gearbox options

[kiwi-jim]

As my restoration progresses slowly, I am starting to think of options for a gear box, I have a standard tr3 4speed and am considering other options such as a 2500 with overdrive option or even a 5speed conversion of some sort.

Can anyone provide information of the 5 speed possibilities and their pros and cons.

[Ian Vincent]

Jim,

 

As astarter this is covered in some detail in Roger Williams's book called "How to Improve Triumph TR2 - 4a". There is also a section on gearbox conversions on the Triumph Technicalities disk that I received when I joined the TR Register. I can send you a copy if you like, but it must be somewhere on the club website I would have thought.

 

Rgds Ian

[tr3timme]

Jim: the advantages (or otherwise) of a 5-speed vs. those of the TR o/drive box, are the subject of regular discussion on the forum - as you probably know.

The 5-speed is, as we know from our moderns, OK for reducing noise and engine wear - and for enhancing fuel economy.

However for sheer fun in keeping up with modern cars as you move away from traffic lights and always seeming to have the right ratio for almost any circumstance - the joys of a part-clutchless 7-speed overdrive box do, in my view, outweigh any and all of the pros of a clutched 5-speed, in which keeping the engine on the cam is always more of an issue. So get an A-type with overdrive!

Tim.

[kiwi-jim]

Ian, Tim

Thanks for the replies, Looking for options to use is confusing, I can source locally rebuilt options such as a TR6 j type overdrive box and/or a dolomite sprint overdrive box. Will either of these be suitable conversions?? and what needs to be altered to fit them, if possible.

I havn't been able to find a link to the triumph technicalites disk you mention Ian so if that offers advise I'd love to see it.

Any other ideas appreciated especially if anyone can suggest models that have suitable gearboxs to consider. Am I right in assuming there are both A andJ type boxs and A and J type overdrive units??

[BrianC]

I agree whole-heartedly with Tim. If your existing gearbox is OK you could be fortunate and simply buy a reconditioned overdrive and associated conversion parts (yes, I was surprised to discover this is still possible - see TRaction #223 pp42-43). Otherwise, try to get an A-type from another donor vehicle.

 

Next best option is a later J-Type which will only give you overdrive on 3rd and 4th, but these are easier and cheaper to acquire. although requiring a little more work and enginuity to fit, there is plenty of information on the Forum and elsewhare from those who have gone this route.

 

Either of these options will also enhance the value and desirability of the car should it ever become necessary

[BrianC]

Ian, Tim

I havn't been able to find a link to the triumph technicalites disk you mention Ian so if that offers advise I'd love to see it.

Jim, if you let me know your email address, I will send you the appropriate section as a PDF file.

[kiwi-jim]

Thanks Brian, ive sent you a message. Will any A type overdrive unit fit my gearbox??

[BrianC]

Thanks Brian, ive sent you a message. Will any A type overdrive unit fit my gearbox??

Sorry Jim - my email system (BT Yahoo) will only allow me to attach files up to 20Mb but the Technicalities Gearbox&Overdrive section is 40.1Mb and it hardly reduces when zipped.

If anyone else has a more generous email system perhaps they can help. Only other possibility is to convert the PDF to Word but I don't have the full Acrobat software on my notebook. I will try on my daughter's workstation when she gets home tonight (unless I can hack it before).

 

Not sure which cars can be used as donors, but I think the big Triumph saloons (2000, 2500) are suitable. It's probably all in the Technicalities article but I haven't read it all! However, I'm sure there are a number of threads on the forum which cover suitable donors, so it might be worth a search.

[kiwi-jim]

Thanks Brian I am searching the forum and reading all the posts made on the topics I guess all the info is out there I just have to find the right overdrive unit. Cheers

[vivdownunder]

Hi Jim,

 

The correct A type overdrive for the seven speed TR2/3/3A gearbox/OD combo has an ID tag 22/61374. Then followed OD 22/61712 on all synchro 3B/TR4's, and the updated overdrive 22/61753 with a modification for a less harsh engagement on TR4A's.

 

Overdrive 22/61275 was used on the first TR2's, but only engaged on top gear, and is considered too weak for use on second and third gears.

 

You are probably aware that conversion of a non-overdrive gearbox to overdrive requires a different mainshaft, so if you find a suitable overdrive, before purchasing it, make sure you can get the matching mainshaft or it will be useless. Gearboxes before TS 26825 take a different mainshaft than those after.

 

You also need to check which top cover you have on your gearbox. Early TR2 non OD gearboxes had one blank plug in the top cover, which took an isolator switch for top gear overdrive only. Later gearbox covers had provision for two isolator switches to allow the overdrive to operate on 2nd, 3rd, and top gears.

 

If you draw a blank in finding an OD in NZ, there are suppliers in the USA who will take a non-overdrive gearbox in exchange for a fully rebuilt overdrive box. I don't have their websites with me, but google Triumphs Only and Quantum Mechanics.

 

Also I suggest you get a toggle switch to engage the overdrive as used from late TR2's, as you can tell easier at night whether you are in or out of OD than with the push-pull switch used on the early TR2's, seing there is no telltale light in the circuit.

 

The only car I know of here with a 5 speeder has a Toyota Supra box, but it's changed hands, and I haven't heard of it for years. It makes sense having the inbuilt reduction top gear in a 5 speeder, as the overdrive is arguably the most prone item on the car to trouble: is usually costly to repair, and parts are becoming very scarce.

 

Beware sedan gearbox/OD's, as being later units they operated with different clutches/flywheels, and can be trouble getting all the right parts to fit into a TR2.

 

Regards,

 

Viv.

[tony-qld]

If you are interested in going for a 5 speed Supra box have a look at www.dellowauto.com.au. They are in Sydney and do a bolt in kit for the TR's. I think the only modification needed for their kit is the prop shaft has to have a new yoke and be shortened.

[jamie hart]

I have a TR3 with a J type overdrive unit from a Triumph Chicane (a local South African version of the 2000). The unit works well but any maintenance is a nightmare as the exhaust pipe prevents one from taking off the small access plate for items such as the filter without jacking up the back of the gearbox.

If you can get an A type unit I would go for that one from this consideration alone.

Good luck!

Jamie Hart

[kiwi-jim]

Thanks guys thats outstanding. i now have a much better appreciation of what to look for.

I have just today talked with a person who says he has a reconditioned box with an Atype overdrive that he would sell so I am just in discussions there at the moment. I'll let you know how it all goes.

Thanks for the advise,

[Rhodri]

Make sure that the o/d is from a TR rather than a Triumph saloon, the speedo drive should point downwards at about 45 degrees , not horizontal. The solenoid should be vertical, not horizontal. This is for the TR4 onwards, presume it is the same for yours.

[kiwi-jim]

we look like we can get this sorted after a fashion.

I have found a TR4A -6 box with A type od from a 4a-6 rebuilt . This should hopefully do the job as I understand it it will just squeeze in. Any thoughts???

[vivdownunder]

Hi Jim,

 

Not quite plain sailing as the 4A-6 cars used a different flywheel to suit a new 8.5" diaphragm clutch, different clutchplate, clutch release bearing and sleeve.

 

At least it's an A type OD, so it's from a car made before January 1973 when the J type OD came in on CF commission TR6's. The back mount should be close, although the all synchro boxes are 1/2" longer, and later ones had a thicker bell housing flange making them longer again. The gearbox cross member mount plate might just need longer elongated holes, but work will be needed to connect up the front.

 

When installed, check there is still sufficient movement in the spline on the tailshaft.

 

I'm not a fan of the diaphragm clutch having had trouble with it on the 5, but later 6 cylinder cars had an improved version with a heavier diaphragm to overcome clutch slip, and at the same time a larger diameter slave cylinder was introduced, if you can get a set of these.

 

If you are still using the TR2 twin master cylinder setup, I cannot recall its clutch master cylinder bore, but the 4A (independent) master cylinder for the diaphragm clutch was 0.70" bore.

 

Another contributor may be able to give you chapter and verse on the parts you need, as I have not swapped a later 4A-6 gearbox into a TR2 , only a 4 box into a 2 which was a snip.

 

Good luck with it... it's bound to have been done before.

 

Viv.

[kiwi-jim]

Thanks Viv I havn't purchased it yet so i'll now try and see what info I can find on the clutch setup for this box. I'm looking at it as an option.

If anyone has any first hand experience please let me know cheers