5 SPEED BOX

[Iain]

Hi there, 

I'm a sad old bastard who at the age of 65 has decided to relive my classic car obsession with my 4th GT6 ,I had three earlier in the 80's so was given a chance to have my favorite classic car for my retirement by my family so jumped at the chance, Yeah!!!!!

Now I know this is going to be a stupid question but has anyone considered putting a 5 speed box into the MK.3 GT6, lets just throw it out there would  say a TR7 5 speed box fit or is there another option?

Another idea is the Stag engine (as it's ally) the same weight as the GT6 engine and would it fit into the chassis? again with a TR7 box and maybe a modified Stag or TR7 rear axle? 

Wow what a special that would be,

As you have noticed want to keep the special and the idea of the 5 speed box all under the Triumph marque.

I'm Iain and I live in Kent near Junction 4 of the M25,

 

[dougbgt6]

aIain, welcome!

Yes a five speed box has been done, I think a ford box is the preferred option. But, GT6s had overdrive as an optional extra and most here prefer that. Also, if you kook around here there's a thread about "no more MOTs for 40 year old cars" which leads on to how modified your car can be to qualify. Some people with GT6 engines in Spitfires getting nervous. 

http://www.frontlinedevelopments.com/part/gt6-full-5-speed-gearbox-kit-short-remote/

My GT has no overdrive but if some money were to fall into my lap I'd go for it.

Doug

 

 

[Iain]

Hi Doug

yes mine is a non o/d model I was thinking of fitting those really nice looking half shafts as I'm not keen on the rotoflex all my other GT6's had straight shafts.

Do you think getting and O/D box would need a different prop shaft?

[AidanT]

Iain

There are some good specialist suppliers who will refurbish and supply the od  boxes. I had this done about three years ago and it cost around £1250 then. It's well worth the investment imho 

Aidan

Yes it does need a different prop but they are not that expensive

[Iain]

Hi Aiden 

are these specialists around all over or are they local to you?

if I could get an o/d box + O/D would that be better ?

Approx 1250 sound really reasonable

 

Iain

[Pete Lewis]

you only need a replacement mainshaft to convert your existing box to fit an overdrive to it the shafts  prices vary but around 150+ 

avalable from OD spares and most triumph outlets think its  TKC923  

then you just need the OD new mounting  and plates, harness,  relay,  and switch to your choice .inhibitor switch and the gearbox remote cam and switch Brkt. and the short propshaft.

pete

[AidanT]

Hi iain

Pete's right if you can diy 

I used a guy called Mike Papworth. You can google him. Based in Coventry which is a few hours away from me He is highly recommended by most on here 

All depends on what skill level you have and what you want to do yourself 

 

Aidan 

Edited January 20, 2018 by AidanT

[dougbgt6]

Iain,

More to it than just fitting new half shafts

Here is what you've got:

https://www.canleyclassics.com/triumph-gt6-mkiii-road-spring-damper-vertical-link-lower-wishbone-and-radius-arm-fitted-up-to-commission-no-ke/kf20000

And here is what you want:

https://www.canleyclassics.com/triumph-gt6-mkiii-road-spring-and-damper-fitted-from-commission-no-ke/kf20001

Doug

 

[AidanT]

12 minutes ago, dougbgt6 said:

Iain,

More to it than just fitting new half shafts

Here is what you've got:

https://www.canleyclassics.com/triumph-gt6-mkiii-road-spring-damper-vertical-link-lower-wishbone-and-radius-arm-fitted-up-to-commission-no-ke/kf20000

And here is what you want:

https://www.canleyclassics.com/triumph-gt6-mkiii-road-spring-and-damper-fitted-from-commission-no-ke/kf20001

Doug

 

Doug's keeping to standard triumph options here There are other options like cv joint kits. It really depends what you want to end up with.

Aidan 

[Clive]

Having fitted a sprint engine in a spitfire years ago, I would say the Stag engine is a no-go. The sprint was difficult enough, the 2nd head would make things impossible. Nice idea though...I wonder if there is a modern V8 that would fit (Lexus maybe?) but the knock on effect is gearbox, brakes, axles and wheels.

My spitfire has a modern powerplant, somewhere around 180bhp and a 4 cylinder, I think that is in the region of a maximum power the chassis really will cope with. I have Vented discs with the std (but spaced) GT6 calipers at the front, with Rotoflex-the rubber bits suspension at the rear (CV conversion, well worth considering) but I have a Subaru Diff. And yes, a pretty short propshaft.

Now to the nitty gritty. What do you want to use the car for? Many people think they want a fast road spitfire/GT6, but in reality it ruins the car. My spitfire was built to be used as a Tourer and some trackdays, and ticks the boxes, but a lot of thought and planning went into it. We recently bought a fast road MK3 spitfire for my wife. Probably the "ultimate" spec, fully adjustable suspension, CV rotoflex rear, 1300 engine that has been carefully built to make in the region of 110+BHP. However, it isn't a success for what we want....too hard, needs to be "driven" and not as relaxing as we wanted, so at some point it will be sold. But sometimes you need to get a good idea of what you really want from the car.

For my money, a GT6 like yours would benefit from overdrive and maybe a 3.63 diff (yours should be 3.27, that is what it got at the factory but can feel a bit too relaxed) I would also consider CV rear shafts. And If you want improved suspension, I woulod maybe use slightly stronger front springs, and importantly quality shocks (ie Koni). Maybe decent front brake pads, teh white box £10 ones are very wooden in feel, Mintex 1144 are rather superior, but at a price. And then make sure the car is in fine fettle. A Hunter 4 wheel alignment can make a squiffy car handle beautifully (but do any suspension work first) and getting the engine set up correctly can bring a so-so engine back to life (my Toledo went from 72 to 91BHP, was more economical but drove sooo much better with a session on the rolling road)

Anyway,let us have your thoughts and aims....

[thescrapman]

On the subject of the gearboxes, Tony Lindsey Dean has been selling fully rebuilt and upgraded gearboxes for what seems to be a very good price. I got one a few weeks ago.

add a prop and still just under £1k

 

[Gully]

My GT6 was a non OD model from the factory. It now runs OD with a 3.63 diff and CV driveshafts in place of the rotoflex doughnuts. Very happy with the changes - particularly changing the diff from the original 3.27, which made it much more sprightly, but still great for motorway cruising: less frenetic than the 3.89 fitted to factory Mk 3s with OD.

Gully