Dolomite overdrive
Posted By : Colin Wake, 15-Sep-2004, 07:43pm
Stevie
Neither of those 2 gearboxes will fit, the first not at all, the 2nd only with extensive modifications, and the gearing will still be wrong.
Sorry
Colin
Neither of those 2 gearboxes will fit, the first not at all, the 2nd only with extensive modifications, and the gearing will still be wrong.
Sorry
Colin
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Dolomite overdrive
Posted By : Stephen Bentley, 16-Sep-2004, 01:35pm
Thanks for the information Colin, I guess I will have to add an overdrive to my list of things to purchase.
Regards
Stevie b-
Dolomite overdrive
Posted By : Colin Wake, 16-Sep-2004, 01:54pm
It's not just the OD you need obviously, it is the other bits that add up, shortened prop, cabling, angle drive, sometimes a different speedo cable, column switch and cowl (ouch territory!)
I am sure you have realised, but just in case you didn't, that you can't just bolt an OD onto a non-OD box.
Colin-
Dolomite overdrive
Posted By : Jason Chinn, 16-Sep-2004, 03:00pm
http://www.canleyclassics.com/featuredproducts.asp...maybe that will help you visualise what you need.
In general all Laycock overdrive units of a type (ie D and J type) are the same - you could pull one out of a Transit van, Volvo, Reliant Scimitar etc and if could be used on a Triumph with the right adapter plates. There are some subtle ratio differences but none that you'd really notice. Adapter plates are available to fit a J type to Herald 3 and single rail boxes. If you see a Laycock overdrive on a box, any box, it's a good thing to save.
Although the overdrive is a separate unit it needs to mate, via an adapter plate, to a box intended for overdrive. You can't just plonk an overdrive onto a non-overdrive box, the output shaft is different
A Dolly 1300 single rail gearbox with a J type will go into a Herald 13/60 - you need a mounting plate and rubber mount. A special clutch plate (the splines are different) but it's a Marina 1.3 plate I think. The prop needs to be a special length too, a standard one won't do. The box should come with a lever and overdrive switch on top - you need a little wiring but there's no relay involved in a J Type so it's fairly straight forward to do. If you want to make it look like a factory Vitesse fit then you'll need a two stalk cowl for the column and a switch - both are remade but at a price. the switch is about &163;40, can't remember what the cowl costs. It all goes in nicely and there's loads of room fo rthe box and overdrive. You can change a solenoid without jacking up anything. You can even change the tail seal and housing with the box in the car - been there and done all that.
Overdrive on a Herald is great, next to electronic ignition it was the single most impressive modification I did. It's not the same driving experience as in a GT6 or Vitesse with overdrive, you can't really power through the change into overdrive but it's excellent for relaxed cruising. It makes the Herald happy at motorway speeds and makes B road driving in third and overdrive a nice experience again.
If you can get yourself a list of the parts you need and acquire them from autojumbles, eBay etc and do it for less than the &163;600 odd for a complete kit then it makes it even better
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Dolomite overdrive
Posted By : David Rumens, 17-Sep-2004, 06:56pm
Overdrive/Gearbox units you can use are as follows;
Spitfire Mk111/IV - Three rail gearbox with D type.
Spitfire 1500 - Single rail gearbox J type.
Dolomite 1500 - Single rail gearbox J type.
But as Colin has said you will also need lots of addtional bits
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Dolomite overdrive
Posted By : William Davies, 17-Sep-2004, 09:44pm
There are a few additions, Spitfire Mk1-3 use the same gearbox design, 3-rail, 3-synchros with D-type overdrive. The MkIV is virtually identical externally, but has synchromesh on all 4 forward gears. Very late MkIVs were fitted with a J-type overdrive on the 3-rail gearbox. This last configuration is very rare as an original installation, but is an excellent choice if you're lucky enough to find one.
Cheers,
Bill.
http://www.rarebits4lcassics.co.uk-
Dolomite overdrive
Posted By : Matthew Holland, 18-Sep-2004, 10:08am
That's the setup I've got.
I didn't realise it was so rare, it works wonderfully though.
: )-
Dolomite overdrive
Posted By : David Rumens, 18-Sep-2004, 04:16pm
As Bill has said the wide ratio three rail with J type is very rare. The gearbox is ths same as used in the pre 1975 Toledo and 1500 TC from 1973 to 1974. A nice easy to select the gears gearbox.
The most common type now available is the 1500 Spit /1500 Dolomite type.
Most of the early Spit type have now all but disappeared and as these are more straight forward to fit is a pity.
One problem with the J type overdrive is the Speedo drive cog was changed to suit the diff ratio. This can cause problems with the speedo calibration or finding a suitable speedo that matches your set-up.
Where as the D type used the same drive cogs irrespective of the diff ratio. The speedo head was changed to suit the diff.
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Dolomite overdrive
Posted By : David Pearson, 20-Sep-2004, 06:52am
The three rail J type was quite rare in production, but in practice it is now relatively common. It is one of the most common conversions we produce and sell. Many years ago we had the special aluminium adapter plate and mainshaft made and these effectively are the only unique parts of the whole thing, the rest of it it is/was easilly sourced.
David-
Dolomite overdrive
Posted By : David Rumens, 21-Sep-2004, 07:04pm
Thanks David, I forgot the present day ones you are producing. But it did give you an opportunity to do a bit of the old sales pitch.
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Dolomite overdrive
Posted By : James Carruthers, 21-Sep-2004, 07:18pm
3-rail J-type is the badgers nadgers... you get the lovely 3-rail and the stronger J-type... easier to wire in too... well a bit anyway...
That's what I have...
James
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Dolomite overdrive
Posted By : Philip Brammer, 21-Sep-2004, 07:28pm
I will agree there, the 3 rail reverse position is a joy whereas the single rail is a pain in the rectum. J type is also much smoother than I recall the D type being.
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