Clutch parts for fitting a Triumph Overdrive gearbox onto a 1970 Triumph Herald 1200

[jagnut66]

Hi, 

I have just collected an overdrive gearbox to fit onto my 1970 Triumph Herald 1200.

What I now need is a clutch that will fit.

At present the Herald has the standard non-overdrive box, clutch and flywheel fitted. 

I have been advised the overdrive gearbox is from a Triumph 1300.

The input shaft has 20 splines (I have counted them) and the seller advised me that I will need a 6 1/2" plate with fine splines. 

I would imagine he advised that size of plate so it would fit my existing flywheel.

Below are pictures of the gearbox (I will clean it up before fitting it😉).

I have posed the question, via email, to Rimmer Bros. but thought I would also 'ask the experts':

So, can you advise me what clutch parts I need to purchase, in terms of release bearing, clutch plate and clutch cover, in order to get this fitted to my Herald?

Many thanks,

Mike.

[johny]

Cant help much but the gearbox is definitely the latest single rail type probably from a 1500 Spitfire. That means it will be 4" longer than your original box...

[DanMi]

you have 2 choices 1 get a 1500 flywheel and 4 sleeves to make the bolt holes smaller then use the 1500 clutch or 2 use the 1300/1147 flywheel and clutch cover with a certain clutch plate from \i believe 1 of the dolomites which is the correct diameter with the fine splines  eg ebay no 174947059033. The release bearing is the same

[DanMi]

spacer for the flywheel bolts to fit 1500 flywheel, I believe is https://www.jamespaddock.co.uk/flywheel-spacer-bush-2 but you would need to check

[DanMi]

plus you will need a custom propshaft probably best to buy new from David Mac or Canleys (who I think get from DM anyway) as it needs to be shorter and have a small flange at the rear and large at the front. You will also need the mounting plate/mount possibly there. and the gear lever, or use a standard 1500 gear lever and add the switch on the column as on early spitfire/vitesse and you will need to make a wiring loom. It all sounds a lot but really pretty simple oh and you may want to cut the prop tunnel a bit and make a cover so that you can access the prop to gearbox bolts (not sure if needed for this conversion)

[NonMember]

8 hours ago, DanMi said:

use the 1300/1147 flywheel and clutch cover with a certain clutch plate from \i believe 1 of the dolomites which is the correct diameter with the fine splines

I would expect that to be the Dolomite 1300 clutch (not the Toledo one as that's a 3-rail gearbox)

[Colin Lindsay]

Re the original clutch question: the Herald with the coil clutch used a 6 1/4 inch clutch plate; the later cars with diaphragm used a 6 1/2 plate. There's a difference in how the covers / types fit the flywheel. The coil clutch fits to the flywheel with two locating dowels, and the diaphragm clutch with three. I'd go for a complete diaphragm clutch kit to suit the gearbox (identify it by the serial number) - I'm hoping that it will also fit the Herald flywheel, if it's a diaphragm unit, as I suspect they were all the same for the smaller four cylinder cars - if not you'll need the correct flywheel plus make sure you have a diaphragm slave cylinder; the one with the notch in the side rather than the ring all the way round. As you've already stated, the release bearing needs to be the domed type rather than the flat.

After that, it's a case of measuring the rear end and having the propshaft shortened or adjusted to fit. I've done two recently and for both I just used a solid Herald prop, in my opinion less bother than sliding joints or straps.

[jagnut66]

9 hours ago, DanMi said:

plus you will need a custom propshaft

Thanks, I've got one made up already.

9 hours ago, DanMi said:

and you may want to cut the prop tunnel a bit and make a cover so that you can access the prop to gearbox bolts (not sure if needed for this conversion)

All advice is greatfully received, as this isn't something I've done before. I will try and leave it as standard / reversible as possible though.

Talking of reverse, I meant to ask, I take it the two wires near the gear lever position (last picture) are for a reversing lamp? I have wired one up at present on a separate switch, as the 1200 doesn't have one.

1 hour ago, Colin Lindsay said:

Re the original clutch question: the Herald with the coil clutch used a 6 1/4 inch clutch plate; the later cars with diaphragm used a 6 1/2 plate. There's a difference in how the covers / types fit the flywheel. The coil clutch fits to the flywheel with two locating dowels, and the diaphragm clutch with three. I'd go for a complete diaphragm clutch kit to suit the gearbox (identify it by the serial number) - I'm hoping that it will also fit the Herald flywheel, if it's a diaphragm unit, as I suspect they were all the same for the smaller four cylinder cars - if not you'll need the correct flywheel plus make sure you have a diaphragm slave cylinder; the one with the notch in the side rather than the ring all the way round. As you've already stated, the release bearing needs to be the domed type rather than the flat.

Rimmer Bros have advised that I need a 6 1/2" Dolomite 1300 clutch plate to fit my 1200 Herald for this conversion, so from this I'm assuming my 1970 car has the diaphragm version. Your 1967 1200 Estate would be the same as mine wouldn't it Colin?

Ironically, in their next sentence, they state they have none in stock! 😄

Fortunately an eBay source was quoted in an earlier post in this topic, so I've sourced one from there.

I don't think I have any clutch issues with the existing set up, so was hoping to use the existing clutch cover, though it may pay me to source a new release bearing, just in case. 

Should I go for a 1200 or 1300 release bearing, though I think someone said they are the same?

Best wishes,

Mike.

[Colin Lindsay]

My 1967 estate was diaphragm, so I think yours should be the same. The serial number will tell you what gearbox it is and so the clutch plate can be bought for that model.

With clutches, unless I'm sure everything is 100% I'll replace what I can - saves taking it all apart later on for some small part that was left alone first time. Get the best clutch you can - cheaper ones may not be as well made, and again you want to fit and forget as much as possible.

Release bearing is GRB207, same for Spitfire and Dolomite 1300.

 

[DanMi]

Be careful I ordered a release bearing on it's last year and the one the supplied was about 5mm thinner so check before using

[jagnut66]

3 hours ago, DanMi said:

Be careful I ordered a release bearing on it's last year and the one the supplied was about 5mm thinner so check before using

Noted, thanks.

7 hours ago, Colin Lindsay said:

Release bearing is GRB207, same for Spitfire and Dolomite 1300.

Thanks Colin, I will order one of those then.

Best wishes,

Mike.

[jagnut66]

On 23/09/2021 at 22:02, johny said:

That means it will be 4" longer than your original box...

It's just occurred to me, as I finally gear up (no pun intended😉) to fit this, will it fit straight onto my existing Herald 1200 gearbox crossmember or do I need to make some alterations / adjustments there for it to sit comfortably?

Or should I purchase a Spitfire crossmember and fit that with new bushes?

I know, I should have thought about this earlier.......🙄

Best wishes,

Mike.

[Clive]

You will need a different mounting plate, and the OD rear rubber mount is totally different.

I expect (but cannot guarantee) you need a spitfire 1500 OD mounting plate.

I ought to know this, I put single rail OD boxes into a few heralds.... last one about 20 years ago hence no recollection of exact details.

I "think" I use a flat bit of steel plate on a couple of conversions, just be careful to get the rear flange of the gearbox the correct height. The centre wants to be the same height off the chassis as your existing box (ie parallel to the diff flange, or very close to parallel)

If you have b=not got a prop yet, remember you need to get the correct sized flanges, teh box has the late flange, your diff the earlier type. Holes in different places and different sizes.

[Colin Lindsay]

52 minutes ago, jagnut66 said:

It's just occurred to me, as I finally gear up (no pun intended😉) to fit this, will it fit straight onto my existing Herald 1200 gearbox crossmember or do I need to make some alterations / adjustments there for it to sit comfortably?

Or should I purchase a Spitfire crossmember and fit that with new bushes?

As Clive says you'll need an overdrive mounting plate; it uses the same holes in the Herald chassis as the original but sits slightly further towards the rear. About £12 from Paddocks. I was lucky in that I used a 3-rail J-type box from a Spitfire so that it ended in roughly the same place as the Herald box so was easily accessible, but if yours is a single rail and then correspondingly longer you may need to cut the centre tunnel to reach the propshaft bolts and then find a blanking plate to cover the extended hole in the tunnel.

    

[jagnut66]

Firstly, to say thanks to everyone for the (ongoing) advice. 😃👍

 

5 hours ago, Colin Lindsay said:

then find a blanking plate to cover the extended hole in the tunnel.

I found this on eBay, it looks the same as the one in your picture but is listed for the Spitfire, do you know if it is the suitable for the Herald tunnel?

https://www.ebay.co.uk/itm/255538604088?hash=item3b7f49a838:g:GoUAAOSwVyligl~x

I've ordered one of these from James Paddock:

http://www.jamespaddock.co.uk/overdrive-mounting-plate-d-type-2

But found this cheaper on eBay:

https://www.googleadservices.com/pagead/aclk?sa=L&ai=DChcSEwjai6qnm6j4AhUJsu0KHUeoAiAYABAJGgJkZw&ohost=www.google.com&cid=CAESbeD2eNCZ58P-2XC6A839VPa4ug6NaY-_a4GaA0cPewNKM5xcxI-xT01UNAakxRrGPklJmMAP80lDlBTDWDFHnvj2cnVUoLfMQbjrDQkOY1IHf3Fm50Wn7PkERqlFPua2bV4Agh7jkI8RscqrKys&sig=AOD64_1VSosLBaqTQuUMRqZPcnsOFXKA4A&ctype=5&q=&ved=2ahUKEwj_hKWnm6j4AhVSeMAKHYpsCIYQ9aACKAB6BQgBEJ0B&adurl=

Best wishes,

Mike.

[johny]

Are you going to do anything to the box before it goes in Mike?

[Pete Lewis]

1 hour ago, jagnut66 said:

do you know if

yes you need all three parts  the plate the mount and the tunnel cover 

you could just part cut the tunnel and fold out the way , bend back when prop is bolted up

fix the loose end witha bracket or suchlike 

[jagnut66]

40 minutes ago, johny said:

Are you going to do anything to the box before it goes in Mike?

Apart from giving it a clean up and replacing the release bearing, no. I was sold it as a working gearbox, I am hoping it is such. 

I am not skilled enough to start stripping down an overdrive gearbox, so it would have to be a professional job and that's a bill I could do without at present. 

It either works or the existing four speed would go back in for now.

Two other questions I do have: Firstly, whilst moving the box into the garage I have noticed the little short back wire, does it connect as I have placed it in the first picture below? (Don't worry about it's condition, I intend to make up a new one.)

Secondly, I take it the strap in the second picture is a severed earth strap to the chassis? If so I shall source a replacement.

Once again, many thanks,

Mike.

 NB: The gearbox isn't stored upended like this, it was just positioned like this for the purpose of taking these pictures.

[jagnut66]

10 minutes ago, Pete Lewis said:

yes you need all three parts  the plate the mount and the tunnel cover

Thanks Pete, I take it I also need these?

https://www.ebay.co.uk/itm/265004020532?epid=25043536613&hash=item3db3787334:g:bX4AAOSwSJlf9fBR

Best wishes,

Mike.

[Colin Lindsay]

15 minutes ago, jagnut66 said:

 

The black wire is the earth; it connects to the bolt as shown, so it's fine. The power comes in at the other spade, so it's a simple straight-through current.

The metal 'strap' is just a support for the wiring, bend it round your cables to hold them steady and protect them.

Your tunnel cover is perfect for the car, the overdrive plate from Paddocks is the correct horizontal plate but you also need the other mount shown, the vertical bush that supports the rear of the box. Once you have that 'banana' shaped one, you don't need the other 'bobbin' versions that go on a non-overdrive box.

[johny]

Not sure about your questions there but your idea of just using the box as sold is a valid one although of course you might have to remove it again later (not a massive job). However a couple of easy things I would do beforehand is check the tightness of all bolts/nuts and also the operation of the overdrive solenoid (that unit with wire you have arrowed in the photo). This last just needs a 12v supply connecting to the terminals and you should hear a click each time as the shuttle valve inside moves back and forth. Im sure there'll be some other suggestions as well.... 

[Josef]

A minimum of a visual inspection for damaged teeth etc would be sensible. Just pop the top off, turn the input shaft by hand and look at all the gear teeth. Select each gear in turn by pushing the shift hubs and check they take a good push to engage and disengage. Basically look for anything glaringly obviously broken! Easier to spend 10 mins doing that now than have to remove the box, mounting, prop shaft etc and swap back. 

[jagnut66]

44 minutes ago, Colin Lindsay said:

The black wire is the earth; it connects to the bolt as shown, so it's fine. The power comes in at the other spade, so it's a simple straight-through current.

The metal 'strap' is just a support for the wiring, bend it round your cables to hold them steady and protect them.

Thanks for this Colin.

43 minutes ago, Josef said:

Just pop the top off,

I'm guessing you mean the 'lid' I've circled in my first picture below. If it's this way up, nothing's going to spring out when I remove it, is it?

I assume this will then need a gasket replacing when I put it back on. 

48 minutes ago, johny said:

the operation of the overdrive solenoid (that unit with wire you have arrowed in the photo). This last just needs a 12v supply connecting to the terminals and you should hear a click each time as the shuttle valve inside moves back and forth.

That makes sense.

Though I am now left wondering what the electrical spade connections circled in my second picture, located on the top of the box are for, I take it they are nothing to do with the overdrive unit?

Best wishes,

Mike.

[Pete Lewis]

1 hour ago, jagnut66 said:

I also need these?

no the two bolt support frommpaddocks is what replaces the rubber cotton reels   they are not needed 

Pete

[Josef]

56 minutes ago, jagnut66 said:

I'm guessing you mean the 'lid' I've circled in my first picture below. If it's this way up, nothing's going to spring out when I remove it, is it?

No, the part that the cover you’ve indicated is bolted to is what I mean. The selector mechanism is fitted to the top cover and pokes down to engage with the shift hubs inside the gearbox. The only thing you need to watch out for is getting the selector forks from the top cover engaged to the shift hubs when you reassemble, but it’s pretty impossible to get this wrong as there’s no space for anything to be in the wrong place. And yes taking the top cover off will require a new gasket to be fitted.