Gearboxes

[martinclan]

Out of interest, as much as anything else, I would like to find out a bit more (well anything really) about the Marina gearbox.

Presumeably the A series and B series gearboxes are different? But how so?

Are the gearboxes used anywhere else? I seem to remember they shared some of the internals with Triumph?

And I guess that the much more common MGB gearbox is completly different?

Cheers, Robin

[MarinaCoupe]

This is a quick synopsis, others I’m sure will fill in the gaps.
Gearbox casing (known as the single rail gearbox) shared with late Spitfire (Mk4 & 1500), also the inline Toledos and the Dolomite (1300, 1500 & 1850), also early 4 speed TR7s.

The Marina/Ital 1300 version has a 7/8” diameter input shaft, with 20 (I think) splines and a 1/2” spigot. Marina/ Ital 1800/1700 has a 1” input shaft with 23 splines and a 1/2” spigot. 1.3 intermediate ratios vary from the 1800/1700. All the bearings, gaskets etc are the same and are also shared with the Triumph cars. No Marina or Ital left the factory with overdrive, but various Triumphs did. It is only possible to fit O/D to a Marina/Ital by first raising transmission tunnel by about 50mm.

The standard gearboxes are easy enough to work on at home I f you are methodical and organised. The gearbox was derived from the Triumph Herald three rail gearbox and has limits to how much they can be thrashed. 1.3 engined cars can see the gearbox last to 60-70k miles. The 1.7/18 gearboxes 40-50k miles due to the engine torque. Whichever the engine, the more you rag them the quicker they fail.

[JoshWard]

Gearboxes can be usable for much longer. I had a 1.8 with over 100k on the clock and the original gearbox. It was noisy, but it worked. Have had several with 50 - 70k on the clock which have been perfect, and one with 24k on the clock which had broken synchro springs. How it's been treated is more important than mileage.
My J reg has Herald gear ratios so presumably the Marina was in production for a short time before the new gearbox plant was fully operational.

[martinclan]

Thanks both. Useful info.
The reason I asked is that I am intending to add a remote gear lever. It's a in a Marlin and you need gorrila length arms to reach it by default. There's someone that has already done it on a 1.3 engined car and I wanted to know mine was at least similar (1.8)

[MarinaCoupe]

The bellhousing, gearbox casing and tail shaft are exactly the same on a 1.8/1.7 & 1.3. If it fits on a 1.3 it will fit exactly the same on a 1.8/1.7.

It’s an interesting idea, any pictures?

[martinclan]

Here's a link to a picture on the Marlin Owners website.

https://marlinownersclub.com/forum/file ... 1574079087

He has also done something clever to incorporate a lock out for reverse gear to stop it accidentally being selected.

[marlin]

https://marlinownersclub.com/forum/file ... 1508143552

Re: Gear stick upgrade

If you look at the picture of the gearbox you will see a long bolt with a spring on it.

That has replaced the short bolt that held the detent in.

Now when you push over for reverse the detent is pushed out of the way thus negating the need to lift the gearstick over said detent.

The choice of spring is critical as is the length of bolt, a lot of trial and error is required.

The one I have gives just enough resistance to let me know when I am using reverse.

I hope this explains how it works.

Adrian

[MarinaCoupe]

I have tried following your links, firsts I have to create an account and then I get “Invalid File Specified”.

[marlin]

Hopefully you can see this

[KwS]

This is a quick synopsis, others I’m sure will fill in the gaps.
Gearbox casing (known as the single rail gearbox) shared with late Spitfire (Mk4 & 1500), also the inline Toledos and the Dolomite (1300, 1500 & 1850), also early 4 speed TR7s.

The Marina/Ital 1300 version has a 7/8” diameter input shaft, with 20 (I think) splines and a 1/2” spigot. Marina/ Ital 1800/1700 has a 1” input shaft with 23 splines and a 1/2” spigot. 1.3 intermediate ratios vary from the 1800/1700. All the bearings, gaskets etc are the same and are also shared with the Triumph cars. No Marina or Ital left the factory with overdrive, but various Triumphs did. It is only possible to fit O/D to a Marina/Ital by first raising transmission tunnel by about 50mm.

The standard gearboxes are easy enough to work on at home I f you are methodical and organised. The gearbox was derived from the Triumph Herald three rail gearbox and has limits to how much they can be thrashed. 1.3 engined cars can see the gearbox last to 60-70k miles. The 1.7/18 gearboxes 40-50k miles due to the engine torque. Whichever the engine, the more you rag them the quicker they fail.

Heres a question, how does the 1750cc E Series gearbox differ, if it does at all? I presume it's the same as a UK 1.8 box?

[MarinaCoupe]

I don’t know about NZ gearboxes. I guess that if the car was a knock down kit from the UK, then it will be the same as the UK box. If it was an Australian export, you’ll need an Aussie expert to advise.

[locost_bryan]

Pretty sure the gearbox is one of the few components imported from the UK, so should be identical. Think the big adaptor plate on the back of the engine mates to the English bellhousing.