/

The inertia of the BN1 flywheel is essential to protect the BN1 gearbox from CRSO. BN1 gears are becoming very difficult to find and destroying another set in a futile attempt to make your Healey sound like a Yamaha is not wise.



Michael Salter
Technical Chairman (Big Healeys)
Austin Healey Concours Committee

PAN Avatar
PAN Alwyn Keepence
Ipswich, Queensland, Australia   AUS
Thanks Michael, very interesting. But now you have me worried!
Cheers,
Alwyn

fts2 Raf S
Munich, Bavaria, Germany   DEU
Thanks Michael too!

So no mods to the flywheel and clutch at all when I will retain the 3-speed gearbox?

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Michael S Avatar
Michael S Michael Salter
Dwight, ON, Canada   CAN
Well that would certainly be my recommendation. Because the gearbox fatigue failure may occur months after the flywheel modification the 2 events are seldom recognized as being connected.



Michael Salter
Technical Chairman (Big Healeys)
Austin Healey Concours Committee

filospinato Avatar
filospinato Jake Voelckers
Manassas, VA, USA   USA
The BJ8 flywheel and clutch option seems to really only be useful in the long run on BN2 gearboxes, then...

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Michael S Avatar
Michael S Michael Salter
Dwight, ON, Canada   CAN
I wouldn't really be able to give a properly calculated answer to that. The BJ8 flywheel and clutch have a different moment of inertia from the original, the clutch springs would have a different spring rate and travel and of course the 100 engine has a significantly larger CRSO than the 6 cylinder engine for which the BJ8 flywheel and clutch assembly were designed.
I think that I would be more inclined to use a diaphragm type of clutch on a 100 flywheel.
Usual disclaimer applies however ...



Michael Salter
Technical Chairman (Big Healeys)
Austin Healey Concours Committee

Michael S Avatar
Michael S Michael Salter
Dwight, ON, Canada   CAN
I wouldn't really be able to give a properly calculated answer to that. The BJ8 flywheel and clutch have a different moment of inertia from the original, the clutch springs would have a different spring rate and travel and of course the 100 engine has a significantly larger CRSO than the 6 cylinder engine for which the BJ8 flywheel and clutch assembly were designed.
I think that I would be more inclined to use a diaphragm type of clutch on a 100 flywheel.
Usual disclaimer applies however ...



Michael Salter
Technical Chairman (Big Healeys)
Austin Healey Concours Committee

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