Herald - Install D Type onto 3 Rail Gearbox

[Jon J 1250]

Hi,

I have been lucky enough over time to acquire a NOS 3 rail gearbox OD spec with the correct mainshaft, and a NOS D Type OD unit.

Being unused, neither the gearbox has had an OD unit attached before and the OD has not been attached to a gearbox before, so although the units are complete, I am missing the parts required to connect them together.

So far as I can tell I think I need the following to fit them together and install in the car, can anybody let me know if I have missed anything.

Gearbox to OD adaptor plate
Mainshaft Oil pump cam, retainer and woodruff key
Mainshaft rear clip
Angle drive for speedo cable
Gearchange Inhibitor switch, mounting plate and fixings
Gearchange Inhibitor cam
OD Wiring loom
OD Column switch and cowl
Lucas Relay
Shortened Propshaft
OD Gearbox chassis mounting plate

Also I will be using the gearchange extension from my existing non OD gearbox, will this be ok with the inhibitor switch?
 

Regards
Jon

Edited September 19 by Jon J 1250

[Pete Lewis]

the inhibitor switch needs simple cam/lever added to the extended remote rod to operate the switch

this is all infront of the remote hsg,  and there's a bracket that hold the switch bolts on the front remote bolts 

something like  MkII Gear Shift Mechanism : Canley Classics

or  Gear Shift Mechanism : Canley Classics

bracket    D Type Overdrive Internals : Canley Classics  133770

early cars also used different  on oposite side for  a reverse switch and double cam on the remote

later reverse was included in the top cover

Pete

 

Edited September 19 by Pete Lewis

[johny]

2 hours ago, Jon J 1250 said:

Gearbox to OD adaptor plate
Mainshaft Oil pump cam, retainer and woodruff key
Mainshaft rear clip
Angle drive for speedo cable
Gearchange Inhibitor switch, mounting plate and fixings
Gearchange Inhibitor cam
OD Wiring loom
OD Column switch and cowl
Lucas Relay
Shortened Propshaft
OD Gearbox chassis mounting plate

Think the list is pretty comprehensive so would only add the mounting rubber which is different to the non OD cotton reels. Oh and the cover plate you'll need for the gap thats got to be cut in the transmission tunnel. Plus another speedo cable as probably need a bit longer than the original.

Whats the serial number on the gearbox? Also the type of drive flange the OD has (and the diff you have) will indicate which style of propshaft you need?

Edited September 19 by johny
technical error

[Pete Lewis]

when it comes to fitting the OD to the gearbox you can read a lot about aligning the hub and splines 

right down inside ...hopeless waste of time

get two decent slim pry bars or decent screwdrivers and when dropping the unit onto the mainshaft 

lever the two piston plates open this releases the clutch and everything just rolls into place

keep fingers out the way as it will drop quickly 

make sure the pump cam is rotated to its shallowest point to aid the pump roller riding up the cam .

remove the levers for the final ... its on 

Pete

[Josef]

5 hours ago, Jon J 1250 said:

Also I will be using the gearchange extension from my existing non OD gearbox, will this be ok with the inhibitor switch?

Pete’s alluded to this, but no you can’t. The overdrive inhibitor requires a different gear change remote, though it’s only one part that actually differs. You need that bit you can see sticking out the end in my first photo here. Second photo is a non overdrive version.

Also, a NOS gearbox and overdrive is quite some find!

Edited September 19 by Josef

[DanMi]

and you can't just put the cam onto the existing shaft as the shaft needs to be longer

[Pete Lewis]

you need 12 7740    in stock  https://www.canleyclassics.com/?catalogue=triumph-gt6-mki/ii&diagram=triumph-gt6-mki/ii-gear-shift-mechanism

Pete

[johny]

Have to confirm that is the longer one as there seems to be some confusion around part numbers for this item. I wonder if there were originally two different lengths and then Triumph standardised on the longer one for both OD and non OD usage...

[Colin Lindsay]

30 minutes ago, johny said:

Have to confirm that is the longer one as there seems to be some confusion around part numbers for this item. I wonder if there were originally two different lengths and then Triumph standardised on the longer one for both OD and non OD usage...

I was trying to find the part numbers earlier; I'm not sure if Canley's website is correct or not as they list the Herald part as 127740 "shaft overdrive operating cam" but as they don't list a non-overdrive version I suspect that could be the O/D part number used on the non O/D diagram, given that O/D wasn't that common on Heralds and the diagram doesn't show the operating cam for the inhibitor switch. The early Spitfire parts diagram has that part as 118041 "gearbox shaft" which MAY be the non O/D part thus as Pete says 127740 is the correct part number.

It'll be a case of waiting until one appears in the used market or obtaining one from a supplier; none on eBay at present.

Edited September 20 by Colin Lindsay
confused myself too

[Pete Lewis]

as most of the range use a 3 rail box  the only variation being 3 sync or 4 sync  

it pays to search around the various parts lists then check  availability  online   

soe will have it some suppliers wont .

eg the inhibitor sw bracket is shown on some but not all same applies to the early reverse sw bracket 

depends where you look but dont stick with your own particular model  widens the pages search 

Pete

[Jon J 1250]

18 hours ago, Pete Lewis said:

when it comes to fitting the OD to the gearbox you can read a lot about aligning the hub and splines 

right down inside ...hopeless waste of time

get two decent slim pry bars or decent screwdrivers and when dropping the unit onto the mainshaft 

lever the two piston plates open this releases the clutch and everything just rolls into place

keep fingers out the way as it will drop quickly 

make sure the pump cam is rotated to its shallowest point to aid the pump roller riding up the cam .

remove the levers for the final ... its on 

Pete

Very helpful advice, thankyou Pete.

[Jon J 1250]

17 hours ago, Josef said:

Pete’s alluded to this, but no you can’t. The overdrive inhibitor requires a different gear change remote, though it’s only one part that actually differs. You need that bit you can see sticking out the end in my first photo here. Second photo is a non overdrive version.

Also, a NOS gearbox and overdrive is quite some find!

 

 

Thanks Josef,

Having never owned an OD car, I am feeling a little out of my depth.
I am hoping to be able to get the inhibitor bits I need new from suppliers, I guess if I can't find one, I could make a longer operating rod for the selector out of some steel round bar.

Just re-watching your video on wiring your Herald OD, very useful. Have you got the car back yet?

Regards
Jon
 

[Jon J 1250]

3 hours ago, Colin Lindsay said:

I was trying to find the part numbers earlier; I'm not sure if Canley's website is correct or not as they list the Herald part as 127740 "shaft overdrive operating cam" but as they don't list a non-overdrive version I suspect that could be the O/D part number used on the non O/D diagram, given that O/D wasn't that common on Heralds and the diagram doesn't show the operating cam for the inhibitor switch. The early Spitfire parts diagram has that part as 118041 "gearbox shaft" which MAY be the non O/D part thus as Pete says 127740 is the correct part number.

It'll be a case of waiting until one appears in the used market or obtaining one from a supplier; none on eBay at present.

Thanks Colin, It appears 127740 is the correct longer shaft/rod for the OD inhibitor operating cam, and unfortunately the cam itself 126750 is not available.

I could be wrong

Regards
Jon

[Jon J 1250]

On 19/09/2024 at 15:42, johny said:

Think the list is pretty comprehensive so would only add the mounting rubber which is different to the non OD cotton reels. Oh and the cover plate you'll need for the gap thats got to be cut in the transmission tunnel. Plus another speedo cable as probably need a bit longer than the original.

Whats the serial number on the gearbox? Also the type of drive flange the OD has (and the diff you have) will indicate which style of propshaft you need?

Hi Jonny,

thanks for advice, why would I need to cut the transmission tunnel, I thought it fit the space ok?

The OD has a circular flange on the back same as photo attached, so hopefully good for the Vitesse propshaft I'll need.

The gearbox has an odd number GR31697\7A - not sure what that relates to. It also has a fitting on the top cover I have not seen before, I am guessing this is for a reverse light switch?

Edited September 20 by Jon J 1250

[johny]

ok an OD gearbox is 3 inches longer than a non version which is why you need another prop. Also to be able to get the gearbox in and out easier and allow access to the flange bolts all the small chassis cars with OD have a section cut out of the transmission tunnel and a cover plate fitted. Heres one:

The new propshaft will need the round flange at one end but the other should be square unless your differential has been changed to a later round type (Rimmers offer all 3 versions for this modification). The gearbox looks like a recon as they are usually overstamped GR which always gives a problem identifying which type it is. Definitely a 3 synchro but could be for a Spitfire or Vitesse 1600 and Im not sure what the differences, if any, are....

And yes that plug is where the reverse switch fits👍

[johny]

yes looking at the manual the two types of 3 synchro boxes arent the same with the Herald/Spitfire version having a input shaft splines outside diameter of 0.875" as opposed to the 1" of the Vitesse 1600. This is an important difference🤞

[Jon J 1250]

34 minutes ago, johny said:

ok an OD gearbox is 3 inches longer than a non version which is why you need another prop. Also to be able to get the gearbox in and out easier and allow access to the flange bolts all the small chassis cars with OD have a section cut out of the transmission tunnel and a cover plate fitted. Heres one:

 

The new propshaft will need the round flange at one end but the other should be square unless your differential has been changed to a later round type (Rimmers offer all 3 versions for this modification). The gearbox looks like a recon as they are usually overstamped GR which always gives a problem identifying which type it is. Definitely a 3 synchro but could be for a Spitfire or Vitesse 1600 and Im not sure what the differences, if any, are....

And yes that plug is where the reverse switch fits👍

Thanks Johnny, really useful info, so very much appreciated. I suspected it was an old factory recon box, but looks like all of the internals have been replaced with new as they are spotless and you can see the machining on the gears and layshaft without any trace of wear, which I guess is unlikely to be the case when you have a box reconditioned these days.

Will check the input spline diameter as advised.

JJ

[DanMi]

That is where the revers switch would be (red arrow)

[DanMi]

Canleys have the overdrive shaft, cam and bracket listed for the spitfire MK4 4 synchro box, no reason why those wouldn't work as the remote is the same. in fact I have an early mk4 box which has the earlier setup so either will work

Edited September 20 by DanMi

[Josef]

4 hours ago, Jon J 1250 said:

Having never owned an OD car, I am feeling a little out of my depth.
I am hoping to be able to get the inhibitor bits I need new from suppliers, I guess if I can't find one, I could make a longer operating rod for the selector out of some steel round bar.

Just re-watching your video on wiring your Herald OD, very useful. Have you got the car back yet?

Yes, I had also thought the longer operating rod would be possible to make as it’s just a steel bar with three holes drilled in it. The switch operating cam and the bracket to hold the inhibitor switch are also things one could make with access to a welder. I have all the parts for my GT6 box knocking around, so happy to provide measurements etc.

I’m afraid my Herald is still in a repair queue, but as we’re heading towards winter I’m guessing I might hear something soon ish. 

[DanMi]

https://www.canleyclassics.com/?catalogue=triumph-spitfire-mkiv/1500&diagram=triumph-spitfire-mkiv/1500-top-cover-extension-and-hand-lever-assembly

these will work and all parts seem to be in stock. Doesn't have the reverse light part but as you have a box with the reverse light blanked that is not a problem

Edited September 20 by DanMi

[Jon J 1250]

21 hours ago, Josef said:

Yes, I had also thought the longer operating rod would be possible to make as it’s just a steel bar with three holes drilled in it. The switch operating cam and the bracket to hold the inhibitor switch are also things one could make with access to a welder. I have all the parts for my GT6 box knocking around, so happy to provide measurements etc.

I’m afraid my Herald is still in a repair queue, but as we’re heading towards winter I’m guessing I might hear something soon ish. 

Many thanks, still doing some research but it looks like Spitfire mk4 parts will do the job, not completely period correct, but if it works then it will save a lot of bother.

Good luck getting the Herald back soon, look forward to seeing how it turns out, though I’m enjoying the GT6 too (slightly envious!) 👍

[Jon J 1250]

20 hours ago, DanMi said:

https://www.canleyclassics.com/?catalogue=triumph-spitfire-mkiv/1500&diagram=triumph-spitfire-mkiv/1500-top-cover-extension-and-hand-lever-assembly

these will work and all parts seem to be in stock. Doesn't have the reverse light part but as you have a box with the reverse light blanked that is not a problem

Many thanks, I really appreciate the effort you have put in to helping answer my question.
Looks like Canleys will be getting another order from me shortly 😁

Regards
JJ

[DanMi]

1 hour ago, Jon J 1250 said:

not completely period correct, but if it works then it will save a lot of bother.

Overdrive in a Herald is not period correct anyway (good mod though)

[johny]

3 hours ago, Jon J 1250 said:

Many thanks, I really appreciate the effort you have put in to helping answer my question.
Looks like Canleys will be getting another order from me shortly 😁

Regards
JJ

Confirm its not a Vitesse 1600 gearbox first as if so it could all get much more complicated😭