Pip,
Although I have no personal experience with this type of failure (thank
goodness), I can offer a couple of theories:
1) It is likely that there was a small bit of wear on the splines or the
flange when fitted. This could allow some degree of movement between the two
parts, especially under heavy acceleration. Tightness of the nut will only
draw the flange down onto the output shaft shoulder. It is unlikely to
eliminate any relative rotational movement.
2) Any such movement will inevitably cause some degree of stress on the
splines. If the shaft was already hard (which is likely) stress fracturing
could ensue with the consequences you describe.
I don't know that this could have been eliminated, but prior to installation
of the replacement shaft, I would make sure there is no rotational slack and
have it x-rayed or magnafluxed to ensure there is no pre-existing stress
cracks.
Cheers,
Lew Palmer
-----Original Message-----
From: owner-mg-mmm@autox.team.net [mailto:owner-mg-mmm@autox.team.net] On
Behalf Of Pip Bucknell
Sent: Thursday, February 05, 2004 2:32 PM
To: MMM List UK
Subject: stripple splines
Nice to have seen the recent issues under discussion.
I wonder if anyone can resolve this for me.
My P-type passed to my son a couple of years ago whilst I made the mistake
of
thinking I could produce a better one.
His car is supercharged and before dragging it off to Adelaide I needed to
remove the special racing gearbox we had built up. In went an old but re
built MG crash box and the brand new box I had went down to Adelaide as a
spare.
Earlier this month, Christopher lost drive (on all 4 gears) in the car and
had
to trailer it home.
The cause was that he had stripped the splines from the flange that joins
the
gearbox output shaft to the tail shaft in a normal P-type. I am told that
the
nut holding the flange was still split pinned. So, it would appear that the
flange was still tight.
I have not heard of this happening before. Can anyone tell me what caused
this to happen and better still how to stop it happening again.
Many thanks
Pip
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