Triumph Herald Overdrive

[Justin Vaughan]

: Strictly the mainshaft of an overdrive gearbox is actually shorter than
: the normal one, but it also has the oil pump cam and different splines
: and end piece. I'm not quite sure what you mean by "extension tunnel"
: but it reminds me that nobody seems to have pointed out the need to cut
: four inches off the front if the propshaft tunnel in the floor panel.
I have two 13/60 convertibles and one 12/50 saloon at the moment. All have -
as original, as far as I can see - a rectangular cutout on the tunnel which
allows a J-type O/D gearbox to fit in with no further cutting. Perhaps it's
different with a D-type - I have been led to believe that the cut out was
needed for the Vitesse and therefore included in all back bodies for
simplicity. It's therefore probably not there on pre-Vitesse Heralds.

It wasn't there on my non-Overdrive Vitesse until I cut one, and that
was a fairly late car (1968). The D-type is shorter than the J-type, so
that the original cut-out I made for the D-type box wasn't enough to get
the J-type one in. It is possible, now I come to think of it, that the
Herald's engine position means a D-type box would just squeeze in
without the cut-out, as it's a couple of inches further forward.
--
Rob Pearce
(Former) Club Triumph Herald derivatives consultant
The above views and opinions are mine, and do not necessarily reflect Club
Triumph policy.

Hi all,
just resurrecting this thread as I am also looking to add an OverDrive unit to my 1969 13/60 Herald, but to complicate matters my car has had a Spitfire 1500 engine installed. I am new to the car and wondered if anyone here know exactly what i will need to carry out this conversion?

thanks, Justin

[Davey]

On Wed, 11 Oct 2023 04:09:51 -0700 (PDT)

Post by Justin Vaughan

: Strictly the mainshaft of an overdrive gearbox is actually
shorter than : the normal one, but it also has the oil pump cam
and different splines : and end piece. I'm not quite sure what you
mean by "extension tunnel" : but it reminds me that nobody seems
to have pointed out the need to cut : four inches off the front if
the propshaft tunnel in the floor panel.
I have two 13/60 convertibles and one 12/50 saloon at the moment.
All have - as original, as far as I can see - a rectangular cutout
on the tunnel which allows a J-type O/D gearbox to fit in with no
further cutting. Perhaps it's different with a D-type - I have
been led to believe that the cut out was needed for the Vitesse
and therefore included in all back bodies for simplicity. It's
therefore probably not there on pre-Vitesse Heralds.

It wasn't there on my non-Overdrive Vitesse until I cut one, and
that was a fairly late car (1968). The D-type is shorter than the
J-type, so that the original cut-out I made for the D-type box
wasn't enough to get the J-type one in. It is possible, now I come
to think of it, that the Herald's engine position means a D-type
box would just squeeze in without the cut-out, as it's a couple of
inches further forward. --
Rob Pearce
(Former) Club Triumph Herald derivatives consultant
The above views and opinions are mine, and do not necessarily
reflect Club Triumph policy.

Hi all,
just resurrecting this thread as I am also looking to add an
OverDrive unit to my 1969 13/60 Herald, but to complicate matters my
car has had a Spitfire 1500 engine installed. I am new to the car and
wondered if anyone here know exactly what i will need to carry out
this conversion?
thanks, Justin

Actually, no, but I did this on my 13/60, with little trouble. A local
place cut down and re-made a spare propshaft to my specifications, and
the result was great.
I do not know anything about D-Type and J-Type boxes, I just modified
whatever I had.
Good luck!

[Indy Jess John]

Post by Justin Vaughan

: Strictly the mainshaft of an overdrive gearbox is actually shorter than
: the normal one, but it also has the oil pump cam and different splines
: and end piece. I'm not quite sure what you mean by "extension tunnel"
: but it reminds me that nobody seems to have pointed out the need to cut
: four inches off the front if the propshaft tunnel in the floor panel.
I have two 13/60 convertibles and one 12/50 saloon at the moment. All have -
as original, as far as I can see - a rectangular cutout on the tunnel which
allows a J-type O/D gearbox to fit in with no further cutting. Perhaps it's
different with a D-type - I have been led to believe that the cut out was
needed for the Vitesse and therefore included in all back bodies for
simplicity. It's therefore probably not there on pre-Vitesse Heralds.

It wasn't there on my non-Overdrive Vitesse until I cut one, and that
was a fairly late car (1968). The D-type is shorter than the J-type, so
that the original cut-out I made for the D-type box wasn't enough to get
the J-type one in. It is possible, now I come to think of it, that the
Herald's engine position means a D-type box would just squeeze in
without the cut-out, as it's a couple of inches further forward.
--
Rob Pearce
(Former) Club Triumph Herald derivatives consultant
The above views and opinions are mine, and do not necessarily reflect Club
Triumph policy.

Hi all,
just resurrecting this thread as I am also looking to add an OverDrive unit to my 1969 13/60 Herald, but to complicate matters my car has had a Spitfire 1500 engine installed. I am new to the car and wondered if anyone here know exactly what i will need to carry out this conversion?
thanks, Justin

A long while ago (somewhere about 1980) I had a Dolomite 1500 with
overdrive where the gearbox self-destructed dumping it oil on the clutch
and the road. I went hunting round the local breakers and found a
replacement overdrive gearbox, but when I got it home it wasn't a
straight swap - the dimensions were different (perhaps the difference
between the D and J units?) - so I took it back for a refund. There was
a non-overdrive gearbox for the Dolomite there, so I took that and the
associated propshaft. The splines were different so I had to get a
different clutch that would fit the gearbox splines. When fitted, the
original overdrive gear lever (with a switch built into the knob) fitted
the gearbox but it wasn't perfectly aligned to the hole in the
transmission tunnel, so that hole needed to be adjusted with a file.

I don't know if the Herald is simpler, but I do know that the overdrive
gearbox is longer so you will need to replace or re-engineer the
propshaft. You might have to check that the gearbox mountings are in
the same position and adjust if necessary too. I think the difference
between the Herald and Spitfire engines are a longer stroke so the
engine blocks should be identical.

[Justin Vaughan]

Post by Indy Jess John

Post by Justin Vaughan

: Strictly the mainshaft of an overdrive gearbox is actually shorter than
: the normal one, but it also has the oil pump cam and different splines
: and end piece. I'm not quite sure what you mean by "extension tunnel"
: but it reminds me that nobody seems to have pointed out the need to cut
: four inches off the front if the propshaft tunnel in the floor panel.
I have two 13/60 convertibles and one 12/50 saloon at the moment. All have -
as original, as far as I can see - a rectangular cutout on the tunnel which
allows a J-type O/D gearbox to fit in with no further cutting. Perhaps it's
different with a D-type - I have been led to believe that the cut out was
needed for the Vitesse and therefore included in all back bodies for
simplicity. It's therefore probably not there on pre-Vitesse Heralds.

It wasn't there on my non-Overdrive Vitesse until I cut one, and that
was a fairly late car (1968). The D-type is shorter than the J-type, so
that the original cut-out I made for the D-type box wasn't enough to get
the J-type one in. It is possible, now I come to think of it, that the
Herald's engine position means a D-type box would just squeeze in
without the cut-out, as it's a couple of inches further forward.
--
Rob Pearce
(Former) Club Triumph Herald derivatives consultant
The above views and opinions are mine, and do not necessarily reflect Club
Triumph policy.

Hi all,
just resurrecting this thread as I am also looking to add an OverDrive unit to my 1969 13/60 Herald, but to complicate matters my car has had a Spitfire 1500 engine installed. I am new to the car and wondered if anyone here know exactly what i will need to carry out this conversion?
thanks, Justin

A long while ago (somewhere about 1980) I had a Dolomite 1500 with
overdrive where the gearbox self-destructed dumping it oil on the clutch
and the road. I went hunting round the local breakers and found a
replacement overdrive gearbox, but when I got it home it wasn't a
straight swap - the dimensions were different (perhaps the difference
between the D and J units?) - so I took it back for a refund. There was
a non-overdrive gearbox for the Dolomite there, so I took that and the
associated propshaft. The splines were different so I had to get a
different clutch that would fit the gearbox splines. When fitted, the
original overdrive gear lever (with a switch built into the knob) fitted
the gearbox but it wasn't perfectly aligned to the hole in the
transmission tunnel, so that hole needed to be adjusted with a file.
I don't know if the Herald is simpler, but I do know that the overdrive
gearbox is longer so you will need to replace or re-engineer the
propshaft. You might have to check that the gearbox mountings are in
the same position and adjust if necessary too. I think the difference
between the Herald and Spitfire engines are a longer stroke so the
engine blocks should be identical.

thank you :)

[Abandoned Trolley]

Post by Justin Vaughan

: Strictly the mainshaft of an overdrive gearbox is actually shorter than
: the normal one, but it also has the oil pump cam and different splines
: and end piece. I'm not quite sure what you mean by "extension tunnel"
: but it reminds me that nobody seems to have pointed out the need to cut
: four inches off the front if the propshaft tunnel in the floor panel.
I have two 13/60 convertibles and one 12/50 saloon at the moment. All have -
as original, as far as I can see - a rectangular cutout on the tunnel which
allows a J-type O/D gearbox to fit in with no further cutting. Perhaps it's
different with a D-type - I have been led to believe that the cut out was
needed for the Vitesse and therefore included in all back bodies for
simplicity. It's therefore probably not there on pre-Vitesse Heralds.

It wasn't there on my non-Overdrive Vitesse until I cut one, and that
was a fairly late car (1968). The D-type is shorter than the J-type, so
that the original cut-out I made for the D-type box wasn't enough to get
the J-type one in. It is possible, now I come to think of it, that the
Herald's engine position means a D-type box would just squeeze in
without the cut-out, as it's a couple of inches further forward.
--
Rob Pearce
(Former) Club Triumph Herald derivatives consultant
The above views and opinions are mine, and do not necessarily reflect Club
Triumph policy.

Hi all,
just resurrecting this thread as I am also looking to add an OverDrive unit to my 1969 13/60 Herald, but to complicate matters my car has had a Spitfire 1500 engine installed. I am new to the car and wondered if anyone here know exactly what i will need to carry out this conversion?
thanks, Justin

Er ... I have turned up at this party a bit late, so a bit reluctant to
throw a spanner in the works, but .....

Has any thought been given to the rear axle ratio ?

I know that a number of cars which had overdrive units factory fitted
had a slightly lower ratio than the "normal" models.

For example, my 3.4 Jaguar Mark 2 has an overdrive and a 3.77 diff
whereas the non-overdrive models were fitted with a 3.54 diff

I have no idea what the overdrive gear ratio might be for the Herald,
but on the Jag its 0.778:1 - which with the normal diff ratio might make
top gear unmanageably tall (obviously I have never tried it)

One other big difference is that overdrive can only be engaged in top
gear on the Jag whereas the Herald might allow it in 3rd or even 2nd ?
On the Herald it might be used as a ratio splitter, whereas on the Jag
it’s just a 5th gear

[Davey]

On Fri, 13 Oct 2023 12:39:32 +0100

Post by Abandoned Trolley
One other big difference is that overdrive can only be engaged in top
gear on the Jag whereas the Herald might allow it in 3rd or even
2nd ? On the Herald it might be used as a ratio splitter, whereas on
the Jag it’s just a 5th gear

The gearbox I purchased didn't have a gearlever attached, so I just put
a toggle switch on the dash. Worked fine, and it operated on all
gears, which could result in an interesting close-ratio box effect.

When I first fitted the box, I didn't know that it had the operating
valve stuck in the 'On' position, so when I first drove the modified
car, it went on its own from first to first-overdrive, and then second-,
third-and fourth-overdrive. The problem was easily fixed.

Note my mention in my other post also about the length pf the propshaft
required.

[Abandoned Trolley]

Post by Davey
On Fri, 13 Oct 2023 12:39:32 +0100

Post by Abandoned Trolley
One other big difference is that overdrive can only be engaged in top
gear on the Jag whereas the Herald might allow it in 3rd or even
2nd ? On the Herald it might be used as a ratio splitter, whereas on
the Jag it’s just a 5th gear

The gearbox I purchased didn't have a gearlever attached, so I just put
a toggle switch on the dash. Worked fine, and it operated on all
gears, which could result in an interesting close-ratio box effect.
When I first fitted the box, I didn't know that it had the operating
valve stuck in the 'On' position, so when I first drove the modified
car, it went on its own from first to first-overdrive, and then second-,
third-and fourth-overdrive. The problem was easily fixed.
Note my mention in my other post also about the length pf the propshaft
required.

OK

Jag owners are warned against fiddling with the overdrive switch to
allow the overdrive to be used in any gear but top.

Theres some sort of torque multiplying effect in the lower gears which
can cause overdrive gear teeth to get stripped, which I imagine is
insanely expensive.

There used to be a prop shaft balancing specialist on an industrial
estate in Wembley, and a good chunk of his work was to do with
overdrives - I guess he is long gone by now though :-\

[Davey]

On Fri, 13 Oct 2023 14:42:42 +0100

Post by Abandoned Trolley
Jag owners are warned against fiddling with the overdrive switch to
allow the overdrive to be used in any gear but top.
Theres some sort of torque multiplying effect in the lower gears
which can cause overdrive gear teeth to get stripped, which I imagine
is insanely expensive.

My engine was a 1300cc Spitfire, with one carburettor, so the main
difference from the 13/60 engine was the camshaft. Base output: 61 bhp
(I think). My car's output was not much more, it just happened at
different engine speeds. Ad I usually only used the O/D in the higher
gears.

Post by Abandoned Trolley
There used to be a prop shaft balancing specialist on an industrial
estate in Wembley, and a good chunk of his work was to do with
overdrives - I guess he is long gone by now though :-\

There is a company near me on the Suffolk/Norfolk border which will
balance anything you take to them.