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BMC C series gearbox code

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webmonster

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May 16, 2009, 3:08:50 AM5/16/09
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I've got a 1958 Morris Isis and I've just bought an overdrive gearbox
that was fitted to a Wolseley 6/90.
This should be a 4-speed gearbox but unfortunately I suspect that it
is a 3 speed overdrive unit from a 6/99 because on the top of the
gearbox is a 'badge' which says Type 29-O-3
Can anyone here confirm/deny that I've got the wrong gearbox?

thanks in advance,
--
Robert

Dave Plowman (News)

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May 16, 2009, 4:39:21 AM5/16/09
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In article
<ca925d0b-1c94-40f6...@d25g2000prn.googlegroups.com>,

I've a feeling those three speed boxes are in fact four speed ones with
first inhibited by the selector mechanism - so could well be just fine if
you use the right bits from your original. IIRC, there was a floor
gearchange conversion for that series which 'released' first gear.

There can't be many Isis left on the roads - pretty rare car even when new.

--
*Why isn't there mouse-flavoured cat food?

Dave Plowman da...@davenoise.co.uk London SW
To e-mail, change noise into sound.

webmonster

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May 16, 2009, 6:49:29 PM5/16/09
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Hi Dave,

On May 16, 8:39 pm, "Dave Plowman (News)" <d...@davenoise.co.uk>
wrote:

> I've a feeling those three speed boxes are in fact four speed ones with
> first inhibited by the selector mechanism - so could well be just fine if
> you use the right bits from your original. IIRC, there was a floor
> gearchange conversion for that series which 'released' first gear.

I've got a 6/99 and Isis workshop manuals and although the gearboxes
are very similar, the layshaft gears and the mainshaft look very
slightly different.
The later 6/110 has a floor change 4-speed 'box, but this looks quite
different.

Given that the overdrives themselves are the same unit what I really
need is the right mainshaft. If I was brave I'm sure I could get my
existing mainshaft shortened and machined to suit.

> There can't be many Isis left on the roads - pretty rare car even when new.

True - I've only seen a photo of one other (a nice red one) on the
road here in NZ. Both the red car and my Isis are the late ones with
the RH floor change and the little fins at the back.
I wonder why they never sold well when new. It certainly goes and
handles quite adequately (running on radials and I've renewed all the
steering/suspension bushes).

regards,
--
Robert

Dave Plowman (News)

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May 17, 2009, 7:06:01 AM5/17/09
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In article
<b22ee15a-cb1f-430d...@g31g2000pra.googlegroups.com>,

webmonster <mon...@caverock.net.nz> wrote:
> > I've a feeling those three speed boxes are in fact four speed ones
> > with first inhibited by the selector mechanism - so could well be just
> > fine if you use the right bits from your original. IIRC, there was a
> > floor gearchange conversion for that series which 'released' first
> > gear.

> I've got a 6/99 and Isis workshop manuals and although the gearboxes are
> very similar, the layshaft gears and the mainshaft look very slightly
> different.

It would be easy to tell from that if it were a true three speed box or a
modified four?

> The later 6/110 has a floor change 4-speed 'box, but this
> looks quite different.

I'm not well up on this series - but I'll ask my brother who has had
several 6 cylinder BMC cars. Indeed he may have a spare A95 box which is 4
speed column change. Although I know he had a clear out of such things
when scrap prices were high.

The 'B' series box had openings top and side to allow the same basic box
to work with either floor or column change - I assumed the 'C' series one
was the same.

> Given that the overdrives themselves are the same unit what I really
> need is the right mainshaft. If I was brave I'm sure I could get my
> existing mainshaft shortened and machined to suit.

> > There can't be many Isis left on the roads - pretty rare car even when
> > new.

> True - I've only seen a photo of one other (a nice red one) on the
> road here in NZ. Both the red car and my Isis are the late ones with
> the RH floor change and the little fins at the back.
> I wonder why they never sold well when new. It certainly goes and
> handles quite adequately (running on radials and I've renewed all the
> steering/suspension bushes).

The Austin version was far more common here. Dunno why. The Isis looked
perhaps rather ungainly against it, though. But beauty is in the eye of
the beholder. ;-)

--
*If you remember the '60s, you weren't really there

Mike P

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May 17, 2009, 7:44:52 AM5/17/09
to
On Sat, 16 May 2009 09:39:21 +0100, Dave Plowman (News) screamed:

> In article
> <ca925d0b-1c94-40f6...@d25g2000prn.googlegroups.com>,
> webmonster <mon...@caverock.net.nz> wrote:
>> I've got a 1958 Morris Isis and I've just bought an overdrive gearbox

<snip>

> There can't be many Isis left on the roads - pretty rare car even when
> new.

36 left on the road in the UK according to this month's Practical
Classics. Of course, that doesn't say how many are lying in barns, fields
or garages.

Mike P

Robert Greenfield

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May 18, 2009, 5:11:29 AM5/18/09
to
In article <505cd30...@davenoise.co.uk>,

Dave Plowman (News) <da...@davenoise.co.uk> wrote:
> In article
> <b22ee15a-cb1f-430d...@g31g2000pra.googlegroups.com>,
> webmonster <mon...@caverock.net.nz> wrote:

> > I've got a 6/99 and Isis workshop manuals and although the gearboxes
> > are very similar, the layshaft gears and the mainshaft look very
> > slightly different.

> It would be easy to tell from that if it were a true three speed box or a
> modified four?

Not for a gearbox oaf like me.
"Look! whirring bits and pieces!"
;-)

I'll open up the 'box and have a look. That will settle it.


> The 'B' series box had openings top and side to allow the same basic box
> to work with either floor or column change - I assumed the 'C' series one
> was the same.

From what I can tell, all early C-series gearboxes were linkage driven -
they all had a shifter and selector lever on the side. Even the Healeys
had their centre floor shift lever offset to the left.


> > True - I've only seen a photo of one other (a nice red one) on the
> > road here in NZ. Both the red car and my Isis are the late ones with
> > the RH floor change and the little fins at the back.
> > I wonder why they never sold well when new. It certainly goes and
> > handles quite adequately (running on radials and I've renewed all the
> > steering/suspension bushes).

> The Austin version was far more common here. Dunno why. The Isis looked
> perhaps rather ungainly against it, though.

The series I Isis looks a little out of proportion to my eye, but the
little fins and 2-tone paint work of the series II Isis look better to me.


> But beauty is in the eye of the beholder. ;-)

True. And I like my Isis :-)

regards,

--
Using Windows� is such a pleasure

Robert Greenfield
change rockcave to caverock to email if you so desire.

Robert Greenfield

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May 18, 2009, 5:15:11 AM5/18/09
to
In article <77ablkF...@mid.individual.net>,

Mike P <pri...@privacy.net> wrote:
> On Sat, 16 May 2009 09:39:21 +0100, Dave Plowman (News) screamed:

> > There can't be many Isis left on the roads - pretty rare car even when
> > new.

> 36 left on the road in the UK according to this month's Practical
> Classics. Of course, that doesn't say how many are lying in barns,
> fields or garages.

That figure will be both series I and II, I imagine. How does that compare
to the A90 and A95 I wonder?

I wonder how many might be left on the road here in NZ.

regards,

--
Pandas will eat only bamboo; I will eat only chocolate biscuits...

Roger

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May 18, 2009, 7:36:51 AM5/18/09
to
The message <505d4c5b...@rockcave.net.nz>
from Robert Greenfield <mon...@rockcave.net.nz> contains these words:

> From what I can tell, all early C-series gearboxes were linkage driven -
> they all had a shifter and selector lever on the side. Even the Healeys
> had their centre floor shift lever offset to the left.

The 1955 BN1 I had back in 1969 had the gearstick offset to the left and
the gate transposed as well. (IIRC top was left and back). First was
supposed to be blanked off (leaving 3 gears) but wasn't and the O/D was
only supposed to work with the top 2 gears but would have worked with
all.

--
Roger Chapman

Dave Plowman (News)

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May 18, 2009, 9:29:44 AM5/18/09
to
In article <505d4c5b...@rockcave.net.nz>,

Robert Greenfield <mon...@rockcave.net.nz> wrote:
> In article <505cd30...@davenoise.co.uk>,
> Dave Plowman (News) <da...@davenoise.co.uk> wrote:
> > In article
> > <b22ee15a-cb1f-430d...@g31g2000pra.googlegroups.com>,
> > webmonster <mon...@caverock.net.nz> wrote:

> > > I've got a 6/99 and Isis workshop manuals and although the gearboxes
> > > are very similar, the layshaft gears and the mainshaft look very
> > > slightly different.

> > It would be easy to tell from that if it were a true three speed box
> > or a modified four?

> Not for a gearbox oaf like me. "Look! whirring bits and pieces!" ;-)

> I'll open up the 'box and have a look. That will settle it.

Assuming they are genuine BMC manuals they'll include line drawings of the
box? My Magnette ZA one does. So just count the gears on the layshaft. The
one at the front is the drive gear off the input shaft. The next one along
first gear, then second, etc. No gear for top as that is direct - the
input and output shafts get locked together.

First gear (on the four speed) is spur teeth - ie at right angles to the
shaft, and slides to engage the rest helical cut and are constant mesh,
the engagement being by synchromesh clutches.

I thought all these boxes were four speed - the old first gear still being
needed for reverse.


> > The 'B' series box had openings top and side to allow the same basic
> > box to work with either floor or column change - I assumed the 'C'
> > series one was the same.

> From what I can tell, all early C-series gearboxes were linkage driven -
> they all had a shifter and selector lever on the side. Even the Healeys
> had their centre floor shift lever offset to the left.

Right.


> > > True - I've only seen a photo of one other (a nice red one) on the
> > > road here in NZ. Both the red car and my Isis are the late ones with
> > > the RH floor change and the little fins at the back.
> > > I wonder why they never sold well when new. It certainly goes and
> > > handles quite adequately (running on radials and I've renewed all the
> > > steering/suspension bushes).

> > The Austin version was far more common here. Dunno why. The Isis looked
> > perhaps rather ungainly against it, though.

> The series I Isis looks a little out of proportion to my eye, but the
> little fins and 2-tone paint work of the series II Isis look better to
> me.


> > But beauty is in the eye of the beholder. ;-)

> True. And I like my Isis :-)

I learned to drive on my father's Series II Oxford - ie the same basic
body.

> regards,

--
*Why don't sheep shrink when it rains?

Robert Greenfield

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May 19, 2009, 4:57:16 AM5/19/09
to
In article <505d63f...@davenoise.co.uk>,

Dave Plowman (News) <da...@davenoise.co.uk> wrote:

> Assuming they are genuine BMC manuals they'll include line drawings of
> the box? My Magnette ZA one does. So just count the gears on the
> layshaft. The one at the front is the drive gear off the input shaft.
> The next one along first gear, then second, etc. No gear for top as that
> is direct - the input and output shafts get locked together.

> First gear (on the four speed) is spur teeth - ie at right angles to the
> shaft, and slides to engage the rest helical cut and are constant mesh,
> the engagement being by synchromesh clutches.

> I thought all these boxes were four speed - the old first gear still
> being needed for reverse.

The reverse idler on the Isis diagram has spur teeth whilst the 6/99's
idler has helical cut gears.

Actually... thanks to your good description above I think I can see what
is the main difference -
On the Isis the smallest gear on the layshaft has spur teeth.

On the 6/99 the layshaft has the same number of gears, but the smallest
gear has helical cut teeth and the gear next to it is *exactly* the same
size (so the equivalent to 1st and 2nd gear on the Isis are identical -
solves the reverse-speed dilemma).

> I learned to drive on my father's Series II Oxford - ie the same basic
> body.

I've got a series II Oxford too - my first car which I bought when I was
19. It was a real minter - 54,000miles when I bought it - 2 previous
owners. Now I'm the ripe old age of 34 (and the Oxford has done
89,000miles) and I've got it off the road for a 'quick tidy-up'.
The boot and engine bay need a repaint and the engine is getting a bit
tired. And the gearchange linkages need re-bushing and I want a new
gearlever knob (column change - the white plastic has cracked like they
all do).

regards,

--
"Geoffery, Bungle's going out" ... "Well put some more petrol on him then!"

Dave Plowman (News)

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May 19, 2009, 12:09:21 PM5/19/09
to
In article <505dcee4...@rockcave.net.nz>,

Robert Greenfield <mon...@rockcave.net.nz> wrote:
> > I thought all these boxes were four speed - the old first gear still
> > being needed for reverse.

> The reverse idler on the Isis diagram has spur teeth whilst the 6/99's
> idler has helical cut gears.

> Actually... thanks to your good description above I think I can see what
> is the main difference -
> On the Isis the smallest gear on the layshaft has spur teeth.

Yes - what I'd suspect.

> On the 6/99 the layshaft has the same number of gears, but the smallest
> gear has helical cut teeth and the gear next to it is *exactly* the same
> size (so the equivalent to 1st and 2nd gear on the Isis are identical -
> solves the reverse-speed dilemma).

Right. So it looks like a specially made three speed. Perhaps the later
engines produced too much torque for the basic box and this was the way
round?

> > I learned to drive on my father's Series II Oxford - ie the same basic
> > body.

> I've got a series II Oxford too - my first car which I bought when I was
> 19. It was a real minter - 54,000miles when I bought it - 2 previous
> owners. Now I'm the ripe old age of 34 (and the Oxford has done
> 89,000miles) and I've got it off the road for a 'quick tidy-up'.
> The boot and engine bay need a repaint and the engine is getting a bit
> tired. And the gearchange linkages need re-bushing and I want a new
> gearlever knob (column change - the white plastic has cracked like they
> all do).

There's a silly bent wire link which fits into rubber bushes and makes the
change very sloppy - even when perfect. My father, who was an engineer,
replaced it with a rose jointed arrangement. Said it improved things no
end - but I only ever drove it after the mod so can't comment on the
difference.


> "Geoffery, Bungle's going out" ... "Well put some more petrol on him
> then!"

That was the very first programme I worked on after moving from the BBC to
Thames TV and was delighted to see how everyone sent it up after the
deadly serious BBC children's department.

--
*When it rains, why don't sheep shrink? *

Robert Greenfield

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May 30, 2009, 5:20:21 AM5/30/09
to
Well, I got permission from the owner to open up the gearbox and yes, it
is a smelly 3-speed from a 6/99, not a 4-speed. Rats.
I also found out why it is jammed - the selector lever has had a hell of a
belt at some time (it has been welded to mend it); this has forced it to
jump out of its slot internally.
Seems a bit silly for BMC to have the external lever pointing downwards.
On my Isis both levers point upwards - out of the way of rocks etc.

In article <505df67...@davenoise.co.uk>,


Dave Plowman (News) <da...@davenoise.co.uk> wrote:

<re: Oxford II gearchange>

> There's a silly bent wire link which fits into rubber bushes and makes
> the change very sloppy - even when perfect. My father, who was an
> engineer, replaced it with a rose jointed arrangement. Said it improved
> things no end - but I only ever drove it after the mod so can't comment
> on the difference.

My Oxford is a late series II with many (most? all??) of the factory mods
already installed for the gearchange. They must have made these changes
for a reason :-)

I've always thought it is quite a nice gearchange until recently when I
noticed I was stuggling more often to find 1st or 2nd.
The other oddity is that the reverse gear 'lockout' on the column lever
needs a surprising pull overcome the spring. My wife can't easily get the
Oxford into reverse.


> > "Geoffery, Bungle's going out" ... "Well put some more petrol on him
> > then!"

> That was the very first programme I worked on after moving from the BBC
> to Thames TV and was delighted to see how everyone sent it up after the
> deadly serious BBC children's department.

It was a fun show :-)

regards,

--
"That's not right. It shouldn't do that" - helpful comment by old car folk

Jim Warren

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May 30, 2009, 6:11:47 AM5/30/09
to
Robert Greenfield wrote:

> I've always thought it is quite a nice gearchange until recently when I

> noticed I was struggling more often to find 1st or 2nd.


> The other oddity is that the reverse gear 'lockout' on the column lever
> needs a surprising pull overcome the spring. My wife can't easily get the
> Oxford into reverse.
>

Just a thought - have you tried disconnecting the change mechanism from
the gearbox and testing how the column change feels when unconnected?
It is possible that the problems you are experiencing could be in the
mechanism rather than the gearbox.

My brother had a column change Ford years ago, and when he thought he
had gearbox difficulties it turned out to be a column linkage bush instead.

Also, make sure the 3rd/4th selector returns cleanly to neutral before
the column can go across to the 1st/2nd position or the interlock in the
gearbox can block the engagement of the lower gears. The Ford had
adjustments on the linkage between the rods at the bottom of the column
and the gearbox, but I don't know the BMC layout so you may or may not
have similar adjustments available. But I thought I would mention it
because it might be something you hadn't thought of.

Jim

Robert Greenfield

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Jun 1, 2009, 4:59:17 AM6/1/09
to
Hi Jim,

In article <DD7Ul.35701$OO7....@text.news.virginmedia.com>,
Jim Warren <jimw...@OMITblueyonder.co.uk> wrote:

> Just a thought - have you tried disconnecting the change mechanism from
> the gearbox and testing how the column change feels when unconnected?
> It is possible that the problems you are experiencing could be in the
> mechanism rather than the gearbox.

> My brother had a column change Ford years ago, and when he thought he
> had gearbox difficulties it turned out to be a column linkage bush
> instead.

I am 90% certain that the problems are in the mechanism/linkages rather
than the gearbox.


> Also, make sure the 3rd/4th selector returns cleanly to neutral before
> the column can go across to the 1st/2nd position or the interlock in the
> gearbox can block the engagement of the lower gears.

Hmm! I hadn't thought of that. Thanks.


> The Ford had
> adjustments on the linkage between the rods at the bottom of the column
> and the gearbox, but I don't know the BMC layout so you may or may not
> have similar adjustments available.

I'll need to have a look - I'm sure the ball-jointed linkages will have
some adjustment, however I doubt this will make up for slogged out bushes.

regards,

--
D.ont R.elax U.ntil G.randma's S.ober

pape...@gmail.com

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Mar 30, 2013, 3:48:11 PM3/30/13
to

Dave Plowman (News)

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Mar 30, 2013, 7:46:02 PM3/30/13
to
In article <4b7b5d5b-0c57-4976...@googlegroups.com>,
<pape...@gmail.com> wrote:
> 2009. m�jus 16., szombat 9:08:50 UTC+2 id�pontban webmonster a
> k�vetkez�t �rta:
> > I've got a 1958 Morris Isis and I've just bought an overdrive gearbox
> > that was fitted to a Wolseley 6/90. This should be a 4-speed gearbox
> > but unfortunately I suspect that it is a 3 speed overdrive unit from
> > a 6/99 because on the top of the gearbox is a 'badge' which says Type
> > 29-O-3 Can anyone here confirm/deny that I've got the wrong gearbox?
> >
> > thanks in advance,
> > --
> > Robert

IIRC, it is still the same four speed internally. If you have both, it
should be possible to make a good one from the two.

--
*TEAMWORK...means never having to take all the blame yourself *

zwge...@gmail.com

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Nov 14, 2015, 4:16:47 AM11/14/15
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