Marina based differential (internals)

[marlintom]

Hello,

I have been wondering for some time now, and doing some research aswell, but I've not found any "concrete" answer to my question:

What differential internals (crownwheel etc...) will be a swap/fit for a marina casing?
I'm not that worried about the ratio's, more about the options I have of making my roadster driveable again.

Do MG Midget, Triumph Spitfire, GT6 , Vitesse ,Ford Capri,.... internals fit, or is it a total no-go?

Already thanking you in advance for any answer provided

[stevejgreen]

Re: Marina based differential (internals)

All you ever wanted to know about Morris Marina differentials is here or there

You don't say what engine your Roadster has but I am guessing it's a 2.0 Vitesse from previous comments. Then, what gearbox have you got. Overdrive is an absolute blessing in a Roadster, changing the rear axle ratio will impact every gear ratio.

In my opinion, shared by others on this forum, rebuilding a differential is beyond the skill of the average home mechanic. Better to replace the differential centre with a professionally rebuilt one.

[marlintom]

Re: Marina based differential (internals)

Thank you, that was a nice amount of information I just know I will be using someday
It's indeed a 2.0 Vitesse engine, and my gearbox is fitted with an overdrive, so no problems there.

After some careful reading in those files, I am coming to the conclusion that my only options are dolomite's and morris ital/marina's? (correct my if i'm mistaken )

A differential centre swap would indeed be the easiest, and preferred road I can travel, but rebuilding one is within my skill range, although I'dd rather not since I simply cannot spend the amount of time needed
to perform that kind of "surgery" in a single timespan, and stretching that over a couple of days is imho asking for trouble

[listerjp2]

Re: Marina based differential (internals)

An expensive option but another idea

https://shop.quaife.co.uk/catalogsearch/result/?vehicle=4&product_type=11&sub_type=&q=Morris+marina

Adrian

[stevejgreen]

Re: Marina based differential (internals)

An expensive option but another idea

https://shop.quaife.co.uk/catalogsearch/result/?vehicle=4&product_type=11&sub_type=&q=Morris+marina

Adrian

Looking at that, Quaife have decided to re-stock. Last time I spoke to them I was told they were discontinued.
Pricey indeed as you have to also budget for a complete new set of standard gears and the rebuild costs.

The last generation of the Marina design was. 2.0 litre O series, overhead cam, automatic Ital, but it still used the same Marina rear axle. At that point the axle was probably at its power design limit, though early Caterham cars were generating more power so they found all the other limits in the axle.
For general road use, the standard Marina axle should be fine. I believe the biggest problem found today is the fact that some of the oil inside the axle will be 40 years old as it is not fitted with a drain plug, or magnet, so can only be truly cleaned of all metallic debris if the axle is removed from the car.
A Dolomite Sprint axle is a reasonably simple fit and will obviously handle a 2.0 litre power admirably better with it's 3.45 as opposed to 3.63 standard Marina ratio.